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Titz A, Hoyos R, Ulrich S. Pulmonary vascular diseases at high altitude - is it safe to live in the mountains? Curr Opin Pulm Med 2024; 30:459-463. [PMID: 39036990 PMCID: PMC11343446 DOI: 10.1097/mcp.0000000000001092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/23/2024]
Abstract
PURPOSE OF REVIEW This review addresses the concern of the health effects associated with high-altitude living and chronic hypoxia with a focus on pulmonary hypertension. With an increasing global population residing at high altitudes, understanding these effects is crucial for public health interventions and clinical management. RECENT FINDINGS Recent literature on the long-term effects of high-altitude residence and chronic hypoxia is comprehensively summarized. Key themes include the mechanisms of hypoxic pulmonary vasoconstriction, the development of pulmonary hypertension, and challenges in distinguishing altitude-related pulmonary hypertension and classical pulmonary vascular diseases, as found at a low altitude. SUMMARY The findings emphasize the need for research in high-altitude communities to unravel the risks of pulmonary hypertension and pulmonary vascular diseases. Clinically, early and tailored management for symptomatic individuals residing at high altitudes are crucial, as well as access to advanced therapies as proposed by guidelines for pulmonary vascular disease. Moreover, identifying gaps in knowledge underscores the necessity for continued research to improve understanding and clinical outcomes in high-altitude pulmonary vascular diseases.
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Affiliation(s)
| | | | - Silvia Ulrich
- University Hospital of Zurich
- University of Zurich, Zurich, Switzerland
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2
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Ren H, Zhu YP, Su R, Li H, Pan YY. Hyperbaric intervention ameliorates the negative effects of long-term high-altitude exposure on cognitive control capacity. Front Physiol 2024; 15:1378987. [PMID: 39282090 PMCID: PMC11392845 DOI: 10.3389/fphys.2024.1378987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 08/21/2024] [Indexed: 09/18/2024] Open
Abstract
Introduction Hypoxia due to reduced partial pressure of oxygen from high-altitude exposure affects the cognitive function of high-altitude migrants. Executive function is an important component of human cognitive function, characterized by high oxygen consumption during activity, and its level can be measured using cognitive control capacity (CCC). In addition, there is evidence for the potential value of hyperbaric oxygen (HBO) interventions in improving cognitive decline on the plateau. Therefore, the objective of this study was to investigate the effect of long-term high-altitude exposure on CCC in high-altitude newcomers and whether hyperbaric oxygen intervention has an ameliorative effect. Methods This study measured the magnitude of participants' CCC using a Backward Masking Majority Function Task (MFT-M). Study 1 was a controlled study of different altitude conditions, with 64 participants in the high-altitude newcomer group and 64 participants in the low-altitude resident group, each completing the MFT-M task once. Study 2 was a controlled HBO intervention study in which newcomers who had lived at a high altitude for 2 years were randomly divided into the HBO group (n = 28) and control group (n = 28). 15 times hyperbaric oxygen interventions were performed in the HBO group. Subjects in both groups completed the MFT-M task once before and once after the intervention. Results Study 1 showed that CCC was significantly higher in the low-altitude resident group than in the high-altitude newcomer group (p = 0.031). Study 2 showed that the CCC in the HBO group was significantly higher after 15 hyperbaric interventions than before (p = 0.005), while there was no significant difference in the control group (p = 0.972). The HBO group had significantly higher correct task rates than the control group after the intervention (p = 0.001). Conclusion This study confirms that long-term high-altitude exposure leads to impairment of CCC in high-altitude newcomers and that hyperbaric oxygen intervention is effective in improving CCC.
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Affiliation(s)
- Hong Ren
- Plateau Key Laboratory of High Altitudes Brain Science and Environmental Acclimation, Tibet University, Lhasa, China
| | - Yun-Peng Zhu
- Plateau Key Laboratory of High Altitudes Brain Science and Environmental Acclimation, Tibet University, Lhasa, China
| | - Rui Su
- Plateau Key Laboratory of High Altitudes Brain Science and Environmental Acclimation, Tibet University, Lhasa, China
| | - Hao Li
- Plateau Key Laboratory of High Altitudes Brain Science and Environmental Acclimation, Tibet University, Lhasa, China
| | - Yong-Yue Pan
- School of Medicine, Tibet University, Lhasa, China
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Hilty MP, Siebenmann C, Rasmussen P, Keiser S, Müller A, Lundby C, Maggiorini M. Beta-adrenergic blockade increases pulmonary vascular resistance and causes exaggerated hypoxic pulmonary vasoconstriction at high altitude: a physiological study. EUROPEAN HEART JOURNAL. CARDIOVASCULAR PHARMACOTHERAPY 2024; 10:316-328. [PMID: 38216517 DOI: 10.1093/ehjcvp/pvae004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 10/13/2023] [Accepted: 01/11/2024] [Indexed: 01/14/2024]
Abstract
BACKGROUND An increasing number of hypertensive persons travel to high altitude (HA) while using antihypertensive medications such as beta-blockers. Nevertheless, while hypoxic exposure initiates an increase in pulmonary artery pressure (Ppa) and pulmonary vascular resistance (PVR), the contribution of the autonomic nervous system is unclear. In animals, beta-adrenergic blockade has induced pulmonary vasoconstriction in normoxia and exaggerated hypoxic pulmonary vasoconstriction (HPV) and both effects were abolished by muscarinic blockade. We thus hypothesized that in humans, propranolol (PROP) increases Ppa and PVR in normoxia and exaggerates HPV, and that these effects of PROP are abolished by glycopyrrolate (GLYC). METHODS In seven healthy male lowlanders, Ppa was invasively measured without medication, with PROP and PROP + GLYC, both at sea level (SL, 488 m) and after a 3-week sojourn at 3454 m altitude (HA). Bilateral thigh-cuff release manoeuvres were performed to derive pulmonary pressure-flow relationships and pulmonary vessel distensibility. RESULTS At SL, PROP increased Ppa and PVR from (mean ± SEM) 14 ± 1 to 17 ± 1 mmHg and from 69 ± 8 to 108 ± 11 dyn s cm-5 (21% and 57% increase, P = 0.01 and P < 0.0001). The PVR response to PROP was amplified at HA to 76% (P < 0.0001, P[interaction] = 0.05). At both altitudes, PROP + GLYC abolished the effect of PROP on Ppa and PVR. Pulmonary vessel distensibility decreased from 2.9 ± 0.5 to 1.7 ± 0.2 at HA (P < 0.0001) and to 1.2 ± 0.2 with PROP, and further decreased to 0.9 ± 0.2% mmHg-1 with PROP + GLYC (P = 0.01). CONCLUSIONS Our data show that beta-adrenergic blockade increases, and muscarinic blockade decreases PVR, whereas both increase pulmonary artery elastance. Future studies may confirm potential implications from the finding that beta-adrenergic blockade exaggerates HPV for the management of mountaineers using beta-blockers for prevention or treatment of cardiovascular conditions.
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Affiliation(s)
- Matthias Peter Hilty
- Institute of Intensive Care Medicine, University Hospital of Zurich, ZH 8091, Switzerland
| | - Christoph Siebenmann
- Center for Integrative Human Physiology (ZIHP), Institute of Physiology, University of Zurich, ZH 8091, Switzerland
- Institute of Mountain Emergency Medicine, EURAC Research, Bolzano, TA 39100, Italy
| | - Peter Rasmussen
- Center for Integrative Human Physiology (ZIHP), Institute of Physiology, University of Zurich, ZH 8091, Switzerland
| | - Stefanie Keiser
- Center for Integrative Human Physiology (ZIHP), Institute of Physiology, University of Zurich, ZH 8091, Switzerland
| | - Andrea Müller
- Institute of Intensive Care Medicine, University Hospital of Zurich, ZH 8091, Switzerland
| | - Carsten Lundby
- Center for Integrative Human Physiology (ZIHP), Institute of Physiology, University of Zurich, ZH 8091, Switzerland
- Department of Health and Exercise Physiology, Inland Norway University of Applied Sciences, Lillehammer, OP 2624, Norway
| | - Marco Maggiorini
- Institute of Intensive Care Medicine, University Hospital of Zurich, ZH 8091, Switzerland
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Dartsch RC, Kraut S, Mayer T, Gabel A, Dietrich A, Weissmann N, Fuchs B, Knoepp F. Use of FRET-Sensor 'Mermaid' to Detect Subtle Changes in Membrane Potential of Primary Mouse PASMCs. Cells 2024; 13:1070. [PMID: 38920698 PMCID: PMC11202191 DOI: 10.3390/cells13121070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 06/27/2024] Open
Abstract
Subtle changes in the membrane potential of pulmonary arterial smooth muscle cells (PASMCs) are pivotal for controlling pulmonary vascular tone, e.g., for initiating Hypoxic Pulmonary Vasoconstriction, a vital mechanism of the pulmonary circulation. In our study, we evaluated the ability of the fluorescence resonance energy transfer (FRET)-based voltage-sensor Mermaid to detect such subtle changes in membrane potential. Mouse PASMCs were isolated and transduced with Mermaid-encoding lentiviral vectors before the acceptor/donor emission ratio was assessed via live cell FRET-imaging. Mermaid's sensitivity was tested by applying specific potassium chloride (KCl) concentrations. These KCl concentrations were previously validated by patch clamp recordings to induce depolarization with predefined amplitudes that physiologically occur in PASMCs. Mermaid's emission ratio dose-dependently increased upon depolarization with KCl. However, Mermaid formed unspecific intracellular aggregates, which limited the usefulness of this voltage sensor. When analyzing the membrane rim only to circumvent these unspecific signals, Mermaid was not suitable to resolve subtle changes in the membrane potential of ≤10 mV. In summary, we found Mermaid to be a suitable alternative for reliably detecting qualitative membrane voltage changes of more than 10 mV in primary mouse PASMCs. However, one should be aware of the limitations associated with this voltage sensor.
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Affiliation(s)
- Ruth C. Dartsch
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Simone Kraut
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Tim Mayer
- Walther-Straub-Institute for Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Ludwig-Maximilians University, 80539 Munich, Germany; (T.M.)
| | - Andreas Gabel
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Alexander Dietrich
- Walther-Straub-Institute for Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Ludwig-Maximilians University, 80539 Munich, Germany; (T.M.)
| | - Norbert Weissmann
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Beate Fuchs
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
| | - Fenja Knoepp
- Cardiopulmonary Institute (CPI), Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), Justus-Liebig-University, 35392 Giessen, Germany
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5
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Titz A, Schneider S, Mueller J, Mayer L, Lichtblau M, Ulrich S. Symposium review: high altitude travel with pulmonary vascular disease. J Physiol 2024. [PMID: 38780974 DOI: 10.1113/jp284585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 04/26/2024] [Indexed: 05/25/2024] Open
Abstract
Pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension are the main precapillary forms of pulmonary hypertension (PH) summarized as pulmonary vascular diseases (PVD). PVDs are characterized by exertional dyspnoea and oxygen desaturation, and reduced quality of life and survival. Medical therapies improve life expectancy and physical performance of PVD patients, of whom many wish to participate in professional work and recreational activities including traveling to high altitude. The exposure to the hypobaric hypoxic environment of mountain regions incurs the risk of high altitude adverse events (AEHA) due to severe hypoxaemia exacerbating symptoms and further increase in pulmonary artery pressure, which may lead to right heart decompensation. Recent prospective and randomized trials show that altitude-induced hypoxaemia, pulmonary haemodynamic changes and impairment of exercise performance in PVD patients are in the range found in healthy people. The vast majority of optimally treated stable PVD patients who do not require long-term oxygen therapy at low altitude can tolerate short-term exposure to moderate altitudes up to 2500 m. PVD patients that reveal persistent severe resting hypoxaemia (S p O 2 ${{S}_{{\mathrm{p}}{{{\mathrm{O}}}_{\mathrm{2}}}}}$ <80% for >30 min) at 2500 m respond well to supplemental oxygen therapy. Although there are no accurate predictors for AEHA, PVD patients with unfavourable risk profiles at low altitude, such as higher WHO functional class, lower exercise capacity with more pronounced exercise-induced desaturation and more severely impaired haemodynamics, are at increased risk of AEHA. Therefore, doctors with experience in PVD and high-altitude medicine should counsel PVD patients before any high-altitude sojourn. This review aims to summarize recent literature and clinical recommendations about PVD patients travelling to high altitude.
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Affiliation(s)
- Anna Titz
- University Hospital of Zurich, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | | | | | - Laura Mayer
- University Hospital of Zurich, Zurich, Switzerland
| | | | - Silvia Ulrich
- University Hospital of Zurich, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
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Raberin A, Burtscher J, Citherlet T, Manferdelli G, Krumm B, Bourdillon N, Antero J, Rasica L, Malatesta D, Brocherie F, Burtscher M, Millet GP. Women at Altitude: Sex-Related Physiological Responses to Exercise in Hypoxia. Sports Med 2024; 54:271-287. [PMID: 37902936 PMCID: PMC10933174 DOI: 10.1007/s40279-023-01954-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2023] [Indexed: 11/01/2023]
Abstract
Sex differences in physiological responses to various stressors, including exercise, have been well documented. However, the specific impact of these differences on exposure to hypoxia, both at rest and during exercise, has remained underexplored. Many studies on the physiological responses to hypoxia have either excluded women or included only a limited number without analyzing sex-related differences. To address this gap, this comprehensive review conducted an extensive literature search to examine changes in physiological functions related to oxygen transport and consumption in hypoxic conditions. The review encompasses various aspects, including ventilatory responses, cardiovascular adjustments, hematological alterations, muscle metabolism shifts, and autonomic function modifications. Furthermore, it delves into the influence of sex hormones, which evolve throughout life, encompassing considerations related to the menstrual cycle and menopause. Among these physiological functions, the ventilatory response to exercise emerges as one of the most sex-sensitive factors that may modify reactions to hypoxia. While no significant sex-based differences were observed in cardiac hemodynamic changes during hypoxia, there is evidence of greater vascular reactivity in women, particularly at rest or when combined with exercise. Consequently, a diffusive mechanism appears to be implicated in sex-related variations in responses to hypoxia. Despite well-established sex disparities in hematological parameters, both acute and chronic hematological responses to hypoxia do not seem to differ significantly between sexes. However, it is important to note that these responses are sensitive to fluctuations in sex hormones, and further investigation is needed to elucidate the impact of the menstrual cycle and menopause on physiological responses to hypoxia.
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Affiliation(s)
- Antoine Raberin
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Johannes Burtscher
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Tom Citherlet
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Giorgio Manferdelli
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Bastien Krumm
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Bourdillon
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Juliana Antero
- Institut de Recherche Bio-Médicale Et d'Épidémiologie du Sport (EA 7329), French Institute of Sport, Paris, France
| | - Letizia Rasica
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | - Davide Malatesta
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | - Franck Brocherie
- Laboratory Sport, Expertise and Performance (EA 7370), French Institute of Sport, Paris, France
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, Austria
| | - Grégoire P Millet
- Institute of Sport Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
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Dang ZC, Yang Z, Liu S, Du GM, Jin L, Zhao ZZ. Efficacy of Sildenafil on healthy humans in high‑altitude hypoxia at rest and during exercise: A meta‑analysis. Exp Ther Med 2024; 27:88. [PMID: 38274336 PMCID: PMC10809317 DOI: 10.3892/etm.2024.12376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 10/23/2023] [Indexed: 01/27/2024] Open
Abstract
The current meta-analysis aimed to fully evaluate the efficacy of Sildenafil in healthy humans at different altitudes, focusing on echocardiographic and hemodynamic parameters. Relevant studies were retrieved from the Cochrane, Embase and PubMed databases. Odds ratios (OR) were determined for dichotomous data and weighted mean differences with 95% confidence intervals (CIs) for continuous data. A total of 16 RCTs were included in the current meta-analysis. Short-term treatment with Sildenafil significantly elevated resting heart rate (P<0.01) at altitudes <4,000 meters. No significant differences in heart rate were observed between the Sildenafil and placebo groups at rest and during exercise at an altitude of >4,000 meters (P>0.05). Sildenafil improved resting cardiac output at an altitude of >5,000 meters (P<0.01) and exercising arterial oxygen saturation at <4,000 meters (P<0.01). Sildenafil reduced resting pulmonary artery systolic pressure (PASP) at altitudes >4,000 meters (P<0.01) and exercising PASP at altitudes >5,000 meters (P<0.01). Therefore, Sildenafil efficacy in healthy humans with high-altitude hypoxia is related to altitude and rest or exercise.
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Affiliation(s)
- Zhan-Cui Dang
- Department of Public Health, Medical College, Qinghai University, Xining, Qinghai 810000, P.R. China
| | - Zhiquan Yang
- Department of Rehabilitation, Women and Children's Hospital of Qinghai Province, Xining, Qinghai 810000, P.R. China
| | - Shou Liu
- Department of Public Health, Medical College, Qinghai University, Xining, Qinghai 810000, P.R. China
| | - Guo-Mei Du
- Department of Physical Examination, Qinghai Red Cross Hospital, Xining, Qinghai 810000, P.R. China
| | - Linde Jin
- Department of Cardiology, Qinghai Provincial People's Hospital, Xining, Qinghai 810000, P.R. China
| | - Zhong-Zhi Zhao
- Department of Endemic Disease Control, Qinghai Provincial Institute for Endemic Disease Prevention and Control, Xining, Qinghai 811602, P.R. China
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Stepanek J, Farina JM, Mahmoud AK, Chao CJ, Alsidawi S, Ayoub C, Barry T, Pereyra M, Scalia IG, Abbas MT, Wraith RE, Brown LS, Radavich MS, Curtisi PJ, Hartzendorf PC, Lasota EM, Umetsu KN, Peterson JM, Karlson KE, Breznak K, Fortuin DF, Lester SJ, Arsanjani R. Identifying the Causes of Unexplained Dyspnea at High Altitude Using Normobaric Hypoxia with Echocardiography. J Imaging 2024; 10:38. [PMID: 38392086 PMCID: PMC10889907 DOI: 10.3390/jimaging10020038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 02/24/2024] Open
Abstract
Exposure to high altitude results in hypobaric hypoxia, leading to physiological changes in the cardiovascular system that may result in limiting symptoms, including dyspnea, fatigue, and exercise intolerance. However, it is still unclear why some patients are more susceptible to high-altitude symptoms than others. Hypoxic simulation testing (HST) simulates changes in physiology that occur at a specific altitude by asking the patients to breathe a mixture of gases with decreased oxygen content. This study aimed to determine whether the use of transthoracic echocardiography (TTE) during HST can detect the rise in right-sided pressures and the impact of hypoxia on right ventricle (RV) hemodynamics and right to left shunts, thus revealing the underlying causes of high-altitude signs and symptoms. A retrospective study was performed including consecutive patients with unexplained dyspnea at high altitude. HSTs were performed by administrating reduced FiO2 to simulate altitude levels specific to patients' history. Echocardiography images were obtained at baseline and during hypoxia. The study included 27 patients, with a mean age of 65 years, 14 patients (51.9%) were female. RV systolic pressure increased at peak hypoxia, while RV systolic function declined as shown by a significant decrease in the tricuspid annular plane systolic excursion (TAPSE), the maximum velocity achieved by the lateral tricuspid annulus during systole (S' wave), and the RV free wall longitudinal strain. Additionally, right-to-left shunt was present in 19 (70.4%) patients as identified by bubble contrast injections. Among these, the severity of the shunt increased at peak hypoxia in eight cases (42.1%), and the shunt was only evident during hypoxia in seven patients (36.8%). In conclusion, the use of TTE during HST provides valuable information by revealing the presence of symptomatic, sustained shunts and confirming the decline in RV hemodynamics, thus potentially explaining dyspnea at high altitude. Further studies are needed to establish the optimal clinical role of this physiologic method.
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Affiliation(s)
- Jan Stepanek
- Aerospace Medicine Program, Department of Internal Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Juan M Farina
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Ahmed K Mahmoud
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Chieh-Ju Chao
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Said Alsidawi
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Chadi Ayoub
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Timothy Barry
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Milagros Pereyra
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Isabel G Scalia
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | | | - Rachel E Wraith
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Lisa S Brown
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Michael S Radavich
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Pamela J Curtisi
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | | | - Elizabeth M Lasota
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Kyley N Umetsu
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Jill M Peterson
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Kristin E Karlson
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Karen Breznak
- Aerospace Medicine Program, Department of Internal Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - David F Fortuin
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Steven J Lester
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
| | - Reza Arsanjani
- Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ 85054, USA
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García-Llorca A, Carta F, Supuran CT, Eysteinsson T. Carbonic anhydrase, its inhibitors and vascular function. Front Mol Biosci 2024; 11:1338528. [PMID: 38348465 PMCID: PMC10859760 DOI: 10.3389/fmolb.2024.1338528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 01/03/2024] [Indexed: 02/15/2024] Open
Abstract
It has been known for some time that Carbonic Anhydrase (CA, EC 4.2.1.1) plays a complex role in vascular function, and in the regulation of vascular tone. Clinically employed CA inhibitors (CAIs) are used primarily to lower intraocular pressure in glaucoma, and also to affect retinal blood flow and oxygen saturation. CAIs have been shown to dilate vessels and increase blood flow in both the cerebral and ocular vasculature. Similar effects of CAIs on vascular function have been observed in the liver, brain and kidney, while vessels in abdominal muscle and the stomach are unaffected. Most of the studies on the vascular effects of CAIs have been focused on the cerebral and ocular vasculatures, and in particular the retinal vasculature, where vasodilation of its vessels, after intravenous infusion of sulfonamide-based CAIs can be easily observed and measured from the fundus of the eye. The mechanism by which CAIs exert their effects on the vasculature is still unclear, but the classic sulfonamide-based inhibitors have been found to directly dilate isolated vessel segments when applied to the extracellular fluid. Modification of the structure of CAI compounds affects their efficacy and potency as vasodilators. CAIs of the coumarin type, which generally are less effective in inhibiting the catalytically dominant isoform hCA II and unable to accept NO, have comparable vasodilatory effects as the primary sulfonamides on pre-contracted retinal arteriolar vessel segments, providing insights into which CA isoforms are involved. Alterations of the lipophilicity of CAI compounds affect their potency as vasodilators, and CAIs that are membrane impermeant do not act as vasodilators of isolated vessel segments. Experiments with CAIs, that shed light on the role of CA in the regulation of vascular tone of vessels, will be discussed in this review. The role of CA in vascular function will be discussed, with specific emphasis on findings with the effects of CA inhibitors (CAI).
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Affiliation(s)
- Andrea García-Llorca
- Department of Physiology, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
| | - Fabrizio Carta
- NEUROFARBA Department, Section of Pharmaceutical and Nutraceutical Sciences, University of Florence, Florence, Italy
| | - Claudiu T. Supuran
- NEUROFARBA Department, Section of Pharmaceutical and Nutraceutical Sciences, University of Florence, Florence, Italy
| | - Thor Eysteinsson
- Department of Physiology, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
- Department of Ophthalmology, Faculty of Medicine, University of Iceland, Reykjavik, Iceland
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Yamamoto S, Sakamaki F, Takahashi G, Kondo Y, Taguchi N, Esashi S, Yuji R, Murakami K, Osaragi K, Tomita K, Kamei S, Matsumoto T, Imai Y, Hasebe T. Retracted: Chest digital dynamic radiography to detect changes in human pulmonary perfusion in response to alveolar hypoxia. J Med Radiat Sci 2023; 70:e1-e11. [PMID: 36101943 PMCID: PMC10715373 DOI: 10.1002/jmrs.619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 08/29/2022] [Indexed: 01/04/2023] Open
Abstract
INTRODUCTION Hypoxic pulmonary vasoconstriction optimises oxygenation in the lung by matching the local-blood perfusion to local-ventilation ratio upon exposure to alveolar hypoxia. It plays an important role in various pulmonary diseases, but few imaging evaluations of this phenomenon in humans. This study aimed to determine whether chest digital dynamic radiography could detect hypoxic pulmonary vasoconstriction as changes in pulmonary blood flow in healthy individuals. METHODS Five Asian men underwent chest digital dynamic radiography before and after 60 sec breath-holding at the maximal inspiratory level in upright and supine positions. Alveolar partial pressure of oxygen and atmospheric pressure were calculated using the blood gas test and digital dynamic radiography imaging, respectively. To evaluate the blood flow, the correlation rate of temporal change in each pixel value between the lung fields and left cardiac ventricles was analysed. RESULTS Sixty seconds of breath-holding caused a mean reduction of 26.7 ± 6.4 mmHg in alveolar partial pressure of oxygen. The mean correlation rate of blood flow in the whole lung was significantly lower after than before breath-holding (before, upright 51.5%, supine 52.2%; after, upright 45.5%, supine 46.1%; both P < 0.05). The correlation rate significantly differed before and after breath-holding in the lower lung fields (upright, 11.8% difference; supine, 10.7% difference; both P < 0.05). The mean radiation exposure of each scan was 0.98 ± 0.09 mGy. No complications occurred. CONCLUSIONS Chest digital dynamic radiography could detect the rapid decrease in pulmonary perfusion in response to alveolar hypoxia. It may suggest hypoxic pulmonary vasoconstriction in healthy individuals.
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Affiliation(s)
- Shota Yamamoto
- Department of RadiologyTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Fumio Sakamaki
- Department of Respiratory MedicineTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Genki Takahashi
- Department of Respiratory MedicineTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Yusuke Kondo
- Department of Respiratory MedicineTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Naoya Taguchi
- Department of Radiological TechnologyTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Shogo Esashi
- Department of Radiological TechnologyTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Ryotaro Yuji
- Department of Radiological TechnologyTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Katsuki Murakami
- Department of Radiological TechnologyTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Kensuke Osaragi
- Department of RadiologyKochi University, Kochi Medical SchoolNankokuKochiJapan
| | - Kosuke Tomita
- Department of RadiologyTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Shunsuke Kamei
- Department of RadiologyTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Tomohiro Matsumoto
- Department of RadiologyKochi University, Kochi Medical SchoolNankokuKochiJapan
| | - Yutaka Imai
- Department of RadiologyTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
| | - Terumitsu Hasebe
- Department of RadiologyTokai University Hachioji Hospital, Tokai University School of MedicineTokyoJapan
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11
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Raberin A, Burtscher J, Burtscher M, Millet GP. Hypoxia and the Aging Cardiovascular System. Aging Dis 2023; 14:2051-2070. [PMID: 37199587 PMCID: PMC10676797 DOI: 10.14336/ad.2023.0424] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 04/24/2023] [Indexed: 05/19/2023] Open
Abstract
Older individuals represent a growing population, in industrialized countries, particularly those with cardiovascular diseases, which remain the leading cause of death in western societies. Aging constitutes one of the largest risks for cardiovascular diseases. On the other hand, oxygen consumption is the foundation of cardiorespiratory fitness, which in turn is linearly related to mortality, quality of life and numerous morbidities. Therefore, hypoxia is a stressor that induces beneficial or harmful adaptations, depending on the dose. While severe hypoxia can exert detrimental effects, such as high-altitude illnesses, moderate and controlled oxygen exposure can potentially be used therapeutically. It can improve numerous pathological conditions, including vascular abnormalities, and potentially slows down the progression of various age-related disorders. Hypoxia can exert beneficial effects on inflammation, oxidative stress, mitochondrial functions, and cell survival, which are all increased with age and have been discussed as main promotors of aging. This narrative review discusses specificities of the aging cardiovascular system in hypoxia. It draws upon an extensive literature search on the effects of hypoxia/altitude interventions (acute, prolonged, or intermittent exposure) on the cardiovascular system in older individuals (over 50 years old). Special attention is directed toward the use of hypoxia exposure to improve cardiovascular health in older individuals.
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Affiliation(s)
- Antoine Raberin
- Institute of Sport Sciences, University of Lausanne, CH-1015, Lausanne, Switzerland.
| | - Johannes Burtscher
- Institute of Sport Sciences, University of Lausanne, CH-1015, Lausanne, Switzerland.
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, A-6020, Austria.
| | - Grégoire P. Millet
- Institute of Sport Sciences, University of Lausanne, CH-1015, Lausanne, Switzerland.
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12
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Hopkins SR, Stickland MK. The Pulmonary Vasculature. Semin Respir Crit Care Med 2023; 44:538-554. [PMID: 37816344 PMCID: PMC11192587 DOI: 10.1055/s-0043-1770059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
The pulmonary circulation is a low-pressure, low-resistance circuit whose primary function is to deliver deoxygenated blood to, and oxygenated blood from, the pulmonary capillary bed enabling gas exchange. The distribution of pulmonary blood flow is regulated by several factors including effects of vascular branching structure, large-scale forces related to gravity, and finer scale factors related to local control. Hypoxic pulmonary vasoconstriction is one such important regulatory mechanism. In the face of local hypoxia, vascular smooth muscle constriction of precapillary arterioles increases local resistance by up to 250%. This has the effect of diverting blood toward better oxygenated regions of the lung and optimizing ventilation-perfusion matching. However, in the face of global hypoxia, the net effect is an increase in pulmonary arterial pressure and vascular resistance. Pulmonary vascular resistance describes the flow-resistive properties of the pulmonary circulation and arises from both precapillary and postcapillary resistances. The pulmonary circulation is also distensible in response to an increase in transmural pressure and this distention, in addition to recruitment, moderates pulmonary arterial pressure and vascular resistance. This article reviews the physiology of the pulmonary vasculature and briefly discusses how this physiology is altered by common circumstances.
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Affiliation(s)
- Susan R. Hopkins
- Department of Radiology, University of California, San Diego, California
| | - Michael K. Stickland
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta
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13
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Abstract
With ascent to high altitude, barometric pressure declines, leading to a reduction in the partial pressure of oxygen at every point along the oxygen transport chain from the ambient air to tissue mitochondria. This leads, in turn, to a series of changes over varying time frames across multiple organ systems that serve to maintain tissue oxygen delivery at levels sufficient to prevent acute altitude illness and preserve cognitive and locomotor function. This review focuses primarily on the physiological adjustments and acclimatization processes that occur in the lungs of healthy individuals, including alterations in control of breathing, ventilation, gas exchange, lung mechanics and dynamics, and pulmonary vascular physiology. Because other organ systems, including the cardiovascular, hematologic and renal systems, contribute to acclimatization, the responses seen in these systems, as well as changes in common activities such as sleep and exercise, are also addressed. While the pattern of the responses highlighted in this review are similar across individuals, the magnitude of such responses often demonstrates significant interindividual variability which accounts for subsequent differences in tolerance of the low oxygen conditions in this environment.
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Affiliation(s)
- Marc Moritz Berger
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Andrew M Luks
- Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Seattle, Washington
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14
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Kizhakke Puliyakote AS, Prisk GK, Elliott AR, Kim NH, Pazar B, Sá RC, Asadi AK, Hopkins SR. The spatial-temporal dynamics of pulmonary blood flow are altered in pulmonary arterial hypertension. J Appl Physiol (1985) 2023; 134:969-979. [PMID: 36861672 PMCID: PMC10085549 DOI: 10.1152/japplphysiol.00463.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 02/16/2023] [Accepted: 02/27/2023] [Indexed: 03/03/2023] Open
Abstract
Global fluctuation dispersion (FDglobal), a spatial-temporal metric derived from serial images of the pulmonary perfusion obtained with MRI-arterial spin labeling, describes temporal fluctuations in the spatial distribution of perfusion. In healthy subjects, FDglobal is increased by hyperoxia, hypoxia, and inhaled nitric oxide. We evaluated patients with pulmonary arterial hypertension (PAH, 4F, aged 47 ± 15, mean pulmonary artery pressure 48 ± 7 mmHg) and healthy controls (CON, 7F, aged 47 ± 12) to test the hypothesis that FDglobal is increased in PAH. Images were acquired at ∼4-5 s intervals during voluntary respiratory gating, inspected for quality, registered using a deformable registration algorithm, and normalized. Spatial relative dispersion (RD = SD/mean) and the percent of the lung image with no measurable perfusion signal (%NMP) were also assessed. FDglobal was significantly increased in PAH (PAH = 0.40 ± 0.17, CON = 0.17 ± 0.02, P = 0.006, a 135% increase) with no overlap in values between the two groups, consistent with altered vascular regulation. Both spatial RD and %NMP were also markedly greater in PAH vs. CON (PAH RD = 1.46 ± 0.24, CON = 0.90 ± 0.10, P = 0.0004; PAH NMP = 13.4 ± 6.1%; CON = 2.3 ± 1.4%, P = 0.001 respectively) consistent with vascular remodeling resulting in poorly perfused regions of lung and increased spatial heterogeneity. The difference in FDglobal between normal subjects and patients with PAH in this small cohort suggests that spatial-temporal imaging of perfusion may be useful in the evaluation of patients with PAH. Since this MR imaging technique uses no injected contrast agents and has no ionizing radiation it may be suitable for use in diverse patient populations.NEW & NOTEWORTHY Using proton MRI-arterial spin labeling to obtain serial images of pulmonary perfusion, we show that global fluctuation dispersion (FDglobal), a metric of temporal fluctuations in the spatial distribution of perfusion, was significantly increased in female patients with pulmonary arterial hypertension (PAH) compared with healthy controls. This potentially indicates pulmonary vascular dysregulation. Dynamic measures using proton MRI may provide new tools for evaluating individuals at risk of PAH or for monitoring therapy in patients with PAH.
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Affiliation(s)
- Abhilash S Kizhakke Puliyakote
- Pulmonary Imaging Laboratory, UC San Diego Health Sciences, San Diego, California, United States
- Department of Radiology, University of California, San Diego, California, United States
| | - G Kim Prisk
- Department of Radiology, University of California, San Diego, California, United States
- Department of Medicine, University of California, San Diego, California, United States
| | - Ann R Elliott
- Pulmonary Imaging Laboratory, UC San Diego Health Sciences, San Diego, California, United States
- Department of Medicine, University of California, San Diego, California, United States
| | - Nick H Kim
- Department of Medicine, University of California, San Diego, California, United States
| | - Beni Pazar
- Pulmonary Imaging Laboratory, UC San Diego Health Sciences, San Diego, California, United States
- Department of Radiology, University of California, San Diego, California, United States
| | - Rui Carlos Sá
- Pulmonary Imaging Laboratory, UC San Diego Health Sciences, San Diego, California, United States
- Department of Medicine, University of California, San Diego, California, United States
| | - Amran K Asadi
- Pulmonary Imaging Laboratory, UC San Diego Health Sciences, San Diego, California, United States
- Department of Radiology, University of California, San Diego, California, United States
| | - Susan R Hopkins
- Pulmonary Imaging Laboratory, UC San Diego Health Sciences, San Diego, California, United States
- Department of Radiology, University of California, San Diego, California, United States
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15
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Doherty CJ, Chang JC, Thompson BP, Swenson ER, Foster GE, Dominelli PB. The Impact of Acetazolamide and Methazolamide on Exercise Performance in Normoxia and Hypoxia. High Alt Med Biol 2023; 24:7-18. [PMID: 36802203 DOI: 10.1089/ham.2022.0134] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Doherty, Connor J., Jou-Chung Chang, Benjamin P. Thompson, Erik R. Swenson, Glen E. Foster, and Paolo B. Dominelli. The impact of acetazolamide and methazolamide on exercise performance in normoxia and hypoxia. High Alt Med Biol. 24:7-18, 2023.-Carbonic anhydrase (CA) inhibitors are commonly prescribed for acute mountain sickness (AMS). In this review, we sought to examine how two CA inhibitors, acetazolamide (AZ) and methazolamide (MZ), affect exercise performance in normoxia and hypoxia. First, we briefly describe the role of CA inhibition in facilitating the increase in ventilation and arterial oxygenation in preventing and treating AMS. Next, we detail how AZ affects exercise performance in normoxia and hypoxia and this is followed by a discussion on MZ. We emphasize that the overarching focus of the review is how the two drugs potentially affect exercise performance, rather than their ability to prevent/treat AMS per se, their interrelationship will be discussed. Overall, we suggest that AZ hinders exercise performance in normoxia, but may be beneficial in hypoxia. Based upon head-to-head studies of AZ and MZ in humans on diaphragmatic and locomotor strength in normoxia, MZ may be a better CA inhibitor when exercise performance is crucial at high altitude.
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Affiliation(s)
- Connor J Doherty
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Jou-Chung Chang
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Benjamin P Thompson
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
| | - Erik R Swenson
- Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Washington, USA
- Medical Service, VA Puget Sound Health Care System, Seattle, Washington, USA
| | - Glen E Foster
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Paolo B Dominelli
- Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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16
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Bauer M, Müller J, Schneider SR, Buenzli S, Furian M, Ulrich T, Carta AF, Bader PR, Lichtblau M, Taalaibekova A, Raimberdiev M, Champigneulle B, Sooronbaev T, Bloch KE, Ulrich S. Hypoxia-altitude simulation test to predict altitude-related adverse health effects in COPD patients. ERJ Open Res 2023; 9:00488-2022. [PMID: 36923563 PMCID: PMC10009702 DOI: 10.1183/23120541.00488-2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/09/2022] [Indexed: 12/24/2022] Open
Abstract
Background/aims Amongst numerous travellers to high altitude (HA) are many with the highly prevalent COPD, who are at particular risk for altitude-related adverse health effects (ARAHE). We then investigated the hypoxia-altitude simulation test (HAST) to predict ARAHE in COPD patients travelling to altitude. Methods This prospective diagnostic accuracy study included 75 COPD patients: 40 women, age 58±9 years, forced expiratory volume in 1 s (FEV1) 40-80% pred, oxygen saturation measured by pulse oximetry (S pO2 ) ≥92% and arterial carbon dioxide tension (P aCO2 ) <6 kPa. Patients underwent baseline evaluation and HAST, breathing normobaric hypoxic air (inspiratory oxygen fraction (F IO2 ) of 15%) for 15 min, at low altitude (760 m). Cut-off values for a positive HAST were set according to British Thoracic Society (BTS) guidelines (arterial oxygen tension (P aO2 ) <6.6 kPa and/or S pO2 <85%). The following day, patients travelled to HA (3100 m) for two overnight stays where ARAHE development including acute mountain sickness (AMS), Lake Louise Score ≥4 and/or AMS score ≥0.7, severe hypoxaemia (S pO2 <80% for >30 min or 75% for >15 min) or intercurrent illness was observed. Results ARAHE occurred in 50 (66%) patients and 23 out of 75 (31%) were positive on HAST according to S pO2 , and 11 out of 64 (17%) according to P aO2 . For S pO2 /P aO2 we report a sensitivity of 46/25%, specificity of 84/95%, positive predictive value of 85/92% and negative predictive value of 44/37%. Conclusion In COPD patients ascending to HA, ARAHE are common. Despite an acceptable positive predictive value of the HAST to predict ARAHE, its clinical use is limited by its insufficient sensitivity and overall accuracy. Counselling COPD patients before altitude travel remains challenging and best focuses on early recognition and treatment of ARAHE with oxygen and descent.
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Affiliation(s)
- Meret Bauer
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Julian Müller
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Simon R. Schneider
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Simone Buenzli
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Michael Furian
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Tanja Ulrich
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Arcangelo F. Carta
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Patrick R. Bader
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Mona Lichtblau
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Ajian Taalaibekova
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
- National Center for Cardiology and Internal Medicine, Bishkek, Kyrgyz Republic
| | - Madiiar Raimberdiev
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
- National Center for Cardiology and Internal Medicine, Bishkek, Kyrgyz Republic
| | - Benoit Champigneulle
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
- HP2 Laboratory, Inserm U1300, Grenoble Alpes University, CHU Grenoble Alpes, Grenoble, France
| | - Talant Sooronbaev
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
- National Center for Cardiology and Internal Medicine, Bishkek, Kyrgyz Republic
| | - Konrad E. Bloch
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
| | - Silvia Ulrich
- University of Zurich and University Hospital of Zurich, Clinic of Pulmonology, University Hospital Zurich, Zurich, Switzerland
- Swiss-Kyrgyz High Altitude Medicine and Research Initiative, Zurich, Switzerland, and Bishkek, Kyrgyz Republic
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Mallet RT, Burtscher J, Pialoux V, Pasha Q, Ahmad Y, Millet GP, Burtscher M. Molecular Mechanisms of High-Altitude Acclimatization. Int J Mol Sci 2023; 24:ijms24021698. [PMID: 36675214 PMCID: PMC9866500 DOI: 10.3390/ijms24021698] [Citation(s) in RCA: 35] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/17/2023] Open
Abstract
High-altitude illnesses (HAIs) result from acute exposure to high altitude/hypoxia. Numerous molecular mechanisms affect appropriate acclimatization to hypobaric and/or normobaric hypoxia and curtail the development of HAIs. The understanding of these mechanisms is essential to optimize hypoxic acclimatization for efficient prophylaxis and treatment of HAIs. This review aims to link outcomes of molecular mechanisms to either adverse effects of acute high-altitude/hypoxia exposure or the developing tolerance with acclimatization. After summarizing systemic physiological responses to acute high-altitude exposure, the associated acclimatization, and the epidemiology and pathophysiology of various HAIs, the article focuses on molecular adjustments and maladjustments during acute exposure and acclimatization to high altitude/hypoxia. Pivotal modifying mechanisms include molecular responses orchestrated by transcription factors, most notably hypoxia inducible factors, and reciprocal effects on mitochondrial functions and REDOX homeostasis. In addition, discussed are genetic factors and the resultant proteomic profiles determining these hypoxia-modifying mechanisms culminating in successful high-altitude acclimatization. Lastly, the article discusses practical considerations related to the molecular aspects of acclimatization and altitude training strategies.
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Affiliation(s)
- Robert T. Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Johannes Burtscher
- Department of Biomedical Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
- Institute of Sport Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
| | - Vincent Pialoux
- Inter-University Laboratory of Human Movement Biology EA7424, University Claude Bernard Lyon 1, University of Lyon, FR-69008 Lyon, France
| | - Qadar Pasha
- Institute of Hypoxia Research, New Delhi 110067, India
| | - Yasmin Ahmad
- Defense Institute of Physiology & Allied Sciences (DIPAS), Defense Research & Development Organization(DRDO), New Delhi 110054, India
| | - Grégoire P. Millet
- Department of Biomedical Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
- Institute of Sport Sciences, University of Lausanne, CH-1005 Lausanne, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, A-6020 Innsbruck, Austria
- Austrian Society for Alpine and High-Altitude Medicine, A-6020 Innsbruck, Austria
- Correspondence:
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18
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Subedi P, Gasho C, Stembridge M, Williams AM, Patrician A, Ainslie PN, Anholm JD. Pulmonary vascular reactivity to supplemental oxygen in Sherpa and lowlanders during gradual ascent to high altitude. Exp Physiol 2023; 108:111-122. [PMID: 36404588 PMCID: PMC10103769 DOI: 10.1113/ep090458] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 10/18/2022] [Indexed: 11/23/2022]
Abstract
NEW FINDINGS What is the central question of this study? How does hypoxic pulmonary vasoconstriction and the response to supplemental oxygen change over time at high altitude? What is the main finding and its importance? Lowlanders and partially de-acclimatized Sherpa both demonstrated pulmonary vascular responsiveness to supplemental oxygen that was maintained for 12 days' exposure to progressively increasing altitude. An additional 2 weeks' acclimatization at 5050 m altitude rendered the pulmonary vasculature minimally responsive to oxygen similar to the fully acclimatized non-ascent Sherpa. Additional hypoxic exposure at that time point did not augment hypoxic pulmonary vasoconstriction. ABSTRACT Prolonged alveolar hypoxia leads to pulmonary vascular remodelling. We examined the time course at altitude, over which hypoxic pulmonary vasoconstriction goes from being acutely reversible to potentially irreversible. Study subjects were lowlanders (n = 20) and two Sherpa groups. All Sherpa were born and raised at altitude. One group (ascent Sherpa, n = 11) left altitude and after de-acclimatization in Kathmandu for ∼7 days re-ascended with the lowlanders over 8-10 days to 5050 m. The second Sherpa group (non-ascent Sherpa, n = 12) remained continuously at altitude. Pulmonary artery systolic pressure (PASP) and pulmonary vascular resistance (PVR) were measured while breathing ambient air and following supplemental oxygen. During ascent PASP and PVR increased in lowlanders and ascent Sherpa; however, with supplemental oxygen, lowlanders had significantly greater decrease in PASP (P = 0.02) and PVR (P = 0.02). After ∼14 days at 5050 m, PASP decreased with supplemental oxygen (mean decrease: 3.9 mmHg, 95% CI 2.1-5.7 mmHg, P < 0.001); however, PVR was unchanged (P = 0.49). In conclusion, PASP and PVR increased with gradual ascent to altitude and decreased via oxygen supplementation in both lowlanders and ascent Sherpa. Following ∼14 days at 5050 m altitude, there was no change in PVR to hypoxia or O2 supplementation in lowlanders or either Sherpa group. These data show that both duration of exposure and residential altitude influence the pulmonary vascular responses to hypoxia.
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Affiliation(s)
- Prajan Subedi
- Division of PulmonaryCritical Care, Sleep, Hyperbaric Medicine and AllergyDept. of MedicineLoma Linda University School of MedicinePulmonary SectionVA Loma Linda Healthcare SystemLoma LindaCaliforniaUSA
| | - Christopher Gasho
- Division of PulmonaryCritical Care, Sleep, Hyperbaric Medicine and AllergyDept. of MedicineLoma Linda University School of MedicinePulmonary SectionVA Loma Linda Healthcare SystemLoma LindaCaliforniaUSA
| | - Michael Stembridge
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
| | - Alexandra M. Williams
- Department of Cellular and Physiological SciencesFaculty of MedicineUniversity of British ColumbiaVancouverBCCanada
| | - Alexander Patrician
- Centre for Heart, Lung and Vascular HealthFaculty of Health and Social DevelopmentUniversity of British Columbia – OkanaganKelownaBCCanada
| | - Philip N. Ainslie
- Centre for Heart, Lung and Vascular HealthFaculty of Health and Social DevelopmentUniversity of British Columbia – OkanaganKelownaBCCanada
| | - James D. Anholm
- Division of PulmonaryCritical Care, Sleep, Hyperbaric Medicine and AllergyDept. of MedicineLoma Linda University School of MedicinePulmonary SectionVA Loma Linda Healthcare SystemLoma LindaCaliforniaUSA
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Mean corpuscular haemoglobin concentration (MCHC): a new biomarker for high-altitude pulmonary edema in the Ecuadorian Andes. Sci Rep 2022; 12:20740. [PMID: 36456626 PMCID: PMC9715691 DOI: 10.1038/s41598-022-25040-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/23/2022] [Indexed: 12/05/2022] Open
Abstract
Ascent to high altitude (> 3000 m height above sea level or m.a.s.l) exposes people to hypobaric atmospheric pressure and hypoxemia, which provokes mountain sickness and whose symptoms vary from the mild acute mountain sickness to the life-threatening, high-altitude pulmonary edema (HAPE). This study analysed the risk factors underlying HAPE in dwellers and travellers of the Ecuadorian Andes after sojourning over 3000 m height. A group of HAPE patients (N = 58) was compared to a NO HAPE group (N = 713), through demographic (ethnicity, sex, and age), red blood cell parameters (erythrocytes counts, hematocrit, median corpuscular volume, median corpuscular haemoglobin, and median corpuscular haemoglobin concentration (MCHC)), altitude (threshold: 3000 m.a.s.l.), and health status (vital signs) variables. Analysis of Deviance for Generalised Linear Model Fits (logit regression) revealed patterns of significant associations. High-altitude dwellers, particularly children and elder people, were HAPE-prone, while women were more tolerant of HAPE than men. Interestingly, HAPE prevalence was strongly related to an increment of MCH. The residence at middle altitude was inversely related to the odds of suffering HAPE. Ethnicity did not have a significant influence in HAPE susceptibility. Elevated MCHC emerges like a blood adaptation of Andean highlanders to high altitude and biomarker of HAPE risk.
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20
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Wang Y, Gong C, Yu F, Zhang Q. Effect of dexmedetomidine on intrapulmonary shunt in patients with sevoflurane maintained during one-lung ventilation: A case-control study. Medicine (Baltimore) 2022; 101:e31818. [PMID: 36401465 PMCID: PMC9678591 DOI: 10.1097/md.0000000000031818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND The effects of dexmedetomidine on the circulatory system are complex. It is difficult to predict its effects on intrapulmonary shunts and hypoxic pulmonary vasoconstriction in patients with one-lung ventilation. This study aimed to investigate the effect of dexmedetomidine on intrapulmonary shunt in patients with sevoflurane during one-lung ventilation. METHODS Forty patients requiring thoracoscopic lobectomy were randomly divided into the dexmedetomidine group (Group D, n = 20) and the normal saline group (Group N, n = 20). The arterial partial pressure of oxygen (PaO2), pulmonary shunt fraction (Qs/Qt), mean end-tidal sevoflurane concentration, mean arterial pressure, and heart rate were compared between the 2 groups at 3 time points: (i) after 5 minutes of two-lung ventilation (T0), (ii) after 30 minutes of one-lung ventilation (OLV) (T1), and (iii) after 45 minutes of OLV (T2). The dosage of sevoflurane from the beginning of OLV to T2 was calculated. RESULTS There were no significant differences in age, body mass index, and FEV1/FVC between Groups D and N (P > .05). At T0, T1, and T2, the PaO2 levels of Group D and Group N were similar (P > .05), and the PaO2 levels of Group D and Group N decreased after OLV. The Qs/Qt level of Groups D and N were similar at T0 (P > .05), and the level of Groups D and N at T1 and T2 was higher than that at T0. The Qs/Qt of Group D was statistically significantly lower than that of Group N at T1 and T2 (P < .05). CONCLUSION Compared with the control group, we found that dexmedetomidine can reduce the intrapulmonary shunt fraction and improve the body's status during OLV.
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Affiliation(s)
- Yewen Wang
- Department of Anesthesiology, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Chunzhi Gong
- Department of Anesthesiology, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Fei Yu
- Department of Anesthesiology, Binzhou Medical University Hospital, Binzhou, Shandong, China
| | - Quanyi Zhang
- Department of Anesthesiology, Binzhou Medical University Hospital, Binzhou, Shandong, China
- * Correspondence: Quanyi Zhang, Department of Anesthesiology, Binzhou Medical University Hospital, No. 661 Huanghe 2nd Road, Binzhou 256603, Shandong, China (e-mail: )
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21
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Rieger MG, Tallon CM, Perkins DR, Smith KJ, Stembridge M, Piombo S, Radom-Aizik S, Cooper DM, Ainslie PN, McManus AM. Cardiopulmonary and cerebrovascular acclimatization in children and adults at 3800 m. J Physiol 2022; 600:4849-4863. [PMID: 36165275 DOI: 10.1113/jp283419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 09/20/2022] [Indexed: 12/24/2022] Open
Abstract
Maturational differences exist in cardiopulmonary and cerebrovascular function at sea-level, but the impact of maturation on acclimatization responses to high altitude is unknown. Ten children (9.8 ± 2.5 years) and 10 adults (34.7 ± 7.1 years) were assessed at sea-level (BL), 3000 m and twice over 4 days at 3800 m (B1, B4). Measurements included minute ventilation ( V ̇ E ${\dot{V}}_{\rm{E}}$ ), end-tidal partial pressures of oxygen ( P ETO 2 ${P}_{{\rm{ETO}}_{\rm{2}}}$ ) and carbon dioxide, echocardiographic assessment of pulmonary artery systolic pressure (PASP) and stroke volume (SV) and ultrasound assessment of blood flow through the internal carotid and vertebral arteries was performed to calculate global cerebral blood flow (gCBF). At 3000 m, V ̇ E ${\dot{V}}_{\rm{E}}$ was increased from BL by 19.6 ± 19.1% (P = 0.031) in children, but not in adults (P = 0.835); SV was reduced in children (-11 ± 13%, P = 0.020) but not adults (P = 0.827), which was compensated for by a larger increase in heart rate in children (+26 beats min-1 vs. +13 beats min-1 , P = 0.019). Between B1 and B4, adults increased V ̇ E ${\dot{V}}_{\rm{E}}$ by 38.5 ± 34.7% (P = 0.006), while V ̇ E ${\dot{V}}_{\rm{E}}$ did not increase further in children. The rise in PASP was not different between groups; however, ∆PASP from BL was related to ∆ P ETO 2 ${P}_{{\rm{ETO}}_{\rm{2}}}$ in adults (R2 = 0.288, P = 0.022), but not children. At BL, gCBF was 43% higher in children than adults (P = 0.017), and this difference was maintained at high altitude, with a similar pattern and magnitude of change in gCBF between groups (P = 0.845). Despite V ̇ E ${\dot{V}}_{\rm{E}}$ increasing in children but not adults at a lower altitude, the pulmonary vascular and cerebrovascular responses to prolonged hypoxia are similar between children and adults. KEY POINTS: Children have different ventilatory and metabolic requirements from adults, which may present differently in the pulmonary and cerebral vasculature upon ascent to high altitude. Children (ages 7-14) and adults (ages 23-44) were brought from sea level to high altitude (3000 to 3800 m) and changes in ventilation, pulmonary artery systolic pressure (PASP) and cerebral blood flow (CBF) were assessed over 1 week. Significant increases in ventilation and decreases in left ventricle stroke volume were observed at a lower altitude in children than adults. PASP and CBF increased by a similar relative amount between children and adults at 3800 m. These results help us better understand age-related differences in compensatory responses to prolonged hypoxia in children, despite similar changes in pulmonary artery pressure and CBF between children and adults.
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Affiliation(s)
- M G Rieger
- Centre for Heart, Lung & Vascular Health, University of British Columbia, Kelowna, British Columbia, Canada
| | - C M Tallon
- Centre for Heart, Lung & Vascular Health, University of British Columbia, Kelowna, British Columbia, Canada
| | - D R Perkins
- Cardiff School of Sport & Health Sciences, Cardiff Metropolitan University, Cardiff, UK.,Youth Physical Development Centre, Cardiff School of Sport & Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - K J Smith
- Cerebrovascular Health, Exercise, and Environmental Research Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - M Stembridge
- Cardiff School of Sport & Health Sciences, Cardiff Metropolitan University, Cardiff, UK.,Youth Physical Development Centre, Cardiff School of Sport & Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - S Piombo
- Pediatric Exercise and Genomics Research Center, University of California Irvine School of Medicine, Irvine, CA, USA
| | - S Radom-Aizik
- Pediatric Exercise and Genomics Research Center, University of California Irvine School of Medicine, Irvine, CA, USA
| | - D M Cooper
- Pediatric Exercise and Genomics Research Center, University of California Irvine School of Medicine, Irvine, CA, USA
| | - P N Ainslie
- Centre for Heart, Lung & Vascular Health, University of British Columbia, Kelowna, British Columbia, Canada
| | - A M McManus
- Centre for Heart, Lung & Vascular Health, University of British Columbia, Kelowna, British Columbia, Canada
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22
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Seeley AD, Caldwell AR, Cahalin LP, Ahn S, Perry AC, Arwari B, Jacobs KA. Seven days of ischemic preconditioning augments hypoxic exercise ventilation and muscle oxygenation in recreationally trained males. Am J Physiol Regul Integr Comp Physiol 2022; 323:R457-R466. [PMID: 35968897 PMCID: PMC9529270 DOI: 10.1152/ajpregu.00335.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/22/2022]
Abstract
This investigation sought to assess whether single or repeated bouts of ischemic preconditioning (IPC) could improve oxyhemoglobin saturation ([Formula: see text]) and/or attenuate reductions in muscle tissue saturation index (TSI) during submaximal hypoxic exercise. Fifteen healthy young men completed submaximal graded exercise under four experimental conditions: 1) normoxia (NORM), 2) hypoxia (HYP) [oxygen fraction of inspired air ([Formula: see text]) = 0.14, ∼3,200 m], 3) hypoxia preceded by a single session of IPC (IPC1-HYP), and 4) hypoxia preceded by seven sessions of IPC, one a day for 7 consecutive days (IPC7-HYP). IPC7-HYP heightened minute ventilation (V̇e) at 80% HYP peak cycling power output (Wpeak) (+10.47 ± 3.35 L·min-1, P = 0.006), compared with HYP, as a function of increased breathing frequency. Both IPC1-HYP (+0.17 ± 0.04 L·min-1, P < 0.001) and IPC7-HYP (+0.16 ± 0.04 L·min-1, P < 0.001) elicited greater oxygen consumption (V̇o2) across exercise intensities compared with NORM, whereas V̇o2 was unchanged with HYP alone. [Formula: see text] was unchanged by either IPC condition at any exercise intensity, yet the reduction of muscle TSI during resting hypoxic exposure was attenuated by IPC7-HYP (+9.9 ± 3.6%, P = 0.040) compared with HYP, likely as a function of reduced local oxygen extraction. Considering all exercise intensities, IPC7-HYP attenuated reductions of TSI with HYP (+6.4 ± 1.8%, P = 0.001). Seven days of IPC heightens ventilation, posing a threat to ventilatory efficiency, during high-intensity submaximal hypoxic exercise and attenuates reductions in hypoxic resting and exercise muscle oxygenation in healthy young men. A single session of IPC may be capable of modulating hypoxic ventilation; however, our present population was unable to demonstrate this with certainty.
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Affiliation(s)
- Afton D Seeley
- Department of Kinesiology and Sport Sciences, School of Education and Human Development, University of Miami, Coral Gables, Florida
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
- Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee
| | - Aaron R Caldwell
- Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts
- Oak Ridge Institute of Science and Education, Oak Ridge, Tennessee
| | - Lawrence P Cahalin
- Department of Physical Therapy, University of Miami Miller School of Medicine, Coral Gables, Florida
| | - Soyeon Ahn
- Department of Educational and Psychological Studies, School of Education and Human Development, University of Miami, Coral Gables, Florida
| | - Arlette C Perry
- Department of Kinesiology and Sport Sciences, School of Education and Human Development, University of Miami, Coral Gables, Florida
| | - Brian Arwari
- Department of Kinesiology and Sport Sciences, School of Education and Human Development, University of Miami, Coral Gables, Florida
| | - Kevin A Jacobs
- Department of Kinesiology and Sport Sciences, School of Education and Human Development, University of Miami, Coral Gables, Florida
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23
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Ulrich S, Lichtblau M, Schneider SR, Saxer S, Bloch KE. Clinician's Corner: Counseling Patients with Pulmonary Vascular Disease Traveling to High Altitude. High Alt Med Biol 2022; 23:201-208. [PMID: 35852848 DOI: 10.1089/ham.2022.0051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Ulrich, Silvia, Mona Lichtblau, Simon R. Schneider, Stéphanie Saxer, and Konrad E. Bloch, Clinician's corner: counseling patients with pulmonary vascular disease traveling to high altitude. High Alt Med Biol. 23:201-208, 2022.-Pulmonary vascular diseases (PVDs) with precapillary pulmonary hypertension (PH), such as pulmonary arterial or chronic thromboembolic PH, impair exercise performance and survival in patients. Vasodilators and other treatments improve quality of life and prognosis to an extent in patients who have PVDs as chronic disorders. Obviously, patients with PVD wish to participate in usual daily activities, including travel to popular settlements and mountainous regions located at high altitude. However, the pulmonary hemodynamic impairment due to PVD leads to blood and tissue hypoxia, particularly during exercise and sleep. It is thus of concern that alveolar hypoxia at higher altitude may exacerbate patients' symptoms and lead to decompensation. Current PH guidelines discourage high-altitude exposure for fear of altitude-related adverse health effects. However, several recent well-designed prospective and randomized trials show that despite altitude-induced hypoxemia, pulmonary hemodynamic changes and impairment of exercise performance in patients with PVD are similar to the responses in healthy people or in patients with mild chronic obstructive pulmonary disease. The vast majority of patients with PVD can tolerate short-term exposure to moderate altitudes up to 2,500 m. For the roughly 10% of patients with stable disease who develop severe hypoxemia when ascending to 2,500 m, they respond well to low-level supplemental oxygen support. The best low-altitude predictors for adverse health effects at high altitude are the known clinical risk factors for PVD such as symptoms, functional class, exercise capacity, and exertional oxygen desaturation, whereas hypoxia altitude simulation testing is of little additive value. In any case, patients should be instructed that altitude-related adverse health effects may be difficult to predict and that in case of worsening symptoms, immediate accompanied descent to lower altitude and oxygen therapy are required. Patients with severe hypoxemia near sea level may safely visit high-altitude regions up to 1,500-2,000 m while continuing oxygen therapy and avoiding strenuous exercise. All PH patients should be counseled before any high-altitude sojourn by doctors with experience in PVD and high-altitude medicine and have an action plan for the occurrence of severe hypoxemia and other altitude-related conditions such as acute mountain sickness.
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Affiliation(s)
- Silvia Ulrich
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Mona Lichtblau
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Simon R Schneider
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Stéphanie Saxer
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Konrad E Bloch
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
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24
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Williams AM, Levine BD, Stembridge M. A change of heart: Mechanisms of cardiac adaptation to acute and chronic hypoxia. J Physiol 2022; 600:4089-4104. [PMID: 35930370 PMCID: PMC9544656 DOI: 10.1113/jp281724] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 07/21/2022] [Indexed: 11/20/2022] Open
Abstract
Over the last 100 years, high-altitude researchers have amassed a comprehensive understanding of the global cardiac responses to acute, prolonged and lifelong hypoxia. When lowlanders are exposed to hypoxia, the drop in arterial oxygen content demands an increase in cardiac output, which is facilitated by an elevated heart rate at the same time as ventricular volumes are maintained. As exposure is prolonged, haemoconcentration restores arterial oxygen content, whereas left ventricular filling and stroke volume are lowered as a result of a combination of reduced blood volume and hypoxic pulmonary vasoconstriction. Populations native to high-altitude, such as the Sherpa in Asia, exhibit unique lifelong or generational adaptations to hypoxia. For example, they have smaller left ventricular volumes compared to lowlanders despite having larger total blood volume. More recent investigations have begun to explore the mechanisms underlying such adaptive responses by combining novel imaging techniques with interventions that manipulate cardiac preload, afterload, and/or contractility. This work has revealed the contributions and interactions of (i) plasma volume constriction; (ii) sympathoexcitation; and (iii) hypoxic pulmonary vasoconstriction with respect to altering cardiac loading, or otherwise preserving or enhancing biventricular systolic and diastolic function even amongst high altitude natives with excessive erythrocytosis. Despite these advances, various areas of investigation remain understudied, including potential sex-related differences in response to high altitude. Collectively, the available evidence supports the conclusion that the human heart successfully adapts to hypoxia over the short- and long-term, without signs of myocardial dysfunction in healthy humans, except in very rare cases of maladaptation.
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Affiliation(s)
- Alexandra M. Williams
- Department of Cellular and Physiological Sciences, Faculty of MedicineUniversity of British ColumbiaVancouverBCCanada
- International Collaboration on Repair DiscoveriesUniversity of British ColumbiaVancouverBCCanada
| | - Benjamin D. Levine
- Institute for Exercise and Environmental MedicineThe University of Texas Southwestern Medical CenterDallasTXUSA
| | - Mike Stembridge
- Cardiff School of Sport and Health SciencesCardiff Metropolitan UniversityCardiffUK
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25
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Yu JJ, Non AL, Heinrich EC, Gu W, Alcock J, Moya EA, Lawrence ES, Tift MS, O'Brien KA, Storz JF, Signore AV, Khudyakov JI, Milsom WK, Wilson SM, Beall CM, Villafuerte FC, Stobdan T, Julian CG, Moore LG, Fuster MM, Stokes JA, Milner R, West JB, Zhang J, Shyy JY, Childebayeva A, Vázquez-Medina JP, Pham LV, Mesarwi OA, Hall JE, Cheviron ZA, Sieker J, Blood AB, Yuan JX, Scott GR, Rana BK, Ponganis PJ, Malhotra A, Powell FL, Simonson TS. Time Domains of Hypoxia Responses and -Omics Insights. Front Physiol 2022; 13:885295. [PMID: 36035495 PMCID: PMC9400701 DOI: 10.3389/fphys.2022.885295] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 05/24/2022] [Indexed: 02/04/2023] Open
Abstract
The ability to respond rapidly to changes in oxygen tension is critical for many forms of life. Challenges to oxygen homeostasis, specifically in the contexts of evolutionary biology and biomedicine, provide important insights into mechanisms of hypoxia adaptation and tolerance. Here we synthesize findings across varying time domains of hypoxia in terms of oxygen delivery, ranging from early animal to modern human evolution and examine the potential impacts of environmental and clinical challenges through emerging multi-omics approaches. We discuss how diverse animal species have adapted to hypoxic environments, how humans vary in their responses to hypoxia (i.e., in the context of high-altitude exposure, cardiopulmonary disease, and sleep apnea), and how findings from each of these fields inform the other and lead to promising new directions in basic and clinical hypoxia research.
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Affiliation(s)
- James J. Yu
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Amy L. Non
- Department of Anthropology, Division of Social Sciences, University of California, San Diego, La Jolla, CA, United States
| | - Erica C. Heinrich
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, United States
| | - Wanjun Gu
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
- Herbert Wertheim School of Public Health and Longevity Sciences, University of California, San Diego, La Jolla, CA, United States
| | - Joe Alcock
- Department of Emergency Medicine, University of New Mexico, Albuquerque, MX, United States
| | - Esteban A. Moya
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Elijah S. Lawrence
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Michael S. Tift
- Department of Biology and Marine Biology, College of Arts and Sciences, University of North Carolina Wilmington, Wilmington, NC, United States
| | - Katie A. O'Brien
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
- Department of Physiology, Development and Neuroscience, Faculty of Biology, School of Biological Sciences, University of Cambridge, Cambridge, ENG, United Kingdom
| | - Jay F. Storz
- School of Biological Sciences, College of Arts and Sciences, University of Nebraska-Lincoln, Lincoln, IL, United States
| | - Anthony V. Signore
- School of Biological Sciences, College of Arts and Sciences, University of Nebraska-Lincoln, Lincoln, IL, United States
| | - Jane I. Khudyakov
- Department of Biological Sciences, University of the Pacific, Stockton, CA, United States
| | | | - Sean M. Wilson
- Lawrence D. Longo, MD Center for Perinatal Biology, Loma Linda, CA, United States
| | | | | | | | - Colleen G. Julian
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Lorna G. Moore
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, Aurora, CO, United States
| | - Mark M. Fuster
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Jennifer A. Stokes
- Department of Kinesiology, Southwestern University, Georgetown, TX, United States
| | - Richard Milner
- San Diego Biomedical Research Institute, San Diego, CA, United States
| | - John B. West
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Jiao Zhang
- Department of Medicine, UC San Diego School of Medicine, San Diego, CA, United States
| | - John Y. Shyy
- Department of Medicine, UC San Diego School of Medicine, San Diego, CA, United States
| | - Ainash Childebayeva
- Department of Archaeogenetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - José Pablo Vázquez-Medina
- Department of Integrative Biology, College of Letters and Science, University of California, Berkeley, Berkeley, CA, United States
| | - Luu V. Pham
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, School of Medicine, Johns Hopkins Medicine, Baltimore, MD, United States
| | - Omar A. Mesarwi
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - James E. Hall
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Zachary A. Cheviron
- Division of Biological Sciences, College of Humanities and Sciences, University of Montana, Missoula, MT, United States
| | - Jeremy Sieker
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Arlin B. Blood
- Department of Pediatrics Division of Neonatology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Jason X. Yuan
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Graham R. Scott
- Department of Pediatrics Division of Neonatology, School of Medicine, Loma Linda University, Loma Linda, CA, United States
| | - Brinda K. Rana
- Moores Cancer Center, UC San Diego, La Jolla, CA, United States
- Department of Psychiatry, UC San Diego, La Jolla, CA, United States
| | - Paul J. Ponganis
- Center for Marine Biotechnology and Biomedicine, La Jolla, CA, United States
| | - Atul Malhotra
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Frank L. Powell
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Tatum S. Simonson
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, United States
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26
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A "Bloody" Surprise: When Having Two Lungs Is Providential. Ann Am Thorac Soc 2022; 19:1419-1427. [PMID: 35913460 DOI: 10.1513/annalsats.202203-184cc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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27
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González-Ruiz FJ, Lazcano-Díaz EA, Baeza Herrera LA, Villalobos-Pedroza M, Toledo Alemán EL, Zuñiga-Salcedo MG, Cruz-Rodríguez C, López-Polanco A, Torres-Pulido A, Sierra-González de Cossio A, Cota Apodaca LA, Manzur-Sandoval D. Endotheliitis, Shunts, and Ventilation-Perfusion Mismatch in Coronavirus Disease 2019: A Literature Review of Disease Mechanisms. Ann Med Surg (Lond) 2022; 78:103820. [PMID: 35600188 PMCID: PMC9112604 DOI: 10.1016/j.amsu.2022.103820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 05/14/2022] [Accepted: 05/15/2022] [Indexed: 10/27/2022] Open
Abstract
The severe acute respiratory syndrome coronavirus 2 pandemic has continued to impact global health. However, while immunity acquired by vaccines has been developed, 40% of the world's population has still not been vaccinated. Economic problems associated with acquiring novel therapies, misinformation, and differences in treatment protocols have generated catastrophic results, especially in low-resource countries. Understanding the pathophysiological aspects of coronavirus disease and the therapeutic strategies that have been validated to date is essential for successful medical care. In this review, I summarize the historical aspects of the virus, molecules involved in infecting the host, and consequences of viral interactions with and in tissues.
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Affiliation(s)
- Francisco J. González-Ruiz
- Department of Cardiovascular Critical Care, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, México
| | - Emmanuel A. Lazcano-Díaz
- Department of Cardiovascular Critical Care, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, México
| | - Luis A. Baeza Herrera
- Department of Cardiovascular Critical Care, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, México
| | | | - Enma L. Toledo Alemán
- Department of Cardiovascular Diseases, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, Mexico
| | - Miriam G. Zuñiga-Salcedo
- Department of Cardiovascular Diseases, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, Mexico
| | - Camelia Cruz-Rodríguez
- Department of Cardiovascular Critical Care, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, México
| | - Alexandra López-Polanco
- Department of Cardiovascular Critical Care, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, México
| | - Abraham Torres-Pulido
- Department of Cardiovascular Critical Care, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, México
| | | | - Luis A. Cota Apodaca
- Department of Cardiovascular Critical Care, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, México
| | - Daniel Manzur-Sandoval
- Department of Cardiovascular Critical Care, National Institute of Cardiology “Dr. Ignacio Chávez,”, Mexico City, México
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Narang BJ, Manferdelli G, Millet GP, Debevec T. Respiratory responses to hypoxia during rest and exercise in individuals born pre-term: a state-of-the-art review. Eur J Appl Physiol 2022; 122:1991-2003. [PMID: 35589858 DOI: 10.1007/s00421-022-04965-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 04/28/2022] [Indexed: 11/28/2022]
Abstract
The pre-term birth survival rate has increased considerably in recent decades, and research investigating the long-term effects of premature birth is growing. Moreover, altitude sojourns are increasing in popularity and are often accompanied by various levels of physical activity. Individuals born pre-term appear to exhibit altered acute ventilatory responses to hypoxia, potentially predisposing them to high-altitude illness. These impairments are likely due to the use of perinatal hyperoxia stunting the maturation of carotid body chemoreceptors, but may also be attributed to limited lung diffusion capacity and/or gas exchange inefficiency. Aerobic exercise capacity also appears to be reduced in this population. This may relate to the aforementioned respiratory impairments, or could be due to physiological limitations in pulmonary blood flow or at the exercising muscle (e.g. mitochondrial efficiency). However, surprisingly, the debilitative effects of exercise when performed at altitude do not seem to be exacerbated by premature birth. In fact, it is reasonable to speculate that pre-term birth could protect against the consequences of exercise combined with hypoxia. The mechanisms that underlie this assertion might relate to differences in oxidative stress responses or in cardiopulmonary morphology in pre-term individuals, compared to their full-term counterparts. Further research is required to elucidate the independent effects of neonatal treatment, sex differences and chronic lung disease, and to establish causality in some of the proposed mechanisms that could underlie the differences discussed throughout this review. A more in-depth understanding of the acclimatisation responses to chronic altitude exposures would also help to inform appropriate interventions in this clinical population.
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Affiliation(s)
- Benjamin J Narang
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia. .,Faculty for Sport, University of Ljubljana, Ljubljana, Slovenia.
| | | | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Tadej Debevec
- Department of Automation, Biocybernetics and Robotics, Jožef Stefan Institute, Jamova Cesta 39, 1000, Ljubljana, Slovenia.,Faculty for Sport, University of Ljubljana, Ljubljana, Slovenia
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29
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Hypoxia and hemorheological properties in older individuals. Ageing Res Rev 2022; 79:101650. [PMID: 35597435 DOI: 10.1016/j.arr.2022.101650] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/20/2022] [Accepted: 05/13/2022] [Indexed: 12/17/2022]
Abstract
Hypoxia is caused by insufficient oxygen availability for the organism leading to reduced oxygen delivery to tissues and cells. It has been regarded as a severe threat to human health and it is indeed implicated in pathophysiological mechanisms involved in the development and progression of many diseases. Nevertheless, the potential of controlled hypoxia interventions (i.e. hypoxia conditioning) for improving cardio-vascular health is gaining increased attention. However, blood rheology is often a forgotten factor for vascular health while aging and hypoxia exposure are both suspected to alter hemorheological properties. These changes in blood rheology may influence the benefits-risks balance of hypoxia exposure in older individuals. The benefits of hypoxia exposure for vascular health are mainly reported for healthy populations and the combined impact of aging and hypoxia on blood rheology could therefore be deleterious in older individuals. This review discusses evidence of hypoxia-related and aging-related changes in blood viscosity and its determinants. It draws upon an extensive literature search on the effects of hypoxia/altitude and aging on blood rheology. Aging increases blood viscosity mainly through a rise in plasma viscosity, red blood cell (RBC) aggregation and a decrease in RBC deformability. Hypoxia also causes an increase in RBC aggregation and plasma viscosity. In addition, hypoxia exposure may increase hematocrit and modulate RBC deformability, depending on the hypoxic dose, i.e, beneficial effect of intermittent hypoxia with moderate dose vs deleterious effect of chronic continuous or intermittent hypoxia or if the hypoxic dose is too high. Special attention is directed toward the risks vs. benefits of hemorheological changes during hypoxia exposure in older individuals, and its clinical relevance for vascular disorders.
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30
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Berger MM, Sareban M, Schiefer LM, Swenson KE, Treff F, Schäfer L, Schmidt P, Schimke MM, Paar M, Niebauer J, Cogo A, Kriemler S, Schwery S, Pickerodt PA, Mayer B, Bärtsch P, Swenson ER. Effects of acetazolamide on pulmonary artery pressure and prevention of high altitude pulmonary edema after rapid active ascent to 4,559 m. J Appl Physiol (1985) 2022; 132:1361-1369. [PMID: 35511718 DOI: 10.1152/japplphysiol.00806.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Acetazolamide prevents acute mountain sickness (AMS) by inhibition of carbonic anhydrase. Since it reduces acute hypoxic pulmonary vasoconstriction (HPV), it may also prevent high-altitude pulmonary edema (HAPE) by lowering pulmonary artery pressure. We tested this hypothesis in a randomized, placebo-controlled, double-blind study. Thirteen healthy, non-acclimatized lowlanders with a history of HAPE ascended (<22h) from 1,130 to 4,559m with one overnight stay at 3,611m. Medications started 48h before ascent (acetazolamide: n=7, 250mg 3x/d; placebo: n=6, 3x/d). HAPE was diagnosed by chest radiography, and pulmonary artery pressure by measurement of right ventricular to atrial pressure gradient (RVPG) by transthoracic echocardiography. AMS was evaluated with the Lake Louise Score (LLS) and AMS-C Score. Incidence of HAPE was 43% vs. 67% (acetazolamide vs. placebo, p=0.39). Ascent to altitude increased RVPG from 20±5 to 43±10mmHg (p<0.001) without a group difference (p=0.68). Arterial PO2 fell to 36±9mmHg (p<0.001) and was 8.5mmHg higher with acetazolamide at high altitude (p=0.025). At high altitude, the LLS and AMS-C score remained lower in those taking acetazolamide (both p<0.05). Although acetazolamide reduced HAPE incidence by 35%, this effect was not statistically significant, and considerably less than reductions of about 70-100% with prophylactic dexamethasone, tadalafil, and nifedipine performed with the same ascent profile at the same location. We could not demonstrate a reduction in RVPG compared to placebo treatment despite reductions in AMS severity and better arterial oxygenation. Limited by a small sample size, our data do not support recommending acetazolamide for prevention of HAPE in mountaineers ascending rapidly to over 4,500m.
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Affiliation(s)
- Marc Moritz Berger
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Mahdi Sareban
- University Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, Salzburg, Austria; Research Institute of Molecular Sports Medicine and Rehabilitation, Paracelsus Medical University, Salzburg, Austria
| | - Lisa Maria Schiefer
- Department of Anesthesiology, Critical Care and Pain Medicine, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Kai Erik Swenson
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, MA, United States
| | - Franziska Treff
- Department of Anesthesiology, Critical Care and Pain Medicine, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Larissa Schäfer
- Department of Anesthesiology, Critical Care and Pain Medicine, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Peter Schmidt
- Department of Anesthesiology, Critical Care and Pain Medicine, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Magdalena M Schimke
- Department of Anesthesiology, Critical Care and Pain Medicine, University Hospital Salzburg, Paracelsus Medical University, Salzburg, Austria
| | - Michael Paar
- Department of Radiology, Paracelsus Medical University, Salzburg, Austria
| | - Josef Niebauer
- University Institute of Sports Medicine, Prevention and Rehabilitation, Paracelsus Medical University, Salzburg, Austria; Research Institute of Molecular Sports Medicine and Rehabilitation, Paracelsus Medical University, Salzburg, Austria
| | - Annalisa Cogo
- Biomedical Sport Studies Center, University of Ferrara, Ferrara, Italy
| | - Susi Kriemler
- Epidemiology, Biostatistics and Public Health Institute, University of Zürich, Zurich, Switzerland
| | | | - Philipp Andreas Pickerodt
- Department of Anesthesiology and Operative Intensive Care Medicine, Campus Charité Mitte and Virchow-Klinikum, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Benjamin Mayer
- Institute for Epidemiology and Medical Biometry, Ulm University, Ulm, Germany
| | - Peter Bärtsch
- Department of Internal Medicine, University of Heidelberg, Heidelberg, Germany
| | - Erik R Swenson
- Pulmonary, Critical Care and Sleep Medicine, VA Puget Sound Health Care System, University of Washington, Seattle, WA, United States
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31
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Zhang XZ, Fu L, Zou XY, Li S, Ma XD, Xie L, Pang B, Ma JB, Wang YJ, Du YR, Guo SC. Lung transcriptome analysis for the identification of genes involved in the hypoxic adaptation of plateau pika (Ochotona curzoniae). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2022; 41:100943. [PMID: 34861554 DOI: 10.1016/j.cbd.2021.100943] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/14/2021] [Accepted: 11/10/2021] [Indexed: 06/13/2023]
Abstract
The plateau pika, a typical hypoxia-tolerant mammal lives 3000-5000 m above sea level on the Qinghai-Tibet Plateau, has acquired many physiological and morphological characteristics and strategies in its adaptation to sustained, high-altitude hypoxia. Blunted hypoxic pulmonary vasoconstriction is one such strategy, but the genes involved in this strategy have not been elucidated. Here, we investigated the genes involved and their expression profiles in the lung transcriptome of plateau pikas subjected to different hypoxic conditions (using low-pressure oxygen cabins). A slight, right ventricular hypertrophy was observed in pikas of the control group (altitude: 3200 m) vs. those exposed to 5000 m altitude conditions for one week. Our assembly identified 67,774 genes; compared with their expression in the control animals, 866 and 8364 genes were co-upregulated and co-downregulated, respectively, in pikas subjected to 5000 m altitude conditions for 1 and 4 w. We elucidated pathways that were associated with pulmonary vascular arterial pressure, including vascular smooth muscle contraction, HIF-1 signalling, calcium signalling, cGMP-PKG signalling, and PI3K-Akt signalling based on the differentially expressed genes; the top-100 pathway enrichments were found between the control group and the group exposed to 5000 m altitude conditions for 4 w. The mRNA levels of 18 candidate gene showed that more than 83% of genes were expressed and the number of transcriptome The up-regulated genes were EPAS1, Hbα, iNOS, CX40, CD31, PPM1B, HIF-1α, MYLK, Pcdh12, Surfactant protein B, the down-regulated genes were RYR2, vWF, RASA1, CLASRP, HIF-3α. Our transcriptome data are a valuable resource for future genomic studies on plateau pika.
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Affiliation(s)
- Xu-Ze Zhang
- School of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China; College of Ecological Environment and Resources, Qinghai Minzu University, Xining 810007, China; Key Laboratory of Evolution and Adaptation of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
| | - Lin Fu
- School of Life Science, Yunnan University, Yunnan 650091, China; Key Laboratory of Evolution and Adaptation of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
| | - Xiao-Yan Zou
- School of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China
| | - Shuang Li
- Key Laboratory of Evolution and Adaptation of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
| | - Xiao-Dong Ma
- College of Ecological Environment and Resources, Qinghai Minzu University, Xining 810007, China; Key Laboratory of Evolution and Adaptation of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
| | - Ling Xie
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Bo Pang
- College of food science and biology, Hebei university of science and technology, Shijiazhuang 050018, China
| | - Jian-Bin Ma
- Key Laboratory of Biodiversity Formation Mechanism, Qinghai Normal University, Xining 810008, China
| | - Yu-Jun Wang
- Key Laboratory of Evolution and Adaptation of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
| | - Yu-Rong Du
- Key Laboratory of Biodiversity Formation Mechanism, Qinghai Normal University, Xining 810008, China.
| | - Song-Chang Guo
- School of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China.
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Udjus C, Sjaastad I, Hjørnholm U, Tunestveit TK, Hoffmann P, Hinojosa A, Espe EKS, Christensen G, Skjønsberg OH, Larsen KO, Rostrup M. Extreme altitude induces divergent mass reduction of right and left ventricle in mountain climbers. Physiol Rep 2022; 10:e15184. [PMID: 35146955 PMCID: PMC8831961 DOI: 10.14814/phy2.15184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 12/31/2021] [Accepted: 01/13/2022] [Indexed: 12/01/2022] Open
Abstract
Mountain climbing at high altitude implies exposure to low levels of oxygen, low temperature, wind, physical and psychological stress, and nutritional insufficiencies. We examined whether right ventricular (RV) and left ventricular (LV) myocardial masses were reversibly altered by exposure to extreme altitude. Magnetic resonance imaging and echocardiography of the heart, dual x‐ray absorptiometry scan of body composition, and blood samples were obtained from ten mountain climbers before departure to Mount Everest or Dhaulagiri (baseline), 13.5 ± 1.5 days after peaking the mountain (post‐hypoxia), and six weeks and six months after expeditions exceeding 8000 meters above sea level. RV mass was unaltered after extreme altitude, in contrast to a reduction in LV mass by 11.8 ± 3.4 g post‐hypoxia (p = 0.001). The reduction in LV mass correlated with a reduction in skeletal muscle mass. After six weeks, LV myocardial mass was restored to baseline values. Extreme altitude induced a reduction in LV end‐diastolic volume (20.8 ± 7.7 ml, p = 0.011) and reduced E’, indicating diastolic dysfunction, which were restored after six weeks follow‐up. Elevated circulating interleukin‐18 after extreme altitude compared to follow‐up levels, might have contributed to reduced muscle mass and diastolic dysfunction. In conclusion, the mass of the RV, possibly exposed to elevated afterload, was not changed after extreme altitude, whereas LV mass was reduced. The reduction in LV mass correlated with reduced skeletal muscle mass, indicating a common denominator, and elevated circulating interleukin‐18 might be a mechanism for reduced muscle mass after extreme altitude.
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Affiliation(s)
- Camilla Udjus
- Department of Pulmonary Medicine, Oslo University Hospital Ullevål, Oslo, Norway.,Institute for Experimental Medical Research, Oslo University Hospital Ullevål and University of Oslo, Oslo, Norway.,K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway.,Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital Ullevål and University of Oslo, Oslo, Norway.,K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway.,Department of Cardiology, Oslo University Hospital Ullevål, Oslo, Norway
| | - Ulla Hjørnholm
- Section of Cardiovascular and Renal Research, Medical Division, Department of Cardiology, Oslo University Hospital Ullevål, Oslo, Norway
| | - Torbjørn K Tunestveit
- Section of Cardiovascular and Renal Research, Medical Division, Department of Cardiology, Oslo University Hospital Ullevål, Oslo, Norway.,University of Oslo, Oslo, Norway
| | - Pavel Hoffmann
- Section for Interventional Cardiology, Division of Cardiovascular and Pulmonary Diseases, Department of Cardiology, Oslo University Hospital, Oslo, Norway
| | - Alexis Hinojosa
- Department of Radiology and Nuclear Medicine, Oslo University Hospital Ullevål, Oslo, Norway.,Interventional Centre (IVS), Oslo University Hospital Rikshospitalet and University of Oslo, Oslo, Norway
| | - Emil K S Espe
- Institute for Experimental Medical Research, Oslo University Hospital Ullevål and University of Oslo, Oslo, Norway.,K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Geir Christensen
- Institute for Experimental Medical Research, Oslo University Hospital Ullevål and University of Oslo, Oslo, Norway.,K.G. Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - Ole H Skjønsberg
- Department of Pulmonary Medicine, Oslo University Hospital Ullevål, Oslo, Norway.,Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Karl-Otto Larsen
- Department of Pulmonary Medicine, Oslo University Hospital Ullevål, Oslo, Norway
| | - Morten Rostrup
- Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway.,Section of Cardiovascular and Renal Research, Medical Division, Department of Cardiology, Oslo University Hospital Ullevål, Oslo, Norway.,Department of Acute Medicine, Oslo University Hospital, Oslo, Norway
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Match Me If You Can: The Relationship between Ventilation and Perfusion with Position Changes in Nonhomogenous Lung Injury. Ann Am Thorac Soc 2022; 19:320-326. [PMID: 35103560 DOI: 10.1513/annalsats.202102-210cc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Affiliation(s)
- Andrew M Luks
- From the Division of Pulmonary, Critical Care, and Sleep Medicine, University of Washington, Seattle (A.M.L.); and the Altitude Research Center, Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora (P.H.H.)
| | - Peter H Hackett
- From the Division of Pulmonary, Critical Care, and Sleep Medicine, University of Washington, Seattle (A.M.L.); and the Altitude Research Center, Division of Pulmonary Sciences and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora (P.H.H.)
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35
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Lovering AT, Kelly TS, DiMarco KG, Bradbury KE, Charkoudian N. Implications of a patent foramen ovale on environmental physiology and pathophysiology: Do we know the hole story? J Physiol 2022; 600:1541-1553. [PMID: 35043424 DOI: 10.1113/jp281108] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 01/14/2022] [Indexed: 11/08/2022] Open
Abstract
The foramen ovale is an essential component of the foetal circulation contributing to oxygenation and carbon dioxide elimination that remains patent under certain circumstances, in ∼ 30% of the healthy adult population, without major negative sequelae in most. Adults with a patent foramen ovale (PFO) have a greater tendency to develop symptoms of acute mountain sickness and high-altitude pulmonary oedema upon ascent to high altitude, and PFO presence is associated with worse cardiopulmonary function in chronic mountain sickness. This increase in altitude illness prevalence may be related to dysregulated cerebral blood flow associated with altered respiratory chemoreflex sensitivity; however, the mechanisms remain to be elucidated. Interestingly, men with a PFO appear to have a shift in thermoregulatory control to higher internal temperatures, both at rest and during exercise, and they have blunted thermal tachypnea. The teleological "reason" for this thermoregulatory shift is unclear, but the shift of ∼0.5°C in core body temperature does not appear to be sufficient to have any significant negative consequences in terms of risk of heat illness. Further work in this area is needed, particularly in women, to evaluate mechanisms of heat storage and dissipation in these individuals as compared to people without a PFO. Consequences of a PFO in SCUBA divers include a greater incidence of unprovoked decompression sickness, but whether PFO is beneficial or detrimental to breath hold diving remains unexplored. Whether PFO presence will explain interindividual variability in responses to, and consequences from, other environmental stressors such as spaceflight remain entirely unknown. Abstract figure legend Associations between PFO and altitude illnesses, core body temperature and diving. This article is protected by copyright. All rights reserved.
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Affiliation(s)
| | - Tyler S Kelly
- University of Oregon, Department of Human Physiology, Eugene, OR
| | | | - Karleigh E Bradbury
- University of Oregon, Department of Human Physiology, Eugene, OR.,United States Army Research Institute of Environmental Medicine, Thermal & Mountain Medicine Division, Natick, MA
| | - Nisha Charkoudian
- United States Army Research Institute of Environmental Medicine, Thermal & Mountain Medicine Division, Natick, MA
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Mamazhakypov A, Sartmyrzaeva M, Kushubakova N, Duishobaev M, Maripov A, Sydykov A, Sarybaev A. Right Ventricular Response to Acute Hypoxia Exposure: A Systematic Review. Front Physiol 2022; 12:786954. [PMID: 35095556 PMCID: PMC8791628 DOI: 10.3389/fphys.2021.786954] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/02/2021] [Indexed: 11/26/2022] Open
Abstract
Background: Acute hypoxia exposure is associated with an elevation of pulmonary artery pressure (PAP), resulting in an increased hemodynamic load on the right ventricle (RV). In addition, hypoxia may exert direct effects on the RV. However, the RV responses to such challenges are not fully characterized. The aim of this systematic review was to describe the effects of acute hypoxia on the RV in healthy lowland adults. Methods: We systematically reviewed PubMed and Web of Science and article references from 2005 until May 2021 for prospective studies evaluating echocardiographic RV function and morphology in healthy lowland adults at sea level and upon exposure to simulated altitude or high-altitude. Results: We included 37 studies in this systematic review, 12 of which used simulated altitude and 25 were conducted in high-altitude field conditions. Eligible studies reported at least one of the RV variables, which were all based on transthoracic echocardiography assessing RV systolic and diastolic function and RV morphology. The design of these studies significantly differed in terms of mode of ascent to high-altitude, altitude level, duration of high-altitude stay, and timing of measurements. In the majority of the studies, echocardiographic examinations were performed within the first 10 days of high-altitude induction. Studies also differed widely by selectively reporting only a part of multiple RV parameters. Despite consistent increase in PAP documented in all studies, reports on the changes of RV function and morphology greatly differed between studies. Conclusion: This systematic review revealed that the study reports on the effects of acute hypoxia on the RV are controversial and inconclusive. This may be the result of significantly different study designs, non-compliance with international guidelines on RV function assessment and limited statistical power due to small sample sizes. Moreover, the potential impact of other factors such as gender, age, ethnicity, physical activity, mode of ascent and environmental factors such as temperature and humidity on RV responses to hypoxia remained unexplored. Thus, this comprehensive overview will promote reproducible research with improved study designs and methods for the future large-scale prospective studies, which eventually may provide important insights into the RV response to acute hypoxia exposure.
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Affiliation(s)
- Argen Mamazhakypov
- Department of Internal Medicine, Excellence Cluster Cardio-Pulmonary Institute (CPI), Member of the German Center for Lung Research (DZL), Justus Liebig University of Giessen, Giessen, Germany
| | - Meerim Sartmyrzaeva
- Department of Mountain and Sleep Medicine and Pulmonary Hypertension, National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
- Kyrgyz Indian Mountain Biomedical Research Center, Bishkek, Kyrgyzstan
| | - Nadira Kushubakova
- Department of Mountain and Sleep Medicine and Pulmonary Hypertension, National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
- Kyrgyz Indian Mountain Biomedical Research Center, Bishkek, Kyrgyzstan
| | - Melis Duishobaev
- Department of Mountain and Sleep Medicine and Pulmonary Hypertension, National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
- Kyrgyz Indian Mountain Biomedical Research Center, Bishkek, Kyrgyzstan
| | - Abdirashit Maripov
- Department of Mountain and Sleep Medicine and Pulmonary Hypertension, National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
- Kyrgyz Indian Mountain Biomedical Research Center, Bishkek, Kyrgyzstan
| | - Akylbek Sydykov
- Department of Internal Medicine, Excellence Cluster Cardio-Pulmonary Institute (CPI), Member of the German Center for Lung Research (DZL), Justus Liebig University of Giessen, Giessen, Germany
- Department of Mountain and Sleep Medicine and Pulmonary Hypertension, National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
| | - Akpay Sarybaev
- Department of Mountain and Sleep Medicine and Pulmonary Hypertension, National Center of Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
- Kyrgyz Indian Mountain Biomedical Research Center, Bishkek, Kyrgyzstan
- *Correspondence: Akpay Sarybaev
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Diaz GF, Marquez A, Ruiz-Parra A, Beghetti M, Ivy D. An Acute Hyperoxia Test Predicts Survival in Children with Pulmonary Hypertension Living at High Altitude. High Alt Med Biol 2021; 22:395-405. [PMID: 34905397 PMCID: PMC8742266 DOI: 10.1089/ham.2021.0026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Diaz, Gabriel F., Alicia Marquez, Ariel Ruiz-Parra, Maurice Beghetti, and Dunbar Ivy. An acute hyperoxia test predicts survival in children with pulmonary hypertension living at high altitude. High Alt Med Biol. 22:395-405, 2021. Background: Pulmonary hypertension (PH) causes significant morbidity and mortality in children at altitude. Materials and Methods: Fifty-two children living at 2,640 m were included. During hyperoxia test (O2Test), patients received high oxygen concentrations (FiO2 >80, through Mask, using Venturi or nonrebreathing mask); echocardiography was used to evaluate pulmonary vasculature reactivity. A decrease >20% from the basal pulmonary artery systolic pressure was considered a positive response. Results: Most of the patients had severe PH. The median age at diagnosis was 4.5 years; 34 were female (65.4%). Idiopathic PH was present in 44 patients (84.6%). Six developed severe PH after ductus closure. They were classified in responders (n = 25), and nonresponders (n = 26). Responders were younger (3 years vs. 7 years, p = 0.02), and 22 (88%), had better functional class (FC) 1-2, than nonresponders: 18 (69.23%) of them had worse FC: 3-4 (p = 0.000). In responders, 10/12 who went to live at low altitude became asymptomatic, compared with 7/13 who remained at high altitude. FC 1-2 was achieved by 70% of the patients with idiopathic PH who went to a low altitude, compared with 30% who continued at high altitude (p = 0.03). In nonresponders, 10/26 patients moved to a low altitude: four improved, one worsened, and five died; of the 16/26 patients living at high altitude, four are stable, eight worsened, and four died. Four patients (30.76%) in responder group and nine (69.24%) in the nonresponder group died (p = 0.03). There were differences between both groups in systolic (88 mm Hg vs. 110 mm Hg; p = 0.037), diastolic (37 mm Hg vs. 56 mm Hg; p = 0.035), and mean pulmonary artery pressures (57 mm Hg vs. 88 mm Hg; p = 0.038). Conclusions: This specific hyperoxia test applied until 24 hours (not published before) helps to predict survival and prognosis of children with PH. Children with PH at a high altitude improve at low altitude.
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Affiliation(s)
- Gabriel F Diaz
- Department of Pediatrics, Universidad Nacional de Colombia, Fundación Santa Fe de Bogotá, Bogotá Colombia
| | - Alicia Marquez
- Clínica De La Mujer, Centro Policlínico del Olaya, Bogotá, Colombia
| | - Ariel Ruiz-Parra
- Instituto de Investigaciones Clínicas and Department of Obstetrics and Gynecology, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Maurice Beghetti
- Head of Pediatric Cardiology Unit (HUG), Director Pulmonary Hypertension Program (HUG) Children's University Hospital, Geneva, Switzerland
| | - Dunbar Ivy
- Chief and Selby's Chair of Pediatric Cardiology, University of Colorado, School of Medicine, Children's Hospital Colorado, Denver, Colorado, USA
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Santos-Martínez LE, Gómez-Tejada RA, Murillo-Jauregui CX, Hoyos-Paladines RA, Poyares-Jardim CV, Orozco-Levi M. [Chronic exposure to altitude. Clinical characteristics and diagnosis]. ARCHIVOS DE CARDIOLOGIA DE MEXICO 2021; 91:500-507. [PMID: 33765369 PMCID: PMC8641469 DOI: 10.24875/acm.20000447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
La exposición crónica a la altitud se ha asociado a hipoxia hipobárica en quienes la experimentan. Dos entidades se han asociado a la hipoxia hipobárica: la hipertensión pulmonar de la alta altitud y el mal de montaña crónico. Se describen sus características fisiológicas y de la circulación pulmonar, así como su perfil clínico y el diagnóstico.
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Affiliation(s)
- Luis E Santos-Martínez
- Departamento de Hipertensión Pulmonar y Corazón Derecho, Unidad Médica de Alta Especialidad Hospital de Cardiología, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Ciudad de México, México.,Departamento de Cuidados Intensivos Posquirúrgicos Cardiovasculares, Secretaría de Salubridad y Asistencia, Instituto Nacional de Cardiología Ignacio Chávez, Ciudad de México, México.,Departamento de Circulación Pulmonar, Asociación Latinoamericana del Tórax, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ricardo A Gómez-Tejada
- Departamento de Circulación Pulmonar, Asociación Latinoamericana del Tórax, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.,División de Neumología, Hospital de Clínicas José de San Martín, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carla X Murillo-Jauregui
- Departamento de Circulación Pulmonar, Asociación Latinoamericana del Tórax, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.,Unidad de Fisiología y Fisiopatología Respiratoria, Instituto Boliviano de Biología de Altura, La Paz, Bolivia
| | - Rodrigo A Hoyos-Paladines
- Departamento de Circulación Pulmonar, Asociación Latinoamericana del Tórax, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.,Clínica de Hipertensión Pulmonar, Hospital Carlos Andrade Marín, Instituto Ecuatoriano de Seguridad Social, Quito, Ecuador
| | - Carlos V Poyares-Jardim
- Departamento de Circulación Pulmonar, Asociación Latinoamericana del Tórax, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.,Divisao de Pneumologia, Instituto do Coracao, InCor/HCFMUSP (Hospital das Clinicas da Universidade de Sao Paulo), Sao Paulo, Brasil
| | - Mauricio Orozco-Levi
- Departamento de Circulación Pulmonar, Asociación Latinoamericana del Tórax, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.,Servicio de Neumología, Hospital Internacional de Colombia, Fundación Cardiovascular de Colombia, Floridablanca, Colombia
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Stembridge M, Hoiland RL, Williams AM, Howe CA, Donnelly J, Dawkins TG, Drane A, Tymko MM, Gasho C, Anholm J, Simpson LL, Moore JP, Bailey DM, MacLeod DB, Ainslie PN. The influence of hemoconcentration on hypoxic pulmonary vasoconstriction in acute, prolonged, and lifelong hypoxemia. Am J Physiol Heart Circ Physiol 2021; 321:H738-H747. [PMID: 34448634 DOI: 10.1152/ajpheart.00357.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hemoconcentration can influence hypoxic pulmonary vasoconstriction (HPV) via increased frictional force and vasoactive signaling from erythrocytes, but whether the balance of these mechanism is modified by the duration of hypoxia remains to be determined. We performed three sequential studies: 1) at sea level, in normoxia and isocapnic hypoxia with and without isovolumic hemodilution (n = 10, aged 29 ± 7 yr); 2) at altitude (6 ± 2 days acclimatization at 5,050 m), before and during hypervolumic hemodilution (n = 11, aged 27 ± 5 yr) with room air and additional hypoxia [fraction of inspired oxygen ([Formula: see text])= 0.15]; and 3) at altitude (4,340 m) in Andean high-altitude natives with excessive erythrocytosis (EE; n = 6, aged 39 ± 17 yr), before and during isovolumic hemodilution with room air and hyperoxia (end-tidal Po2 = 100 mmHg). At sea level, hemodilution mildly increased pulmonary artery systolic pressure (PASP; +1.6 ± 1.5 mmHg, P = 0.01) and pulmonary vascular resistance (PVR; +0.7 ± 0.8 wu, P = 0.04). In contrast, after acclimation to 5,050 m, hemodilution did not significantly alter PASP (22.7 ± 5.2 vs. 24.5 ± 5.2 mmHg, P = 0.14) or PVR (2.2 ± 0.9 vs. 2.3 ± 1.2 wu, P = 0.77), although both remained sensitive to additional acute hypoxia. In Andeans with EE at 4,340 m, hemodilution lowered PVR in room air (2.9 ± 0.9 vs. 2.3 ± 0.8 wu, P = 0.03), but PASP remained unchanged (31.3 ± 6.7 vs. 30.9 ± 6.9 mmHg, P = 0.80) due to an increase in cardiac output. Collectively, our series of studies reveal that HPV is modified by the duration of exposure and the prevailing hematocrit level. In application, these findings emphasize the importance of accounting for hematocrit and duration of exposure when interpreting the pulmonary vascular responses to hypoxemia.NEW & NOTEWORTHY Red blood cell concentration influences the pulmonary vasculature via direct frictional force and vasoactive signaling, but whether the magnitude of the response is modified with duration of exposure is not known. By assessing the pulmonary vascular response to hemodilution in acute normobaric and prolonged hypobaric hypoxia in lowlanders and lifelong hypobaric hypoxemia in Andean natives, we demonstrated that a reduction in red cell concentration augments the vasoconstrictive effects of hypoxia in lowlanders. In high-altitude natives, hemodilution lowered pulmonary vascular resistance, but a compensatory increase in cardiac output following hemodilution rendered PASP unchanged.
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Affiliation(s)
- Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada.,Department of Anesthesiology, Pharmacology, and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alexandra M Williams
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada.,Faculty of Medicine, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Joseph Donnelly
- Department of Anaesthesiology, University of Auckland, Auckland, New Zealand
| | - Tony G Dawkins
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Aimee Drane
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, United Kingdom
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada.,Neurovascular Health Laboratory, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Christopher Gasho
- Division of Pulmonary and Critical Care, School of Medicine, Loma Linda University, Loma Linda, California
| | - James Anholm
- Division of Pulmonary and Critical Care, School of Medicine, Loma Linda University, Loma Linda, California
| | - Lydia L Simpson
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Wales, United Kingdom
| | - Jonathan P Moore
- Extremes Research Group, School of Sport, Health and Exercise Sciences, Bangor University, Wales, United Kingdom
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, United Kingdom
| | - David B MacLeod
- Human Pharmacology and Physiology Laboratory, Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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Abstract
The pathophysiology of acute respiratory distress syndrome (ARDS) is marked by inflammation-mediated disruptions in alveolar-capillary permeability, edema formation, reduced alveolar clearance and collapse/derecruitment, reduced compliance, increased pulmonary vascular resistance, and resulting gas exchange abnormalities due to shunting and ventilation-perfusion mismatch. Mechanical ventilation, especially in the setting of regional disease heterogeneity, can propagate ventilator-associated injury patterns including barotrauma/volutrauma and atelectrauma. Lung injury due to the novel coronavirus SARS-CoV-2 resembles other causes of ARDS, though its initial clinical characteristics may include more profound hypoxemia and loss of dyspnea perception with less radiologically-evident lung injury, a pattern not described previously in ARDS.
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Affiliation(s)
- Kai Erik Swenson
- Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, 55 Fruit Street, BUL 148, Boston, MA 02114, USA; Division of Pulmonary, Critical Care, and Sleep Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
| | - Erik Richard Swenson
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of Washington, Seattle, WA, USA; Medical Service, Veterans Affairs Puget Sound Health Care System, 1660 South Columbian Way, Campus Box 358280 (S-111 Pulm), Seattle, WA 98108, USA
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41
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Herberg U, Knies R, Müller N, Breuer J. Altitude exposure in pediatric pulmonary hypertension-are we ready for (flight) recommendations? Cardiovasc Diagn Ther 2021; 11:1122-1136. [PMID: 34527538 DOI: 10.21037/cdt-20-494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 08/27/2020] [Indexed: 11/06/2022]
Abstract
Patients with congenital heart disease are surviving further into adulthood and want to participate in multiple activities. This includes exposure to high altitude by air travel or recreational activities, such as hiking and skiing. However, at an altitude of about 2,500 m, the barometric environmental pressure is reduced and the partial pressure of inspired oxygen drops from 21% to 15% (hypobaric hypoxia). In physiologic response to high-altitude-related hypoxia, pulmonary vasoconstriction is induced within minutes of exposure followed by compensatory hyperventilation and increased cardiac output. Even in healthy children and adults, desaturation can be profound and lead to a significant rise in pulmonary pressure and resistance. Individuals with already increased pulmonary pressure may be placed at risk during high-altitude exposure, as compensatory mechanisms may be limited. Little is known about the physiological response and risk of developing clinically relevant events on altitude exposure in pediatric pulmonary hypertension (PAH). Current guidelines are, in the absence of clinical studies, mainly based on expert opinion. Today, healthcare professionals are increasingly faced with the question, how best to assess and advise on the safety of individuals with PAH planning air travel or an excursion to mountain areas. To fill the gap, this article summarises the current clinical knowledge on moderate to high altitude exposure in patients with different forms of pediatric PAH.
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Affiliation(s)
- Ulrike Herberg
- Department of Pediatric Cardiology, University Hospital Bonn, Bonn, Germany
| | - Ralf Knies
- Department of Pediatric Cardiology, University Hospital Bonn, Bonn, Germany
| | - Nicole Müller
- Department of Pediatric Cardiology, University Hospital Bonn, Bonn, Germany
| | - Johannes Breuer
- Department of Pediatric Cardiology, University Hospital Bonn, Bonn, Germany
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42
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Swenson KE, Ruoss SJ, Swenson ER. The Pathophysiology and Dangers of Silent Hypoxemia in COVID-19 Lung Injury. Ann Am Thorac Soc 2021; 18:1098-1105. [PMID: 33621159 PMCID: PMC8328372 DOI: 10.1513/annalsats.202011-1376cme] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/23/2021] [Indexed: 01/08/2023] Open
Abstract
The ongoing coronavirus disease (COVID-19) pandemic has been unprecedented on many levels, not least of which are the challenges in understanding the pathophysiology of these new critically ill patients. One widely reported phenomenon is that of a profoundly hypoxemic patient with minimal to no dyspnea out of proportion to the extent of radiographic abnormality and change in lung compliance. This apparently unique presentation, sometimes called "happy hypoxemia or hypoxia" but better described as "silent hypoxemia," has led to the speculation of underlying pathophysiological differences between COVID-19 lung injury and acute respiratory distress syndrome (ARDS) from other causes. We explore three proposed distinctive features of COVID-19 that likely bear on the genesis of silent hypoxemia, including differences in lung compliance, pulmonary vascular responses to hypoxia, and nervous system sensing and response to hypoxemia. In the context of known principles of respiratory physiology and neurobiology, we discuss whether these particular findings are due to direct viral effects or, equally plausible, are within the spectrum of typical ARDS pathophysiology and the wide range of hypoxic ventilatory and pulmonary vascular responses and dyspnea perception in healthy people. Comparisons between lung injury patterns in COVID-19 and other causes of ARDS are clouded by the extent and severity of this pandemic, which may underlie the description of "new" phenotypes, although our ability to confirm these phenotypes by more invasive and longitudinal studies is limited. However, given the uncertainty about anything unique in the pathophysiology of COVID-19 lung injury, there are no compelling pathophysiological reasons at present to support a therapeutic approach for these patients that is different from the proven standards of care in ARDS.
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Affiliation(s)
- Kai E. Swenson
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Stephen J. Ruoss
- Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Stanford University, Stanford, California
| | - Erik R. Swenson
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of Washington, Seattle, Washington; and
- Medical Service, Veterans Affairs Puget Sound Health Care System, Seattle, Washington
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43
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Pham K, Parikh K, Heinrich EC. Hypoxia and Inflammation: Insights From High-Altitude Physiology. Front Physiol 2021; 12:676782. [PMID: 34122145 PMCID: PMC8188852 DOI: 10.3389/fphys.2021.676782] [Citation(s) in RCA: 86] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 04/26/2021] [Indexed: 12/19/2022] Open
Abstract
The key regulators of the transcriptional response to hypoxia and inflammation (hypoxia inducible factor, HIF, and nuclear factor-kappa B, NF-κB, respectively) are evolutionarily conserved and share significant crosstalk. Tissues often experience hypoxia and inflammation concurrently at the site of infection or injury due to fluid retention and immune cell recruitment that ultimately reduces the rate of oxygen delivery to tissues. Inflammation can induce activity of HIF-pathway genes, and hypoxia may modulate inflammatory signaling. While it is clear that these molecular pathways function in concert, the physiological consequences of hypoxia-induced inflammation and how hypoxia modulates inflammatory signaling and immune function are not well established. In this review, we summarize known mechanisms of HIF and NF-κB crosstalk and highlight the physiological consequences that can arise from maladaptive hypoxia-induced inflammation. Finally, we discuss what can be learned about adaptive regulation of inflammation under chronic hypoxia by examining adaptive and maladaptive inflammatory phenotypes observed in human populations at high altitude. We aim to provide insight into the time domains of hypoxia-induced inflammation and highlight the importance of hypoxia-induced inflammatory sensitization in immune function, pathologies, and environmental adaptation.
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Affiliation(s)
| | | | - Erica C. Heinrich
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
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44
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Durand F, Raberin A. Exercise-Induced Hypoxemia in Endurance Athletes: Consequences for Altitude Exposure. Front Sports Act Living 2021; 3:663674. [PMID: 33981992 PMCID: PMC8107360 DOI: 10.3389/fspor.2021.663674] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/25/2021] [Indexed: 11/26/2022] Open
Abstract
Exercise-induced hypoxemia (EIH) is well-described in endurance-trained athletes during both maximal and submaximal exercise intensities. Despite the drop in oxygen (O2) saturation and provided that training volumes are similar, athletes who experience EIH nevertheless produce the same endurance performance in normoxia as athletes without EIH. This lack of a difference prompted trainers to consider that the phenomenon was not relevant to performance but also suggested that a specific adaptation to exercise is present in EIH athletes. Even though the causes of EIH have been extensively studied, its consequences have not been fully characterized. With the development of endurance outdoor activities and altitude/hypoxia training, athletes often train and/or compete in this stressful environment with a decrease in the partial pressure of inspired O2 (due to the drop in barometric pressure). Thus, one can reasonably hypothesize that EIH athletes can specifically adapt to hypoxemic episodes during exercise at altitude. Although our knowledge of the interactions between EIH and acute exposure to hypoxia has improved over the last 10 years, many questions have yet to be addressed. Firstly, endurance performance during acute exposure to altitude appears to be more impaired in EIH vs. non-EIH athletes but the corresponding physiological mechanisms are not fully understood. Secondly, we lack information on the consequences of EIH during chronic exposure to altitude. Here, we (i) review research on the consequences of EIH under acute hypoxic conditions, (ii) highlight unresolved questions about EIH and chronic hypoxic exposure, and (iii) suggest perspectives for improving endurance training.
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Affiliation(s)
- Fabienne Durand
- Images Espace Dev, Université de Perpignan Via Domitia, Perpignan, France
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45
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High-altitude illnesses: Old stories and new insights into the pathophysiology, treatment and prevention. SPORTS MEDICINE AND HEALTH SCIENCE 2021; 3:59-69. [PMID: 35782163 PMCID: PMC9219347 DOI: 10.1016/j.smhs.2021.04.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/11/2021] [Accepted: 04/11/2021] [Indexed: 01/19/2023] Open
Abstract
Areas at high-altitude, annually attract millions of tourists, skiers, trekkers, and climbers. If not adequately prepared and not considering certain ascent rules, a considerable proportion of those people will suffer from acute mountain sickness (AMS) or even from life-threatening high-altitude cerebral (HACE) or/and pulmonary edema (HAPE). Reduced inspired oxygen partial pressure with gain in altitude and consequently reduced oxygen availability is primarily responsible for getting sick in this setting. Appropriate acclimatization by slowly raising the hypoxic stimulus (e.g., slow ascent to high altitude) and/or repeated exposures to altitude or artificial, normobaric hypoxia will largely prevent those illnesses. Understanding physiological mechanisms of acclimatization and pathophysiological mechanisms of high-altitude diseases, knowledge of symptoms and signs, treatment and prevention strategies will largely contribute to the risk reduction and increased safety, success and enjoyment at high altitude. Thus, this review is intended to provide a sound basis for both physicians counseling high-altitude visitors and high-altitude visitors themselves.
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46
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Rossetti GM, d'Avossa G, Rogan M, Macdonald JH, Oliver SJ, Mullins PG. Reversal of neurovascular coupling in the default mode network: Evidence from hypoxia. J Cereb Blood Flow Metab 2021; 41:805-818. [PMID: 32538282 PMCID: PMC7983511 DOI: 10.1177/0271678x20930827] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Local changes in cerebral blood flow are thought to match changes in neuronal activity, a phenomenon termed neurovascular coupling. Hypoxia increases global resting cerebral blood flow, but regional cerebral blood flow (rCBF) changes are non-uniform. Hypoxia decreases baseline rCBF to the default mode network (DMN), which could reflect either decreased neuronal activity or altered neurovascular coupling. To distinguish between these hypotheses, we characterized the effects of hypoxia on baseline rCBF, task performance, and the hemodynamic (BOLD) response to task activity. During hypoxia, baseline CBF increased across most of the brain, but decreased in DMN regions. Performance on memory recall and motion detection tasks was not diminished, suggesting task-relevant neuronal activity was unaffected. Hypoxia reversed both positive and negative task-evoked BOLD responses in the DMN, suggesting hypoxia reverses neurovascular coupling in the DMN of healthy adults. The reversal of the BOLD response was specific to the DMN. Hypoxia produced modest increases in activations in the visual attention network (VAN) during the motion detection task, and had no effect on activations in the visual cortex during visual stimulation. This regional specificity may be particularly pertinent to clinical populations characterized by hypoxemia and may enhance understanding of regional specificity in neurodegenerative disease pathology.
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Affiliation(s)
- Gabriella Mk Rossetti
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Giovanni d'Avossa
- Bangor Imaging Centre, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
| | - Matthew Rogan
- Bangor Imaging Centre, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
| | - Jamie H Macdonald
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Samuel J Oliver
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Paul G Mullins
- Bangor Imaging Centre, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
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Willie CK, Patrician A, Hoiland RL, Williams AM, Gasho C, Subedi P, Anholm J, Drane A, Tymko MM, Nowak-Flück D, Plato S, McBride E, Varoli G, Binsted G, Eller LK, Reimer RA, MacLeod DB, Stembridge M, Ainslie PN. Influence of iron manipulation on hypoxic pulmonary vasoconstriction and pulmonary reactivity during ascent and acclimatization to 5050 m. J Physiol 2021; 599:1685-1708. [PMID: 33442904 DOI: 10.1113/jp281114] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 12/16/2020] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Iron acts as a cofactor in the stabilization of the hypoxic-inducible factor family, and plays an influential role in the modulation of hypoxic pulmonary vasoconstriction. It is uncertain whether iron regulation is altered in lowlanders during either (1) ascent to high altitude, or (2) following partial acclimatization, when compared to high-altitude adapted Sherpa. During ascent to 5050 m, the rise in pulmonary artery systolic pressure (PASP) was blunted in Sherpa, compared to lowlanders; however, upon arrival to 5050 m, PASP levels were comparable in both groups, but the reduction in iron bioavailability was more prevalent in lowlanders compared to Sherpa. Following partial acclimatization to 5050 m, there were differential influences of iron status manipulation (via iron infusion or chelation) at rest and during exercise between lowlanders and Sherpa on the pulmonary vasculature. ABSTRACT To examine the adaptational role of iron bioavailability on the pulmonary vascular responses to acute and chronic hypobaric hypoxia, the haematological and cardiopulmonary profile of lowlanders and Sherpa were determined during: (1) a 9-day ascent to 5050 m (20 lowlanders; 12 Sherpa), and (2) following partial acclimatization (11 ± 4 days) to 5050 m (18 lowlanders; 20 Sherpa), where both groups received an i.v. infusion of either iron (iron (iii)-hydroxide sucrose) or an iron chelator (desferrioxamine). During ascent, there were reductions in iron status in both lowlanders and Sherpa; however, Sherpa appeared to demonstrate a more efficient capacity to mobilize stored iron, compared to lowlanders, when expressed as a Δhepcidin per unit change in either body iron or the soluble transferrin receptor index, between 3400-5050 m (P = 0.016 and P = 0.029, respectively). The rise in pulmonary artery systolic pressure (PASP) was blunted in Sherpa, compared to lowlanders during ascent; however, PASP was comparable in both groups upon arrival to 5050 m. Following partial acclimatization, despite Sherpa demonstrating a blunted hypoxic ventilatory response and greater resting hypoxaemia, they had similar hypoxic pulmonary vasoconstriction when compared to lowlanders at rest. Iron-infusion attenuated PASP in both groups at rest (P = 0.005), while chelation did not exaggerate PASP in either group at rest or during exaggerated hypoxaemia ( P I O 2 = 67 mmHg). During exercise at 25% peak wattage, PASP was only consistently elevated in Sherpa, which persisted following both iron infusion or chelation. These findings provide new evidence on the complex interplay of iron regulation on pulmonary vascular regulation during acclimatization and adaptation to high altitude.
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Affiliation(s)
- Christopher K Willie
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Alexander Patrician
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada.,Department of Anaesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alexandra M Williams
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher Gasho
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System and Department of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - Prajan Subedi
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System and Department of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - James Anholm
- Pulmonary/Critical Care Section, VA Loma Linda Healthcare System and Department of Medicine, Loma Linda University, Loma Linda, CA, USA
| | - Aimee Drane
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Michael M Tymko
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada.,Neurovascular Health Laboratory, University of Alberta, Edmonton, Alberta, Canada
| | - Daniela Nowak-Flück
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Sawyer Plato
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Emily McBride
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Giovanfrancesco Varoli
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Gordon Binsted
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Lindsay K Eller
- Faculty of Kinesiology and Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - Raylene A Reimer
- Faculty of Kinesiology and Cumming School of Medicine, University of Calgary, Alberta, Canada
| | - David B MacLeod
- Human Pharmacology & Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Michael Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - Philip N Ainslie
- Centre for Heart, Lung, & Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
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Lucas SJE, Malein WL, Thomas OD, Ashdown KM, Rue CA, Joyce KE, Newman C, Cadigan P, Johnson B, Myers SD, Myers FA, Wright AD, Delamere J, Imray CHE, Bradwell AR, Edsell M. Effect of losartan on performance and physiological responses to exercise at high altitude (5035 m). BMJ Open Sport Exerc Med 2021; 7:e000982. [PMID: 33489310 PMCID: PMC7797254 DOI: 10.1136/bmjsem-2020-000982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2020] [Indexed: 12/15/2022] Open
Abstract
Objective Altitude-related and exercise-related elevations in blood pressure (BP) increase the likelihood of developing pulmonary hypertension and high-altitude illness during high-altitude sojourn. This study examined the antihypertensive effect and potential exercise benefit of the angiotensin II receptor antagonist losartan when taken at altitude. Methods Twenty participants, paired for age and ACE genotype status, completed a double-blinded, randomised study, where participants took either losartan (100 mg/day) or placebo for 21 days prior to arrival at 5035 m (Whymper Hut, Mt Chimborazo, Ecuador). Participants completed a maximal exercise test on a supine cycle ergometer at sea level (4 weeks prior) and within 48 hours of arrival to 5035 m (10-day ascent). Power output, beat-to-beat BP, oxygen saturation (SpO2) and heart rate (HR) were recorded during exercise, with resting BP collected from daily medicals during ascent. Before and immediately following exercise at 5035 m, extravascular lung water prevalence was assessed with ultrasound (quantified via B-line count). Results At altitude, peak power was reduced relative to sea level (p<0.01) in both groups (losartan vs placebo: down 100±29 vs 91±28 W, p=0.55), while SpO2 (70±6 vs 70±5%, p=0.96) and HR (146±21 vs 149±24 bpm, p=0.78) were similar between groups at peak power, as was the increase in systolic BP from rest to peak power (up 80±37 vs 69±33 mm Hg, p=0.56). Exercise increased B-line count (p<0.05), but not differently between groups (up 5±5 vs 8±10, p=0.44). Conclusion Losartan had no observable effect on resting or exercising BP, exercise-induced symptomology of pulmonary hypertension or performance at 5035 m.
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Affiliation(s)
- Samuel J E Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | | | - Owen D Thomas
- Department of Anaesthesia, Royal Gwent Hospital, Aneurin Bevan University Health Board, Newport, UK
| | - Kimberly M Ashdown
- Occupational Performance Research Group, University of Chichester, Chichester, West Sussex, UK
| | - Carla A Rue
- Occupational Performance Research Group, University of Chichester, Chichester, West Sussex, UK
| | - Kelsey E Joyce
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, UK
| | - Charles Newman
- Royal Centre for Defence Medicine, Queen Elizabeth Hospital Birmingham, Birmingham, UK
| | - Patrick Cadigan
- Birmingham Medical Research Expeditionary Society, Birmingham, UK
| | - Brian Johnson
- Birmingham Medical Research Expeditionary Society, Birmingham, UK
| | - Stephen D Myers
- Occupational Performance Research Group, University of Chichester, Chichester, West Sussex, UK
| | - Fiona A Myers
- School of Biological Sciences, University of Portsmouth, Portsmouth, Hampshire, UK
| | | | - John Delamere
- School of Medicine, University of Birmingham, Birmingham, UK
| | - Chris H E Imray
- Department of Vascular Surgery, University Hospitals of Coventry and Warwickshire, Warwick Medical School, University of Warwick, Coventry, UK
| | | | - Mark Edsell
- Department of Anaesthesia, St George's University Hospitals NHS Foundation Trust, London, UK
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Gaur P, Sartmyrzaeva M, Maripov A, Muratali Uulu K, Saini S, Ray K, Kishore K, Akunov A, Sarybaev A, Kumar B, Singh SB, Vats P. Cardiac Acclimatization at High Altitude in Two Different Ethnicity Groups. High Alt Med Biol 2021; 22:58-69. [PMID: 33400909 DOI: 10.1089/ham.2020.0035] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Gaur, Priya, Meerim Sartmyrzaeva, Abdirashit Maripov, Kubatbek Muratali Uulu, Supriya Saini, Koushik Ray, Krishna Kishore, Almaz Akunov, Akpay Sarybaev, Bhuvnesh Kumar, Shashi Bala Singh, and Praveen Vats. Cardiac acclimatization at high altitude in two different ethnicity groups. High Alt Med Biol. 22:58-69, 2021. Introduction: High altitude (HA) exposure causes substantial increase in pulmonary artery pressure (PAP) and resistance. However, the effects of HA hypoxia exposure on cardiac function remain incompletely understood. Studies evaluating interethnic differences in cardiac functions in response to HA exposure are lacking. We aimed to compare the cardiac performance in Indian versus Kyrgyz healthy lowland subjects over the course of a 3-week HA exposure at 4,111 m. Methodology: Ten Indians and 20 Kyrgyz subjects were studied to assess cardiac acclimatization noninvasively by echocardiography in two different ethnic groups for 3 weeks of stay at HA. Pulmonary hemodynamics, right and left ventricular functions were evaluated at basal and on days 3, 7, 14, and 21 of HA exposure and on day 3 of deinduction. Results: HA exposure significantly increased PAP, pulmonary vascular resistance, cardiac output (CO), and heart rates (HRs) in both groups. Tricuspid regurgitant gradient increased significantly in both the group at day 3 versus basal; 38.9 mmHg (31.8, 42.9) versus 21.9 mmHg (19.5, 22.6) in Kyrgyz; and 34.1 mmHg (30.2, 38.5) versus 20.4 mmHg (19.7, 21.3) in Indians. HR increased significantly in Indians at day 3 and 7, whereas in Kyrgyz throughout exposure. CO increased significantly in both groups at day 3 versus basal with 5.9 L/min (5.5, 6.4) versus 5.1 L/min (4.4, 5.9) in Kyrgyz, and 5.7 L/min (5.56, 5.98) versus 4.9 L/min (4.1, 5.3) in Indians. Both groups exhibited preserved right ventricular diastolic and systolic functions at HAs. HA exposure changed the left ventricular diastolic parameters only in Kyrgyz subjects with impaired mitral inflow E/A, but not in Indian subjects. All cardiac changes induced at HAs have been recovered fully upon deinduction in both, except lateral-septal A', which remained low in Indians. Conclusion: Although pulmonary hemodynamics responses were similar in both groups, there were differences in cardiac functional parameters between the two in response to HA exposure that may be accounted to ethnic variation.
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Affiliation(s)
- Priya Gaur
- Endocrinology and Metabolism Division, Defense Institute of Physiology and Allied Sciences, Delhi, India
| | | | - Abdirashit Maripov
- Kyrgyz Indian Mountain Biomedical Research Center, Bishkek, Kyrgyz Republic
| | | | - Supriya Saini
- Endocrinology and Metabolism Division, Defense Institute of Physiology and Allied Sciences, Delhi, India
| | - Koushik Ray
- Endocrinology and Metabolism Division, Defense Institute of Physiology and Allied Sciences, Delhi, India
| | - Krishna Kishore
- Endocrinology and Metabolism Division, Defense Institute of Physiology and Allied Sciences, Delhi, India
| | - Almaz Akunov
- Kyrgyz Indian Mountain Biomedical Research Center, Bishkek, Kyrgyz Republic
| | - Akpay Sarybaev
- Kyrgyz Indian Mountain Biomedical Research Center, Bishkek, Kyrgyz Republic
| | - Bhuvnesh Kumar
- Endocrinology and Metabolism Division, Defense Institute of Physiology and Allied Sciences, Delhi, India
| | - Shashi Bala Singh
- Endocrinology and Metabolism Division, Defense Institute of Physiology and Allied Sciences, Delhi, India
| | - Praveen Vats
- Endocrinology and Metabolism Division, Defense Institute of Physiology and Allied Sciences, Delhi, India
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50
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Brito J, Siques P, Pena E. Long-term chronic intermittent hypoxia: a particular form of chronic high-altitude pulmonary hypertension. Pulm Circ 2020; 10:5-12. [PMID: 33110494 PMCID: PMC7557688 DOI: 10.1177/2045894020934625] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/26/2020] [Indexed: 12/19/2022] Open
Abstract
In some subjects, high-altitude hypobaric hypoxia leads to high-altitude pulmonary
hypertension. The threshold for the diagnosis of high-altitude pulmonary hypertension is a
mean pulmonary artery pressure of 30 mmHg, even though for general pulmonary hypertension
is ≥25 mmHg. High-altitude pulmonary hypertension has been associated with high hematocrit
findings (chronic mountain sickness), and although these are two separate entities, they
have a synergistic effect that should be considered. In recent years, a new condition
associated with high altitude was described in South America named long-term chronic
intermittent hypoxia and has appeared in individuals who commute to work at high altitude
but live and rest at sea level. In this review, we discuss the initial epidemiological
pattern from the early studies done in Chile, the clinical presentation and possible
molecular mechanism and a discussion of the potential management of this condition.
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Affiliation(s)
- Julio Brito
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile.,Institute DECIPHER, German-Chilean Institute for Research on Pulmonary Hypoxia and Its Health Sequelae, Hamburg, Germany
| | - Patricia Siques
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile.,Institute DECIPHER, German-Chilean Institute for Research on Pulmonary Hypoxia and Its Health Sequelae, Hamburg, Germany
| | - Eduardo Pena
- Institute of Health Studies, Universidad Arturo Prat, Iquique, Chile.,Institute DECIPHER, German-Chilean Institute for Research on Pulmonary Hypoxia and Its Health Sequelae, Hamburg, Germany
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