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Stepanek J, Blue RS, Connolly D. Pulmonary Function in Human Spaceflight. Semin Respir Crit Care Med 2023; 44:696-704. [PMID: 37459884 DOI: 10.1055/s-0043-1770064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
Abstract
Human spaceflight is entering a time of markedly increased activity fueled by collaboration between governmental and private industry entities. This has resulted in successful mission planning for destinations in low Earth orbit, lunar destinations (Artemis program, Gateway station) as well as exploration to Mars. The planned construction of additional commercial space stations will ensure continued low Earth orbit presence and destinations for science but also commercial spaceflight participants. The human in the journey to space is exposed to numerous environmental challenges including increased gravitational forces, microgravity, altered human physiology during adaptation to weightlessness in space, altered ambient pressure, as well as other important stressors contingent on the type of mission and destination. This chapter will cover clinically important aspects relevant to lung function in a normally proceeding mission; emergency scenarios such as decompression, fire, etc., will not be covered as these are beyond the scope of this review. To date, participation in commercial spaceflight by those with pre-existing chronic medical conditions is very limited, and hence, close collaboration between practicing pulmonary specialists and aerospace medicine specialists is of critical importance to guarantee safety, proper clinical management, and hence success in these important endeavors.
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Affiliation(s)
- Jan Stepanek
- Aerospace Medicine Program, Department of Medicine, Mayo Clinic, Scottsdale, Arizona
| | - Rebecca S Blue
- Aerospace Medicine Program Aerospace Medicine and Vestibular Research Laboratory (AMVRL), Mayo Clinic, Scottsdale, Arizona
| | - Desmond Connolly
- Human Performance, Air & Space Division, QinetiQ Plc, Farnborough, United Kingdom
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2
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Berger MM, Luks AM. High Altitude. Semin Respir Crit Care Med 2023; 44:681-695. [PMID: 37816346 DOI: 10.1055/s-0043-1770063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/12/2023]
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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Davis JT, Elliott JE, Duke JW, Cristobal A, Lovering AT. Hyperoxia-induced stepwise reduction in blood flow through intrapulmonary, but not intracardiac, shunt during exercise. Am J Physiol Regul Integr Comp Physiol 2023; 325:R96-R105. [PMID: 37184225 PMCID: PMC10292968 DOI: 10.1152/ajpregu.00014.2023] [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: 01/17/2023] [Revised: 04/25/2023] [Accepted: 05/11/2023] [Indexed: 05/16/2023]
Abstract
Blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) (QIPAVA) increases during exercise breathing air, but it has been proposed that QIPAVA is reduced during exercise while breathing a fraction of inspired oxygen ([Formula: see text]) of 1.00. It has been argued that the reduction in saline contrast bubbles through IPAVA is due to altered in vivo microbubble dynamics with hyperoxia reducing bubble stability, rather than closure of IPAVA. To definitively determine whether breathing hyperoxia decreases saline contrast bubble stability in vivo, the present study included individuals with and without patent foramen ovale (PFO) to determine if hyperoxia also eliminates left heart contrast in people with an intracardiac right-to-left shunt. Thirty-two participants consisted of 16 without a PFO; 8 females, 8 with a PFO; 4 females, and 8 with late-appearing left-sided contrast (4 females) completed five, 4-min bouts of constant-load cycle ergometer exercise (males: 250 W, females: 175 W), breathing an [Formula: see text] = 0.21, 0.40, 0.60, 0.80, and 1.00 in a balanced Latin Squares design. QIPAVA was assessed at rest and 3 min into each exercise bout via transthoracic saline contrast echocardiography and our previously used bubble scoring system. Bubble scores at [Formula: see text]= 0.21, 0.40, and 0.60 were unchanged and significantly greater than at [Formula: see text]= 0.80 and 1.00 in those without a PFO. Participants with a PFO had greater bubble scores at [Formula: see text]= 1.00 than those without a PFO. These data suggest that hyperoxia-induced decreases in QIPAVA during exercise occur when [Formula: see text] ≥ 0.80 and is not a result of altered in vivo microbubble dynamics supporting the idea that hyperoxia closes QIPAVA.
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Affiliation(s)
- James T Davis
- Indiana University School of Medicine, Department of Anatomy, Cell Biology and Physiology Bloomington, Indiana, United States
| | - Jonathan E Elliott
- Veterans Affairs Portland Health Care Systeme, Research Servic, Portland, Oregon, United States
- Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States
| | - Joseph W Duke
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, United States
| | - Alberto Cristobal
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States
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Chen A, Zhu J, Zhu L, Tang Y, Li Y, Zhang Q, Zhao Y, Ma C, Liu X. Neglected intrapulmonary arteriovenous anastomoses: A comparative study of pulmonary right-to-left shunts in patients with patent foramen ovale. Front Cardiovasc Med 2023; 10:1111818. [PMID: 37089892 PMCID: PMC10117845 DOI: 10.3389/fcvm.2023.1111818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/16/2023] [Indexed: 04/09/2023] Open
Abstract
ObjectivePulmonary right-to-left shunt (P-RLS) and patent foramen ovale right-to-left shunt (PFO-RLS) often appear in combination, and there are often differences and connections between them. Intrapulmonary arteriovenous anastomoses (IPAVAs), as part of P-RLS, are often overlooked because there are no technologies to detect and identify them. This study aimed to further clarify the incidence and characteristics of P-RLS with the help of contrast transesophageal echocardiography (c-TEE) and contrast transthoracic echocardiography (c-TTE), providing a reference for clinically relevant research and patent foramen ovale (PFO) management disposal decisions.MethodsWe retrospectively investigated 414 subjects who came to our hospital for c-TEE from October 2021 to July 2022, and all subjects completed c-TTE simultaneously. 7 Patients who were newly diagnosed with an atrial septal defect were excluded. Eventually, 407 patients were included in this study. Among them, 157 patients with PFO (58 patients were treated with PFO closure subsequently) and 250 patients without PFO confirmed by c-TEE were finally enrolled. In the process, we observed and analysed the presence of P-RLS.ResultsA total of 407 patients were included in the final analysis and divided into PFO group (N = 157) and non-PFO group (N = 250) according to the results of c-TEE. Whether at rest or after Valsalva maneuver, the incidence of P-RLS was significantly higher under c-TEE than under c-TTE in the two groups (P < 0.001). For both c-TTE and c-TEE, the incidence of P-RLS was slightly higher after Valsalva maneuver than at rest, but the difference was not significant (c-TTE: rest vs. Valsalva maneuver, P = 0.214; c-TEE: rest vs. Valsalva maneuver, P = 0.076). The Valsalva maneuver increased the incidence of P-RLS in the group without PFO, which was more significant in c-TEE (c-TTE: rest vs. Valsalva maneuver, P = 0.591; c-TEE: rest vs. Valsalva maneuver, P = 0.008). In both groups, the P-RLS semiquantitative grading was statistical significance under different states and examinations (P < 0.001).ConclusionThe vast majority of P-RLS are grade 1–2 and are derived from physiological IPAVAs. Even so, attention should be given to the differentiation between P-RLS and PFO-RLS. c-TEE is an effective method to detect P-RLS; however, the recruitments of c-TEE and Valsalva maneuver to P-RLS should be noted.
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Affiliation(s)
- Anni Chen
- Department of Ultrasound, The First Affiliated Hospital of Shaoxing University, Shaoxing, China
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Jianbo Zhu
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Lei Zhu
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Yunyi Tang
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Yun Li
- Department of Ultrasound, The First Affiliated Hospital of Shaoxing University, Shaoxing, China
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Qi Zhang
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Yeping Zhao
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Caiye Ma
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
- Correspondence: Xiatian Liu Caiye Ma
| | - Xiatian Liu
- Department of Ultrasound, The First Affiliated Hospital of Shaoxing University, Shaoxing, China
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
- Correspondence: Xiatian Liu Caiye Ma
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Fahrni G, Rocha AC, Gudmundsson L, Pozzessere C, Qanadli SD, Rotzinger DC. Impact of COVID-19 pneumonia on pulmonary vascular volume. Front Med (Lausanne) 2023; 10:1117151. [PMID: 37035332 PMCID: PMC10073514 DOI: 10.3389/fmed.2023.1117151] [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: 12/20/2022] [Accepted: 02/24/2023] [Indexed: 04/11/2023] Open
Abstract
Background Pulmonary manifestations of COVID-19 pneumonia are well known. However, COVID-19 is also associated with a range of vascular manifestations such as embolism, congestion, and perfusion changes. Regarding congestion, research from different groups has suggested arteriovenous anastomosis dysregulation as a contributing factor. In this study, we aim to better describe the changes in vascular volume in affected lung zones and to relate them to pathophysiological hypotheses. Methods We performed automatic vascular volume extraction in 10 chest CTs of patients, including 2 female and 8 male with a mean age of 63.5 ± 9.3 years, diagnosed with COVID-19 pneumonia. We compared the proportion of vascular volumes between manually segmented regions of lung parenchyma with and without signs of pneumonia. Results The proportion of vascular volume was significantly higher in COVID (CVasc) compared to non-COVID (NCVasc) areas. We found a mean difference (DVasc) of 5% and a mean ratio (RVasc) of 3.7 between the two compartments (p < 0.01). Conclusion Vascular volume in COVID-19 affected lung parenchyma is augmented relative to normal lung parenchyma, indicating venous congestion and supporting the hypothesis of pre-existing intra-pulmonary arteriovenous shunts.
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Affiliation(s)
- Guillaume Fahrni
- Cardiothoracic and Vascular Division, Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Ana-Carolina Rocha
- Cardiothoracic and Vascular Division, Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Louis Gudmundsson
- Cardiothoracic and Vascular Division, Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Chiara Pozzessere
- Cardiothoracic and Vascular Division, Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Salah D. Qanadli
- Riviera Chablais Hospital and University of Lausanne, Lausanne, Switzerland
| | - David C. Rotzinger
- Cardiothoracic and Vascular Division, Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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Brinks J, van Dijk EHC, Meijer OC, Schlingemann RO, Boon CJF. Choroidal arteriovenous anastomoses: a hypothesis for the pathogenesis of central serous chorioretinopathy and other pachychoroid disease spectrum abnormalities. Acta Ophthalmol 2022; 100:946-959. [PMID: 35179828 PMCID: PMC9790326 DOI: 10.1111/aos.15112] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 01/26/2022] [Indexed: 12/30/2022]
Abstract
The pachychoroid disease spectrum (PDS) includes several chorioretinal diseases that share specific choroidal abnormalities. Although their pathophysiological basis is poorly understood, diseases that are part of the PDS have been hypothesized to be the result of venous congestion. Within the PDS, central serous chorioretinopathy is the most common condition associated with vision loss, due to an accumulation of subretinal fluid in the macula. Central serous chorioretinopathy is characterized by distinct risk factors, most notably a high prevalence in males and exposure to corticosteroids. Interestingly, sex differences and corticosteroids are also strongly associated with specific types of arteriovenous anastomoses in the human body, including dural arteriovenous fistula and surgically created arteriovenous shunts. In this manuscript, we assess the potential of such arteriovenous anastomoses in the choroid as a causal mechanism of the PDS. We propose how this may provide a novel unifying concept on the pathophysiological basis of the PDS, and present cases in which this mechanism may play a role.
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Affiliation(s)
- Joost Brinks
- Department of OphthalmologyLeiden University Medical CentreLeidenThe Netherlands
| | - Elon H. C. van Dijk
- Department of OphthalmologyLeiden University Medical CentreLeidenThe Netherlands
| | - Onno C. Meijer
- Department of Medicine, Division of Endocrinology and MetabolismLeiden University Medical CentreLeidenThe Netherlands
| | - Reinier O. Schlingemann
- Department of Ophthalmology, Amsterdam University Medical CentresUniversity of AmsterdamAmsterdamThe Netherlands,Department of OphthalmologyUniversity of Lausanne, Jules‐Gonin Eye Hospital, Fondation Asile des AveuglesLausanneSwitzerland
| | - Camiel J. F. Boon
- Department of OphthalmologyLeiden University Medical CentreLeidenThe Netherlands,Department of Ophthalmology, Amsterdam University Medical CentresUniversity of AmsterdamAmsterdamThe Netherlands
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Hou H, Guo C, Que C, Nie L, Zhang Q, Zhao H, Nong L, Ma W, Wang Q, Liang Z, Wang B, Ma J, Wang G. Diffuse large B-cell lymphoma presenting as reversible intrapulmonary arteriovenous shunts with hypoxia, fever and progressive jaundice: a case report and literature review. BMC Pulm Med 2022; 22:89. [PMID: 35292006 PMCID: PMC8922084 DOI: 10.1186/s12890-022-01881-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 03/07/2022] [Indexed: 11/16/2022] Open
Abstract
Background Intrapulmonary arteriovenous shunts is rare seen in a patient without lung involvement. Case presentation This is the first report of reversible intrapulmonary arteriovenous shunts secondary to extrapulmonary lymphoma as one initial symptom. The patient presented as fever of unknown origin and dyspnea, and examinations of infection were negative. Diagnosis of DLBCL was finally confirmed through bone marrow and splenic biopsies. Intrapulmonary arteriovenous shunts were diagnosed through 100% oxygen inhalation test and transthoracic contrast echocardiography (TTCE). After the treatment of lymphoma, his respiratory failure was relieved. We rechecked the 100% oxygen inhalation test and TTCE, which both indicated that his intrapulmonary arteriovenous shunts had resolved. Conclusions We speculated the prominent inflammation from active DLBCL was the most possible mechanism associated with the reversible intrapulmonary shunt in this patient. These findings will assist us to better understand the mechanism of intrapulmonary shunts.
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Affiliation(s)
- Huan Hou
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Cuiyan Guo
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Chengli Que
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Ligong Nie
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Qi Zhang
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Hong Zhao
- Department of Infectious Diseases, Center for Liver Disease, Peking University First Hospital, Beijing, China
| | - Lin Nong
- Department of Pathology, Peking University First Hospital, Beijing, China
| | - Wei Ma
- Department of Cardiology, Peking University First Hospital, Beijing, China
| | - Qian Wang
- Department of Hematology, Peking University First Hospital, Beijing, China
| | - Zeyin Liang
- Department of Hematology, Peking University First Hospital, Beijing, China
| | - Bingjie Wang
- Department of Hematology, Peking University First Hospital, Beijing, China
| | - Jing Ma
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China.
| | - Guangfa Wang
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
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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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Vargas-Mendoza N, Angeles-Valencia M, Morales-González Á, Morales-Martínez M, Madrigal-Bujaidar E, Álvarez-González I, Fregoso-Aguilar T, Delgado-Olivares L, Madrigal-Santillán EO, Morales-González JA. Effect of Silymarin Supplementation in Lung and Liver Histological Modifications during Exercise Training in a Rodent Model. J Funct Morphol Kinesiol 2021; 6:jfmk6030072. [PMID: 34564191 PMCID: PMC8482127 DOI: 10.3390/jfmk6030072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/25/2021] [Accepted: 08/27/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Exercise training induces adaptive physiological and morphological modifications in the entire organism; however, excessive loads of training may increase damage in tissues. The purpose of this study was to evaluate the effect of silymarin in lung and liver histological changes in rats subjected to exercise training (ET). METHODS Male Wistar rats were subjected to an 8-week ET treadmill program 5 days per week, 60 min/session, and were previously administered 100 mg ascorbic acid or 100 mg of silymarin. RESULTS Silymarin increased alveolar and bronchial muscle size, improve vascularization, and reduced tissue inflammation. In liver, silymarin promoted the reduction of lipid content. CONCLUSION Silymarin supplementation may improve inflammation in pulmonary tissue after 8 weeks of the ET treadmill program, improve cell recovery, and reduce intrahepatic lipid content.
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Affiliation(s)
- Nancy Vargas-Mendoza
- Laboratorio de Medicina de Conservación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, Col. Casco de Santo Tomás, Del. Miguel Hidalgo, Ciudad de México 11340, Mexico; (N.V.-M.); (M.A.-V.)
| | - Marcelo Angeles-Valencia
- Laboratorio de Medicina de Conservación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, Col. Casco de Santo Tomás, Del. Miguel Hidalgo, Ciudad de México 11340, Mexico; (N.V.-M.); (M.A.-V.)
| | - Ángel Morales-González
- Escuela Superior de Cómputo, Instituto Politécnico Nacional, Av. Juan de Dios Bátiz s/n Esquina Miguel Othón de Mendizabal, Unidad Profesional Adolfo López Mateos, Ciudad de México 07738, Mexico;
| | - Mauricio Morales-Martínez
- Licenciatura en Nutrición, Universidad Intercontinental, Insurgentes Sur 4303, Santa Úrsula Xitla, Alcaldía Tlalpan, Ciudad de México 14420, Mexico;
| | - Eduardo Madrigal-Bujaidar
- Laboratorio de Genética, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Unidad Profesional A. López Mateos, Av. Wilfrido Massieu, Col., Lindavista, Ciudad de México 07738, Mexico; (E.M.-B.); (I.Á.-G.)
| | - Isela Álvarez-González
- Laboratorio de Genética, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Unidad Profesional A. López Mateos, Av. Wilfrido Massieu, Col., Lindavista, Ciudad de México 07738, Mexico; (E.M.-B.); (I.Á.-G.)
| | - Tomás Fregoso-Aguilar
- Laboratorio de Hormonas y Conducta, Departamento de Fisiología, ENCB Campus Zacatenco, Instituto Politécnico Nacional, Ciudad de México 07700, Mexico;
| | - Luis Delgado-Olivares
- Centro de Investigación Interdisciplinario, Área Académica de Nutrición, Instituto de Ciencias de la Salud, Universidad Autónoma del Estado de Hidalgo, Circuito Actopan-Tilcuauttla, s/n, Ex Hacienda La Concepción, San Agustín Tlaxiaca 42160, Hidalgo, Mexico;
| | - Eduardo Osiris Madrigal-Santillán
- Laboratorio de Medicina de Conservación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, Col. Casco de Santo Tomás, Del. Miguel Hidalgo, Ciudad de México 11340, Mexico; (N.V.-M.); (M.A.-V.)
- Correspondence: (E.O.M.-S.); (J.A.M.-G.); Tel.: +52-55-5729-6300 (E.O.M.-S. & J.A.M.-G.)
| | - José A. Morales-González
- Laboratorio de Medicina de Conservación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Plan de San Luis y Díaz Mirón, Col. Casco de Santo Tomás, Del. Miguel Hidalgo, Ciudad de México 11340, Mexico; (N.V.-M.); (M.A.-V.)
- Correspondence: (E.O.M.-S.); (J.A.M.-G.); Tel.: +52-55-5729-6300 (E.O.M.-S. & J.A.M.-G.)
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10
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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: 2] [Impact Index Per Article: 0.7] [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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11
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Qanadli SD, Rocha AC, Rotzinger DC. Case Report: Intrapulmonary Arteriovenous Anastomoses in COVID-19-Related Pulmonary Vascular Changes: A New Player in the Arena? Front Med (Lausanne) 2021; 8:639152. [PMID: 33634156 PMCID: PMC7900139 DOI: 10.3389/fmed.2021.639152] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 01/06/2021] [Indexed: 01/09/2023] Open
Abstract
Up to now, COVID-19-related vascular changes were mainly described as thrombo-embolic events. A handful of researchers reported another type of vascular abnormality referred to as "vascular thickening" or "vascular enlargement," without specifying whether the dilated vessels are arteries or veins nor providing a physiopathological hypothesis. Our observations indicate that the vascular dilatation occurs in the venous compartment, and underlying mechanisms might include increased blood flow due to inflammation and the activation of arteriovenous anastomoses.
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Affiliation(s)
- Salah D. Qanadli
- Cardiothoracic and Vascular Division, Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | | | - David C. Rotzinger
- Cardiothoracic and Vascular Division, Department of Diagnostic and Interventional Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
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12
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Nitsure M, Sarangi B, Shankar GH, Reddy VS, Walimbe A, Sharma V, Prayag S. Mechanisms of Hypoxia in COVID-19 Patients: A Pathophysiologic Reflection. Indian J Crit Care Med 2020; 24:967-970. [PMID: 33281323 PMCID: PMC7689135 DOI: 10.5005/jp-journals-10071-23547] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Coronavirus disease-2019 (COVID-19) causes severe hypoxemia which fulfills the criteria of acute respiratory distress syndrome (ARDS) but is not accompanied by typical features of the syndrome. The combination of factors including low P/F ratios, high A-a gradient, relatively preserved lung mechanics, and normal pulmonary pressures may imply a process occurring on the vascular side of the alveolar–capillary unit. The scant but rapidly evolving data available on the pathophysiology are seemingly conflicting, indicating the relative dominance of intrapulmonary shunting or dead space in different studies. In this hypothesis paper, we attempt to gather and explain these observations within a unified conceptual framework by invoking the relative contributions of microvascular thrombosis, along with two proposed vascular mechanisms of capillary flow redistribution and flow through intrapulmonary arteriovenous anastomoses (IPAVA). How to cite this article: Nitsure M, Sarangi B, Shankar GH, Reddy VS, Walimbe A, Sharma V, et al. Mechanisms of Hypoxia in COVID-19 Patients: A Pathophysiologic Reflection. Indian J Crit Care Med 2020;24(10):967–970.
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Affiliation(s)
- Mohana Nitsure
- Department of Pediatrics, Bharati Vidyapeeth Medical College and Hospital, Pune, Maharashtra, India
| | - Bhakti Sarangi
- Department of Pediatrics, Bharati Vidyapeeth Medical College and Hospital, Pune, Maharashtra, India
| | - Guruprasad H Shankar
- Department of Pediatrics, Bharati Vidyapeeth Medical College and Hospital, Pune, Maharashtra, India
| | - Venkat S Reddy
- Department of Pediatrics, Bharati Vidyapeeth Medical College and Hospital, Pune, Maharashtra, India
| | - Ajay Walimbe
- Department of Pediatrics, Bharati Vidyapeeth Medical College and Hospital, Pune, Maharashtra, India
| | - Varsha Sharma
- Department of Pediatrics, Bharati Vidyapeeth Medical College and Hospital, Pune, Maharashtra, India
| | - Shirish Prayag
- Critical Care Medicine, Prayag Hospital, Shree Medical Foundation, Pune, Maharashtra, India
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13
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Usefulness of ventilatory gas analysis for the non-invasive evaluation of the severity of chronic thromboembolic pulmonary hypertension. Int J Cardiol 2019; 296:149-154. [DOI: 10.1016/j.ijcard.2019.07.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 05/28/2019] [Accepted: 07/05/2019] [Indexed: 01/01/2023]
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14
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Lichtblau M, Furian M, Aeschbacher SS, Bisang M, Sheraliev U, Mademilov M, Marazhapov NH, Ulrich S, Sooronbaev T, Bloch KE, Ulrich S. Right-to-left shunts in lowlanders with COPD traveling to altitude: a randomized controlled trial with dexamethasone. J Appl Physiol (1985) 2019; 128:117-126. [PMID: 31751183 DOI: 10.1152/japplphysiol.00548.2019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Right-to-left shunts (RLS) are prevalent in patients with chronic obstructive pulmonary disease (COPD) and might exaggerate oxygen desaturation, especially at altitude. The aim of this study was to describe the prevalence of RLS in patients with COPD traveling to altitude and the effect of preventive dexamethasone. Lowlanders with COPD [Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 1-2, oxygen saturation assessed by pulse oximetry (SpO2) >92%] were randomized to dexamethasone (4 mg bid) or placebo starting 24 h before ascent from 760 m and while staying at 3,100 m for 48 h. Saline-contrast echocardiography was performed at 760 m and after the first night at altitude. Of 87 patients (81 men, 6 women; mean ± SD age 57 ± 9 yr, forced expiratory volume in 1 s 89 ± 22% pred, SpO2 95 ± 2%), 39 were assigned to placebo and 48 to dexamethasone. In the placebo group, 19 patients (49%) had RLS, of which 13 were intracardiac. In the dexamethasone group 23 patients (48%) had RLS, of which 11 were intracardiac (P = 1.0 vs. dexamethasone). Eleven patients receiving placebo and 13 receiving dexamethasone developed new RLS at altitude (P = 0.011 for both changes, P = 0.411 between groups). RLS prevalence at 3,100 m was 30 (77%) in the placebo and 36 (75%) in the dexamethasone group (P = not significant). Development of RLS at altitude could be predicted at lowland by a higher resting pulmonary artery pressure, a lower arterial partial pressure of oxygen, and a greater oxygen desaturation during exercise but not by treatment allocation. Almost half of lowlanders with COPD revealed RLS near sea level, and this proportion significantly increased to about three-fourths when traveling to 3,100 m irrespective of dexamethasone prophylaxis.NEW & NOTEWORTHY The prevalence of intracardiac and intrapulmonary right-to-left shunts (RLS) at altitude in patients with chronic obstructive pulmonary disease (COPD) has not been studied so far. In a large cohort of patients with moderate COPD, our randomized trial showed that the prevalence of RLS increased from 48% at 760 m to 75% at 3,100 m in patients taking placebo. Preventive treatment with dexamethasone did not significantly reduce the altitude-induced recruitment of RLS. Development of RLS at 3,100 m could be predicted at 760 m by a higher resting pulmonary artery pressure and arterial partial pressure of oxygen and a more pronounced oxygen desaturation during exercise. Dexamethasone did not modify the RLS prevalence at 3,100 m.
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Affiliation(s)
- Mona Lichtblau
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Michael Furian
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Sayaka S Aeschbacher
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Maya Bisang
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Ulan Sheraliev
- National Center for Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
| | - Maamed Mademilov
- National Center for Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
| | | | - Stefanie Ulrich
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Talant Sooronbaev
- National Center for Cardiology and Internal Medicine, Bishkek, Kyrgyzstan
| | - Konrad E Bloch
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
| | - Silvia Ulrich
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland
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15
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Carter EA, Koch S, O'Donovan JP, Sheel AW, Milsom WK, Koehle MS. Perfusion of Intrapulmonary Arteriovenous Anastomoses Is Not Related to VO 2max in Hypoxia and Is Unchanged by Oral Sildenafil. High Alt Med Biol 2019; 20:399-406. [PMID: 31618060 DOI: 10.1089/ham.2019.0051] [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: 11/12/2022] Open
Abstract
Background: Perfusion of intrapulmonary arteriovenous anastomoses (IPAVA) is increased during exercise and in hypoxia and is associated with variations in oxygen saturation (SPO2), resulting in blood bypassing the pulmonary microcirculation. Sildenafil is a pulmonary vasodilator that improves SPO2 and endurance performance in hypoxia. The purpose of this study was to determine if 50 mg sildenafil would reduce IPAVA perfusion (QIPAVA) and if the decrement in maximal exercise capacity (VO2max) in hypoxia is related to QIPAVA. We hypothesized that during progressive levels of hypoxia at rest (FIO2 = 0.21, 0.14, 0.12), sildenafil would increase SPO2 and reduce bubble score (estimate of QIPAVA) compared to placebo, and that the decrement in VO2max in hypoxia would be positively correlated with bubble score at rest in hypoxia. Materials and Methods: Fourteen endurance-trained men performed a graded maximal exercise test at sea level and at a simulated altitude of 3000 m, followed by two experimental visits where, after randomly ingesting sildenafil or placebo, they underwent agitated saline contrast echocardiography during progressive levels of hypoxia at rest. Results: All participants experienced a decrement in power output in hypoxia that ranged from 9% to 19% lower than sea level values. Compared to normoxia, bubble score increased significantly in hypoxia (p < 0.001) with no effect of sildenafil (p = 0.580). There was a negative correlation between SPO2 and bubble score (p < 0.001). The decrement in peak power output at VO2max in hypoxia was unrelated to IPAVA perfusion in resting hypoxia (p = 0.32). Several participants demonstrated QIPAVA greater than zero in room air, indicating that arterial hypoxemia may not be the sole mechanism for QIPAVA. Conclusion: These results indicate that the VO2max decrement caused by hypoxia is not related to QIPAVA and that sildenafil does not improve VO2max in hypoxia through modulation of QIPAVA.
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Affiliation(s)
- Eric A Carter
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - Sarah Koch
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - James P O'Donovan
- Sports Medicine Department, Sports Surgery Clinic, Santry, Ireland.,Division of Sport and Exercise Medicine, Department of Family Practice, University of British Columbia, Vancouver, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Michael S Koehle
- School of Kinesiology, University of British Columbia, Vancouver, Canada.,Division of Sport and Exercise Medicine, Department of Family Practice, University of British Columbia, Vancouver, Canada
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16
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Phillips DB, Stickland MK. Respiratory limitations to exercise in health: a brief review. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.05.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Akizuki M, Sugimura K, Aoki T, Kakihana T, Tatebe S, Yamamoto S, Sato H, Satoh K, Shimokawa H, Kohzuki M. Non‐invasive screening using ventilatory gas analysis to distinguish between chronic thromboembolic pulmonary hypertension and pulmonary arterial hypertension. Respirology 2019; 25:427-434. [DOI: 10.1111/resp.13618] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 04/25/2019] [Accepted: 05/22/2019] [Indexed: 01/28/2023]
Affiliation(s)
- Mina Akizuki
- Department of Internal Medicine and Rehabilitation ScienceTohoku University Graduate School of Medicine Sendai Japan
| | - Koichiro Sugimura
- Department of Cardiovascular MedicineTohoku University Graduate School of Medicine Sendai Japan
| | - Tatsuo Aoki
- Department of Cardiovascular MedicineTohoku University Graduate School of Medicine Sendai Japan
| | - Takaaki Kakihana
- Department of Internal Medicine and Rehabilitation ScienceTohoku University Graduate School of Medicine Sendai Japan
| | - Shunsuke Tatebe
- Department of Cardiovascular MedicineTohoku University Graduate School of Medicine Sendai Japan
| | - Saori Yamamoto
- Department of Cardiovascular MedicineTohoku University Graduate School of Medicine Sendai Japan
| | - Haruka Sato
- Department of Cardiovascular MedicineTohoku University Graduate School of Medicine Sendai Japan
| | - Kimio Satoh
- Department of Cardiovascular MedicineTohoku University Graduate School of Medicine Sendai Japan
| | - Hiroaki Shimokawa
- Department of Cardiovascular MedicineTohoku University Graduate School of Medicine Sendai Japan
| | - Masahiro Kohzuki
- Department of Internal Medicine and Rehabilitation ScienceTohoku University Graduate School of Medicine Sendai Japan
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18
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Abstract
The pulmonary circulation carries deoxygenated blood from the systemic veins through the pulmonary arteries to be oxygenated in the capillaries that line the walls of the pulmonary alveoli. The pulmonary circulation carries the cardiac output with a relatively low driving pressure, and so differs considerably in structure and function from the systemic circulation to maintain a low-resistance vascular system. The pulmonary circulation is often considered to be a quasi-static system in both experimental and computational studies of pulmonary perfusion and its matching to ventilation (air flow) for exchange. However, the system is highly dynamic, with cardiac output and regional perfusion changing with posture, exercise, and over time. Here we review this dynamic system, with a focus on understanding the physiology of pulmonary vascular dynamics across spatial and temporal scales, and the changes to these dynamics that are reflective of disease. © 2019 American Physiological Society. Compr Physiol 9:1081-1100, 2019.
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Affiliation(s)
- Alys Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Merryn Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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19
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Petrassi FA, Davis JT, Beasley KM, Evero O, Elliott JE, Goodman RD, Futral JE, Subudhi A, Solano-Altamirano JM, Goldman S, Roach RC, Lovering AT. AltitudeOmics: effect of reduced barometric pressure on detection of intrapulmonary shunt, pulmonary gas exchange efficiency, and total pulmonary resistance. J Appl Physiol (1985) 2018; 124:1363-1376. [PMID: 29357511 PMCID: PMC6008081 DOI: 10.1152/japplphysiol.00474.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 12/06/2017] [Accepted: 12/10/2017] [Indexed: 11/22/2022] Open
Abstract
Blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA) occurs in healthy humans at rest and during exercise when breathing hypoxic gas mixtures at sea level and may be a source of right-to-left shunt. However, at high altitudes, QIPAVA is reduced compared with sea level, as detected using transthoracic saline contrast echocardiography (TTSCE). It remains unknown whether the reduction in QIPAVA (i.e., lower bubble scores) at high altitude is due to a reduction in bubble stability resulting from the lower barometric pressure (PB) or represents an actual reduction in QIPAVA. To this end, QIPAVA, pulmonary artery systolic pressure (PASP), cardiac output (QT), and the alveolar-to-arterial oxygen difference (AaDO2) were assessed at rest and during exercise (70-190 W) in the field (5,260 m) and in the laboratory (1,668 m) during four conditions: normobaric normoxia (NN; [Formula: see text] = 121 mmHg, PB = 625 mmHg; n = 8), normobaric hypoxia (NH; [Formula: see text] = 76 mmHg, PB = 625 mmHg; n = 7), hypobaric normoxia (HN; [Formula: see text] = 121 mmHg, PB = 410 mmHg; n = 8), and hypobaric hypoxia (HH; [Formula: see text] = 75 mmHg, PB = 410 mmHg; n = 7). We hypothesized QIPAVA would be reduced during exercise in isooxic hypobaria compared with normobaria and that the AaDO2 would be reduced in isooxic hypobaria compared with normobaria. Bubble scores were greater in normobaric conditions, but the AaDO2 was similar in both isooxic hypobaria and normobaria. Total pulmonary resistance (PASP/QT) was elevated in HN and HH. Using mathematical modeling, we found no effect of hypobaria on bubble dissolution time within the pulmonary transit times under consideration (<5 s). Consequently, our data suggest an effect of hypobaria alone on pulmonary blood flow. NEW & NOTEWORTHY Blood flow through intrapulmonary arteriovenous anastomoses, detected by transthoracic saline contrast echocardiography, was reduced during exercise in acute hypobaria compared with normobaria, independent of oxygen tension, whereas pulmonary gas exchange efficiency was unaffected. Modeling the effect(s) of reduced air density on contrast bubble lifetime did not result in a significantly reduced contrast stability. Interestingly, total pulmonary resistance was increased by hypobaria, independent of oxygen tension, suggesting that pulmonary blood flow may be changed by hypobaria.
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Affiliation(s)
- Frank A Petrassi
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - James T Davis
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Kara M Beasley
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Oghenero Evero
- Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus , Denver, Colorado
| | - Jonathan E Elliott
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Randall D Goodman
- Oregon Heart and Vascular Institute, Echocardiography, Springfield, Oregon
| | - Joel E Futral
- Oregon Heart and Vascular Institute, Echocardiography, Springfield, Oregon
| | - Andrew Subudhi
- Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus , Denver, Colorado
| | | | - Saul Goldman
- Department of Chemistry, University of Guelph , Guelph, Ontario , Canada
| | - Robert C Roach
- Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus , Denver, Colorado
| | - Andrew T Lovering
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
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20
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Brugniaux JV, Coombs GB, Barak OF, Dujic Z, Sekhon MS, Ainslie PN. Highs and lows of hyperoxia: physiological, performance, and clinical aspects. Am J Physiol Regul Integr Comp Physiol 2018; 315:R1-R27. [PMID: 29488785 DOI: 10.1152/ajpregu.00165.2017] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Molecular oxygen (O2) is a vital element in human survival and plays a major role in a diverse range of biological and physiological processes. Although normobaric hyperoxia can increase arterial oxygen content ([Formula: see text]), it also causes vasoconstriction and hence reduces O2 delivery in various vascular beds, including the heart, skeletal muscle, and brain. Thus, a seemingly paradoxical situation exists in which the administration of oxygen may place tissues at increased risk of hypoxic stress. Nevertheless, with various degrees of effectiveness, and not without consequences, supplemental oxygen is used clinically in an attempt to correct tissue hypoxia (e.g., brain ischemia, traumatic brain injury, carbon monoxide poisoning, etc.) and chronic hypoxemia (e.g., severe COPD, etc.) and to help with wound healing, necrosis, or reperfusion injuries (e.g., compromised grafts). Hyperoxia has also been used liberally by athletes in a belief that it offers performance-enhancing benefits; such benefits also extend to hypoxemic patients both at rest and during rehabilitation. This review aims to provide a comprehensive overview of the effects of hyperoxia in humans from the "bench to bedside." The first section will focus on the basic physiological principles of partial pressure of arterial O2, [Formula: see text], and barometric pressure and how these changes lead to variation in regional O2 delivery. This review provides an overview of the evidence for and against the use of hyperoxia as an aid to enhance physical performance. The final section addresses pathophysiological concepts, clinical studies, and implications for therapy. The potential of O2 toxicity and future research directions are also considered.
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Affiliation(s)
| | - Geoff B Coombs
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada
| | - Otto F Barak
- Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Faculty of Sport and Physical Education, University of Novi Sad, Novi Sad, Serbia
| | - Zeljko Dujic
- Department of Integrative Physiology, School of Medicine, University of Split , Split , Croatia
| | - Mypinder S Sekhon
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada.,Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia , Vancouver, British Columbia , Canada
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada
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21
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Norris HC, Mangum TS, Kern JP, Elliott JE, Beasley KM, Goodman RD, Mladinov S, Barak OF, Bakovic D, Dujic Z, Lovering AT. Intrapulmonary arteriovenous anastomoses in humans with chronic obstructive pulmonary disease: implications for cryptogenic stroke? Exp Physiol 2018; 101:1128-42. [PMID: 27339093 DOI: 10.1113/ep085811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 06/20/2016] [Indexed: 12/13/2022]
Abstract
What is the central question of this study? Do individuals with chronic obstructive pulmonary disease have blood flow through intrapulmonary arteriovenous anastomoses at rest or during exercise? What is the main finding and its importance? Individuals with chronic obstructive pulmonary disease have a greater prevalence of blood flow through intrapulmonary arteriovenous anastomoses at rest than age-matched control subjects. Given that the intrapulmonary arteriovenous anastomoses are large enough to permit venous emboli to pass into the arterial circulation, patients with chronic obstructive pulmonary disease and an elevated risk of thrombus formation may be at risk of intrapulmonary arteriovenous anastomosis-facilitated embolic injury (e.g. stroke or transient ischaemic attack). The pulmonary capillaries prevent stroke by filtering venous emboli from the circulation. Intrapulmonary arteriovenous anastomoses are large-diameter (≥50 μm) vascular connections in the lung that may compromise the integrity of the pulmonary capillary filter and have recently been linked to cryptogenic stroke and transient ischaemic attack. Prothrombotic populations, such as individuals with chronic obstructive pulmonary disease (COPD), may be at increased risk of stroke and transient ischaemic attack facilitated by intrapulmonary arteriovenous anastomoses, but the prevalence and degree of blood flow through intrapulmonary arteriovenous anastomoses in this population has not been fully examined and compared with age-matched healthy control subjects. We used saline contrast echocardiography to assess blood flow through intrapulmonary arteriovenous anastomoses at rest (n = 29 COPD and 19 control subjects) and during exercise (n = 10 COPD and 10 control subjects) in subjects with COPD and age-matched healthy control subjects. Blood flow through intrapulmonary arteriovenous anastomoses was detected in 23% of subjects with COPD at rest and was significantly higher compared with age-matched healthy control subjects. Blood flow through intrapulmonary arteriovenous anastomoses at rest was reduced or eliminated in subjects with COPD after breathing hyperoxic gas. Sixty per cent of subjects with COPD who did not have blood flow through the intrapulmonary arteriovenous anastomoses at rest had blood flow through them during exercise. The combination of blood flow through intrapulmonary arteriovenous anastomoses and potential for thrombus formation in individuals with COPD may permit venous emboli to pass into the arterial circulation and cause stroke and transient ischaemic attack. Breathing supplemental oxygen may reduce this risk in COPD. The link between blood flow through intrapulmonary arteriovenous anastomoses, stroke and transient ischaemic attack is worthy of future investigation in COPD and other populations.
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Affiliation(s)
- H Cameron Norris
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
| | - Tyler S Mangum
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
| | - Julia P Kern
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
| | | | - Kara M Beasley
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
| | | | - Suzana Mladinov
- Clinical Department for Pulmonary Diseases, University Hospital Center Split, Split, Croatia
| | - Otto F Barak
- Department of Physiology, University of Novi Sad, Novi Sad, Serbia
| | - Darija Bakovic
- Division of Cardiology, Department of Internal Medicine, University Hospital Center Split, Split, Croatia.,Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Zeljko Dujic
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
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22
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Myers GJ. Air in intravenous lines: a need to review old opinions. Perfusion 2017; 32:432-435. [DOI: 10.1177/0267659117706834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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23
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Bush D, Deterding R, Weinman J, Galambos C. Hypoxemia in Lipoid Pneumonia: Role of Intrapulmonary Bronchopulmonary Anastomoses. Am J Respir Crit Care Med 2017; 195:1531-1532. [PMID: 28534692 DOI: 10.1164/rccm.201611-2243im] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Douglas Bush
- 1 Section of Pulmonary Medicine, Department of Pediatrics
| | | | | | - Csaba Galambos
- 3 Department of Pathology and Laboratory Medicine, University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado
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24
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Duke JW, Elliott JE, Laurie SS, Voelkel T, Gladstone IM, Fish MB, Lovering AT. Relationship between quantitative and descriptive methods of studying blood flow through intrapulmonary arteriovenous anastomoses during exercise. Respir Physiol Neurobiol 2017; 243:47-54. [PMID: 28536067 DOI: 10.1016/j.resp.2017.05.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 05/09/2017] [Accepted: 05/15/2017] [Indexed: 10/19/2022]
Abstract
Several methods exist to study intrapulmonary arteriovenous anastomoses (IPAVA) in humans. Transthoracic saline contrast echocardiography (TTSCE), i.e., bubble scores, is minimally-invasive, but cannot be used to quantify the magnitude of blood flow through IPAVA (QIPAVA). Radiolabeled macroaggregates of albumin (99mTc-MAA) have been used to quantify QIPAVA in humans, but this requires injection of radioactive particles. Previous work has shown agreement between 99mTc-MAA and TTSCE, but this has not been tested simultaneously in the same group of subjects. Thus, the purpose of this study was to determine if there was a relationship between QIPAVA quantified with 99mTc-MAA and bubble scores obtained with TTSCE. To test this, we used 99mTc-MAA and TTSCE to quantify and detect QIPAVA at rest and during exercise in humans. QIPAVA significantly increased from rest to exercise using 99mTc-MAA and TTSCE and there was a moderately-strong, but significant relationship between methods. Our data suggest that high bubble scores generally correspond with large QIPAVA quantified with 99mTc-MAA during exercise.
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Affiliation(s)
- Joseph W Duke
- Northern Arizona University, Department of Biological Sciences, Flagstaff, AZ, USA.
| | | | | | - Thomas Voelkel
- Sacred Heart Medical Center, Department of Nuclear Medicine, Springfield, OR, USA
| | - Igor M Gladstone
- Oregon Health and Sciences University, Department of Pediatrics, Portland, OR, USA
| | - Mathews B Fish
- Sacred Heart Medical Center, Department of Nuclear Medicine, Springfield, OR, USA
| | - Andrew T Lovering
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
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Romac R, Barak O, Glavas D, Susilovic Grabovac Z, Lozo P, Roje I, Caljkusic K, Drmic-Hofman I, Davis JT, Dujic Z, Lovering AT. Characterization of blood flow through intrapulmonary arteriovenous anastomoses and patent foramen ovale at rest and during exercise in stroke and transient ischemic attack patients. Echocardiography 2017; 34:676-682. [DOI: 10.1111/echo.13519] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Rinaldo Romac
- Department of Neurology; University Hospital Center Split; Split Croatia
| | - Otto Barak
- Department of Integrative Physiology; University of Split School of Medicine; Split Croatia
- Faculty of Medicine; University of Novi Sad; Novi Sad Serbia
| | - Duska Glavas
- Division of Cardiology; Department of Internal Medicine; University Hospital Center Split; Split Croatia
| | - Zora Susilovic Grabovac
- Division of Cardiology; Department of Internal Medicine; University Hospital Center Split; Split Croatia
| | - Petar Lozo
- Division of Cardiology; Department of Internal Medicine; University Hospital Center Split; Split Croatia
| | - Igor Roje
- Department of Neurology; University Hospital Center Split; Split Croatia
| | - Kresimir Caljkusic
- Department of Anesthesiology; University Hospital Center Split; Split Croatia
| | - Irena Drmic-Hofman
- Department of Pathology, Forensic Medicine and Cytology; University Hospital Center Split; Split Croatia
- Department of Medical Chemistry and Biochemistry; University of Split School of Medicine; Split Croatia
| | - James T. Davis
- Department of Kinesiology, Recreation and Sport; Indiana State University; Terre Haute IN USA
| | - Zeljko Dujic
- Department of Integrative Physiology; University of Split School of Medicine; Split Croatia
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Parra JA, Cuesta JM, Zarrabeitia R, Fariñas-Álvarez C, Bueno J, Marqués S, Parra-Fariñas C, Botella ML, Bernabéu C, Zarauza J. Screening pulmonary arteriovenous malformations in a large cohort of Spanish patients with hemorrhagic hereditary telangiectasia. Int J Cardiol 2016; 218:240-245. [DOI: 10.1016/j.ijcard.2016.05.065] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 04/06/2016] [Accepted: 05/12/2016] [Indexed: 11/26/2022]
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27
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Hackett HK, Boulet LM, Dominelli PB, Foster GE. A methodological approach for quantifying and characterizing the stability of agitated saline contrast: implications for quantifying intrapulmonary shunt. J Appl Physiol (1985) 2016; 121:568-76. [PMID: 27365283 DOI: 10.1152/japplphysiol.00422.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 06/27/2016] [Indexed: 12/26/2022] Open
Abstract
Agitated saline contrast echocardiography is often used to determine blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA). We applied indicator dilution theory to time-acoustic intensity curves obtained from a bolus injection of hand-agitated saline contrast to acquire a quantitative index of contrast mass. Using this methodology and an in vitro model of the pulmonary circulation, the purpose of this study was to determine the effect of transit time and gas composition [air vs. sulphur hexafluoride (SF6)] on contrast conservation between two detection sites separated by a convoluted network of vessels. We hypothesized that the contrast lost between the detection sites would increase with transit times and be reduced by using contrast bubbles composed of SF6 Changing the flow and/or reducing the volume of the circulatory network manipulated transit time. Contrast conservation was measured as the ratio of outflow and inflow contrast masses. For air, 53.2 ± 3.4% (SE) of contrast was conserved at a transit time of 9.25 ± 0.02 s but dropped to 16.0 ± 1.0% at a transit time of 10.17 ± 0.06 s. Compared with air, SF6 contrast conservation was significantly greater (P < 0.05) with 114.3 ± 2.9% and 73.7 ± 3.3% of contrast conserved at a transit time of 10.39 ± 0.02 s and 13.46 ± 0.04 s, respectively. In summary, time-acoustic intensity curves can quantify agitated saline contrast, but loss of contrast due to bubble dissolution makes measuring Q̇IPAVA across varying transit time difficult. Agitated saline composed of SF6 is stabilized and may be a suitable alternative for Q̇IPAVA measurement.
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Affiliation(s)
- Heather K Hackett
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada; and
| | - Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada; and
| | - Paolo B Dominelli
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada; and
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28
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Foster GE, Bain AR, Tremblay JC, Boulet LM, Lemaitre F, Madden D, Dujic Z, Barak O, Boussuges A, Gavarry O, Duke JW, Elliott JE, Laurie SS, Lovering AT, Balestra C, Eichhorn L, Vagula MC, Fitz-Clarke JR, Muth CM. Commentaries on Viewpoint: Why predominantly neurological DCS in breath-hold divers? J Appl Physiol (1985) 2016; 120:1478-82. [PMID: 27306840 DOI: 10.1152/japplphysiol.00242.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Glen E Foster
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Anthony R Bain
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Joshua C Tremblay
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Lindsey M Boulet
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Frederic Lemaitre
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Dennis Madden
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Zeljko Dujic
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Otto Barak
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Alain Boussuges
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Olivier Gavarry
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Joseph W Duke
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Jonathan E Elliott
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Steven S Laurie
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Andrew T Lovering
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Costantino Balestra
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Lars Eichhorn
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Mary C Vagula
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - John R Fitz-Clarke
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
| | - Claus-Martin Muth
- University of British Columbia, KelownaUniversite de Rouen, FranceUniversity of Split, CroatiaUniversity of Novi Sad, SerbiaAix-Marseille UniversitéUniversité de ToulonOhio UniversityMayo ClinicNASA Johnson Space CenterUniversity of OregonUniversité Libre de BruxellesUniversitätsklinikum BonnGannon UniversityDalhousie University, CanadaUniversitaetsklinikum Ulm, Germany
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Duke JW, Davis JT, Ryan BJ, Elliott JE, Beasley KM, Hawn JA, Byrnes WC, Lovering AT. Decreased arterial PO2, not O2 content, increases blood flow through intrapulmonary arteriovenous anastomoses at rest. J Physiol 2016; 594:4981-96. [PMID: 27062157 DOI: 10.1113/jp272211] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/23/2016] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS The mechanism(s) that regulate hypoxia-induced blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA ) are currently unknown. Our previous work has demonstrated that the mechanism of hypoxia-induced QIPAVA is not simply increased cardiac output, pulmonary artery systolic pressure or sympathetic nervous system activity and, instead, it may be a result of hypoxaemia directly. To determine whether it is reduced arterial PO2 (PaO2) or O2 content (CaO2) that causes hypoxia-induced QIPAVA , individuals were instructed to breathe room air and three levels of hypoxic gas at rest before (control) and after CaO2 was reduced by 10% by lowering the haemoglobin concentration (isovolaemic haemodilution; Low [Hb]). QIPAVA , assessed by transthoracic saline contrast echocardiography, significantly increased as PaO2 decreased and, despite reduced CaO2 (via isovolaemic haemodilution), was similar at iso-PaO2. These data suggest that, with alveolar hypoxia, low PaO2 causes the hypoxia-induced increase in QIPAVA , although where and how this is detected remains unknown. ABSTRACT Alveolar hypoxia causes increased blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA ) in healthy humans at rest. However, it is unknown whether the stimulus regulating hypoxia-induced QIPAVA is decreased arterial PO2 (PaO2) or O2 content (CaO2). CaO2 is known to regulate blood flow in the systemic circulation and it is suggested that IPAVA may be regulated similar to the systemic vasculature. Thus, we hypothesized that reduced CaO2 would be the stimulus for hypoxia-induced QIPAVA . Blood volume (BV) was measured using the optimized carbon monoxide rebreathing method in 10 individuals. Less than 5 days later, subjects breathed room air, as well as 18%, 14% and 12.5% O2 , for 30 min each, in a randomized order, before (CON) and after isovolaemic haemodilution (10% of BV withdrawn and replaced with an equal volume of 5% human serum albumin-saline mixture) to reduce [Hb] (Low [Hb]). PaO2 was measured at the end of each condition and QIPAVA was assessed using transthoracic saline contrast echocardiography. [Hb] was reduced from 14.2 ± 0.8 to 12.8 ± 0.7 g dl(-1) (10 ± 2% reduction) from CON to Low [Hb] conditions. PaO2 was no different between CON and Low [Hb], although CaO2 was 10.4%, 9.2% and 9.8% lower at 18%, 14% and 12.5% O2 , respectively. QIPAVA significantly increased as PaO2 decreased and, despite reduced CaO2, was similar at iso-PaO2. These data suggest that, with alveolar hypoxia, low PaO2 causes the hypoxia-induced increase in QIPAVA . Whether the low PO2 is detected at the carotid body, airway and/or the vasculature remains unknown.
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Affiliation(s)
- Joseph W Duke
- Ohio University, Division of Exercise Physiology, Athens, OH, USA
| | - James T Davis
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
| | - Benjamin J Ryan
- University of Colorado at Boulder, Department of Integrative Physiology, Boulder, CO, USA
| | | | - Kara M Beasley
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
| | - Jerold A Hawn
- Oregon Heart and Vascular Institute, Springfield, OR, USA
| | - William C Byrnes
- University of Colorado at Boulder, Department of Integrative Physiology, Boulder, CO, USA
| | - Andrew T Lovering
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
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Lovering AT, Lozo M, Barak O, Davis JT, Lojpur M, Lozo P, Čaljkušić K, Dujić Ž. Resting arterial hypoxaemia in subjects with chronic heart failure, pulmonary hypertension and patent foramen ovale. Exp Physiol 2016; 101:657-70. [DOI: 10.1113/ep085657] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 03/14/2016] [Indexed: 01/09/2023]
Affiliation(s)
| | - Mislav Lozo
- Department of Cardiology; University Hospital Centre Split; Split Croatia
| | - Otto Barak
- Department of Integrative Physiology; University of Split, School of Medicine; Split Croatia
- Department of Physiology; University of Novi Sad; Novi Sad Serbia
| | - James T. Davis
- Department of Human Physiology; University of Oregon; Eugene OR USA
| | - Mihajlo Lojpur
- Department of Anesthesiology; University Hospital Centre Split; Split Croatia
| | - Petar Lozo
- Department of Cardiology; University Hospital Centre Split; Split Croatia
| | - Krešimir Čaljkušić
- Department of Neurology; University Hospital Centre Split; Split Croatia
| | - Željko Dujić
- Department of Integrative Physiology; University of Split, School of Medicine; Split Croatia
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31
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Elliott JE, Duke JW, Hawn JA, Halliwill JR, Lovering AT. Reply from Jonathan E. Elliott, Joseph W. Duke, Jerold A. Hawn, John R. Halliwill and Andrew T. Lovering. J Physiol 2015; 593:483-4. [DOI: 10.1113/jphysiol.2014.286807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
| | - Joseph W. Duke
- University of Oregon; Department of Human Physiology; Eugene OR USA
| | - Jerold A. Hawn
- Oregon Heart & Vascular Institute; Cardiology; Springfield OR USA
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