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Simpson LL, Stembridge M, Siebenmann C, Moore JP, Lawley JS. Mechanisms underpinning sympathoexcitation in hypoxia. J Physiol 2024. [PMID: 38533641 DOI: 10.1113/jp284579] [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: 11/06/2023] [Accepted: 02/28/2024] [Indexed: 03/28/2024] Open
Abstract
Sympathoexcitation is a hallmark of hypoxic exposure, occurring acutely, as well as persisting in acclimatised lowland populations and with generational exposure in highland native populations of the Andean and Tibetan plateaus. The mechanisms mediating altitude sympathoexcitation are multifactorial, involving alterations in both peripheral autonomic reflexes and central neural pathways, and are dependent on the duration of exposure. Initially, hypoxia-induced sympathoexcitation appears to be an adaptive response, primarily mediated by regulatory reflex mechanisms concerned with preserving systemic and cerebral tissue O2 delivery and maintaining arterial blood pressure. However, as exposure continues, sympathoexcitation is further augmented above that observed with acute exposure, despite acclimatisation processes that restore arterial oxygen content (C a O 2 ${C_{{\mathrm{a}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ). Under these conditions, sympathoexcitation may become maladaptive, giving rise to reduced vascular reactivity and mildly elevated blood pressure. Importantly, current evidence indicates the peripheral chemoreflex does not play a significant role in the augmentation of sympathoexcitation during altitude acclimatisation, although methodological limitations may underestimate its true contribution. Instead, processes that provide no obvious survival benefit in hypoxia appear to contribute, including elevated pulmonary arterial pressure. Nocturnal periodic breathing is also a potential mechanism contributing to altitude sympathoexcitation, although experimental studies are required. Despite recent advancements within the field, several areas remain unexplored, including the mechanisms responsible for the apparent normalisation of muscle sympathetic nerve activity during intermediate hypoxic exposures, the mechanisms accounting for persistent sympathoexcitation following descent from altitude and consideration of whether there are sex-based differences in sympathetic regulation at altitude.
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Affiliation(s)
- Lydia L Simpson
- Department of Sport Science, Performance Physiology and Prevention, Universität Innsbruck, Innsbruck, Austria
| | - Mike Stembridge
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | | | - Jonathan P Moore
- School of Psychology and Sport Science, Institute of Applied Human Physiology, Bangor University, Bangor, UK
| | - Justin S Lawley
- Department of Sport Science, Performance Physiology and Prevention, Universität Innsbruck, Innsbruck, Austria
- Institute of Mountain Emergency Medicine, EURAC Research, Bolzano, Italy
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Richalet JP, Hermand E, Lhuissier FJ. Cardiovascular physiology and pathophysiology at high altitude. Nat Rev Cardiol 2024; 21:75-88. [PMID: 37783743 DOI: 10.1038/s41569-023-00924-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/16/2023] [Indexed: 10/04/2023]
Abstract
Oxygen is vital for cellular metabolism; therefore, the hypoxic conditions encountered at high altitude affect all physiological functions. Acute hypoxia activates the adrenergic system and induces tachycardia, whereas hypoxic pulmonary vasoconstriction increases pulmonary artery pressure. After a few days of exposure to low oxygen concentrations, the autonomic nervous system adapts and tachycardia decreases, thereby protecting the myocardium against high energy consumption. Permanent exposure to high altitude induces erythropoiesis, which if excessive can be deleterious and lead to chronic mountain sickness, often associated with pulmonary hypertension and heart failure. Genetic factors might account for the variable prevalence of chronic mountain sickness, depending on the population and geographical region. Cardiovascular adaptations to hypoxia provide a remarkable model of the regulation of oxygen availability at the cellular and systemic levels. Rapid exposure to high altitude can have adverse effects in patients with cardiovascular diseases. However, intermittent, moderate hypoxia might be useful in the management of some cardiovascular disorders, such as coronary heart disease and heart failure. The aim of this Review is to help physicians to understand the cardiovascular responses to hypoxia and to outline some recommendations that they can give to patients with cardiovascular disease who wish to travel to high-altitude destinations.
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Affiliation(s)
- Jean-Paul Richalet
- Hypoxie et Poumon, Université Sorbonne Paris Nord, INSERM U1272, Paris, France.
| | - Eric Hermand
- Unité de Recherche Pluridisciplinaire Sport Santé Société, ULR 7369-URePSSS, Université Littoral Côte d'Opale, Université Artois, Université Lille, CHU Lille, Dunkirk, France
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Tymko MM, Young D, Vergel D, Matenchuk BA, Maier LE, Sivak A, Davenport MH, Steinback CD. The effect of hypoxemia on muscle sympathetic nerve activity and cardiovascular function: a systematic review and meta-analysis. Am J Physiol Regul Integr Comp Physiol 2023; 325:R474-R489. [PMID: 37642283 DOI: 10.1152/ajpregu.00021.2023] [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] [Received: 01/23/2023] [Revised: 08/01/2023] [Accepted: 08/08/2023] [Indexed: 08/31/2023]
Abstract
We conducted a systematic review and meta-analysis to determine the effect of acute poikilocapnic, high-altitude, and acute isocapnia hypoxemia on muscle sympathetic nerve activity (MSNA) and cardiovascular function. A comprehensive search across electronic databases was performed until June 2021. All observational designs were included: population (healthy individuals); exposures (MSNA during hypoxemia); comparators (hypoxemia severity and duration); outcomes (MSNA; heart rate, HR; and mean arterial pressure, MAP). Sixty-one studies were included in the meta-analysis. MSNA burst frequency increased by a greater extent during high-altitude hypoxemia [P < 0.001; mean difference (MD), +22.5 bursts/min; confidence interval (CI) = -19.20 to 25.84] compared with acute poikilocapnic hypoxemia (P < 0.001; MD, +5.63 bursts/min; CI = -4.09 to 7.17) and isocapnic hypoxemia (P < 0.001; MD, +4.72 bursts/min; CI = -3.37 to 6.07). MSNA burst amplitude was only elevated during acute isocapnic hypoxemia (P = 0.03; standard MD, +0.46 au; CI = -0.03 to 0.90), and MSNA burst incidence was only elevated during high-altitude hypoxemia [P < 0.001; MD, 33.05 bursts/100 heartbeats; CI = -28.59 to 37.51]. Meta-regression analysis indicated a strong relationship between MSNA burst frequency and hypoxemia severity for acute isocapnic studies (P < 0.001) but not acute poikilocapnia (P = 0.098). HR increased by the same extent across each type of hypoxemia [P < 0.001; MD +13.81 heartbeats/min; 95% CI = 12.59-15.03]. MAP increased during high-altitude hypoxemia (P < 0.001; MD, +5.06 mmHg; CI = 3.14-6.99), and acute isocapnic hypoxemia (P < 0.001; MD, +1.91 mmHg; CI = 0.84-2.97), but not during acute poikilocapnic hypoxemia (P = 0.95). Both hypoxemia type and severity influenced sympathetic nerve and cardiovascular function. These data are important for the better understanding of healthy human adaptation to hypoxemia.
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Affiliation(s)
- Michael M Tymko
- Integrative Cerebrovascular and Environmental Physiology SB Laboratory, Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario, Canada
- Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Desmond Young
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Daniel Vergel
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Brittany A Matenchuk
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
- Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sports and Recreation, Women and Children's Health Research Institute, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Lauren E Maier
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Allison Sivak
- H.T. Coutts Education and Physical Education Library, University of Alberta, Edmonton, Alberta, Canada
| | - Margie H Davenport
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
- Program for Pregnancy and Postpartum Health, Faculty of Kinesiology, Sports and Recreation, Women and Children's Health Research Institute, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Craig D Steinback
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, Edmonton, Alberta, Canada
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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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Chen R, Ye X, Sun M, Yang J, Zhang J, Gao X, Liu C, Ke J, He C, Yuan F, Lv H, Yang Y, Cheng R, Tan H, Huang L. Blood Pressure Load: An Effective Indicator of Systemic Circulation Status in Individuals With Acute Altitude Sickness. Front Cardiovasc Med 2022; 8:765422. [PMID: 35047574 PMCID: PMC8761955 DOI: 10.3389/fcvm.2021.765422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 12/13/2021] [Indexed: 12/23/2022] Open
Abstract
Background: Acute high altitude (HA) exposure results in blood pressure (BP) variations in most subjects. Previous studies have demonstrated that higher BP is potentially correlated with acute mountain sickness (AMS). The BP load may be of clinical significance regarding systemic circulation status. Objectives: This study aimed to examine HA-induced BP changes in patients with AMS compared to those in healthy subjects. Further, we provided clinical information about the relationship between variations in 24-h ambulatory parameters (BP level, BP variability, and BP load) and AMS. Methods: Sixty-nine subjects were enrolled and all participants ascended Litang (4,100 m above sea level). They were monitored using a 24-h ambulatory blood pressure device and underwent echocardiography within 24 h of altitude exposure. The 2018 Lake Louise questionnaire was used to evaluate AMS. Results: The AMS group comprised more women than men [15 (65.2%) vs. 13 (28.3%), P < 0.001] and fewer smokers [4 (17.4%) vs. 23 (50.0%), P = 0.009]. The AMS group exhibited significant increases in 24-h BP compared to the non-AMS group (24-h SBP variation: 10.52 ± 6.48 vs. 6.03 ± 9.27 mmHg, P = 0.041; 24-h DBP variation: 8.70 ± 4.57 vs. 5.03 ± 4.98 mmHg, P = 0.004). The variation of mean 24-h cBPL (cumulative BP load) (mean 24-h cSBPL: 10.58 ± 10.99 vs. 4.02 ± 10.58, P = 0.016; 24-h mean cDBPL: 6.03 ± 5.87 vs. 2.89 ± 4.99, P = 0.034) was also obviously higher in AMS subjects than in non-AMS subjects after HA exposure. 24-h mean cSBPL variation (OR = 1.07, P = 0.024) and 24-h mean cDBPL variation (OR = 1.14, P = 0.034) were independent risk factors of AMS. Moreover, variation of 24-h mean cSBPL showed a good correlation with AMS score (R = 0.504, P < 0.001). Conclusions: Our study demonstrated that patients with AMS had higher BP and BP load changes after altitude exposure than healthy subjects. Excessive BP load variations were associated with AMS. Thus, BP load could be an effective indicator regarding systemic circulation status of AMS.
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Affiliation(s)
- Renzheng Chen
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Xiaowei Ye
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Mengjia Sun
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Jie Yang
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Jihang Zhang
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Xubin Gao
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Chuan Liu
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Jingbin Ke
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Chunyan He
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Fangzhengyuan Yuan
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Hailin Lv
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Yuanqi Yang
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Ran Cheng
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Hu Tan
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Lan Huang
- Institute of Cardiovascular Diseases of Chinese People's Liberation Army (PLA), The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- Department of Cardiology, The Second Affiliated Hospital, Third Military Medical University (Army Medical University), Chongqing, China
- *Correspondence: Lan Huang
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Mallet RT, Burtscher J, Richalet JP, Millet GP, Burtscher M. Impact of High Altitude on Cardiovascular Health: Current Perspectives. Vasc Health Risk Manag 2021; 17:317-335. [PMID: 34135590 PMCID: PMC8197622 DOI: 10.2147/vhrm.s294121] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 05/12/2021] [Indexed: 12/12/2022] Open
Abstract
Globally, about 400 million people reside at terrestrial altitudes above 1500 m, and more than 100 million lowlanders visit mountainous areas above 2500 m annually. The interactions between the low barometric pressure and partial pressure of O2, climate, individual genetic, lifestyle and socio-economic factors, as well as adaptation and acclimatization processes at high elevations are extremely complex. It is challenging to decipher the effects of these myriad factors on the cardiovascular health in high altitude residents, and even more so in those ascending to high altitudes with or without preexisting diseases. This review aims to interpret epidemiological observations in high-altitude populations; present and discuss cardiovascular responses to acute and subacute high-altitude exposure in general and more specifically in people with preexisting cardiovascular diseases; the relations between cardiovascular pathologies and neurodegenerative diseases at altitude; the effects of high-altitude exercise; and the putative cardioprotective mechanisms of hypobaric hypoxia.
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Affiliation(s)
- Robert T Mallet
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Johannes Burtscher
- Department of Biomedical Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
- Institute of Sport Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
| | - Jean-Paul Richalet
- Laboratoire Hypoxie & Poumon, UMR Inserm U1272, Université Sorbonne Paris Nord 13, Bobigny Cedex, F-93017, France
| | - Gregoire P Millet
- Department of Biomedical Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
- Institute of Sport Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
| | - Martin Burtscher
- Department of Sport Science, University of Innsbruck, Innsbruck, A-6020, Austria
- Austrian Society for Alpine and High-Altitude Medicine, Mieming, Austria
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Blood Pressure Changes While Hiking at Moderate Altitudes: A Prospective Cohort Study. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17217978. [PMID: 33142996 PMCID: PMC7663232 DOI: 10.3390/ijerph17217978] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/19/2020] [Accepted: 10/28/2020] [Indexed: 11/17/2022]
Abstract
Recreational hiking in the mountains is a common activity, whether for a single day or for several days in a row. We sought to measure blood pressure (BP) response during a 10-day trek at moderate-altitude elevation (6500-13,000 feet) and observe for uncontrolled hypertension and/or adverse cardiovascular outcomes. A total of 1279 adult participants completed an observational study of resting BP during a 10-day trek in the Sangre de Cristo mountains. Following initial recruitment, participants were issued a trail data card to record BP measurements at day 0 (basecamp), day 3, day 6 and day 9. BP was measured using a sphygmomanometer and auscultation. Demographic data, height, weight, home altitude, daily water and sports drink intake, existence of pre-arrival hypertension and BP medication class were also recorded. We observed a rise in mean blood pressure for the cohort during all exposures to moderate altitudes. The increases were greatest for individuals with pre-existing hypertension and/or obesity. There were no observed life-threatening cardiovascular events for participants. We conclude that for individuals with a modestly controlled blood pressure of 160/95 mmHg, hiking at a moderate altitude is a safe activity.
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Duke CB, Sallade TD, Starling J, Pant S, Sheets A, McElwee MK, Young DS, Taylor RA, Keyes LE. Hypertension and Acute Mountain Sickness in Himalayan Trekkers in Nepal: An Observational Cohort Study. Wilderness Environ Med 2020; 31:157-164. [PMID: 32205041 DOI: 10.1016/j.wem.2020.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 01/03/2020] [Accepted: 01/15/2020] [Indexed: 01/14/2023]
Abstract
INTRODUCTION A history of preexisting hypertension is common in people participating in mountain activities; however, the relationship between blood pressure (BP), preexisting hypertension, and acute mountain sickness (AMS) is not well studied. We sought to determine these relationships among trekkers in the Everest region of Nepal. METHODS This was a prospective observational cohort study of a convenience sample of adult, nonpregnant volunteers trekking in the Everest Base Camp region in Nepal. We recorded Lake Louise Scores for AMS and measured BP at 2860 m, 3400 m, and 4300 m. The primary outcome was AMS. RESULTS A total of 672 trekkers (including 60 with history of preexisting hypertension) were enrolled at 2860 m. We retained 529 at 3400 m and 363 at 4300 m. At 3400 m, 11% of participants had AMS, and 13% had AMS at 4300 m. We found no relationship between AMS and measured BP values (P>0.05), nor was there any relation of BP to AMS severity as measured by higher Lake Louise Scores (P>0.05). Preexisting hypertension (odds ratio [OR] 0.16; 95% CI 0.025-0.57), male sex (OR 0.59; 95% CI 0.37-0.96), and increased SpO2 (OR 0.93; 95% CI 0.87-0.98) were associated with reduced rates of AMS in multivariate analyses adjusting for known risk factors for AMS. CONCLUSIONS AMS is common in trekkers in Nepal, even at 3400 m. There is no relationship between measured BP and AMS. However, a medical history of hypertension may be associated with a lower risk of AMS. More work is needed to confirm this novel finding.
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Affiliation(s)
- Charles B Duke
- Department of Emergency Medicine, Yale School of Medicine, New Haven, CT
| | - T Douglas Sallade
- Department of Emergency Medicine, Geisinger Medical Center, Danville, PA
| | - Jennifer Starling
- Department of Emergency Medicine, University of Colorado and Colorado Permanente Medical Group, Saint Joseph Hospital, Denver, CO
| | - Sushil Pant
- Mountain Medicine Society of Nepal, Kathmandu, Nepal
| | | | - Matthew K McElwee
- Department of Medicine, Division of Rheumatic and Autoimmune Diseases, University of Minnesota, Minneapolis, MN
| | - David S Young
- Department of Emergency Medicine, University of Colorado School of Medicine, Aurora, CO
| | | | - Linda E Keyes
- University of Colorado Emergency Medicine and Boulder Emergency Physicians, Boulder, CO.
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Phelan B, Mather L, Regmi N, Starling J, Twillmann D, McElwee M, Paudel P, Basnyat B, Keyes LE. Ambulatory Blood Pressure at Sea Level and High Altitude in a Climber with a Kidney Transplant and Hypertension. High Alt Med Biol 2019; 20:307-311. [PMID: 31298585 DOI: 10.1089/ham.2018.0118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background and Objectives: High altitude may increase blood pressure (BP) and the kidney plays an important role in acclimatization. Little is known about how transplanted kidneys respond to the hypoxic stress at high altitude. We compared 24 hour ambulatory BP in a climber with a kidney transplant and hypertension at sea level and at high altitude (2860-4300 m). Methods: Welch-Allyn ABPM 6100 monitor was used to collect heart rate, systolic BP (SBP), and diastolic BP every 30 minutes while awake, and hourly while asleep. BP was monitored for 49 hours at sea level and for 53 hours at 2860-4300 m. Results: Overall mean SBP did not differ between altitudes. At high altitude, the participant's mean nocturnal BP increased, but this "reverse dipping" pattern was not observed at sea level. The participant had no evidence of altitude illness or infectious complications at high altitude. Conclusions: This case builds on previous reports that kidney transplant recipients may safely travel to high altitude. Further study is required to determine the generalizability to other travelers with kidney transplant and/or underlying hypertension, and the clinical significance of short-term elevated nocturnal BP at high altitude.
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Affiliation(s)
- Benoit Phelan
- Emergency Medicine, Dalhousie University, Halifax, Canada.,Department of Family Medicine, Memorial University of Newfoundland, St John's, Canada.,Department of Family Medicine, Queen Elizabeth Hospital, Charlottetown, Canada
| | - Luke Mather
- Yukon-Kuskokwim Heath Corporation, Fairbanks, Alaska
| | - Nirajan Regmi
- The Wright Center for Graduate Medical Education, Scranton, Pennsylvania
| | - Jennifer Starling
- Department of Emergency Medicine, Colorado Permanente Medical Group, Saint Joseph Hospital, Denver, Colorado
| | - David Twillmann
- Department of Emergency Medicine, University of Colorado, Aurora, Colorado
| | - Matthew McElwee
- Division of Autoimmune and Rheumatic Diseases, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | | | - Buddha Basnyat
- Oxford University Clinical Research Unit-Nepal, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom.,Nepal International Clinic, Kathmandu, Nepal
| | - Linda E Keyes
- Department of Emergency Medicine, University of Colorado, Aurora, Colorado
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Savla JJ, Levine BD, Sadek HA. The Effect of Hypoxia on Cardiovascular Disease: Friend or Foe? High Alt Med Biol 2019; 19:124-130. [PMID: 29939783 DOI: 10.1089/ham.2018.0044] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Savla, Jainy J., Benjamin D. Levine, and Hesham A. Sadek. The effect of hypoxia on cardiovascular disease: Friend or foe? High Alt Med Biol. 19:124-130, 2018.-Over 140 million people reside at altitudes exceeding 2500 m across the world, resulting in exposure to atmospheric (hypobaric) hypoxia. Whether this chronic exposure is beneficial or detrimental to the cardiovascular system, however, is uncertain. On one hand, multiple studies have suggested a protective effect of living at moderate and high altitudes for cardiovascular risk factors and cardiovascular disease (CVD) events. Conversely, residence at high altitude comes at the tradeoff of developing diseases such as chronic mountain sickness and high-altitude pulmonary hypertension and worsens outcomes for diseases such as chronic obstructive pulmonary disease. Interestingly, recently published data show a potential role for severe hypoxia as a unique and unexpected therapy after myocardial infarction. In this review, we will discuss the current literature evaluating the effects of altitude exposure and the accompanying hypoxia on health and the potential therapeutic applications of hypoxia on CVD.
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Affiliation(s)
- Jainy J Savla
- 1 Department of Cardiology, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Benjamin D Levine
- 1 Department of Cardiology, University of Texas Southwestern Medical Center , Dallas, Texas
- 2 Institute for Exercise and Environmental Medicine , Texas Health Presbyterian Hospital, Dallas, Texas
| | - Hesham A Sadek
- 1 Department of Cardiology, University of Texas Southwestern Medical Center , Dallas, Texas
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