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Venkat D, Dhillon K, Rowley JA. Effects of High Altitude on Sleep and Respiratory System. CURRENT PULMONOLOGY REPORTS 2021. [DOI: 10.1007/s13665-021-00276-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Ju JD, Zhang C, Sgambati FP, Lopez LM, Pham LV, Schwartz AR, Accinelli RA. Acute Altitude Acclimatization in Young Healthy Volunteers: Nocturnal Oxygenation Increases Over Time, Whereas Periodic Breathing Persists. High Alt Med Biol 2020; 22:14-23. [PMID: 33185483 DOI: 10.1089/ham.2020.0009] [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] [Indexed: 11/12/2022] Open
Abstract
Ju, Jia-Der, Cristian Zhang, Francis P. Sgambati, Lidia M. Lopez, Luu V. Pham, Alan R. Schwartz, and Roberto A. Accinelli. Acute altitude acclimatization in young healthy volunteers: nocturnal oxygenation increases over time whereas periodic breathing persists. High Alt Med Biol. 22:14-23, 2021. Study Objectives: This study aimed to examine the acute effects of high altitude (HA) on sleep disordered breathing (sleep apnea and nocturnal hypoxemia) and acute mountain sickness and to characterize acclimatization over time. Methods: Ten native lowlanders residing at sea level (SL) completed the Lake Louise Score (LLS) and underwent nocturnal polygraphy (ApneaLink Plus) for nine consecutive nights (N1-N9) at HA (2,761 m) and two nights before and after HA. Nocturnal oxygen profiles were assessed by measuring the mean nocturnal oxyhemoglobin saturation (SpO2) during sleep, and sleep apnea severity as assessed by measuring the Apnea-Hypopnea Index (AHI). Mixed-effects linear regression was used to model responses in outcomes (mean nocturnal SpO2, logAHI, and LLS) between HA and SL. Changes in SpO2 and AHI were examined in subgroups with mild versus marked nocturnal SpO2 and low versus high AHI during exposure to HA and compared between subgroups. Results: Compared with SL, the mean nocturnal SpO2 was lower (p < 0.0001) and AHI was higher (p < 0.0001) at HA. The mean nocturnal SpO2 increased progressively (p < 0.001), whereas AHI remained high (p < 0.978) and relatively unchanged over nine successive nights at HA. Those with markedly reduced SpO2 upon arrival at HA exhibited progressive increases in the mean nocturnal SpO2 over time at HA compared with those with mild nocturnal desaturation. LLS rose at HA, but no differences were observed between subgroups. Conclusions: In healthy HA sojourners, the mean nocturnal SpO2 increased progressively over time, whereas AHI remained elevated, suggesting distinctive phenotypes and acclimatization responses to HA.
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Affiliation(s)
- Jia-Der Ju
- Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Cristian Zhang
- Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Francis P Sgambati
- Johns Hopkins Sleep Center and Center for Interdisciplinary Sleep Research Education, Baltimore, Maryland, USA
| | - Lidia M Lopez
- Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru.,Hospital Cayetano Heredia, Lima, Perú
| | - Luu V Pham
- Johns Hopkins Sleep Center and Center for Interdisciplinary Sleep Research Education, Baltimore, Maryland, USA.,Johns Hopkins School of Medicine, Baltimore, Maryland, USA
| | - Alan R Schwartz
- Adjunct Professor, Perelman School of Medicine, University of Pennsylvania, Lima, Perú.,Distinguished Visiting Professor, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Roberto A Accinelli
- Instituto de Investigaciones de la Altura, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Peru.,Hospital Cayetano Heredia, Lima, Perú
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3
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Carr J, Stone R, Tymko C, Tymko K, Coombs GB, Hoiland RL, Howe CA, Tymko MM, Ainslie PN, Patrician A. Global REACH 2018: The Effect of an Expiratory Resistance Mask with Dead Space on Sleep and Acute Mountain Sickness During Acute Exposure to Hypobaric Hypoxia. High Alt Med Biol 2020; 21:297-302. [DOI: 10.1089/ham.2019.0124] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Jay Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia–Okanagan Campus, Kelowna, Canada
| | - Rachel Stone
- Department of Kinesiology, University of Windsor, Windsor, Canada
| | - Courtney Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia–Okanagan Campus, Kelowna, Canada
| | - Kaitlyn Tymko
- Department of Kinesiology, University of Manitoba, Winnipeg, Canada
| | - Geoff B. Coombs
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia–Okanagan Campus, Kelowna, Canada
| | - Ryan L. Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia–Okanagan Campus, Kelowna, Canada
- Department of Anaesthesiology, Pharmacology, and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, Canada
| | - Connor A. Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia–Okanagan Campus, Kelowna, Canada
| | - Michael M. Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia–Okanagan Campus, Kelowna, Canada
| | - Philip N. Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia–Okanagan Campus, Kelowna, Canada
| | - Alexander Patrician
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia–Okanagan Campus, Kelowna, Canada
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Patrician A, Tymko MM, Caldwell HG, Howe CA, Coombs GB, Stone R, Hamilton A, Hoiland RL, Ainslie PN. The Effect of an Expiratory Resistance Mask with Dead Space on Sleep, Acute Mountain Sickness, Cognition, and Ventilatory Acclimatization in Normobaric Hypoxia. High Alt Med Biol 2019; 20:61-70. [PMID: 30720346 DOI: 10.1089/ham.2018.0074] [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: 12/11/2022] Open
Abstract
We examined the hypothesis that an expiratory resistance mask containing a small amount of dead space (ER/DS) would reduce the apnea-hypopnea index (AHI) during sleep, attenuate the severity of acute mountain sickness (AMS), and offset decrements in cognitive function compared with a sham mask. In a double-blinded, randomized, sham-controlled, crossover design, 19 volunteers were exposed to two nights of normobaric hypoxia (FIO2 = 0.125), using a ER/DS mask (3.5 mm restrictive expiratory orifice; 125 mL DS volume) and sham mask (zero-flow resistance; 50 mL DS volume). Cognitive function, AMS, and ventilatory acclimatization were assessed before and after the 12-hour normobaric hypoxia exposure. Polysomnography was conducted during sleep. AHI was reduced using the ER/DS sleep mask compared with the sham (30.1 ± 23.9 events·hr-1 vs. 58.9 ± 34.4 events·hr-1, respectively; p = 0.01). Likewise, oxygen desaturation index and headache severity were reduced (both p < 0.05). There were also benefits on limiting the hypoxia-induced reductions in select measures of reaction speed and attention (p < 0.05). Our study indicates that a simple noninvasive and portable ER/DS mask resulted in reductions (49%) in AHI, and reduced headache severity and aspects of cognitive decline. The field applications of this ER/DS mask should be investigated before recommendations can be made to support its benefit for travel to high altitude.
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Affiliation(s)
- Alexander Patrician
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Michael M Tymko
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Hannah G Caldwell
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Connor A Howe
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Geoff B Coombs
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Rachel Stone
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Allison Hamilton
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Ryan L Hoiland
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
| | - Philip N Ainslie
- Center for Heart, Lung and Vascular Health, University of British Columbia, Okanagan, Kelowna, Canada
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Muza SR. Wearable physiological sensors and real-time algorithms for detection of acute mountain sickness. J Appl Physiol (1985) 2018; 124:557-563. [DOI: 10.1152/japplphysiol.00367.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
This is a minireview of potential wearable physiological sensors and algorithms (process and equations) for detection of acute mountain sickness (AMS). Given the emerging status of this effort, the focus of the review is on the current clinical assessment of AMS, known risk factors (environmental, demographic, and physiological), and current understanding of AMS pathophysiology. Studies that have examined a range of physiological variables to develop AMS prediction and/or detection algorithms are reviewed to provide insight and potential technological roadmaps for future development of real-time physiological sensors and algorithms to detect AMS. Given the lack of signs and nonspecific symptoms associated with AMS, development of wearable physiological sensors and embedded algorithms to predict in the near term or detect established AMS will be challenging. Prior work using [Formula: see text], HR, or HRv has not provided the sensitivity and specificity for useful application to predict or detect AMS. Rather than using spot checks as most prior studies have, wearable systems that continuously measure SpO2 and HR are commercially available. Employing other statistical modeling approaches such as general linear and logistic mixed models or time series analysis to these continuously measured variables is the most promising approach for developing algorithms that are sensitive and specific for physiological prediction or detection of AMS.
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Affiliation(s)
- Stephen R. Muza
- Strategic Science Management Office, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Patrician A, Engan H, Lundsten D, Grote L, Vigetun-Haughey H, Schagatay E. The Effect of Dietary Nitrate on Nocturnal Sleep-Disordered Breathing and Arterial Oxygen Desaturation at High Altitude. High Alt Med Biol 2018; 19:21-27. [DOI: 10.1089/ham.2017.0039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Alexander Patrician
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Harald Engan
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
- LHL Klinikkene Röros, Norwegian Heart and Lung Patient Organization, Oslo, Norway
| | - David Lundsten
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Ludger Grote
- Pulmonary Medicine, Sleep Disorders Center, Sahlgrenska University Hospital, Gothenburg, Sweden
| | | | - Erika Schagatay
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
- Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden
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Tannheimer M, van der Spek R, Brenner F, Lechner R, Steinacker JM, Treff G. Oxygen saturation increases over the course of the night in mountaineers at high altitude (3050-6354 m). J Travel Med 2017; 24:3954788. [PMID: 28931132 DOI: 10.1093/jtm/tax041] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/24/2017] [Indexed: 11/13/2022]
Abstract
BACKGROUND Blood oxygen saturation (SpO 2 ) is frequently measured to determine acclimatization status in high-altitude travellers. However, little is known about nocturnal time course of SpO 2 (SpO 2N ), but alterations in SpO 2N might be practically relevant as well. To this end, we describe the time-course of SpO 2N in mountaineers at high altitude. METHODS SpO 2N was continuously measured in ten male mountaineers during a three-week expedition in Peru (3,050-6,354m). Average SpO 2N of the first (SpO 2N1 ) and second half (SpO 2N2 ) of an individual's sleep duration was calculated from 2h intervals of uninterrupted sleep. Heart rate oscillations and sleep dairies were used to exclude periods of wakefulness. SpO 2 was also measured at rest in the morning. RESULTS SpO 2N significantly increased from SpO 2N1 to SpO 2N2 . The magnitude of this increase (ΔSpO 2 ) was reduced with time spent at altitude. On night 1 (3,050m) SpO 2 increased from 83.4% (N1) to 86.3% (N2). At the same location on night 21, SpO 2 increased from 88.3% to 90.1%, which is a relative change of 4.7% and 2.0%, respectively. This pattern of increase in SpO 2N was perturbed when individual acclimatization was poor or altitude was extreme (5630m). SpO 2N was significantly lower than SpO 2 at rest in the morning. CONCLUSIONS This study is the first to demonstrate an increase of SpO 2 during the night in mountaineers at high altitude (3,050-6,354m) with high consistency between and within subjects. The magnitude of ΔSpO 2N decreased as acclimatization improved, suggesting that these changes in ΔSpO 2 between nights might be a valuable indicator of individual acclimatization. In addition, the failure of any increase in SpO 2N during the night might indicate insufficient acclimatization. Even though underlying mechanisms for the nocturnal increase remain unclear, the timing of SpO 2N measurement is obviously of utmost importance for its interpretation. Finally our study illustrates the detailed effects of ventilatory acclimatization over several weeks.
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Affiliation(s)
| | - Rianne van der Spek
- Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam
| | | | - Raimund Lechner
- Department of Anesthesiology, German Armed Forces Hospital Ulm
| | | | - Gunnar Treff
- Division of Sports and Rehabilitation Medicine, Universitat Ulm
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Donegani E, Paal P, Küpper T, Hefti U, Basnyat B, Carceller A, Bouzat P, van der Spek R, Hillebrandt D. Drug Use and Misuse in the Mountains: A UIAA MedCom Consensus Guide for Medical Professionals. High Alt Med Biol 2016; 17:157-184. [PMID: 27583821 DOI: 10.1089/ham.2016.0080] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Donegani, Enrico, Peter Paal, Thomas Küpper, Urs Hefti, Buddha Basnyat, Anna Carceller, Pierre Bouzat, Rianne van der Spek, and David Hillebrandt. Drug use and misuse in the mountains: a UIAA MedCom consensus guide for medical professionals. High Alt Med Biol. 17:157-184, 2016.-Aims: The aim of this review is to inform mountaineers about drugs commonly used in mountains. For many years, drugs have been used to enhance performance in mountaineering. It is the UIAA (International Climbing and Mountaineering Federation-Union International des Associations d'Alpinisme) Medcom's duty to protect mountaineers from possible harm caused by uninformed drug use. The UIAA Medcom assessed relevant articles in scientific literature and peer-reviewed studies, trials, observational studies, and case series to provide information for physicians on drugs commonly used in the mountain environment. Recommendations were graded according to criteria set by the American College of Chest Physicians. RESULTS Prophylactic, therapeutic, and recreational uses of drugs relevant to mountaineering are presented with an assessment of their risks and benefits. CONCLUSIONS If using drugs not regulated by the World Anti-Doping Agency (WADA), individuals have to determine their own personal standards for enjoyment, challenge, acceptable risk, and ethics. No system of drug testing could ever, or should ever, be policed for recreational climbers. Sponsored climbers or those who climb for status need to carefully consider both the medical and ethical implications if using drugs to aid performance. In some countries (e.g., Switzerland and Germany), administrative systems for mountaineering or medication control dictate a specific stance, but for most recreational mountaineers, any rules would be unenforceable and have to be a personal decision, but should take into account the current best evidence for risk, benefit, and sporting ethics.
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Affiliation(s)
- Enrico Donegani
- 1 Department of Cardiovascular Surgery, Sabah Al-Ahmed Cardiac Center , Al-Amiri Hospital, Kuwait, State of Kuwait
| | - Peter Paal
- 2 Department of Anaesthesiology and Critical Care Medicine, Innsbruck University Hospital , Innsbruck, Austria .,3 Department of Perioperative Medicine, Barts Heart Centre, St. Bartholomew's Hospital, Barts Health NHS Trust, Queen Mary University of London, London, United Kingdom .,4 Perioperative Medicine, St. Bartholomew's Hospital , London, United Kingdom
| | - Thomas Küpper
- 5 Institute of Occupational and Social Medicine, RWTH Aachen University , Aachen, Germany
| | - Urs Hefti
- 6 Department of Orthopedic and Trauma Surgery, Swiss Sportclinic , Bern, Switzerland
| | - Buddha Basnyat
- 7 Oxford University Clinical Research Unit-Nepal , Nepal International Clinic, and Himalayan Rescue, Kathmandu, Nepal
| | - Anna Carceller
- 8 Sports Medicine School, Instituto de Medicina de Montaña y del Deporte (IMMED), Federació d'Entitats Excursionistes (FEEC), University of Barcelona , Barcelona, Spain
| | - Pierre Bouzat
- 9 Department of Anesthesiology and Critical Care, University Hospital, INSERM U1236, Neuroscience Institute, Alps University, Grenoble, France
| | - Rianne van der Spek
- 10 Department of Endocrinology and Metabolism, Academic Medical Center Amsterdam, University of Amsterdam , Amsterdam, The Netherlands
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Tellez HF, Morrison SA, Neyt X, Mairesse O, Piacentini MF, Macdonald-Nethercott E, Pangerc A, Dolenc-Groselj L, Eiken O, Pattyn N, Mekjavic IB, Meeusen R. Exercise during Short-Term and Long-Term Continuous Exposure to Hypoxia Exacerbates Sleep-Related Periodic Breathing. Sleep 2016; 39:773-83. [PMID: 26951389 PMCID: PMC4791611 DOI: 10.5665/sleep.5626] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 11/21/2015] [Indexed: 12/21/2022] Open
Abstract
STUDY OBJECTIVES Exposure to hypoxia elevates chemosensitivity, which can lead to periodic breathing. Exercise impacts gas exchange, altering chemosensitivity; however, interactions between sleep, exercise and chronic hypoxic exposure have not been examined. This study investigated whether exercise exacerbates sleep-related periodic breathing in hypoxia. METHODS Two experimental phases. Short-Term Phase: a laboratory controlled, group-design study in which 16 active, healthy men (age: 25 ± 3 y, height: 1.79 ± 0.06 m, mass: 74 ± 8 kg) were confined to a normobaric hypoxic environment (FIO2 = 0.139 ± 0.003, 4,000 m) for 10 days, after random assignment to a sedentary (control, CON) or cycle-exercise group (EX). Long-Term Phase: conducted at the Concordia Antarctic Research Station (3,800 m equivalent at the Equator) where 14 men (age: 36 ± 9 y, height: 1.77 ± 0.09 m, mass: 75 ± 10 kg) lived for 12-14 months, continuously confined. Participants were stratified post hoc based on self-reported physical activity levels. We quantified apnea-hypopnea index (AHI) and physical activity variables. RESULTS Short-Term Phase: mean AHI scores were significantly elevated in the EX group compared to CON (Night1 = CON: 39 ± 51, EX: 91 ± 59; Night10 = CON: 32 ± 32, EX: 92 ± 48; P = 0.046). Long-Term Phase: AHI was correlated to mean exercise time (R(2) = 0.4857; P = 0.008) and the coefficient of variation in night oxyhemoglobin saturation (SpO2; R(2) = 0.3062; P = 0.049). CONCLUSIONS Data indicate that exercise (physical activity) per se affects night SpO2 concentrations and AHI after a minimum of two bouts of moderate-intensity hypoxic exercise, while habitual physical activity in hypobaric hypoxic confinement affects breathing during sleep, up to 13+ months' duration.
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Affiliation(s)
- Helio Fernandez Tellez
- Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium
- Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium
| | - Shawnda A. Morrison
- Department of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
- Institute of Clinical Neurophysiology, University Clinical Centre, Ljubljana, Slovenia
| | - Xavier Neyt
- Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium
- Royal Military Academy Brussels, CISS, Brussels, Belgium
| | - Olivier Mairesse
- Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium
- Sleep Laboratory & Unit for Chronobiology-Brugmann University Hospital Free University of Brussels (U.L.B./V.U.B), Brussels, Belgium
| | - Maria Francesca Piacentini
- Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium
- Department of Movement, Human and Health Sciences, University of Rome Foro Italico, Rome, Italy
| | - Eoin Macdonald-Nethercott
- JF Intensive Care Unit, Addenbrooke's Hospital, Cambridge, United Kingdom
- Institut polaire français Paul-Emile Victor, Technopôle Brest-Iroise, Plouzané, France
| | - Andrej Pangerc
- Institute of Clinical Neurophysiology, University Clinical Centre, Ljubljana, Slovenia
| | - Leja Dolenc-Groselj
- Institute of Clinical Neurophysiology, University Clinical Centre, Ljubljana, Slovenia
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Nathalie Pattyn
- Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium
- Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium
- Experimental and Applied Psychology Department, Brussels, Belgium
| | - Igor B. Mekjavic
- Department of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - Romain Meeusen
- Vrije Universiteit Brussels, Human Physiology & Sports Medicine Department, Brussels, Belgium
- School of Public Health, Tropical Medicine and Health Sciences, James Cook University, Townsville City, Queensland, Australia
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Lipman GS, Kanaan NC, Phillips C, Pomeranz D, Cain P, Fontes K, Higbee B, Meyer C, Shaheen M, Wentworth S, Walsh D. Study Looking at End Expiratory Pressure for Altitude Illness Decrease (SLEEP-AID). High Alt Med Biol 2015; 16:154-61. [DOI: 10.1089/ham.2014.1110] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Grant S. Lipman
- Stanford University School of Medicine, Stanford, California
| | | | | | - Dave Pomeranz
- LA County—USC Emergency Medicine Residency, Los Angeles, California
| | - Patrick Cain
- Midwestern University Emergency Medicine Residency, Chicago, Illinois
| | - Kristin Fontes
- Stanford—Kaiser Emergency Medicine Residency, Palo Alto, California
| | - Becky Higbee
- Stanford—Kaiser Emergency Medicine Residency, Palo Alto, California
| | - Carolyn Meyer
- St. Luke's–Roosevelt Emergency Medicine Residency, New York City, New York
| | - Michael Shaheen
- Stanford—Kaiser Emergency Medicine Residency, Palo Alto, California
| | - Sean Wentworth
- University of Arizona Emergency Medicine Residency, Tucson, Arizona
| | - Diane Walsh
- University of Utah Medical School, Salt Lake City, Utah
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Abstract
Problems at altitude are most often thought of in trained athletes summiting extremes of elevation. A more common group that needs consideration is the average person with obstructive sleep apnea who must travel to high altitudes for business or pleasure. While the altitudes involved are not likely to be as extreme as for those athletes climbing peaks like Mt. Everest, the increases in elevation may present difficulties for patients, especially if overnight stay is expected. The pathophysiology of altitude-related CNS, respiratory, and sleep disorders is discussed along with treatment options.
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Affiliation(s)
- Terry Rolan
- Department of Neurology, University of Missouri, Columbia
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12
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Tellez HF, Pattyn N, Mairesse O, Dolenc-Groselj L, Eiken O, Mekjavic IB, Migeotte PF, Macdonald-Nethercott E, Meeusen R, Neyt X. eAMI: a qualitative quantification of periodic breathing based on amplitude of oscillations. Sleep 2015; 38:381-9. [PMID: 25581914 DOI: 10.5665/sleep.4494] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 09/26/2014] [Indexed: 12/16/2022] Open
Abstract
STUDY OBJECTIVES Periodic breathing is sleep disordered breathing characterized by instability in the respiratory pattern that exhibits an oscillatory behavior. Periodic breathing is associated with increased mortality, and it is observed in a variety of situations, such as acute hypoxia, chronic heart failure, and damage to respiratory centers. The standard quantification for the diagnosis of sleep related breathing disorders is the apnea-hypopnea index (AHI), which measures the proportion of apneic/ hypopneic events during polysomnography. Determining the AHI is labor-intensive and requires the simultaneous recording of airflow and oxygen saturation. In this paper, we propose an automated, simple, and novel methodology for the detection and qualification of periodic breathing: the estimated amplitude modulation index (eAMI). PATIENTS OR PARTICIPANTS Antarctic Cohort (3800 meters): 13 normal individuals. Sleep Clinic Cohort: 39 different patients suffering from diverse sleep-related pathologies. MEASUREMENTS AND RESULTS When tested in a population with high levels of periodic breathing (Antarctic Cohort), eAMI was closely correlated with AHI (r = 0.95, P < 0.001). When tested in the clinical setting, the proposed method was able to detect portions of the signal in which subclinical periodic breathing was validated by an expert (n = 93; accuracy = 0.85). Average eAMI was also correlated with the loop gain for the combined clinical and Antarctica cohorts (r = 0.58, P < 0.001). CONCLUSIONS In terms of quantification and temporal resolution, the eAMI is able to estimate the strength of periodic breathing and the underlying loop gain at any given time within a record. The impaired prognosis associated with periodic breathing makes its automated detection and early diagnosis of clinical relevance.
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Affiliation(s)
- Helio Fernandez Tellez
- Vrije Universiteit Brussel, Human Physiology & Sportsmedicine Department, Brussels, Belgium.,Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium
| | - Nathalie Pattyn
- Vrije Universiteit Brussel, Human Physiology & Sportsmedicine Department, Brussels, Belgium.,Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.,Vrije Universiteit Brussels, Biological Psychology Department, Brussels, Belgium
| | - Olivier Mairesse
- Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.,Vrije Universiteit Brussels, Biological Psychology Department, Brussels, Belgium.,Sleep Laboratory & Unit for Chronobiology - Brugmann University Hospital Free University of Brussels, Brussels, Belgium
| | - Leja Dolenc-Groselj
- Clinical Institute of Clinical Neurophysiology, University Clinical Centre, Ljubljana, Slovenia
| | - Ola Eiken
- Department of Environmental Physiology, Swedish Aerospace Physiology Centre, Royal Institute of Technology, Stockholm, Sweden
| | - Igor B Mekjavic
- Deptartment of Automation, Biocybernetics, and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia
| | - P F Migeotte
- Université Libre de Bruxelles, Erasmus Hospital, Brussels, Belgium
| | - Em Macdonald-Nethercott
- The Princess Alexandra Hospital NHS Trust, Harlow, UK.,Institut polaire français Paul-Emile Victor, France
| | - Romain Meeusen
- Vrije Universiteit Brussel, Human Physiology & Sportsmedicine Department, Brussels, Belgium
| | - Xavier Neyt
- Royal Military Academy of Brussels, VIPER Research Unit, Brussels, Belgium.,CISS Department, Royal Military Academy of Brussels, Brussels, Belgium
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Impact of rapid ascent to high altitude on sleep. Sleep Breath 2014; 19:819-26. [PMID: 25491080 DOI: 10.1007/s11325-014-1093-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 11/24/2014] [Accepted: 11/30/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE Sleep disturbance at high altitude is common in climbers. In this study, we intended to evaluate the effect of rapid ascent on sleep architecture using polysomnography (PSG) and to compare the differences between subjects with and without acute mountain sickness (AMS). METHODS The study included 40 non-acclimatized healthy subjects completing PSG at four time points, 3 days before the ascent (T0), two successive nights at 3150 m (T1 and T2), and 2 days after the descent (T3). All subjects were transported by bus from 555 to 3150 m within 3 h. AMS was diagnosed using self-reported questionnaire of Lake Louise score. RESULTS Twenty of 40 (50%) subjects developed AMS. At high altitude, awakening percentages increased in AMS group but changed insignificantly in non-AMS group. Arousal index and apnea/hypopnea index (AHI) increased irrespective of AMS. The increases of AHI were more evident in non-AMS group than in AMS group. Compared to subjects without AMS, those with AMS had significantly lower sleep efficiency, lower central apnea index, and longer latencies to sleep and rapid eye movement (REM) sleep at T1 and lower REM sleep percentages at T1 and T2. Subjects with older age and lower minimum arterial oxygen saturation during sleep at sea level were prone to develop AMS. CONCLUSIONS Higher AHI did not cause more frequent awakenings and arousals at high altitude. Central sleep apneas were observed in non-AMS but not in AMS group. Subjects unacclimatized to acute hypobaric hypoxia might have delayed and less REM sleep.
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Macinnis MJ, Lanting SC, Rupert JL, Koehle MS. Is poor sleep quality at high altitude separate from acute mountain sickness? Factor structure and internal consistency of the Lake Louise Score Questionnaire. High Alt Med Biol 2014; 14:334-7. [PMID: 24377339 DOI: 10.1089/ham.2013.1030] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The factor structure and internal consistency of the Lake Louise Score Questionnaire (LLSQ) have not been determined in a large population at high altitude; however, a single-factor structure and a high internal consistency are preferable for accurate clinical and research applications of the LLSQ. METHODS A large group of Nepalese pilgrims (n=491) were assessed for acute mountain sickness with a verbal Nepali translation of the LLSQ after rapidly ascending from 1950 m to 4380 m. The factor structure and internal consistency of the LLSQ were determined with a confirmatory factor analysis (CFA) and the ordinal alpha coefficient, respectively. RESULTS A one-factor structure with all five items of the LLSQ was accepted. Four items (headache, gastrointestinal upset, fatigue/weakness, and dizziness/lightheadedness) loaded strongly on this factor (>0.70), but sleep quality had a low factor loading (0.33). The internal consistency (ordinal alpha coefficient) was 0.79, but removing the sleep quality item improved this value to 0.84. CONCLUSIONS The sleep quality item of the LLSQ was weakly related to the other items of the LLSQ. Future research should further investigate whether impaired sleep at altitude should be considered separately from other symptoms of AMS.
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Affiliation(s)
- Martin J Macinnis
- 1 School of Kinesiology, University of British Columbia , Vancouver, Canada
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Latshang TD, Lo Cascio CM, Stöwhas AC, Grimm M, Stadelmann K, Tesler N, Achermann P, Huber R, Kohler M, Bloch KE. Are nocturnal breathing, sleep, and cognitive performance impaired at moderate altitude (1,630-2,590 m)? Sleep 2013; 36:1969-76. [PMID: 24293773 PMCID: PMC3825448 DOI: 10.5665/sleep.3242] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Newcomers at high altitude (> 3,000 m) experience periodic breathing, sleep disturbances, and impaired cognitive performance. Whether similar adverse effects occur at lower elevations is uncertain, although numerous lowlanders travel to moderate altitude for professional or recreational activities. We evaluated the hypothesis that nocturnal breathing, sleep, and cognitive performance of lowlanders are impaired at moderate altitude. DESIGN Randomized crossover trial. SETTING University hospital at 490 m, Swiss mountain villages at 1,630 m and 2,590 m. PARTICIPANTS Fifty-one healthy men, median (quartiles) age 24 y (20-28 y), living below 800 m. INTERVENTIONS Studies at Zurich (490 m) and during 4 consecutive days at 1,630 m and 2,590 m, respectively, 2 days each. The order of altitude exposure was randomized. Polysomnography, psychomotor vigilance tests (PVT), the number back test, several other tests of cognitive performance, and questionnaires were evaluated. MEASUREMENTS AND RESULTS The median (quartiles) apnea-hypopnea index at 490 m was 4.6/h (2.3; 7.9), values at 1,630 and 2,590 m, day 1 and 2, respectively, were 7.0/h (4.1; 12.6), 5.4/h (3.5; 10.5), 13.1/h (6.7; 32.1), and 8.0/h (4.4; 23.1); corresponding values of mean nocturnal oxygen saturation were 96% (95; 96), 94% (93; 95), 94% (93; 95), 90% (89; 91), 91% (90; 92), P < 0.05 versus 490 m, all instances. Slow wave sleep on the first night at 2,590 m was 21% (18; 25) versus 24% (20; 27) at 490 m (P < 0.05). Psychomotor vigilance and various other measures of cognitive performance did not change significantly. CONCLUSIONS Healthy men acutely exposed during 4 days to hypoxemia at 1,630 m and 2,590 m reveal a considerable amount of periodic breathing and sleep disturbances. However, no significant effects on psychomotor reaction speed or cognitive performance were observed. CLINICAL TRIALS REGISTRATION Clinicaltrials.gov: NCT01130948.
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Affiliation(s)
| | | | | | - Mirjam Grimm
- Sleep Disorders Center and Pulmonary Division, University Hospital Zurich
| | | | - Noemi Tesler
- Child Development Center, Children's University Hospital Zurich
| | - Peter Achermann
- Institute of Pharmacology and Toxicology, University of Zurich
- Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
| | - Reto Huber
- Child Development Center, Children's University Hospital Zurich
- Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
| | - Malcolm Kohler
- Sleep Disorders Center and Pulmonary Division, University Hospital Zurich
- Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
| | - Konrad E. Bloch
- Sleep Disorders Center and Pulmonary Division, University Hospital Zurich
- Zurich Center for Integrative Human Physiology, University of Zurich, Switzerland
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MacInnis MJ, Carter EA, Freeman MG, Pandit BP, Siwakoti A, Subedi A, Timalsina U, Widmer N, Thapa GB, Koehle MS, Rupert JL. A prospective epidemiological study of acute mountain sickness in Nepalese pilgrims ascending to high altitude (4380 m). PLoS One 2013; 8:e75644. [PMID: 24130729 PMCID: PMC3794000 DOI: 10.1371/journal.pone.0075644] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 08/16/2013] [Indexed: 01/14/2023] Open
Abstract
Background Each year, thousands of pilgrims travel to the Janai Purnima festival in Gosainkunda, Nepal (4380 m), ascending rapidly and often without the aid of pharmaceutical prophylaxis. Methods During the 2012 Janai Purnima festival, 538 subjects were recruited in Dhunche (1950 m) before ascending to Gosainkunda. Through interviews, subjects provided demographic information, ratings of AMS symptoms (Lake Louise Scores; LLS), ascent profiles, and strategies for prophylaxis. Results In the 491 subjects (91% follow-up rate) who were assessed upon arrival at Gosainkunda, the incidence of AMS was 34.0%. AMS was more common in females than in males (RR = 1.57; 95% CI = 1.23, 2.00), and the AMS incidence was greater in subjects >35 years compared to subjects ≤35 years (RR = 1.63; 95% CI = 1.36, 1.95). There was a greater incidence of AMS in subjects who chose to use garlic as a prophylactic compared to those who did not (RR = 1.69; 95% CI = 1.26, 2.28). Although the LLS of brothers had a moderate correlation (intraclass correlation = 0.40, p = 0.023), sibling AMS status was a weak predictor of AMS. Conclusions The incidence of AMS upon reaching 4380 m was 34% in a large population of Nepalese pilgrims. Sex, age, and ascent rate were significant factors in the development of AMS, and traditional Nepalese remedies were ineffective in the prevention of AMS.
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Affiliation(s)
- Martin J. MacInnis
- School of Kinesiology, University of British Columbia, Vancouver, Canada
- * E-mail:
| | - Eric A. Carter
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | | | - Bidur Prasad Pandit
- Maharajgunj Medical Campus, Institute of Medicine, Tribhuvan University, Nepal
| | - Ashmita Siwakoti
- Maharajgunj Medical Campus, Institute of Medicine, Tribhuvan University, Nepal
| | - Ankita Subedi
- Maharajgunj Medical Campus, Institute of Medicine, Tribhuvan University, Nepal
| | - Utsav Timalsina
- Maharajgunj Medical Campus, Institute of Medicine, Tribhuvan University, Nepal
| | - Nadia Widmer
- Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Ghan Bahadur Thapa
- Maharajgunj Medical Campus, Institute of Medicine, Tribhuvan University, Nepal
| | - Michael S. Koehle
- School of Kinesiology, University of British Columbia, Vancouver, Canada
- Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Jim L. Rupert
- School of Kinesiology, University of British Columbia, Vancouver, Canada
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Ainslie PN, Lucas SJ, Burgess KR. Breathing and sleep at high altitude. Respir Physiol Neurobiol 2013; 188:233-56. [DOI: 10.1016/j.resp.2013.05.020] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Revised: 05/04/2013] [Accepted: 05/16/2013] [Indexed: 10/26/2022]
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Castiglioni P, Meriggi P, Rizzo F, Vaini E, Faini A, Parati G, Di Rienzo M. Seismocardiography while sleeping at high altitude. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:3793-6. [PMID: 23366754 DOI: 10.1109/embc.2012.6346793] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Current advancements in sensor technology allow the prolonged assessment of the seismocadiogram (SCG) out of the laboratory setting. Aim of this study is to evaluate whether SCG, as measured by a recently proposed wearable device, can detect cardio-respiratory alterations during sleep in healthy subjects exposed to high altitude hypoxia.
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Affiliation(s)
- Paolo Castiglioni
- Biomedical Technology Dept., Don C. Gnocchi Foundation, via Capecelatro 66, I 20148 Milan, Italy.
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Nussbaumer-Ochsner Y, Schuepfer N, Ursprung J, Siebenmann C, Maggiorini M, Bloch KE. Sleep and breathing in high altitude pulmonary edema susceptible subjects at 4,559 meters. Sleep 2012; 35:1413-21. [PMID: 23024440 PMCID: PMC3443768 DOI: 10.5665/sleep.2126] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Susceptible subjects ascending rapidly to high altitude develop pulmonary edema (HAPE). We evaluated whether HAPE leads to sleep and breathing disturbances that are alleviated by dexamethasone. DESIGN Double-blind, randomized, placebo-controlled trial with open-label extension. SETTING One night in sleep laboratory at 490 m, 2 nights in mountain hut at 4,559 m. PARTICIPANTS 21 HAPE susceptibles. INTERVENTION Dexamethasone 2 × 8 mg/d, either 24 h prior to ascent and at 4,559 m (dex-early), or started on day 2 at 4,559 m only (dex-late). MEASUREMENTS Polysomnography, questionnaires on sleep and acute mountain sickness. RESULTS Polysomnographies at 490 m were normal. In dex-late (n = 12) at 4,559 m, night 1 and 3, median oxygen saturation was 71% and 80%, apnea/hypopnea index 91.3/h and 9.6/h. In dex-early (n = 9), corresponding values were 78% and 79%, and 85.3/h and 52.3/h (P < 0.05 vs. 490 m, all instances). In dex-late, ascending from 490 m to 4,559 m (night 1), sleep efficiency decreased from 91% to 65%, slow wave sleep from 20% to 8% (P < 0.05, both instances). In dex-early, corresponding sleep efficiencies were 96% and 95%, slow wave sleep 18% and 9% (P < 0.05). From night 1 to 3, sleep efficiency remained unchanged in both groups while slow wave sleep increased to 20% in dex-late (P < 0.01). Compared to dex-early, initial AMS scores in dex-late were higher but improved during stay at altitude. CONCLUSIONS HAPE susceptibles ascending rapidly to high altitude experience pronounced nocturnal hypoxemia, and reduced sleep efficiency and deep sleep. Dexamethasone taken before ascent prevents severe hypoxemia and sleep disturbances, while dexamethasone taken 24 h after arrival at 4,559 m increases oxygenation and deep sleep.
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Affiliation(s)
- Yvonne Nussbaumer-Ochsner
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Nicole Schuepfer
- Institute of Human Movement Sciences and Sports, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Justyna Ursprung
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Christoph Siebenmann
- Institute of Human Movement Sciences and Sports, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Marco Maggiorini
- Medical Intensive Care Unit, University Hospital of Zurich, and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Konrad E. Bloch
- Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, and Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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Clarenbach CF, Senn O, Christ AL, Fischler M, Maggiorini M, Bloch KE. Lung function and breathing pattern in subjects developing high altitude pulmonary edema. PLoS One 2012; 7:e41188. [PMID: 22829927 PMCID: PMC3400591 DOI: 10.1371/journal.pone.0041188] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 06/18/2012] [Indexed: 11/18/2022] Open
Abstract
Introduction The purpose of the study was to comprehensively evaluate physiologic changes associated with development of high altitude pulmonary edema (HAPE). We tested whether changes in pulmonary function and breathing pattern would herald clinically overt HAPE at an early stage. Methods In 18 mountaineers, spirometry, diffusing capacity, nitrogen washout, nocturnal ventilation and pulse oximetry were recorded at 490 m and during 3 days after rapid ascent to 4559 m. Findings were compared among subjects developing HAPE and those remaining well (controls). Results In 8 subjects subsequently developing radiographically documented HAPE at 4559 m, median FVC declined to 82% of low altitude baseline while closing volume increased to 164% of baseline (P<0.05, both instances). In 10 controls, FVC decreased slightly (to 93% baseline, P<0.05) but significantly less than in subjects with HAPE and closing volume remained unchanged. Sniff nasal pressure was reduced in both subjects with and without subsequent HAPE. During nights at 4559 m, mean nocturnal oxygen saturation dropped to lower values while minute ventilation, the number of periodic breathing cycles and heart rate were higher (60%; 8.6 L/min; 97 cycles/h; 94 beats/min, respectively) in subjects subsequently developing HAPE than in controls (73%; 5.1 L/min; 48 cycles/h; 79 beats/min; P<0.05 vs. HAPE, all instances). Conclusion The results comprehensively represent the pattern of physiologic alterations that precede overt HAPE. The changes in lung function are consistent with reduced lung compliance and impaired gas exchange. Pronounced nocturnal hypoxemia, ventilatory control instability and sympathetic stimulation are further signs of subsequent overt HAPE. Registration ClinicalTrials.gov identifier: NCT00274430
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Affiliation(s)
| | - Oliver Senn
- Pulmonary Division, University Hospital Zurich, Zurich, Switzerland
| | | | - Manuel Fischler
- Medical Intensive Care Unit, University Hospital Zurich, Zurich, Switzerland
| | - Marco Maggiorini
- Medical Intensive Care Unit, University Hospital Zurich, Zurich, Switzerland
- Center for Human Integrative Physiology, University of Zurich, Zurich, Switzerland
| | - Konrad E. Bloch
- Pulmonary Division, University Hospital Zurich, Zurich, Switzerland
- Center for Human Integrative Physiology, University of Zurich, Zurich, Switzerland
- * E-mail:
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Bloch KE, Latshang TD, Turk AJ, Hess T, Hefti U, Merz TM, Bosch MM, Barthelmes D, Hefti JP, Maggiorini M, Schoch OD. Nocturnal periodic breathing during acclimatization at very high altitude at Mount Muztagh Ata (7,546 m). Am J Respir Crit Care Med 2010; 182:562-8. [PMID: 20442435 DOI: 10.1164/rccm.200911-1694oc] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Quantitative data on ventilation during acclimatization at very high altitude are scant. Therefore, we monitored nocturnal ventilation and oxygen saturation in mountaineers ascending Mt. Muztagh Ata (7,546 m). OBJECTIVES To investigate whether periodic breathing persists during prolonged stay at very high altitude. METHODS A total of 34 mountaineers (median age, 46 yr; 7 women) climbed from 3,750 m within 19-20 days to the summit at 7,546 m. During ascent, repeated nocturnal recordings of calibrated respiratory inductive plethysmography, pulse oximetry, and scores of acute mountain sickness were obtained. MEASUREMENTS AND MAIN RESULTS Nocturnal oxygen saturation decreased, whereas minute ventilation and the number of periodic breathing cycles increased with increasing altitude. At the highest camp (6,850 m), median nocturnal oxygen saturation, minute ventilation, and the number of periodic breathing cycles were 64%, 11.3 L/min, and 132.3 cycles/h. Repeated recordings within 5-8 days at 4,497 m and 5,533 m, respectively, revealed increased oxygen saturation, but no decrease in periodic breathing. The number of periodic breathing cycles was positively correlated with days of acclimatization, even when controlled for altitude, oxygen saturation, and other potential confounders, whereas symptoms of acute mountain sickness had no independent effect on periodic breathing. CONCLUSIONS Our field study provides novel data on nocturnal oxygen saturation, breathing patterns, and ventilation at very high altitude. It demonstrates that periodic breathing increases during acclimatization over 2 weeks at altitudes greater than 3,730 m, despite improved oxygen saturation consistent with a progressive increase in loop gain of the respiratory control system. Clinical trial registered with www.clinicaltrials.gov (NCT00514826).
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Affiliation(s)
- Konrad E Bloch
- Department of Internal Medicine, University Hospital of Zurich, Zurich Centre for Integrative Human Physiology, University of Zurich, Switzerland.
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Johnson PL, Popa DA, Prisk GK, Edwards N, Sullivan CE. Non-invasive positive pressure ventilation during sleep at 3800 m: Relationship to acute mountain sickness and sleeping oxyhaemoglobin saturation. Respirology 2009; 15:277-82. [PMID: 20051046 DOI: 10.1111/j.1440-1843.2009.01678.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
UNLABELLED Overnight oxyhaemoglobin desaturation is related to AMS. AMS can be debilitating and may require descent. Positive pressure ventilation during sleep at high altitude may prevent AMS and therefore be useful in people travelling to high altitude, who are known to suffer from AMS. BACKGROUND AND OBJECTIVE Ascent to high altitude results in hypobaric hypoxia and some individuals will develop acute mountain sickness (AMS), which has been shown to be associated with low oxyhaemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake results in a reduction in AMS symptoms and higher oxyhaemoglobin saturation. We aimed to determine whether positive pressure ventilation would prevent AMS by increasing oxygenation during sleep. METHODS We compared sleeping oxyhaemoglobin saturation and the incidence and severity of AMS in seven subjects sleeping for two consecutive nights at 3800 m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of AMS were assessed by administration of the Lake Louise questionnaire. RESULTS We found significant increases in the mean and minimum sleeping oxyhaemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. CONCLUSIONS The use of positive pressure ventilation during sleep at 3800 m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation.
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Affiliation(s)
- Pamela L Johnson
- David Read Laboratory, Department of Medicine, University of Sydney, Australia.
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Mees K, de la Chaux R. Polygraphy of Sleep at Altitudes Between 5300m and 7500m During an Expedition to Mt. Everest (MedEx 2006). Wilderness Environ Med 2009; 20:161-5. [DOI: 10.1580/08-weme-br-187r2.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Küpper TEAH, Strohl KP, Hoefer M, Gieseler U, Netzer CM, Netzer NC. Low-dose theophylline reduces symptoms of acute mountain sickness. J Travel Med 2008; 15:307-14. [PMID: 19006503 DOI: 10.1111/j.1708-8305.2008.00228.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Headache, nausea, and sleeplessness at altitude [acute mountain sickness (AMS)] are major health problems for several million mountain recreationists who ascend to high altitudes each year. We aimed to test the efficacy of low-dose, slow-release theophylline for the prevention of AMS in a placebo-controlled, double-blind, randomized trial. METHODS Twenty healthy male volunteers (mean age 34.7 y) were randomized (random allocation) to receive either 300 mg theophylline daily or placebo 5 days prior, during ascent, and during a stay at 4,559 m altitude. AMS symptoms were collected using the Lake Louise Score on each day during ascent and at high altitude. A 12-channel sleep recorder recorded sleep and breathing parameters during the first night at 4,559 m. Theophylline serum levels were drawn prior to the sleep study. RESULTS Seventeen completed the entire study. Theophylline (n = 9) compared to placebo (n = 8) significantly reduced AMS symptoms at 4,559 m (Lake Louise Score: 1.5 +/- 0.5 vs placebo 2.3 +/- 2.37; p < 0.001), events of periodic breathing (34.3/h vs placebo 74.2/h; p < 0.05), and oxygen desaturations (62.3/h vs placebo 121.6/h; p < 0.01). No significant differences in sleep efficiency or sleep structure were present in the two groups. No adverse drug effects were reported. CONCLUSIONS Low-dose, slow-release theophylline reduces symptoms of AMS in association with alleviation of events of periodic breathing and oxygen desaturations.
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Affiliation(s)
- Thomas E A H Küpper
- Hermann Buhl Institute for Hypoxia Research and Sleep Medicine, Paracelsus Medical University Salzburg, Bad Aibling, Germany.
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Bärtsch P, Saltin B. General introduction to altitude adaptation and mountain sickness. Scand J Med Sci Sports 2008; 18 Suppl 1:1-10. [DOI: 10.1111/j.1600-0838.2008.00827.x] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Snyder EM, Stepanek J, Bishop SL, Johnson BD. Ventilatory Responses to Hypoxia and High Altitude During Sleep in Aconcagua Climbers. Wilderness Environ Med 2007; 18:138-45. [PMID: 17590060 DOI: 10.1580/06-weme-br-041r.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND/OBJECTIVE We examined the changes in ventilation during sleep at high altitude using the LifeShirt monitoring system on 2 climbers who were attempting to summit Mount Aconcagua (6956 m). METHODS Prior to the summit attempt, we measured cardiovascular and pulmonary function at 401 m (Rochester, MN) and gathered respiratory and cardiovascular data during sleep using the LifeShirt monitoring system with exposure to normobaric normoxia and normobaric hypoxia (simulated 4300 m). We then monitored the ventilatory response during sleep at 3 altitudes (4100 m, 4900 m, and 5900 m). RESULTS During normoxic sleep, subjects had normal oxygen saturation (O(2sat)), heart rate (HR), respiratory rate (RR), tidal volume (V(T)) and minute ventilation (V(E)), and exhibited no periodic breathing (O(2sat) = 100 +/- 2%, HR = 67 +/- 1 beats/min, RR = 16 +/- 3 breaths/min, V(T) = 516 +/- 49 mL, and V(E) = 9 +/- 1 L/min, mean +/- SD). Sleep during simulated 4300 m caused a reduction in O(2sat), an increase in HR, RR, V(T), and V(E), and induced periodic breathing in both climbers (O(2sat) = 79 +/- 4%, HR = 72 +/- 14 beats/min, RR = 20 +/- 3 breaths/min, V(T) = 701 +/- 180 mL, and V(E) = 14 +/- 3 L/min). All 3 levels of altitude had profound effects on O(2sat), HR, and the ventilatory strategy during sleep (O(2sat) = 79 +/- 2, 70 +/- 8, 60 +/- 2%; HR = 70 +/- 12, 76 +/- 6, 80 +/- 3 beats/min; RR = 17 +/- 6, 18 +/- 4, 20 +/- 6 breaths/min; V(T) = 763 +/- 300, 771 +/- 152, 1145 +/- 123 mL; and V(E) = 13 +/- 1, 14 +/- 0, 22 +/- 4 L/min; for 4100 m, 4900 m, and 5900 m, respectively). There were strong negative correlations between O(2sat) and V(E) and ventilatory drive (V(T)/T(i), where T(i) is the inspiratory time) throughout the study. CONCLUSIONS Interestingly, the changes in ventilatory response during simulated altitude and at comparable altitude on Aconcagua during the summit attempt were similar, suggesting reductions in FiO(2), rather than in pressure, alter this response.
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Affiliation(s)
- Eric M Snyder
- Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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Leaf DE, Goldfarb DS. Mechanisms of action of acetazolamide in the prophylaxis and treatment of acute mountain sickness. J Appl Physiol (1985) 2006; 102:1313-22. [PMID: 17023566 DOI: 10.1152/japplphysiol.01572.2005] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Acetazolamide, a potent carbonic anhydrase (CA) inhibitor, is the most commonly used and best-studied agent for the amelioration of acute mountain sickness (AMS). The actual mechanisms by which acetazolamide reduces symptoms of AMS, however, remain unclear. Traditionally, acetazolamide's efficacy has been attributed to inhibition of CA in the kidneys, resulting in bicarbonaturia and metabolic acidosis. The result is offsetting hyperventilation-induced respiratory alkalosis and allowance of chemoreceptors to respond more fully to hypoxic stimuli at altitude. Studies performed on both animals and humans, however, have shown that this explanation is unsatisfactory and that the efficacy of acetazolamide in the context of AMS is likely due to a multitude of effects. This review summarizes the known systemic effects of acetazolamide and incorporates them into a model encompassing several factors that are likely to play a key role in the drug's efficacy. Such factors include not only metabolic acidosis resulting from renal CA inhibition but also improvements in ventilation from tissue respiratory acidosis, improvements in sleep quality from carotid body CA inhibition, and effects of diuresis.
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Milledge JS. Altitude medicine and physiology including heat and cold: A review. Travel Med Infect Dis 2006; 4:223-37. [PMID: 16887744 DOI: 10.1016/j.tmaid.2005.06.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2005] [Accepted: 06/21/2005] [Indexed: 11/22/2022]
Abstract
With increasing numbers of people travelling to high altitude destinations for recreation or work, there is a need for practitioners of Travel Medicine to be familiar with altitude illnesses and the physiology of altitude. In mountainous areas travellers may also be exposed to problems of heat and cold. This article reviews these topics and gives practical advice on the management of the clinical problems involved, together with a discussion of underlying mechanisms, as far as they are understood at present.
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Basnyat B. High altitude cerebral and pulmonary edema. Travel Med Infect Dis 2005; 3:199-211. [PMID: 17292039 DOI: 10.1016/j.tmaid.2004.06.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2004] [Accepted: 06/17/2004] [Indexed: 11/17/2022]
Abstract
Altitude illness, which comprises of acute mountain sickness (AMS) and its life threatening complications, high altitude cerebral edema (HACE) and high altitude pulmonary edema (HAPE) is now a well recognized disease process. AMS and HACE are generally thought to be a continuum. Some historical facts about the illness, its new intriguing pathophysiological processes, and clinical picture are discussed here. Although the review deals with both HACE and HAPE, HAPE is covered in greater detail due to the recent important findings related to its pathophysiology and prevention mechanisms. Relevant clinical correlation, the differential diagnosis of altitude sickness for a more sophisticated approach to the disease phenomenon, the possibility of dehydration being a risk factor for altitude sickness, the hypothetical role of angiogenesis in cerebral edema, and the emphasis on some vulnerable groups at high altitude are some of the other newer material discussed in this review. A clear-cut treatment and basic prevention guidelines are included in two panels, and finally the limited literature on the role of genetic factors on susceptibility to altitude sickness is briefly discussed.
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Affiliation(s)
- Buddha Basnyat
- Nepal International Clinic and Himalayan Rescue Association, Patan Hospital, Lal Durbar, GPO Box: 3596, Kathmandu, Nepal
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Maloney JP, Broeckel U. Epidemiology, Risk Factors, and Genetics of High-Altitude–Related Pulmonary Disease. Clin Chest Med 2005; 26:395-404, v. [PMID: 16140134 DOI: 10.1016/j.ccm.2005.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
High-altitude-related pulmonary disease is a spectrum of acute and chronic illnesses with a well-described epidemiology. The risk for these illnesses is related to well-known environmental risk factors and lesser-known but important genetic factors. Prevention of acute high-altitude illness is possible in most visitors from lower elevations. Chronic high-altitude illnesses have an important worldwide impact.
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Affiliation(s)
- James P Maloney
- Division of Pulmonary and Critical Medicine, University of Colorado Health Sciences Center, 4220 East 9th Avenue, C-272, Denver, CO 80262, USA.
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Ge RL, Stone JA, Levine BD, Babb TG. Exaggerated respiratory chemosensitivity and association with level at 3568m in obesity. Respir Physiol Neurobiol 2005; 146:47-54. [PMID: 15733778 DOI: 10.1016/j.resp.2004.11.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 10/19/2004] [Accepted: 11/15/2004] [Indexed: 11/24/2022]
Abstract
To investigate whether obesity is associated with alterations in respiratory chemosensitivity, we compared the ventilatory response to hypoxia (HVR) and hypercapnia (HCVR) in 9 obese men (BMI: 37.0+/-4.3 kg m(-2)) and 10 lean men (BMI: 25.8+/-4.8 kg m(-2)). HVR (DeltaVE, L min(-1) per DeltaSaO2, %) was measured by a progressive isocapnic hypoxia technique, and HCVR (DeltaVE/DeltaPETCO2, L min(-1)Torr(-1)) was measured by a progressive hypercapnic method. HCVR, was greater (p<0.001) in the obese men (2.68+/-0.78) than in the lean men (1.4+/-0.45) as was HVR (p<0.05) (1.26+/-0.65 versus 0.71+/-0.43, respectively). The difference (DeltaSaO2, 4.30+/-3.69 and 10.54+/-3.45 in the lean and obese men, respectively, p<0.01) between daytime (86+/-1 and 86+/-1%) and nighttime SaO2 (81+/-3 and 76+/-4%) at a simulated altitude of 3658 m was significantly (p<0.05) correlated with both HVR (r=0.51) and HCVR (r=0.48). These results suggest that chemosensitivity in mildly obese men is increased, not blunted. Furthermore, otherwise healthy, obese individuals have the potential for significant desaturation during sleep at high altitude possibly due to exaggerated sleep-disordered breathing.
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Affiliation(s)
- Ri-Li Ge
- Research Center for High Altitude Medicine, Qinghai Medical College, 16 Kunlun Road, Xining, Qinghai 180001, PR China
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Burgess KR, Johnson P, Edwards N, Cooper J. Acute mountain sickness is associated with sleep desaturation at high altitude. Respirology 2004; 9:485-92. [PMID: 15612960 DOI: 10.1111/j.1440-1843.2004.00625.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE This study was intended to demonstrate a biologically important association between acute mountain sickness (AMS) and sleep disordered breathing. METHODOLOGY A total of 14 subjects (eight males, six females aged 36 +/- 10 years) were studied at six different altitudes from sea level to 5050 m over 12 days on a trekking route in the Nepal Himalaya. AMS was quantified by Lake Louise (LL) score. At each altitude, sleep was studied by 13 channel polysomnography (PSG). Resting arterial blood gases (ABG) and exercise SaO2 were measured. Ventilatory responses (VR) were measured at sea level. Individual data were analysed for association at several altitudes and mean data were analysed for association over all altitudes. RESULTS ABG showed partial acclimatization. For the mean data, there were strong positive correlations between LL score and altitude, and periodic breathing, as expected. Strong negative correlations existed between LL score and PaO2, PaCO2, sleep SaO2 and exercise SaO2, but there was no correlation with sea level VR. There were equally tight correlations between LLs/PaO2 and LL score/sleep SaO2. The individual data showed no significant correlations with LL score at any altitude, probably reflecting the non-steady state nature of the experiment. In addition, mean SaO2 during sleep was similar to minimum exercise SaO2 at each altitude and minimum sleep SaO2 was lower, suggesting that the hypoxic insult during sleep was equivalent to or greater than walking at high altitude. CONCLUSIONS It is concluded that desaturation during sleep has a biologically important association with AMS, and it is speculated that under similar conditions (trekking) it is an important cause of AMS.
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Affiliation(s)
- Keith R Burgess
- Peninsula Private Sleep Laboratory, Manly, New South Wales, Australia.
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Abstract
New arrivals to altitude commonly experience poor-quality sleep. These complaints are associated with increased fragmentation of sleep by frequent brief arousals, which are in turn linked to periodic breathing. Changes in sleep architecture include a shift toward lighter sleep stages, with marked decrements in slow-wave sleep and with variable decreases in rapid eye movement (REM) sleep. Respiratory periodicity at altitude reflects alternating respiratory stimulation by hypoxia and subsequent inhibition by hyperventilation-induced hypocapnia. Increased hypoxic ventilatory responsiveness and loss of regularization of breathing during sleep contribute to the occurrence of periodicity. Interventions that improve sleep quality at high altitude include acetazolamide and benzodiazepines.
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Affiliation(s)
- John V Weil
- Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, 4200 East NinthAvenue, Denver 80262, USA.
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Abstract
High-altitude illness is the collective term for acute mountain sickness (AMS), high-altitude cerebral oedema (HACE), and high-altitude pulmonary oedema (HAPE). The pathophysiology of these syndromes is not completely understood, although studies have substantially contributed to the current understanding of several areas. These areas include the role and potential mechanisms of brain swelling in AMS and HACE, mechanisms accounting for exaggerated pulmonary hypertension in HAPE, and the role of inflammation and alveolar-fluid clearance in HAPE. Only limited information is available about the genetic basis of high-altitude illness, and no clear associations between gene polymorphisms and susceptibility have been discovered. Gradual ascent will always be the best strategy for preventing high-altitude illness, although chemoprophylaxis may be useful in some situations. Despite investigation of other agents, acetazolamide remains the preferred drug for preventing AMS. The next few years are likely to see many advances in the understanding of the causes and management of high-altitude illness.
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Schirlo C, Pavlicek V, Jacomet A, Gibbs JSR, Koller E, Oelz O, Seebauer M, Kohl J. Characteristics of the ventilatory response in subjects susceptible to high altitude pulmonary edema during acute and prolonged hypoxia. High Alt Med Biol 2003; 3:267-76. [PMID: 12396880 DOI: 10.1089/152702902320604241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
The present study compares the changes in ventilation in response to sustained hypobaric hypoxia and acute normobaric hypoxia between subjects susceptible to high altitude pulmonary edema (HAPE-S) and control subjects (C-S). Seven HAPE-S and five C-S were exposed to simulated high altitude of 4000 m for 23 h in a hypobaric chamber. Resting minute ventilation (V(E)), tidal volume (V(T)), and respiratory frequency (f(R)), as well as the end-tidal partial pressures of oxygen (P(ET(O2))) and carbon dioxide (P(ET(CO2))) were measured in all subjects sitting in a standardized position. Six measurement periods were recorded: ZH1 at 450 m at Zurich level, HA1 on attaining 3600 m altitude, HA2 after 20 min at 4000 m, HA3 after 21 h and HA4 after 23 h at 4000 m altitude, and ZH2 immediately after recompression to Zurich level. At ZH1 and HA3, the measurements were first done in lying, then in sitting, and afterwards in standing. Peripheral arterial oxygen saturation (Sa(O2)) was continuously recorded. All respiratory parameters were also measured during exercise lasting 30 min, the work load being 50% of maximal oxygen consumption (V(O2max)) at Zurich level and 26% of the Zurich V(O2max) at 4000 m. V(E), P(ET(O2)) and P(ET(CO2)) did not significantly differ between HAPE-S and C-S at rest and during exercise periods at Zurich level and at high altitude. However, Sa(O2) was significantly lower in HAPE-S than in C-S at rest and during exercise at 4000 m. Breathing through the mouthpiece during ventilation measurements increased significantly the Sa(O2) in HAPE-S in posture tests at HA3. This effect was most pronounced in the supine posture, in which HAPE-S had the lowest Sa(O2) values. These data provide evidence that (1) gas exchange might be impaired on the level of ventilation-perfusion mismatch or due to diffusion limitation in HAPE-S during the first 23 h of exposure to a simulated altitude of 4000 m, and (2) contrary to C-S, the Sa(O2) in HAPE-S is significantly affected by body position and by mouthpiece breathing.
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Joseph V, Pequignot JM, Van Reeth O. Neurochemical perspectives on the control of breathing during sleep. Respir Physiol Neurobiol 2002; 130:253-63. [PMID: 12093622 DOI: 10.1016/s0034-5687(02)00012-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A specific depression of minute ventilation occurs during sleep in normal subjects. This sleep-related ventilatory depression is partially related to mechanical events and upper airway atonia but some data also indicate that it is likely to be centrally mediated. This paper reviews the anatomical and neurochemical connections between sleep/wake- and respiratory-related areas in an attempt to identify the potential implication of sleep-related neurochemicals (serotonin, catecholamines, GABA, acetylcholine) in the sleep-related hypoventilation. The review of available data suggests that the sleep-related ventilatory depression depends upon the enhanced GABAergic activity together with a loss of suprapontine influence depending on the cessation of activity of the reticular formation. During REM sleep, an additional inhibitory activity emerges from the pontine cholinergic neurons, which contributes to the breathing irregularities and the associated depression of minute ventilation and ventilatory response to chemical stimuli. This model may contribute to a better understanding of the neurochemical environment of respiratory neurons during sleep, which remains a question of importance regarding the numerous pathological states that are linked to specific perturbations of breathing control during sleep.
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Affiliation(s)
- Vincent Joseph
- Centre d'Etudes des Rythmes Biologiques, ULB Hôpital Erasme, 808 Route de Lennik, 1070, Brussels, Belgium.
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Abstract
Sleep at high altitude is characterized by poor subjective quality, increased awakenings, frequent brief arousals, marked nocturnal hypoxemia, and periodic breathing. A change in sleep architecture with an increase in light sleep and decreasing slow-wave and REM sleep have been demonstrated. Periodic breathing with central apnea is almost universally seen amongst sojourners to high altitude, although it is far less common in long-standing high altitude dwellers. Hypobaric hypoxia in concert with periodic breathing appears to be the principal cause of sleep disruption at altitude. Increased sleep fragmentation accounts for the poor sleep quality and may account for some of the worsened daytime performance at high altitude. Hypoxic sleep disruption contributes to the symptoms of acute mountain sickness. Hypoxemia at high altitude is most severe during sleep. Acetazolamide improves sleep, AMS symptoms, and hypoxemia at high altitude. Low doses of a short acting benzodiazepine (temazepam) may also be useful in improving sleep in high altitude.
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Affiliation(s)
- Himanshu Wickramasinghe
- Pulmonary and Intensive Care Section, Department of Internal Medicine, Loma Linda University School of Medicine, Loma Linda, California
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Brundrett G. Sickness at high altitude: a literature review. THE JOURNAL OF THE ROYAL SOCIETY FOR THE PROMOTION OF HEALTH 2002; 122:14-20. [PMID: 11989137 DOI: 10.1177/146642400212200109] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
When some individuals spend just a few hours at low atmospheric pressure above 1,500 m (5,000 ft)--such as when climbing a mountain or flying in a plane at high altitude--they become ill. Altitude sickness studies originally concentrated on life-threatening illnesses which beset determined and athletic climbers at extreme altitudes. In recent years, however, research attention is moving towards milder forms of sickness reported by a significant proportion of the growing number of visitors to mountain and ski resorts at more moderate altitude. Some of this research is also relevant in understanding the problems experienced by passengers in newer planes that fly at a significantly higher equivalent cabin altitude, i.e. 2,440 m (8,000 ft), than earlier designs. Engineering solutions--such as enriched oxygen in enclosed spaces at altitude, or in the case of aircraft, lower cabin altitudes--are possible, but for an economic assessment to be realistic an engineer needs to identify the scale of the problem and to understand the factors determining susceptibility. This review concentrates on the problems of mountain sickness in the ordinary population at altitudes of around 3,000 m (10,000 ft); this is a problem of growing concern as ski resorts develop, mountain trekking increases in popularity, and as higher altitude cabin pressures are achieved in aircraft.
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Barash IA, Beatty C, Powell FL, Prisk GK, West JB. Nocturnal oxygen enrichment of room air at 3800 meter altitude improves sleep architecture. High Alt Med Biol 2002; 2:525-33. [PMID: 11809093 DOI: 10.1089/152702901753397090] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Sleep is known to be impaired at high altitude, and this may be a factor contributing to reduced work efficiency, general malaise, and the development of acute mountain sickness (AMS). Nocturnal room oxygen enrichment at 3800 m has been shown to reduce the time spent in periodic breathing and the number of apneas, to improve subjective quality of sleep, and to reduce the AMS score. The present study was designed to evaluate the effect of oxygen enrichment to 24% at 3800 m (lowering the equivalent altitude to 2800 m) on sleep architecture. Full polysomnography and actigraphy were performed on 12 subjects who ascended in 1 day to 3800 m and slept in a specially constructed room that allowed oxygen enrichment or ambient air conditions in a randomized, crossover, double-blind study. The results showed that subjects spent a significantly greater percentage of time in deep sleep (stages III and IV combined, or slow wave sleep) with oxygen enrichment versus ambient air (17.2 +/- 10.0% and 13.9 +/- 6.7%, respectively; p < 0.05 in paired analysis). No differences between treatments were seen with subjective assessments of sleep quality or with subject's assessment of the extent to which they suffered from AMS. This study provides further objective evidence of improved sleep as a result of oxygen enrichment at 3800 m and suggests that alleviating hypoxia may improve sleep quality.
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Affiliation(s)
- I A Barash
- Department of Medicine, University of California San Diego, La Jolla, CA 92093-0623, USA
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McElroy MK, Gerard A, Powell FL, Prisk GK, Sentse N, Holverda S, West JB. Nocturnal O2 enrichment of room air at high altitude increases daytime O2 saturation without changing control of ventilation. High Alt Med Biol 2001; 1:197-206. [PMID: 11254229 DOI: 10.1089/15270290050144190] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In a randomized, double-blind study, 24 sea-level residents drove to 3,800-m altitude in 1 day, and then slept the first night in either ambient air or 24% oxygen, and the second night in the treatment that they did not receive on the first night. Oxygen enrichment, compared with ambient air, resulted in significantly fewer apneas, and significantly less time spent in periodic breathing during the night. The increase in SaO2 between evening and morning was significantly higher after sleeping in the oxygen-enriched atmosphere, compared with ambient air. However, this significant improvement in SaO2 did not persist into mid-day. The overnight treatment did not alter the ventilatory response to hypoxia or to carbon dioxide as measured the following morning. The results suggest that the elevation in SaO2 following overnight oxygen enrichment is probably not due to a change in the control of ventilation, but possibly to differences in subclinical lung pathology.
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Affiliation(s)
- M K McElroy
- Department of Medicine, University of California San Diego, La Jolla 92093-0623, USA
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Affiliation(s)
- M T Naughton
- Alfred Sleep Disorders and Ventilatory Failure Service, Department of Respiratory Medicine, Alfred Hospital, Prahran, Victoria, Australia
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