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Front Pharmacol 2022 20;13:873867. Epub 2022 May 20.

Department of Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Delhi, India.

Dexamethasone can be taken prophylactically to prevent hypobaric hypoxia-associated disorders of high-altitude. While dexamethasone-mediated protection against high-altitude disorders has been clinically evaluated, detailed sex-based mechanistic insights have not been explored. As part of our India-Leh-Dexamethasone-expedition-2020 (INDEX 2020) programme, we examined the phenotype of control ( = 14) and dexamethasone ( = 13) groups, which were airlifted from Delhi (∼225 m elevation) to Leh, Ladakh (∼3,500 m), India, for 3 days. Read More

BMC Pulm Med 2022 May 9;22(1):187. Epub 2022 May 9.

Service de pneumologie, Centre Hospitalier du Valais Romand, Avenue du Grand-Champsec 80, 1950, Sion, Switzerland.

Once reserved for the fittest, worldwide altitude travel has become increasingly accessible for ageing and less fit people. As a result, more and more individuals with varying degrees of respiratory conditions wish to travel to altitude destinations. Exposure to a hypobaric hypoxic environment at altitude challenges the human body and leads to a series of physiological adaptive mechanisms. Read More

Int J Gen Med 2022 31;15:3559-3565. Epub 2022 Mar 31.

Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, Jazan University, Jazan, Saudi Arabia.

Purpose: Complete blood count (CBC) is a commonly used blood test for health checks. This study was conducted to compare CBC from two different altitudes and from sea-level populations in order to suggest correction factor for altitude-related increment on the hemoglobin and red blood cell indices.

Patients And Methods: In this retrospective lab records study, large datasets of CBCs over 5-year period were screened from three different regions of Saudi Arabia, Jeddah (a coastal city), Taif City located at 1879 m above sea level, and Abha City at located 2270 m above sea level. Read More

Nat Ecol Evol 2022 May 24;6(5):630-643. Epub 2022 Mar 24.

Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA.

Primates have adapted to numerous environments and lifestyles but very few species are native to high elevations. Here we investigated high-altitude adaptations in the gelada (Theropithecus gelada), a monkey endemic to the Ethiopian Plateau. We examined genome-wide variation in conjunction with measurements of haematological and morphological traits. Read More

Sci China Life Sci 2022 Mar 14. Epub 2022 Mar 14.

State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China.

The gut microbiota is involved in host responses to high altitude. However, the dynamics of intestinal microecology and their association with altitude-related illness are poorly understood. Here, we used a rat model of hypobaric hypoxia challenge to mimic plateau exposure and monitored the gut microbiome, short-chain fatty acids (SCFAs), and bile acids (BAs) over 28 d. Read More

Molecules 2022 Jan 4;27(1). Epub 2022 Jan 4.

Department of Pharmaceutical Chemistry & Pharmacognosy, Unaizah College of Pharmacy, Qassim University, Uniazah 51911, Saudi Arabia.

At high altitudes, drops in oxygen concentration result in the creation of reactive oxygen and nitrogen species (RONS), which cause a variety of health concerns. We addressed these health concerns and reported the synthesis, characterization, and biological activities of a series of 10 oxoquinolines. -Aryl-7-hydroxy-4-methyl-2-oxoquinoline-1(2)carboxamides (-) were accessed in two steps under ultrasonicated irradiation, as per the reported method. Read More

Int J Chron Obstruct Pulmon Dis 2021;16:3503-3512. Epub 2021 Dec 24.

Department of Pulmonology and Sleep Disorders Centre, University Hospital Zurich, Zurich, Switzerland.

Purpose: Patients with chronic obstructive pulmonary disease (COPD) are particularly vulnerable to hypoxia-induced autonomic dysregulation. Hypoxemia is marked during sleep. In COPD, altitude exposure is associated with an increase in blood pressure (BP) and a decrease in baroreflex-sensitivity (BRS). Read More

Sci Rep 2021 10 13;11(1):20355. Epub 2021 Oct 13.

Department of Respiratory Medicine, University Hospital of Zurich, Raemistrasse 100, 8091, Zurich, Switzerland.

This trial evaluates whether nocturnal oxygen therapy (NOT) during a stay at 2048 m improves altitude-induced exercise intolerance in lowlanders with chronic obstructive pulmonary disease (COPD). 32 lowlanders with moderate to severe COPD, mean ± SD forced expiratory volume in the first second of expiration (FEV) 54 ± 13% predicted, stayed for 2 days at 2048 m twice, once with NOT, once with placebo according to a randomized, crossover trial with a 2-week washout period at < 800 m in-between. Semi-supine, constant-load cycle exercise to exhaustion at 60% of maximal work-rate was performed at 490 m and after the first night at 2048 m. Read More

Cardiovasc Diagn Ther 2021 Aug;11(4):1122-1136

Department of Pediatric Cardiology, University Hospital Bonn, Bonn, Germany.

Patients with congenital heart disease are surviving further into adulthood and want to participate in multiple activities. This includes exposure to high altitude by air travel or recreational activities, such as hiking and skiing. However, at an altitude of about 2,500 m, the barometric environmental pressure is reduced and the partial pressure of inspired oxygen drops from 21% to 15% (hypobaric hypoxia). Read More

Front Physiol 2021 7;12:689863. Epub 2021 Jul 7.

Department of Pulmonology, University Hospital Zurich, Zurich, Switzerland.

Introduction: We investigated whether nocturnal oxygen therapy (NOT) mitigates the increase of pulmonary artery pressure in patients during daytime with chronic obstructive pulmonary disease (COPD) traveling to altitude.

Methods: Patients with COPD living below 800 m underwent examinations at 490 m and during two sojourns at 2,048 m (with a washout period of 2 weeks < 800 m between altitude sojourns). During nights at altitude, patients received either NOT (3 L/min) or placebo (ambient air 3 L/min) via nasal cannula according to a randomized crossover design. Read More

Pulmonology 2021 Sep-Oct;27(5):394-402. Epub 2021 Mar 3.

Pulmonary Division and Sleep Disorders Center, University Hospital of Zurich, Raemistrasse 100, 8091 Zurich, Switzerland. Electronic address:

Background: High altitude pulmonary hypertension (HAPH), a chronic altitude related illness, is associated with hypoxemia, dyspnea and reduced exercise performance. We evaluated ECG and pulse wave-derived markers of cardiovascular risk in highlanders with HAPH (HAPH+) in comparison to healthy highlanders (HH) and lowlanders (LL) and the effects of hyperoxia.

Methods: We studied 34 HAPH+ and 54 HH at Aksay (3250m), and 34 LL at Bishkek (760m), Kyrgyzstan. Read More

Wilderness Environ Med 2021 Mar 9;32(1):36-40. Epub 2021 Jan 9.

Department of Medicine, Kilimanjaro Christian Medical Center, Moshi Kilimanjaro, United Republic of Tanzania.

Introduction: A significant number of climbers on Mount Kilimanjaro are affected by altitude-related disorders. The aim of this study was to determine the main causes of morbidity and mortality in a representative cohort of climbers based on local hospital records.

Methods: We conducted a 2-y retrospective chart review of all patients presenting to the main referral hospital in the region after a climb on Mount Kilimanjaro, including all relevant records and referrals for postmortem studies. Read More

J Sleep Res 2021 06 9;30(3):e13153. Epub 2020 Aug 9.

Department of Respiratory Medicine, Sleep Disorders Center, University Hospital of Zurich, Zurich, Switzerland.

High-altitude pulmonary hypertension (HAPH) is an altitude-related illness associated with hypoxaemia that may promote sympathetic excitation and prolongation of the QT interval. The present case-control study tests whether QT intervals, markers of malignant cardiac arrhythmias, are prolonged in highlanders with HAPH (HAPH+) compared to healthy highlanders (HH) and healthy lowlanders (LL). The mean pulmonary artery pressure (mPAP) was measured by echocardiography in 18 HAPH+ (mPAP, 34 mmHg) and 18 HH (mPAP, 23 mmHg) at 3,250 m, and 18 LL (mPAP, 18 mmHg) at 760 m, Kyrgyzstan (p < . Read More

Sleep Sci 2020 Apr-Jun;13(2):138-144

Hospital Britanico de Buenos Aires, Medicine Respiratory Unit - Buenos Aires - CABA - Argentina.

Objective: to compare mountaineers with and without asymptomatic sleep apnea (OSA) before the ascent and to study high altitude-related sleep disorders, its interaction with metabolic, neuroendocrine and immunological components.

Material And Methods: During an expedition to Mount Aconcagua, researchers assessed the respiratory polygraphy (RP), clinical condition and inflammatory parameters, and rhythm of cortisol secretion in mountaineers sleeping at different altitude camps.

Results: 8 athletes (4 women), 36 years old (25-51) participated. Read More

JAMA Netw Open 2020 06 1;3(6):e207940. Epub 2020 Jun 1.

Sleep Disorders Center, Department of Respiratory Medicine, University Hospital of Zurich, Zurich, Switzerland.

Importance: There are no established measures to prevent nocturnal breathing disturbances and other altitude-related adverse health effects (ARAHEs) among lowlanders with chronic obstructive pulmonary disease (COPD) traveling to high altitude.

Objective: To evaluate whether nocturnal oxygen therapy (NOT) prevents nocturnal hypoxemia and breathing disturbances during the first night of a stay at 2048 m and reduces the incidence of ARAHEs.

Design, Setting, And Participants: This randomized, placebo-controlled crossover trial was performed from January to October 2014 with 32 patients with COPD living below 800 m with forced expiratory volume in the first second of expiration (FEV1) between 30% and 80% predicted, pulse oximetry of at least 92%, not requiring oxygen therapy, and without history of sleep apnea. Read More

Ergonomics 2020 Oct 11;63(10):1281-1292. Epub 2020 Jun 11.

Laboratory of Exercise and Physical Activity Sciences, School of Physiotherapy, Universidad Finis Terrae, Santiago, Chile.

Mining activities expose workers to diverse working conditions, rotational shifts and high altitude-related hypobaric hypoxia. Separately, each condition has been reported having a negative impact on miners' health risk; however, the combination of both stressors has been poorly explored. The present study aimed to analyse the effects of exposure to rotational work shift (RWS) alone or in combination with high altitude-related chronic intermittent hypobaric hypoxia (CIHH) on cardiometabolic, physical activity and sleep quality related markers in copper miners from Los Pelambres mine in Chile. Read More

Exp Physiol 2021 01 6;106(1):86-103. Epub 2020 May 6.

Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada.

New Findings: What is the central question of this study? Herein, a methodological overview of our research team's (Global REACH) latest high altitude research expedition to Peru is provided. What is the main finding and its importance? The experimental objectives, expedition organization, measurements and key cohort data are discussed. The select data presented in this manuscript demonstrate the haematological differences between lowlanders and Andeans with and without excessive erythrocytosis. Read More

Brain Behav 2020 05 23;10(5):e01604. Epub 2020 Mar 23.

Neuroscience Research Lab, Department of Neurology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.

Introduction: Incidence of high altitude-related sickness is increasing due to more number of people visiting the areas of high altitude which may result in life-threatening conditions including acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), high altitude cerebral edema (HACE), and High-altitude pulmonary hypertension (HAPH). We hypothesized that an advanced yoga regimen may be beneficial in dealing with the physiology of acclimatization.

Methods: Anthropometric, Biochemical, and Psychological assessments were carried out in 48 participants before and after the advance meditation program (AMP) in the experimental group. Read More

BMJ Mil Health 2021 Dec 20;167(6):424-428. Epub 2020 Feb 20.

Nuffield Department of Clinical Neurosciences, Oxford University, Oxford, Oxfordshire, UK.

Introduction: Sleep disturbance is common at high altitude and likely driven by an exaggerated peripheral chemoreceptor response which leads to apnoeic episodes and arousal. We hypothesised that this heightened response is in part mediated through angiotensin II receptors in the carotid body. To examine this link, we studied the effect of angiotensin II receptor blocker on sleep disturbance. Read More

Front Physiol 2019 28;10:1116. Epub 2019 Aug 28.

Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland.

The first ascent of Mount Everest by Tenzing Norgay and Sir Edmund Hillary in 1953 brought global attention to the Sherpa people and human performance at altitude. The Sherpa inhabit the Khumbu Valley of Nepal, and are descendants of a population that has resided continuously on the Tibetan plateau for the past ∼25,000 to 40,000 years. The long exposure of the Sherpa to an inhospitable environment has driven genetic selection and produced distinct adaptive phenotypes. Read More

Int J Mol Sci 2019 Aug 22;20(17). Epub 2019 Aug 22.

Department of Anesthesiology, Perioperative and General Critical Care Medicine, University Hospital Salzburg, 5020 Salzburg, Austria.

Individuals ascending rapidly to altitudes >2500 m may develop symptoms of acute mountain sickness (AMS) within a few hours of arrival and/or high-altitude pulmonary edema (HAPE), which occurs typically during the first three days after reaching altitudes above 3000-3500 m. Both diseases have distinct pathologies, but both present with a pronounced decrease in oxygen saturation of hemoglobin in arterial blood (SO). This raises the question of mechanisms impairing the diffusion of oxygen (O) across the alveolar wall and whether the higher degree of hypoxemia is in causal relationship with developing the respective symptoms. Read More

High Alt Med Biol 2019 12 21;20(4):352-360. Epub 2019 Aug 21.

Department of Psychiatry, Psychotherapy and Psychosomatics, University Clinic for Psychiatry II, Innsbruck Medical University, Innsbruck, Austria.

Psychotic symptoms during exposure to high altitude (HA) have been linked to accidents or near accidents on the mountains. It is thus of great importance to directly identify psychotic symptoms in individuals who are exposed to HA quickly and reliably on the mountain, even in the absence of experienced medical personnel. Psychotic features at HA frequently include positive psychotic symptoms such as hallucinations, delusions, or disorganized thinking/speech. Read More

High Alt Med Biol 2019 09 25;20(3):207-214. Epub 2019 Jul 25.

Institute of Mountain Emergency Medicine, EURAC Research, Bolzano, Italy.

Psychiatric disorders have a high lifetime prevalence affecting about 30% of the global population. Not much is known about high altitude (HA) sojourns in individuals living with a psychiatric condition. This lack of scientific evidence contrasts with the anticipated increase in numbers of individuals with preexisting psychiatric conditions seeking medical advice on HA exposure. Read More

Addict Behav Rep 2019 Jun 18;9:100167. Epub 2019 Feb 18.

Department of Psychiatry, University of Utah School of Medicine, 383 Colorow Drive, Salt Lake City, UT, 84108, United States.

Objective: Prescription opioid misuse and fatal overdoses have increased significantly over the last two decades. Living at altitude has been linked to greater reward benefits of other drugs of abuse, and living at altitude may also exacerbate the respiratory depression linked to opioid use. Therefore, we examined the relationships between living at altitude, and prescription opioid misuse and fatal overdoses. Read More

Pract Neurol 2019 Oct 8;19(5):404-411. Epub 2019 Jun 8.

Internal Medicine, Kilimanjaro Christian Medical Centre, Moshi, United Republic of Tanzania.

Mountain climbers may develop specific illnesses that largely depend on the altitude reached and the rate of ascent. The popularity of travel to high altitude destinations, extreme tourist activities and mountain climbing means that neurologists in low-altitude countries are increasingly likely to encounter neurological problems and disorders in people exposed to high altitude. Additionally, they may have to advise patients with pre-existing neurological conditions on the risks of ascent to altitude. Read More

Respiration 2019;97(2):125-134. Epub 2018 Sep 28.

Department of Pulmonology, University Hospital Zurich, Zurich,

Background: Changes in pulmonary hemodynamics and cardiac function in patients with chronic obstructive pulmonary disease (COPD) traveling to altitude have not been assessed despite an increasing prevalence of the disease.

Objectives: We hypothesized that pulmonary artery pressure (PAP) significantly increases and cardiac function deteriorates during exposure to hypobaric hypoxia as encountered by traveling to moderate altitude or air flight.

Methods: A total of 37 patients (17 female; median age [quartiles] 66 years [60; 69] with COPD GOLD grade 2-3 [FEV1 57% predicted (49; 71)]) living < 800 m underwent echocardiography in Zurich (490 m) and after 1 night at Davos Jakobshorn (2,590 m) in a randomized order of allocation. Read More

Front Physiol 2018 22;9:752. Epub 2018 Jun 22.

Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland.

To evaluate the effects of acute exposure to high altitude and preventive dexamethasone treatment on postural control in patients with chronic obstructive pulmonary disease (COPD). In this randomized, double-blind parallel-group trial, 104 lowlanders with COPD GOLD 1-2 age 20-75 years, living near Bishkek (760 m), were randomized to receive either dexamethasone (2 × 4 mg/day p.o. Read More

Chest 2018 10 10;154(4):788-797. Epub 2018 Jul 10.

Department of Respiratory Medicine, University Hospital Zurich, Zurich, Switzerland; Kyrgyz-Swiss High Altitude Clinic and Medical Research Center, Tuja-Ashu, Kyrgyz Republic; Department of Respiratory Medicine, National Center for Cardiology and Internal Medicine, Bishkek, Kyrgyz Republic. Electronic address:

Background: Patients with COPD may experience acute mountain sickness (AMS) and other altitude-related adverse health effects (ARAHE) when traveling to high altitudes. This study evaluated whether dexamethasone, a drug used for the prevention of AMS in healthy individuals, would prevent AMS/ARAHE in patients with COPD.

Methods: This placebo-controlled, double-blind, parallel-design trial included patients with COPD and Global Initiative for Obstructive Lung Disease grade 1 to 2 who were living below 800 m. Read More

Physiol Behav 2018 05 16;188:262-269. Epub 2018 Feb 16.

Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, Kelowna, Canada.

With exposure to acute normobaric hypoxia, global cerebral oxygen delivery is maintained via increases in cerebral blood flow (CBF); therefore, regional and localized changes in oxygen tension may explain neurocognitive impairment. Neurovascular coupling (NVC) is the close temporal and regional relationship of CBF to changes in neural activity and may aid in explaining the localized CBF response with cognitive activation. High-altitude related cognitive impairment is likely affected by hypocapnic cerebral vasoconstriction that may influence regional CBF regulation independent of hypoxia. Read More