High-altitude illnesses: Old stories and new insights into the pathophysiology, treatment and prevention

Burtscher, Martin; Hefti, Urs; Hefti, Jacqueline Pichler

doi:10.1016/j.smhs.2021.04.001

Cited by 47 publications

(42 citation statements)

References 137 publications

(200 reference statements)

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“…Individuals rapidly ascending from low to high altitudes (>2000 m) are at risk to develop acute mountain sickness (AMS), which is characterized by headache as the predominant symptom, commonly accompanied by nausea, lack of appetite, vomiting, insomnia, dizziness, and/or fatigue. 45 The AMS prevalence was shown to increase from 7% at 2200 m to 38% at 3500 m, and to 52% when rapidly ascending to 4559 m in the alpine regions, 45,46 and a similar risk has been derived from Chinese highland military medical records. 47 Usually, AMS symptoms resolve during the first days at altitude, but may in rare cases progress to life-threatening diseases such as high-altitude cerebral edema (HACE) and/or high-altitude pulmonary edema (HAPE).…”

Section: Acute and Subacute Effects Of High-altitude Exposurementioning

confidence: 78%

“…50 Adverse effects of acute high altitude exposure are largely avoidable by proper acclimatization, ie, low ascent rates, or the use of appropriate pre-acclimatization strategies. 45 A precise understanding of physiological responses to acute high altitude is required to optimize the individual acclimatization process and to avoid potentially associated risks to the cardiovascular system. Declining partial pressure of oxygen, PO 2 , parallels decreasing barometric pressure (P B ) with increasing altitude.…”

Section: Acute and Subacute Effects Of High-altitude Exposurementioning

confidence: 99%

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Impact of High Altitude on Cardiovascular Health: Current Perspectives

Mallet¹,

Burtscher²,

Richalet³

et al. 2021

VHRM

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Globally, about 400 million people reside at terrestrial altitudes above 1500 m, and more than 100 million lowlanders visit mountainous areas above 2500 m annually. The interactions between the low barometric pressure and partial pressure of O 2 , climate, individual genetic, lifestyle and socio-economic factors, as well as adaptation and acclimatization processes at high elevations are extremely complex. It is challenging to decipher the effects of these myriad factors on the cardiovascular health in high altitude residents, and even more so in those ascending to high altitudes with or without preexisting diseases. This review aims to interpret epidemiological observations in high-altitude populations; present and discuss cardiovascular responses to acute and subacute high-altitude exposure in general and more specifically in people with preexisting cardiovascular diseases; the relations between cardiovascular pathologies and neurodegenerative diseases at altitude; the effects of high-altitude exercise; and the putative cardioprotective mechanisms of hypobaric hypoxia.

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Section: Acute and Subacute Effects Of High-altitude Exposurementioning

confidence: 78%

Section: Acute and Subacute Effects Of High-altitude Exposurementioning

confidence: 99%

Impact of High Altitude on Cardiovascular Health: Current Perspectives

Mallet¹,

Burtscher²,

Richalet³

et al. 2021

VHRM

Self Cite

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“…Pre-acclimatization by HC is primarily intended to prevent high-altitude illnesses (HAI). Acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) are cerebral forms of HAI because associated symptoms are primarily originating in the brain, e.g., headache [25]. While AMS is the most frequent HAI, usually benign and resolving after a few days at altitude, HACE develops rather rarely but represents a potentially life-threatening disease [25,26,91].…”

Section: High-altitude Illnessesmentioning

confidence: 99%

“…Acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) are cerebral forms of HAI because associated symptoms are primarily originating in the brain, e.g., headache [25]. While AMS is the most frequent HAI, usually benign and resolving after a few days at altitude, HACE develops rather rarely but represents a potentially life-threatening disease [25,26,91]. This is also true for high-altitude pulmonary edema, a pulmonary form of HAI, rarely developing below 3000 m but life-threatening if not treated immediately and appropriately [117].…”

Section: High-altitude Illnessesmentioning

confidence: 99%

“…The Lake Louise Scoring system (LLS) or the shortened (11-item) version (ESQ-C) of the 67-item Environmental Symptoms Questionnaire (ESQ-III) are frequently used diagnosis tools for AMS (M. [25,26]. The LLS is a selfassessment questionnaire including five main symptoms (headache, nausea, dizziness, fatigue, and difficulty sleeping), each rated with a score from 0 to 3 (0 for no discomfort, 1 for mild, 2 for moderate, and 3 for severe symptoms).…”

Section: High-altitude Illnessesmentioning

confidence: 99%

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Hypoxia Conditioning for High-Altitude Pre-acclimatization

Burtscher

Millet

Burtscher

2022

J. of SCI. IN SPORT AND EXERCISE

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Purpose Main purposes of pre-acclimatization by hypoxia conditioning (HC) are the prevention of high-altitude illnesses and maintenance of aerobic exercise performance. However, robust evidence for those effects or evidence-based guidelines for exposure strategies, including recommendations to ensure safety, are largely lacking. Therefore, we summarize the current knowledge on the physiology of acclimatization to hypoxia and HC with the aim to derive implications for pre-acclimatization strategies before going on high-altitude treks and expeditions. Methods Based on the literature search and personal experience, core studies and important observations have been selected in order to present a balanced view on the current knowledge of high-altitude illnesses and the acclimatization process, specifically focusing on pre-acclimatization strategies by HC. Results and Conclusions It may be concluded that in certain cases even short periods (e.g., 7 h) of pre-acclimatization by HC are effective, but longer periods (e.g., > 60 h) are needed to elicit more robust effects. About 300 h of HC (intermittently applied) may be the optimal preparation for extreme altitude sojourns, although every additional hour spent in hypoxia may confer further benefits. The inclusion of hypobaric exposures (i.e., real altitude) in pre-acclimatization protocols could further increase their efficacy. The level of simulated altitude is progressively increased or individually adjusted ideally. HC should not be terminated earlier than 1–2 weeks before altitude sojourn. Medical monitoring of the pre-acclimatization program is strongly recommended.

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Neurofilament Light Chain Is Associated With Acute Mountain Sickness

Berek,

Lindner,

Pauli

et al. 2024

Brain and Behavior

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BackgroundNeurological symptoms are common in acute mountain sickness (AMS); however, the extent of neuroaxonal damage remains unclear. Neurofilament light chain (NfL) is an established blood biomarker for neuroaxonal damage.ObjectiveTo investigate whether plasma (p) NfL levels increase after simulated altitude exposure, correlate with the occurrence of AMS, and might be mitigated by preacclimatization.MethodsHealthy subjects were exposed to simulated high altitude (4500 m) by the use of a normobaric hypoxic chamber at the University of Innsbruck two times, that is, within Cycle 1 (C1) over 12 h, and within Cycle 2 (C2) for another 12 h but with a random assignment to prior acclimatization or sham acclimatization. Before each cycle (measurement [M] 1 and 3) and after each cycle (M2 and M4), clinical data (arterial oxygen saturation [SaO2], heart rate, and Lake Louise AMS score [LLS]) and plasma samples were collected. pNfL was measured using single‐molecule array (Simoa) technique.ResultspNfL levels did not significantly change within each study cycle, but increased over the total study period (M1: 4.57 [3.34–6.39], M2: 4.58 [3.74–6.0], M3: 5.64, and M4: 6.53 [4.65–7.92] pg/mL, p < 0.001). Subjects suffering from AMS during the study procedures showed higher pNfL levels at M4 (6.80 [6.19–8.13] vs. 5.75 [4.17–7.35], p = 0.048), a higher total pNfL increase (2.88 [1.21–3.48] vs. 0.91 [0.53–1.48], p = 0.022) compared to subjects without AMS. An effect of preacclimatization on pNfL levels could not be observed.ConclusionspNfL increases alongside exposure to simulated altitude and is associated with AMS.

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High-altitude illnesses: Old stories and new insights into the pathophysiology, treatment and prevention

Cited by 47 publications

References 137 publications

Impact of High Altitude on Cardiovascular Health: Current Perspectives

Impact of High Altitude on Cardiovascular Health: Current Perspectives

Hypoxia Conditioning for High-Altitude Pre-acclimatization

Neurofilament Light Chain Is Associated With Acute Mountain Sickness

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