Physiological Responses in Humans Acutely Exposed to High Altitude (3480 m): Minute Ventilation and Oxygenation Are Predictive for the Development of Acute Mountain Sickness

Abstract

Physiological responses in humans acutely exposed to high altitude (3480 m): Minute ventilation and oxygenation are predictive for the development of acute mountain sickness. High Alt Med Biol. 20:192-197, 2019.-The importance of arterial oxygen saturation for the prediction of acute mountain sickness (AMS) is still a matter of debate. Reasons for discrepancies may result from varying laboratory or field conditions and their interactions. Thus, we analyzed data from our prior high-altitude studies, including participants of a broad range of age of both sexes (20 males and 20 females, aged between 20 and 67 years) under strictly standardized conditions of pre-exposure and acute exposure to real high altitude (3480 m). A set of resting cardiovascular, respiratory, hematological, and metabolic variables were recorded at high altitude (Testa Grigia, Plateau Rosa, 3480 m; Swiss-Italian boarder) after performing pretests at low altitude (Innsbruck, 600 m, Austria). Our analyses indicate that (1) smaller changes in resting minute ventilation (VE) and a larger decrease of peripheral oxygen saturation (SpO 2) during the first 3 hours of acute exposure to high altitude were independent predictors for subsequent development of AMS (90% correct prediction), (2) there are no differences of responses between sexes, and (3) there is no association of responses with age. Considering the independent effects of both responses (VE and SpO 2) may be of clinical/practical relevance. Moreover, the presented data derived from a broad age range of both sexes might be of interest for comparative purposes.

Changes in prefrontal cerebral oxygenation and microvascular blood volume in hypoxia and possible association with acute mountain sickness

“…From a physiological perspective, it was intriguing to observe that S pO 2 at 3647 m was significantly lower in AMS + subjects compared with AMS − individuals. This supports previous findings that greater decreases in S pO 2 during acute high-altitude exposure are independent predictors for the subsequent development of AMS (Burtscher et al, 2019).…”

“…This last point has been confirmed recently by Burtscher et al. (2019), who observed lower resting peripheral oxyhaemoglobin saturation () values (possibly linked to a reduced pulmonary ventilation response to hypoxia) during the first 3 h of exposure to 3480 m in people who later developed AMS.…”

“…Nevertheless, hypoxaemia is considered the primary stimulus (Bailey, Bärtsch, Knauth, & Baumgartner, 2009), and in some studies AMS-prone individuals present more severe hypoxaemia than their healthier counterparts (Loeppky et al, 2008). This last point has been confirmed recently by Burtscher et al (2019), who observed lower resting peripheral oxyhaemoglobin saturation (S pO 2 ) values (possibly linked to a reduced pulmonary ventilation response to hypoxia) during the first 3 h of exposure to 3480 m in people who later developed AMS.…”

The Hen or the Egg: Impaired Alveolar Oxygen Diffusion and Acute High-altitude Illness?

“…Many studies report decreased SO 2 in hypoxia in individuals suffering from AMS in comparison with healthy controls, some of which suggest that decreased SO 2 might be predictive of AMS (e.g., [1,50,51,52,53,54]). However, even in healthy individuals there is great variability in SO 2 at high-altitude, which challenges this argument.…”

Hematologic and spirometric characteristics of Tajik and Kyrgyz highlanders in the Pamir Mountains

“…In this study, we measured the hematologic and spirometric parameters related to adaptation to high altitude in the Tajik and Kyrgyz highlanders of the Pamir Mountains to investigate adaptive patterns in response to hypoxic stress. Exposure to high altitude almost universally reduces SaO 2 , which is the primary cause of cardiorespiratory response to hypoxia (Burtscher et al, 2019; Burtscher, Flatz, & Faulhaber, 2004; O'Connor, Dubowitz, & Bickler, 2004; Ottestad, Kasin, & Hoiseth, 2018). In our study, SaO 2 levels of the Sarikoli Tajik (3100 m, male, 92.99%; female, 93.47%), Wakhi Tajik (3500 m, male: 91.18%; female:90.95%), and Kyrgyz (3250 m, male: 92.37%; female: 92.77%) are significantly lower than those of the Uyghurs (1300 m, male:96.00%; female: 96.70%) (Figure 2A; Tables S1 and S2), re‐illustrating the trend that SaO 2 decreases while altitude increases.…”