Hypoxic ventilatory decline during the first 7 days of exposure in intermittent mountain altitude between 4400 and 6960 m

Ventilatory function and oxygen delivery at high altitude in the Himalayas

This study aimed to evaluate changes in lung function assessed by spirometry and blood gas content in healthy high-altitude sojourners during a trek in the Himalayas. A group of 19 Italian adults (11 males and 8 females, mean age 43 ±15 years, and BMI 24.2 ±3.7kg/m²) were evaluated as part of a Mount Everest expedition in Nepal. Spirometry and arterial blood gas content were evaluated at baseline in Kathmandu (≈1400m), at the Pyramid Laboratory - Observatory (peak altitude of ≈5000m), and on return to Kathmandu 2-3 days after arrival at each site. All participants took 250mg of acetazolamide per os once daily during the ascent. We found that arterial hemoglobin saturation, O₂ and CO₂ partial pressures, and the bicarbonate level all decreased (in all cases, p<0.001 with R²=0.70-0.90), while pHa was maintained stable at the peak altitude. Forced vital capacity (FVC) remained stable, while forced expiratory volume in 1sec (FEV1) decreased (p=0.010, n²_p=0.228), resulting in a lower FEV1/FVC ratio (p<0.001, n²_p=0.380). The best predictor for acute mountain sickness was the O₂ partial pressure at the peak altitude (p=0.004, R²=0.39). Finger pulse oximetry overestimated peripheral saturation relative to arterial saturation. We conclude that high-altitude hypoxia alters the respiratory function and the oxygen saturation of the arterial blood hemoglobin. Additionally, air rarefaction and temperature reduction, favoring hypoxic bronchoconstriction, could affect respiration. Pulse oximetry seems not enough to assist medical decisions at high altitudes.

Neuropsychological and Neuroimaging Correlates of High-Altitude Hypoxia Trekking During the "Gokyo Khumbu/Ama Dablam" Expedition

Committeri Giorgia, Danilo Bondi, Carlo Sestieri, Ginevra Di Matteo, Claudia Piervincenzi, Christian Doria, Roberto Ruffini, Antonello Baldassarre, Tiziana Pietrangelo, Rosamaria Sepe, Riccardo Navarra, Piero Chiacchiaretta, Antonio Ferretti, and Vittore Verratti. Neuropsychological and neuroimaging correlates of high-altitude hypoxia trekking during the "Gokyo Khumbu/Ama Dablam" expedition. High Alt Med Biol 00:000-000, 2021. Background: Altitude hypoxia exposure may produce cognitive detrimental adaptations and damage to the brain. We aimed at investigating the effects of trekking and hypoxia on neuropsychological and neuroimaging measures. Methods: We recruited two balanced groups of healthy adults, trekkers (n = 12, 6 F and 6 M, trekking in altitude hypoxia) and controls (gender- and age-matched), who were tested before (baseline), during (5,000 m, after 9 days of trekking), and after the expedition for state anxiety, depression, verbal fluency, verbal short-term memory, and working memory. Personality and trait anxiety were also assessed at a baseline level. Neuroimaging measures of cerebral perfusion (arterial spin labeling), white-matter microstructural integrity (diffusion tensor imaging), and resting-state functional connectivity (functional magnetic resonance imaging) were assessed before and after the expedition in the group of trekkers. Results: At baseline, the trekkers showed lower trait anxiety (p = 0.003) and conscientiousness (p = 0.03) than the control group. State anxiety was lower in the trekkers throughout the study (p < 0.001), and state anxiety and depression decreased at the end of the study in both groups (p = 0.043 and p = 0.007, respectively). Verbal fluency increased at the end of the study in both groups (p < 0.001), whereas verbal short-term memory and working memory performance did not change. No significant differences between before and after the expedition were found for neuroimaging measures. Conclusions: We argue that the observed differences in the neuropsychological measures mainly reflect aspecific familiarity and learning effects due to the repeated execution of the same questionnaires and task. The present results thus suggest that detrimental effects on neuropsychological and neuroimaging measures do not necessarily occur as a consequence of short-term exposure to altitude hypoxia up to 5,000 m, especially in the absence of altitude sickness.

Kilimanjaro Abruzzo expedition: effects of high-altitude trekking on anthropometric, cardiovascular and blood biochemical parameters

The effect of the combination of trekking and balanced appropriated diet were studied in mountaineers who spent 6 days at an altitude ranging from 900 to 5895 m above sea level (a.s.l.), during the Kilimanjaro Abruzzo Expedition. This study explored whether anthropometric, cardiovascular and blood biochemical parameters were significantly changed by a regular trekking performed at high altitude, with reduced oxygen levels, together with a macronutrient-containing balanced diet (total daily caloric intake: 3000–3500 Kcals). In consideration of the short period of high-altitude exposure, high-altitude exercise appeared to provide beneficial and rapid effects on the lipid profile and to modulate cardiovascular functions. These effects rely on both high-altitude hypoxia and physical activity. The most interesting observation is that even just a few days of high-altitude exercise, along with a balanced diet, was able to improve plasma lipid profiles.