Waldner Nina F, Hartmann Sara E, Muralt Lara, Lichtblau Mona, Bader Patrick R, Rawling Jean M, Lopez Ivan, Ulrich Silvia, Poulin Marc J, Bloch Konrad E, Furian Michael
Pulmonary Division and Sleep Disorders Center, Department of Respiratory Medicine, University Hospital of Zurich, Rämistrasse 100, 8091, Zurich, Switzerland.
Department of Physiology and Pharmacology and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada.
Sci Rep. 2025 Apr 15;15(1):12987. doi: 10.1038/s41598-025-97554-7.
This study aimed to quantify the effect of two consecutive prolonged, intermittent exposures to high and very high altitudes on oxygen saturation (SpO) and acute mountain sickness (AMS). For this, healthy lowlanders (N = 21), aged 18-30 years, underwent two 7-day sojourns at the ALMA observatory, Chile (6 h/day at 5050 m, 18 h/day at 2900 m), separated by 1-week at 520 m. SpO (pulse oximetry) and AMS severity (AMSc, Environmental Symptom Questionnaire cerebral score) diagnosing AMS (AMSc ≥ 0.7) were assessed daily at both altitudes. The study was registered at www.ClinicalTrials.gov: NCT02730143. SpO at 2900 m and 5050 m on arrival was mean ± SD 93.6 ± 0.5% and 79.9 ± 1.0% (P < 0.05 between altitudes), whereas the AMSc scores were 0.43 ± 0.08 and 0.97 ± 0.11 (P < 0.05 between altitudes), respectively. At 2900 m during a 7-day intermittent hypoxic exposure, SpO increased by a mean (95% CI) 0.3 %/day (0.1;0.4) and by 0.9 %/day (0.4;1.3) at 5050 m. Similarly, AMSc decreased by 0.05 points/day (0.01;0.08) at 2900 m and by 0.16 points/day (0.11;0.21) at 5050 m. During the second sojourn (vs. 1st sojourn), day 1, SpO at 2900 m was unchanged but higher at 5050 m by 2.9% (0.6;5.3). AMSc was lower at 2900 m and 5050 m by 0.37 (0.16;0.59) and 0.37 (0.11;0.63) (P < 0.05 both comparisons vs 1st sojourn), respectively. Acclimatization with the 2nd sojourn increased SpO at 2900 m by 0.3%/day (0.1;0.4) and 5050 m by 0.5%/day (0.1;0.8). AMSc remained unchanged with acclimatization at 2900 m but decreased at 5050 m by 0.08 points/day (0.04;0.11). In conclusion, in healthy lowlanders, a 7-day intermittent hypobaric hypoxic exposure improved SpO and AMS severity at 2900 m, with larger improvements at 5050 m. During a second identical sojourn, initial AMS severity was reduced despite comparable SpO at 2900 m compared to the 1st sojourn. No further acclimatization effects were observed in SpO but in AMS symptoms at 2900 m. In contrast, re-exposure to 5050 m showed higher initial SpO and lower AMSc values with further improvement with intermittent re-exposures. These findings highlight altitude-dependent acclimatization patterns and confirm pre-conditioning's effectiveness in preventing AMS.
本研究旨在量化连续两次长时间、间歇性暴露于高海拔和极高海拔对血氧饱和度（SpO）和急性高山病（AMS）的影响。为此，18至30岁的健康低地人（N = 21）在智利的阿塔卡马大型毫米/亚毫米波阵列天文台（ALMA）进行了两次为期7天的停留（每天6小时处于5050米，每天18小时处于2900米），中间间隔1周处于520米。在两个海拔高度均每日评估SpO（脉搏血氧测定法）和诊断AMS的AMS严重程度（AMSc，环境症状问卷脑部评分）（AMSc≥0.7）。该研究已在www.ClinicalTrials.gov注册：NCT02730143。到达时2900米和5050米处的SpO分别为平均值±标准差93.6±0.5%和79.9±1.0%（海拔之间P<0.05），而AMSc分数分别为0.43±0.08和0.97±0.11（海拔之间P<0.05）。在2900米进行为期7天的间歇性低氧暴露期间，SpO平均每天增加（95%CI）0.3%（0.1；0.4），在5050米处为每天增加0.9%（0.4；1.3）。同样，AMSc在2900米处每天降低0.05分（0.01；0.08），在5050米处为每天降低0.16分（0.11；0.21）。在第二次停留期间（与第一次停留相比），第1天，2900米处的SpO无变化，但5050米处升高了2.9%（0.6；5.3）。2900米和5050米处的AMSc分别降低了0.37（0.16；0.59）和0.37（0.11；0.63）（与第一次停留相比，两次比较P<0.05）。第二次停留的适应使2900米处的SpO每天增加0.3%（0.1；0.4），5050米处每天增加率为0.5%（0.1；0.8）。AMSc在2900米处随适应保持不变，但在5050米处每天降低0.08分（0.04；0.11）。总之，在健康低地人中，为期7天的间歇性低压低氧暴露改善了2900米处的SpO和AMS严重程度，在5050米处改善更大。在第二次相同停留期间，尽管2900米处的SpO与第一次停留相比相当，但初始AMS严重程度降低。在SpO方面未观察到进一步的适应效果，但在2900米处的AMS症状方面有效果。相比之下，再次暴露于5050米显示初始SpO较高且AMSc值较低，间歇性再次暴露后有进一步改善。这些发现突出了海拔依赖性适应模式，并证实了预处理在预防AMS方面的有效性。
