Institute of Mountain Emergency Medicine, Eurac Research, 39100 Bolzano, Italy.
Department of Anaesthesia and Intensive Care, "F. Tappeiner" Hospital, 39012 Merano, Italy.
Int J Environ Res Public Health. 2021 May 20;18(10):5455. doi: 10.3390/ijerph18105455.
Bioelectrical impedance vector analysis (BIVA) is a method used to estimate variation in body hydration. We assessed the potential of BIVA for monitoring daily body hydration fluctuations in nine healthy, normally active males under matching normoxic (NX) and hypobaric hypoxic (HH) experimental conditions. Furthermore, we aimed to investigate whether changes in BIVA may correspond with the development of acute mountain sickness (AMS). Subjects were exposed in a hypobaric chamber to both NX (corresponding to an altitude of 262 m) and HH conditions corresponding to an altitude of 3500 m during two four-day sojourns within which food, water intake and physical activity were controlled. Bioimpedance and body weight measurements were performed three times a day and medical symptoms were assessed every morning using the Lake Louise score (LLS). Total body water (TBW) was also assessed on the last day of both sojourns using the deuterium dilution technique. We detected circadian changes in vector length, indicating circadian body water variations that did not differ between NX and HH conditions (ANOVA effects: time: = 0.018, eta = 0.149; interaction: = 0.214, eta = 0.083; condition: = 0.920, eta = 0.001). Even though none of the subjects developed AMS, four subjects showed clinical symptoms according to the LLS during the first 24 hours of HH conditions. These subjects showed a pronounced (Cohen's d: 1.09), yet not statistically significant ( = 0.206) decrease in phase angle 6 hours after exposure, which may indicate fluid shift from the intracellular to the extracellular compartment. At the end of each sojourn, vector length correlated with deuterium dilution TBW "gold standard" measurements (linear regression: NX: = 0.002 and r = 0.756, HH: < 0.001 and r = 0.84). BIVA can be considered a valuable method for monitoring body hydration changes at altitude. Whether such changes are related to the development of clinical symptoms associated with AMS, as indicated in the present investigation, must be confirmed in future studies.
生物电阻抗向量分析（BIVA）是一种用于估计身体水合变化的方法。我们评估了 BIVA 在监测 9 名健康、正常活动男性在匹配常氧（NX）和低氧（HH）实验条件下日常身体水合波动中的潜力。此外，我们旨在研究 BIVA 的变化是否与急性高山病（AMS）的发展有关。在两个为期四天的逗留期间，受试者在低压舱中暴露于 NX（相当于海拔 262 米）和 HH 条件下，对应于海拔 3500 米的高度，在此期间，食物、水的摄入和体力活动都受到控制。每天进行三次生物阻抗和体重测量，并使用路易湖评分（LLS）每天早上评估医疗症状。在两次逗留的最后一天，使用氘稀释技术评估总体水量（TBW）。我们检测到向量长度的昼夜变化，表明昼夜身体水分变化在 NX 和 HH 条件下没有差异（方差分析效应：时间：= 0.018，eta = 0.149；交互作用：= 0.214，eta = 0.083；条件：= 0.920，eta = 0.001）。尽管没有受试者出现 AMS，但有 4 名受试者在 HH 条件的前 24 小时根据 LLS 出现临床症状。这些受试者在暴露后 6 小时表现出明显（Cohen's d：1.09）但无统计学意义（= 0.206）的相位角下降，这可能表明液体从细胞内转移到细胞外。在每次逗留结束时，向量长度与氘稀释 TBW“金标准”测量值相关（线性回归：NX：= 0.002 和 r = 0.756，HH：< 0.001 和 r = 0.84）。BIVA 可被视为监测高海拔地区身体水合变化的有价值方法。在本研究中，BIVA 的变化是否与与 AMS 相关的临床症状的发展有关，这必须在未来的研究中得到证实。
