Stewart Ian B, Dias Brittany, Borg David N, Bach Aaron J E, Feigl Beatrix, Costello Joseph T
School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland University of Technology Brisbane, QLD, Australia.
School of Biomedical Sciences and Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland University of Technology Brisbane, QLD, Australia.
Front Physiol. 2017 Feb 1;8:36. doi: 10.3389/fphys.2017.00036. eCollection 2017.
Current hydration assessments involve biological fluids that are either compromised in dehydrated individuals or require laboratory equipment, making timely results unfeasible. The eye has been proposed as a potential site to provide a field-based hydration measure. The present study evaluated the efficacy and sensitivity of intraocular pressure (IOP) to assess hydration status. Twelve healthy males undertook two 150 min walking trials in 40°C 20% relative humidity. One trial matched fluid intake to body mass loss (control, CON) and the other had fluid restricted (dehydrated, DEH). IOP (rebound tonometry) and hydration status (nude body mass and serum osmolality) were determined every 30 min. Body mass and serum osmolality were significantly ( < 0.05) different between trials at all-time points following baseline. Body mass losses reached 2.5 ± 0.2% and serum osmolality 299 ± 5 mOsmol.kg in DEH. A significant trial by time interaction was observed for IOP ( = 0.042), indicating that over the duration of the trials IOP declined to a greater extent in the DEH compared with the CON trial. Compared with baseline measurements IOP was reduced during DEH (150 min: -2.7 ± 1.9 mm Hg; < 0.05) but remained stable in CON (150 min: -0.3 ± 2.4 mm Hg). However, using an IOP value of 13.2 mm Hg to predict a 2% body mass loss resulted in only 57% of the data being correctly classified (sensitivity 55% and specificity 57%). The use of ΔIOP (-2.4 mm Hg) marginally improved the predictive ability with 77% of the data correctly classified (sensitivity: 55%; specificity: 81%). The present study provides evidence that the large inter-individual variability in baseline IOP and in the IOP response to progressive dehydration, prevents the use of IOP as an acute single assessment marker of hydration status.
目前的水合作用评估涉及生物体液，这些体液在脱水个体中要么受到影响，要么需要实验室设备，这使得及时获得结果变得不可行。眼睛已被提议作为提供现场水合作用测量的潜在部位。本研究评估了眼压（IOP）评估水合状态的有效性和敏感性。12名健康男性在40°C、相对湿度20%的环境下进行了两次150分钟的步行试验。一次试验使液体摄入量与体重减轻相匹配（对照组，CON），另一次试验限制液体摄入（脱水组，DEH）。每隔30分钟测量一次眼压（回弹式眼压计）和水合状态（裸体体重和血清渗透压）。在基线后的所有时间点，两次试验之间的体重和血清渗透压存在显著差异（<0.05）。在脱水组中，体重减轻达到2.5±0.2%，血清渗透压达到299±5 mOsmol.kg。观察到眼压存在显著的试验×时间交互作用（=0.042），表明在试验过程中，与对照组试验相比，脱水组的眼压下降幅度更大。与基线测量相比，脱水组眼压在试验期间降低（150分钟时：-2.7±1.9毫米汞柱；<0.05），而对照组保持稳定（150分钟时：-0.3±2.4毫米汞柱）。然而，使用13.2毫米汞柱的眼压值预测2%的体重减轻，只有57%的数据被正确分类（敏感性55%，特异性57%）。使用眼压变化值（-2.4毫米汞柱）略微提高了预测能力，77%的数据被正确分类（敏感性：55%；特异性：81%）。本研究提供的证据表明，基线眼压以及眼压对渐进性脱水反应的个体间差异很大，这使得眼压不能作为水合状态的急性单一评估指标。
