Water transport and local (airway) hydration are critical for the normal functioning of lungs and airways. Currently, there is uncertainty regarding the effects of systemic dehydration on pulmonary function. Our aims were: i) to clarify the impact of exercise- or fluid restriction-induced dehydration on pulmonary function in healthy adults; and ii) to establish whether systemic or local rehydration can reverse dehydration-induced alterations in pulmonary function. Ten healthy participants performed four experimental trials in a randomized order (2 h exercise in the heat twice, and 28 h fluid restriction twice). Pulmonary function was assessed using spirometry and whole-body plethysmography in the euhydrated, dehydrated, and rehydrated states. Oral fluid consumption was used for systemic rehydration, and nebulized isotonic saline inhalation for local rehydration. Both exercise and fluid restriction induced mild dehydration (2.7±0.7% and 2.5±0.4% body mass loss, respectively; p<0.001) and elevated plasma osmolality (p<0.001). Dehydration across all four trials was accompanied by a reduction in forced vital capacity (152±143 mL, p<0.01) and concomitant increases in residual volume (216±177 mL, p<0.01) and functional residual capacity (130±144 mL, p<0.01), with no statistical differences between modes of dehydration. These changes were normalized by fluid consumption, but not nebulization. Our results suggest that, in healthy adults: i) mild systemic dehydration induced by exercise or fluid restriction leads to pulmonary function impairment, primarily localized to small airways; and ii) systemic, but not local, rehydration reverses these potentially deleterious alterations.

中文翻译：

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系统性但非本地化恢复在健康成人中恢复由脱水引起的肺功能变化

水的运输和局部（气道）水合作用对于肺部和气道的正常运转至关重要。目前，关于全身脱水对肺功能的影响尚不确定。我们的目标是：i）阐明运动或体液限制引起的脱水对健康成年人肺功能的影响；ii）确定全身或局部补液能否逆转由脱水引起的肺功能改变。十名健康参与者以随机顺序进行了四项实验性试验（在热度下进行2小时运动两次，两次体液限制在28小时内）。使用肺活量测定法和全身体积描记法评估处于水合，脱水和再水合状态的肺功能。口服液体消耗用于全身补液，吸入等渗的雾化盐水进行局部补液。运动和体液限制均引起轻度脱水（分别为2.7±0.7％和2.5±0.4％体重减轻； p <0.001）和升高的血浆渗透压（p <0.001）。在所有四项试验中，脱水均伴随着强制肺活量的减少（152±143 mL，p <0.01），伴随而来的是残余容量的增加（216±177 mL，p <0.01）和功能残余容量（130±144 mL， p <0.01），脱水方式之间无统计学差异。这些变化通过液体消耗而不是雾化来标准化。我们的结果表明，在健康成年人中：i）运动或体液限制引起的轻度全身性脱水会导致肺功能损害，主要局限于小气道；ii）系统性而非局部性，