Systemic but not local rehydration restores dehydration-induced changes in pulmonary function in healthy adults

Abstract

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.

Effect of Hydration on Pulmonary Function and Development of Exercise-Induced Bronchoconstriction among Professional Male Cyclists

“…A previous study supported that systemic rehydration restores dehydration-induced changes in pulmonary function in healthy adults [51]. This study aimed to clarify the impact of exercise-induced dehydration or fluid restriction-induced dehydration on pulmonary function in healthy adults and establish whether systemic or local rehydration can reverse dehydration-induced alterations in pulmonary function.…”

Mouth breathing, dry air, and low water permeation promote inflammation, and activate neural pathways, by osmotic stresses acting on airway lining mucus

“…PCL thickness can be restored (or further thinned) by deposition of hypertonic (or hypotonic) saline on the surface of the ALF. Unlike the case of isotonic saline, for which deposition on the surface of ALF increases the condensation layer thickness without increasing PCL thickness and, therefore, is incapable of modulating dysfunction (Marshall et al , 2021 ), deposition of droplets of mass M D with hypertonic (or hypotonic) salt ion concentration C D may raise (or lower) the tonicity of the ALF sufficiently to hydrate (or dehydrate) the PCL by osmotic water flux from epithelial cells. This mass can be estimated by a simple mass balance.…”

Decrease of extracellular volume triggers exercise-induced bronchoconstriction to protect the body from water loss

“…This study has shown that ECV was lower in patients with EIB, it means that EIB is related to the dehydration of the body. A latest research (Hannah Marshall et al 2020) which has proposed that "in healthy adults: i) mild systemic dehydration induced by exercise or uid restriction leads to pulmonary function impairment, primarily localized to small airways; and ii) systemic, but not local, rehydration reverses these potentially deleterious alterations." also supported our proposal.…”