Effect of gravity on chest wall mechanics.
Bettinelli, D ; Kays, C ; Bailliart, O ; et al. ; - ASI Sponsor
Mar - 2002
ISSN : 8750-7587 ;
journal : Journal of applied physiology (Bethesda, Md. : 1985)
Issue : 2
type: Article Journal
Abstract
Chest wall mechanics was studied in four subjects on changing gravity in the craniocaudal direction (G(z)) during parabolic flights. The thorax appears very compliant at 0 G(z): its recoil changes only from -2 to 2 cmH(2)O in the volume range of 30-70\% vital capacity (VC). Increasing G(z) from 0 to 1 and 1.8 G(z) progressively shifted the volume-pressure curve of the chest wall to the left and also caused a fivefold exponential decrease in compliance. For lung volume <30\% VC, gravity has an inspiratory effect, but this effect is much larger going from 0 to 1 G(z) than from 1 to 1.8 G(z). For a volume from 30 to 70\% VC, the effect is inspiratory going from 0 to 1 G(z) but expiratory from 1 to 1.8 G(z). For a volume greater than approximately 70\% VC, gravity always has an expiratory effect. The data suggest that the chest wall does not behave as a linear system when exposed to changing gravity, as the effect depends on both chest wall volume and magnitude of G(z).
keywords : Compliance,Female,Gravitation,Humans,Inhalation,Inhalation: physiology,Lung,Lung Volume Measurements,Lung: physiology,Male,Middle Aged,Pressure,Residual Volume,Respiratory Mechanics,Thorax,Thorax: physiology,Total Lung Capacity,Vital Capacity,Weightlessness