title: Effect of gravity on chest wall mechanics.
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).
authors.affiliation: Dipartimento di Medicina Sperimentale, Ambientale e Biotecnologie Mediche, Università di Milano-Bicocca, I-20052 Monza, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Bettinelli
authors.forename: C
authors.initials: C
authors.lastname: Kays
authors.forename: O
authors.initials: O
authors.lastname: Bailliart
authors.forename: A
authors.initials: A
authors.lastname: Capderou
authors.forename: P
authors.initials: P
authors.lastname: Techoueyres
authors.forename: J L
authors.initials: JL
authors.lastname: Lachaud
authors.forename: P
authors.initials: P
authors.lastname: Vaïda
authors.forename: G
authors.initials: G
authors.lastname: Miserocchi
mesh_terms: D003187:Compliance; D005260:Female; D006112:Gravitation; D006801:Humans; D001239:Inhalation / Q000502:physiology; D008168:Lung / Q000502:physiology; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D011312:Pressure; D012115:Residual Volume; D015656:Respiratory Mechanics; D013909:Thorax / Q000502:physiology*; D014109:Total Lung Capacity; D014797:Vital Capacity; D014893:Weightlessness