Human rib cage distortability.
Chihara, Koji, Chris M. Kenyon, and Peter T. Macklem.
Meakins-Christie Laboratories, McGill University Clinic Royal
Victoria Hospital, Montreal and the Respiratory Health Network of
Centres of Excellence
APStracts 3:0164A, 1996.
In 5 normal males we divided the rib cage into lung-apposed (RCp) and
diaphragm-apposed (RCa) compartments, and calculated their absolute
cross-sectional areas (Arc,p and Arc,a) by AP and lateral dimensions
measured by magnetometry. Distortion was quantified as the
displacement of RCp and RCa produced by diaphragmatic twitches away
from the relaxed configuration. We measured transdiaphragmatic
pressure (Pdi) as the difference between gastric (Pga) and esophageal
pressures. Distortability was expressed as % distortion/Pdi and
varied among individuals from 0.02-0.23%/cm H2O. The pressure acting
to restore the distorted rib cage back to its relaxed shape (Plink)
varied from 0.1-31.3 cm H2O per % distortion. Distortion correlated
positively(r= 0.92)and Plink per % distortion negatively(r = 0.90)
with RCa compliance (Plink per % distortion, Plink per % distortion
(during the relaxation manoeuvre ([delta]Arc,a/[delta]Pga). We
conclude that rib cage distortability varies widely among normal
subjects and is closely linked to RCa compliance.
Received 21 June 1994; accepted in final form 9 February 1996.
APS Manuscript Number A608-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96