Journal of Applied Physiology, Vol 52, Issue 3 638-641, Copyright © 1982 by American Physiological Society
Nonhomogeneous alveolar pressure swings: effect of different respiratory muscles
R. Brown, S. M. Scharf and R. Ingram Jr
We tested the hypothesis in dogs that during isovolumic inspiratory efforts
the degree of nonhomogeneity of alveolar pressure changes is influenced by
regional differences in respiratory muscle activity. Pressure distal to an
occluded right lower lobe bronchus (PRLL) was compared with pressure in the
occluded airway opening (PaO) during spontaneous inspiratory efforts (S),
during right (RP), left (LP), and bilateral (BP) phrenic nerve stimulation,
and during spontaneous inspiratory efforts after cutting both phrenic
nerves (SCP), Upper and lower rib cage and abdominal dimensional changes
were monitored by magnetometers. PRLL was greater than Pao during S and the
difference was greater during BP and greater during RP, whereas with LP and
SCP Pao exceeded PRLL. Compared with S, during RP, LP, and BP there was
greater upper rib cage inward motion relative to abdominal outward motion.
SCP resulted in opposite upper rib cage-abdomen relative motions. Thus
activities of various muscle groups produced different regional pressures
and deformations of rib cage and abdomen. These results may relate to
potential errors in plethysmographic determination of thoracic gas volume
in the presence of airway closure.
