Journal of Applied Physiology, Vol 60, Issue 6 1834-1838, Copyright © 1986 by American Physiological Society
Changes in regional emptying sequence need not change maximum expiratory flow
R. B. Filuk and N. R. Anthonisen
Nine normal young men inhaled boluses of He at the onset of slow vital
capacity (VC) inspirations. During the subsequent VC expirations, we
measured expired flow, volume, and He concentrations. Expirations consisted
of full or partial maximum expiratory flow-volume (MEFV) maneuvers. Full
maneuvers were forced expirations from total lung capacity (TLC). Partial
maneuvers were accomplished by expiring slowly from TLC to 70, 60, 50, and
40% VC and then initiating forced expiration. Expired He concentrations
from full and partial maneuvers were compared with each other and with
those resulting from slow expirations. At comparable volumes less than 50%
VC, flow during partial and full MEFV maneuvers did not differ. Expired He
concentrations were higher during partial maneuvers than during full ones;
at the onset of partial maneuvers upper zone emptying predominated, whereas
this was not the case at the same lung volumes during maneuvers initiated
at TLC. We observed substantial differences in regional emptying sequence
that did not influence maximum expiratory flow.
