Journal of Applied Physiology, Vol 59, Issue 4 1171-1177, Copyright © 1985 by American Physiological Society
Transmission of airway pressure to pleural space during lung edema and chest wall restriction
R. J. O'Quin, J. J. Marini, B. H. Culver and J. Butler
To investigate the influence of positive end-expiratory pressure (PEEP) on
hemodynamic measurements we examined the transmission of airway pressure to
the pleural space during varying conditions of lung and chest wall
compliance. Eight ventilated anesthetized dogs were studied in the supine
position with the chest closed. Increases in pleural pressure were similar
for both small and large PEEP increments (5-20 cmH2O), whether measured in
the esophagus (Pes) or in the juxtacardiac space by a wafer sensor (Pj).
Increments in Pj exceeded the increments in Pes at all levels of PEEP and
under each condition of altered lung and chest wall compliance. When chest
wall compliance was reduced by thoracic and abdominal binding, the fraction
of PEEP sensed in the pleural space increased as theoretically predicted.
Acute edematous lung injury produced by oleic acid (OA) did not alter the
deflation limb pressure-volume characteristics of the lung, provided that
end-inspiratory volume was adequate. With the chest and abdomen restricted
OA was associated with less than normal transmission of airway pressure to
the pleural space, most likely because the end-inspiratory volume required
to restore normal deflation characteristics was not attained. Together
these results indicate that the influence of acute edematous lung injury on
the transmission of airway pressure to the pleural space depends
importantly on the peak volume achieved during inspiration.
