Journal of Applied Physiology, Vol 68, Issue 3 843-848, Copyright © 1990 by American Physiological Society
Mechanical effects of PEEP in patients with adult respiratory distress syndrome
J. Dall'ava-Santucci, A. Armaganidis, F. Brunet, J. F. Dhainaut, S. Nouira, D. Morisseau and A. Lockhart
Department of Physiology, Cochin-Port Royal University Hospital, Paris, France.
In 10 patients with adult respiratory distress syndrome, we studied the
effects on respiratory system mechanics of two levels of positive
end-expiratory pressure (PEEP), best PEEP (BP) and half of this value
(HBP), using a respiratory inductive plethysmograph (RIP) combined with a
super syringe. We found the following. 1) Inflation compliance of
pressure-volume (PV) curves did not change significantly. 2) End-expiratory
volume increased with HBP and further with BP (278 +/- 186 and 464 +/- 313
ml, respectively, P less than 0.01). This increase was positively
correlated with inflation compliance for HBP and BP (r = 0.794, P less than
0.01 and r = 0.876, P less than 0.01, respectively). 3) No dynamic
hyper-inflation was detected on mechanical ventilation at zero
end-expiratory pressure (ZEEP), and the time constant of the respiratory
system was in the normal range (0.79 +/- 0.21 s). 4) Hysteresis of PVrip
curves, which were corrected for gas exchange, decreased significantly with
PEEP (P less than 0.05). We conclude that PEEP does not change inflation PV
curve but induces an increase in intrathoracic volume whose magnitude is
related to compliance and PEEP level. The reduction of hysteresis with PEEP
suggests less gas trapping and thus a functional improvement.
