Journal of Applied Physiology, Vol 58, Issue 1 77-82, Copyright © 1985 by American Physiological Society
Lower body positive pressure vs. dopamine during PEEP in humans
D. M. Payen, P. A. Carli, C. J. Brun-Buisson, Y. J. Huet, B. P. Teisseire, B. Chiron-Payen and F. L. Lemaire
The application of lower body positive pressure (LBPP) of approximately 40
Torr was used to increase cardiac index (CI) in eight patients with acute
respiratory failure (ARF) during positive end-expiratory pressure (PEEP)
ventilation. The effects of LBPP on hemodynamics and gas exchange were
compared with those of dopamine at the same level of CI without blood
volume expansion. LBPP increased CI via an increase in stroke index without
associated tachycardia, whereas dopamine combined both effects. A positive
linear relationship (r = 0.82) was evidenced between CI and right atrial
pressure (Pra) during application of LBPP according to the Frank-Starling
mechanism, whereas dopamine did not increase Pra. The increase in CI with
dopamine was associated with a significant rise in venous admixture (r =
0.84, P less than 0.001), whereas no such effect was observed with LBPP (r
= 0.088). Changes in venous admixture were directly related to changes in
mixed venous O2 pressure (PVO2) in both situations (r = 0.733, P less than
0.01), but the increase in PVO2 was more pronounced with dopamine than with
LBPP (P less than 0.04). We conclude that LBPP can effectively
counterbalance peripheral venous blood pooling during PEEP ventilation in
humans with ARF and that changes in PVO2 appear as a major determinant of
venous admixture in this setting.
