Effects of extrinsic positive end-expiratory pressure on cardiopulmonary function in patients with chronic obstructive pulmonary disease

Abstract

Objective: To choose one optimal extrinsic positive end-expiratory pressure (PEEPe) for ventilated patients with chronic obstructive pulmonary disease (COPD) and to compare two methods for choosing the optimal level of PEEPe.

Methods: Ten ventilated patients with COPD were included in the study. First, static intrinsic positive end-expiratory pressure (PEEPi, st) was measured when PEEPe was zero, and the PEEPi, st was called PEEPi, stz. PEEPe at 0%, 40%, 50%, 60%, 70%, 80%, 90% and 100% of PEEPi, stz, respectively, were applied randomly. Respiratory mechanics, hemodynamics, and oxygen dynamics were recorded 30 minutes after the level of PEEPe was changed.

Results: When PEEPe was not higher than 80% of PEEPi, stz, no measurement changed significantly. When PEEPe was increased to 90% and 100% of PEEPi, stz, PEEPi, st, peak inspiratory pressure, plateau pressure, pulmonary capillary wedge pressure and central venous pressure increased significantly, P < 0.01. Cardiac output and left ventricular work index decreased significantly, P < 0.01. Oxygen delivery decreased significantly, P < 0.05. When PEEPe was increased to 100% of PEEPi, stz, the right ventricular work index decreased significantly, P < 0.05.

Conclusion: Eighty percent of PEEPi, stz was the upper limit of PEEPe. The results of the two methods used to set the level of PEEPe were identical.