Cardiopulmonary hemodynamic changes in the critically ill surgical patients

We inserted a balloon tipped pulmonary artery catheter into 27 hypoxemic patients (mean PaO2 = 53.6 mmHg) and measured pu1monary artery (PPA). pulmonary wedge (PPW) and central venous (CVP) pressures. In seven patients, without previous cardiorespiratory disease, we measured cardiac output (C.O.) by dye dilution and ca1culated pulmonary-vascular resistance (PVR) at 21%, 40% and 100% inspired oxygen. CVP correlated poorly with PPW in 13 of the 27 patients who had prior cardiorespiratory disease (p 0.05). CVP correlated well with PPW in the other 14 patients (p 0.001). In the seven patients in whom it was measured, C.O. was high (mean 6.9 L/min). pH was normal or increased (mean 7.41 units), PPW normal (mean 7 mmHg) and, PVR low (mean 1.9 units). Breathing 100% oxygen had no effect on PPW (mean 7.4 mmHg), C.O. increased (mean 8.3 L/min) and PVR fell slightly (mean 1.2 units). We conclude that in critically ill patients CVP is a reasonable index of PPW only in the absence of cardiorespiratory disease. Despite severe hypoxemia PVR is normal. The lack of significant may be explained by the normal or high pH in contrast to patients with respiratory acidosis. Breathing oxygen enriched mixtures did not increase PPW or reduce C.O