Influence of elevated pulmonary vascular resistance on the relationship between central venous pressure and pulmonary artery occluded pressure following cardiopulmonary bypass.

This study has demonstrated that CVP measurement is an unreliable index of left ventricular filling pressure in unselected patients undergoing A-C bypass procedures. The influence of altered PVR on the disparity between right and left ventricular filling pressures is not of prime importance. The inconsistent relationship between CVP and PAo is primarily a result of ventricular dysfunction and not altered PVR. This suggests that following A-C bypass surgery patients cannot be grouped with respect to altered PVR as the variable which determines whether CVP will be a reliable guide to changes in left atrial pressure. Routine use of Swan-Ganz catheters would improve the precision of monitoring and fluid administration in all patients following CPB. However, it would also increase the cost and complexity of routine care and add a very low incidence of complications to all patients having cardiac surgery. At present, we monitor high risk patients from the time of surgery and advocate early insertion of Swan-Ganz catheters in low risk patients if they are not responding to appropriate management.