Changes in central venous pressure and pulmonary capillary wedge pressure do not indicate changes in right and left heart volume in patients undergoing coronary artery bypass surgery

The value of pulmonary artery catheterization is a matter for discussion. P revious studies suggest that direct measurements of intravascular volume di stribution and cardiac volume indices may be of greater relevance than cent ral venous and pulmonary capillary wedge pressure. We therefore used a ther mo-dye dilution technique for the quantification of central blood volume, r ight ventricular end-diastolic volume and left heart volume in patients und ergoing coronary artery bypass surgery. Measurements were performed after t he induction of anaesthesia as well as 1, 6 and 24 h after surgery. Central venous pressure was significantly increased at 1 and 6 h, whereas right ve ntricular end-diastolic volume was increased only at 6 h post-operatively. Pulmonary capillary wedge pressure showed a tendency to increase whereas le ft heart and central blood volume decreased significantly after surgery. Th e results of the present study suggest that changes in cardiac filling pres sure do not indicate changes in indices of cardiac volume in patients after coronary bypass surgery.