Effects of a phosphodiesterase III inhibitor on circulating blood volume after cardiopulmonary bypass

Using a new method based on pulse dye densitometry, circulating blood volum e (BV) was measured without direct sampling in patients undergoing open-hea rt surgery, and the effects of phosphodiesterase (PDE) III inhibitor admini stration during cardiopulmonary bypass (CPB) were evaluated. Sixteen patien ts scheduled for elective coronary artery bypass grafting were randomly ass igned to the PDE III inhibitor group or control group. BV was determined be fore CPB, and immediately, and 4 and 12h after operation. After declamping of the aorta, the PDE III inhibitor amrinone (1 mg/kg) was infused as a sin gle bolus into the venous reservoir in the PDE III inhibitor group. BV decr eased significantly soon after the operation in the control group. It did n ot decrease in the PDE III inhibitor group (48.6 +/- 44 and 60.6 +/- 8.0 ml /kg for the control and PDE III inhibitor groups, respectively). Four hours after surgery and beyond no significant changes in BV were observed in eit her group. The body fluid balance was negative in both groups. In conclusio n, a single administration of PDE III inhibitor during CPB was found to sus tain BV soon after operation and, therefore, is useful for postoperative ma nagement of open-heart surgery.