The effect of amrinone on gas exchange and oxygen metabolism were evaluated in eight patients after cardiovascular surgery for cardiopulmonary bypass.Amrinone was adminisered without bolus infusion (infusion rate: 10μg·kg-1·min-1). Data were obtained 30 minutes and 90 minutes following amrinone administration and were compared to the control data. Values are described as mean±SD.Non-nutrient blood flow (NNBF) and conventional parameters for oxygen metabolism were used to evaluate regional blood flow. NNBF was calculated with Farrell's formula.Both the respiratory index (from 1.4±1.1 to 2.1±1.2 (30min), 2.4±1.5L·min-1·m-2 (90min)) and pulmonary shunt (from 10.1±to 11.6±6% (30m), 12.1±5% (90min)) significantly (p<0.05) increased. Mean pulmonaly arterial pressure (from 23±8 to 18±7mmHg (90min)) and the pulmonaly vascular resistance index (from 317±87 to 221±61 dyne sec·cm-5·m-2 (90min)) significantly decreased (p<0.05).The cardiac index increased significantly (p<0.05) (from 2.5±0.6 to 3.0±0.9L·min-1·m-2 (90min)). Oxygen consumption showed a significant (p<0.05) increase (from 185±34 to 220±88ml/min. (90min)) but oxygen saturation of mixed venous blood was not altered (from 68±5 to 65±6% (90min)). The control values of NNBF indicated insufficient regional blood flow. Amrinone significantly increased NNBF (from-34±25 to -8±33% (90min)).These results suggest that amrinone increases cardiac output and regional blood flow, thus improving oxygen metabolism. They also suggest, however, that amrinone increases pulmonary shunt which leads to decreased gas exchange in patients after cardiovascular surgery.