AbstractWe studied the circulatory and respiratory effects of methylprednisolone (MPS) associated with catecholamine after cardiopulmonary bypass (CPB). Forty patients undergoing coronary artery bypass grafting were randomly divided into two groups. Twnety patients in group 1 (MPS (-) group) did not receive MPS and 20 patients in group 2 (MPS (+) group) received MPS 15 mg/ kg i.v. 15 min after CPB. The circulatory, respiratory and matabolic parameters were measured 15, 30, 60, 90 and 120 min after CPB. The values in MPS (-) group were compared with those in MPS (+) group. CI decreased and SVRI increased in MPS (-) group, but those values were unchanged in MPS (+) group. SVI, CVP and PCWP were unchanged in MPS (-) group, but those values increased in MPS (+) group. HR, mAP, mPAP and PVRI increaed in both groups. PaO_2 decreased in MPS (-) group, but this was unchanged in MPS (+) group. Q_S/Q_T, OER and L/P were unchanged in MPS (-) group, but Q_S/Q_T increased and L/P and OER decreased in MPS (+) group. The other blood gases were not different in the two groups. Blood cortisol, epinephrine and norepinephrine were also the same within the two groups. Methylprednisolone had an effect on improving the decreased CI and the increased SVRI. No respiratory problems were observed in patients for coronary artery bypass grafting with catecholamine administration after cardiopulmonary bypass.