Abstract: [Abstract] OBJECTIVE To explore the influence of different blood pressure in mixed venous oxygen saturation(SvO2) and lactic acid(Lac). METHODS Forty patients undergoing coronary artery bypass graft(CABG) surgery with extracorporeal circulation(ECC) were selected and divided randomly into two groups: the patients in group I were applied with drugs to keep blood pressure between 60 and 90mmHg duringECC. Those in group II were to keep blood pressure between 40 and 60mmHg. The arterial and venous blood gas were examined at time points of before extracorporeal circulation(T1), five minutes after clamping the ascending aorta (T2), before rewarming (T3), before the end of ECC (T4) and before delivering (T5). Hematocrit, arterial oxygen saturation and glucose, and electrolytes were maintained within the normal range during ECC. The values of SvO, Lac and temperature at all time points were recorded. RESULTS 1. The normal data, ECC clinical data and the result of blood gas had no significant statistical. differences between the two groups(P>0.05). 2. There were no significant statistical differences in SvO2 of the two groups. 3. There were significant statistical difference in Lac of the two groups with point T4 and T5: the results of Lac in group II were higher than in group I (P<0.05). CONCLUSION Maintenance of a higher blood pressure with vasoactive drugs during extracorporeal circulation is favorable to decrease the blood lac after rebeating.

Key words: blood pressure, Extracorporeal circulation, coronary artery bypass graftinging, mixed venous oxygen saturation, lactic acid