DOPEXAMINE AND DOPAMINE IN THE PREVENTION OF LOW GASTRIC-MUCOSAL PH FOLLOWING CARDIOPULMONARY BYPASS

The effect of low-dose dopexamine and dopamine on gastric intramucosal pH (pH(i)) during cardiac surgery and 16 hours postoperatively was studied in 35 adult patients (coronary artery bypass grafting and/or valve replacement). The patients were assigned randomly to treatment groups with either dopexamine 1 mu g . kg(-1) . min(-1) (n=12), dopamine 2.5 mu g . kg(-1) . min(-1) (n=11) or to a control group (n=12). The infusions were starred after induction of anesthesia and were continued until 16 hours after CPB. pH(i) and arterial pH (pH(a)) did not differ between groups and remained unchanged during cardiopulmonary by-pass and for the first four postoperative hours. Both the carbon dioxide tension of arterial blood (PaCO2) and of the saline in the tonometer (PtonCO2) changed in parallel with a decrease during CPB and an increase after CPB and surgery with maximal values 12 hours after termination of CPB. A significant correlation was noted between pH(i) and pH(a) and between arterial and tonometric PCO2. It is concluded that low dose dopexamine and dopamine have no influence on pH(i) during and after cardiac surgery. The observed changes in pH(i) and PtonCO2 were due to changes in pH(a) and in PaCO2 and not a sign of gastric mucosal ischemia.