The effect of different bypass flow rates and low-dose dopamine on gut mucosal perfusion and outcome in cardiac surgical patients

The aim of this double-blind, randomized, placebo-controlled trial was to i nvestigate the effects of different cardiopulmonary bypass flow rates and l ow-dose dopamine on gastric mucosal pH (pHi) and outcome. We hypothesized t hat by minimizing gut mucosal hypoperfusion during and after cardiac surger y endotoxin translocation may be prevented, resulting in an improved clinic al outcome. Four groups of 25 patients each receiving high or low flows dur ing bypass and low-dose dopamine or saline for 24 hours after induction of anaesthesia were studied. The pHi was measured at six time intervals over 2 4 hours. The combination of low-dose dopamine and a low bypass flow rate was associa ted with a significantly greater frequency and severity of low pHi. This gr oup also demonstrated a significantly lower vascular resistance on admissio n to the intensive care unit. There may be an association between low pHi a nd low vascular resistance.