Gastrointestinal permeability following cardiopulmonary bypass: A randomised study comparing the effects of dopamine and dopexamine

Objective: To compare the effects of dopexamine and dopamine on the mucosal permeability of the gastrointestinal tract (GIT). Design: Prospective, randomised clinical trial. Setting: Intensive care unit of a postgraduate teaching hospital, London, England. Patients: Thirty patients undergoing elective surgery involving cardiopulmonary bypass, performed by a single surgeon. Interventions: Patients were randomly assigned to receive either dopexamine 2.0 mu g/kg per min or dopamine 2.5 mu g/kg per min for the duration of the study period. Measurements and main results: Hemodynamic parameters and gastric intramucosal pH (pHi) were measured at intervals throughout the study. GIT permeability was measured once, post-operatively, using the ratio of absorbed lactulose to L-rhamnose. The groups were similar with respect to demographics, pre- and post-operative risk factors. The lactulose/rhamnose ratio was (mean +/- SEM) 0.34 +/- 0.10 in the dopexamine group vs 0.65 +/- 0.08 in that receiving dopamine (p < 0.05). The dopexamine group had a significantly higher oxygen delivery preoperatively (479.5 +/- 32.0 ml/min per m(2) vs 344.4 +/- 23.9 ml/min per m(2) for dopamine, p < 0.01), but no other significant differences emerged between the groups. Conclusions: Compared to dopamine, dopexamine reduces GIT permeability following surgery involving cardiopulmonary bypass. The mechanism of this effect remains unclear.