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

To compare the effects of dopexamine and dopamine on the mucosal permeability of the gastrointestinal tract (GIT). Prospective, randomised clinical trial. Intensive care unit of a postgraduate teaching hospital, London, England. Thirty patients undergoing elective surgery involving cardiopulmonary bypass, performed by a single surgeon. Patients were randomly assigned to receive either dopexamine 2.0 micrograms/kg per min or dopamine 2.5 micrograms/kg per min for the duration of the study period. 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) 0.44 +/- 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 m2 vs 344.4 +/- 23.9 ml/min per m2 for dopamine, p < 0.01), but no other significant differences emerged between the groups. Compared to dopamine, dopexamine reduces GIT permeability following surgery involving cardiopulmonary bypass. The mechanism of this effect remains unclear.