A placebo-controlled study of the effects of dopexamine on gastric mucosal perfusion in infants undergoing hypothermic cardiopulmonary bypass.

We used a laser Doppler probe to measure gastric mucosal blood flow (flux) and a paediatric tonometer to intermittently calculate gastric-arterial PCO2 difference (PrCO2-PaCO2 gap) in 50 infants aged 0.3-52 weeks who required hypothermic cardiopulmonary bypass (CPB). During CPB, patients in group 2 (n = 25) were given dopexamine 1.0 mg kg-1 over 5 min, followed by an infusion of 2 micrograms kg-1 min-1. Patients in group 1 (n = 25) received an equal volume of saline. Drug allocation was random and blinded. Measurements of flux, PrCO2-PaCO2 gap and mean femoral arterial pressure (MAP) were made over 5 min during steady state before and after cooling on CPB to 18-24 degrees C. MAP and blood lactate concentrations were similar in both groups throughout CPB. Mean flux decreased from 182 (SD 60) at the beginning of CPB to 158 (51) after rewarming on CPB in group 1, whereas it increased from 180 (56) to 196 (49) in group 2. This post-rewarm flux was significantly greater in group 2 than in group 1 (P = 0.01). Similarly, mean PrCO2-PaCO2 gap increased significantly from 3.6 (6.3) to 8.2 (6.7) in group 1 (P = 0.01) compared with a significant decrease from 5.8 (5.5) to 2.1 (5.5) in group 2 (P = 0.02). Mean PrCO2-PaCO2 gap after rewarming in group 2 was significantly higher than that in group 1 (P = 0.001). These data indicate that dopexamine may be useful in maintaining normal gut perfusion in infants requiring hypothermic CPB.