[How should we treat intestinal ischemia?--1: Effects of dobutamine and dopamine].

Intestinal mucosal ischemia is one of the earliest manifestations of impaired core tissue perfusion in critically ill patients. The aim of this study was to investigate the effects of dobutamine and dopamine on intestinal ischemia in ten anesthetized dogs. Intestinal intramural pH (pHi) by tonometry is an early reliable marker of assessing the adequacy of tissue oxygenation. A tonometer was inserted into the midjejunum through enterotomy. The superior mesenteric artery (SMA) blood flow was measured by a transit-time ultrasonic flowmeter. A vascular screw clamp for blood flow reduction was placed at the origin of the SMA, proximal to the flow probe. The SMA blood flow was maintained at 70% of baseline flow for three hours. After two hours of decreased blood flow, intravenous dobutamine or dopamine was infused at a rate of 5 micrograms.kg-1.min-1 for one hour. The pHi fell significantly from 7.16 +/- 0.04 to 7.08 +/- 0.04 in dobutamine group, and from 7.18 +/- 0.04 to 7.06 +/- 0.05 in dopamine group two hours after induction of intestinal ischemia. Treatments with dobutamine and dopamine increased the SMA blood flow to near baseline levels. Dobutamine caused a significant increase in pHi to 7.11 +/- 0.04. On the contrary, dopamine tended to decrease pHi further to 7.01 +/- 0.09. These results suggest that dobutamine may improve intestinal tissue oxygenation. However, dopamine even at lower doses, may induce constriction of the intestinal mucosal arterioles.