Regional perfusion and gastrointestinal function after cardiac surgery

Because low cardiac output, systemic inflammation, and increased metabolism may coexist after cardiopulmonary bypass (CPB), patients undergoing cardia c surgery are at risk of tissue hypoperfusion. Although infrequent, complic ations after CPB are associated with high morbidity, mortality, and cost. M any of these complications may be related to the perfusion of the gastroint estinal tract. The currently available vasoactive drugs do not selectively improve splanchnic blood dow and may induce blood flow redistribution withi n the splanchnic circulation and thereby worsen mucosal blood how Gastric m ucosal acidosis occurs frequently after CPB; this condition has been interp reted as mucosal hypoperfusion. However, there are alternative explanations for this finding; especially the Haldane effect and effects of changing me tabolism are probably underestimated. In this article, we review the pathop hysiology of hepatosplanchnic blood flow associated with CPB and the postop erative period, and the evidence of insufficient or marginal tissue perfusi on peri- and postoperatively.