Effect of acute hemodilution on intestinal perfusion and intramucosal pH after shock

Background: Restoration of oxygen delivery, especially to the splanchnic bed, is of critical importance during trauma resuscitation. Acute normovolemic hemodilution (ANH) has been used to reduce blood transfusion requirement during elective surgery. The effect of hemodilution on the splanchnic circulation during hemorrhagic shock (HS) is not well defined. Methods: swine were instrumented to measure systemic and splanchnic circulation effects of ANH after HS, The adequacy of the splanchnic circulation was assessed by changes in measured mucosal blood flow, mucosal tonometry, as well as by portal venous blood O-2 saturation, portal venous CO2 saturation, and lactate. Results: ANH after HS resulted in a final hematocrit of 18 +/- 2%, Superior mesenteric artery blood flow was returned to baseline levels; however, mucosal blood flow was still only 64% of baseline levels. However, at the same time mucosal P-CO2 and intramucosal pH as web as portal ;venous O-2 and CO2 saturation had normalized. Conclusions: As long as an adequate intravascular volume is maintained, hemodilution is wed tolerated by the gut after IES. Concern about the adequacy of gut perfusion should not be a transfusion trigger after HS.