Jejunal mucosal perfusion is well maintained during mild hypothermic cardiopulmonary bypass in humans

In the present study, the effects of mild hypothermic (34 degrees C) cardiopulmonary bypass (CPB) on jejunal mucosal perfusion (JMP), gastric tonometry, splanchnic lactate, and oxygen extraction were studied in low-risk cardiac surgical patients (n = 10), anesthetized and managed according to clinical routine. JMP was assessed by endoluminal laser Doppler flowmetry. Patients were studied during seven 10-min measurement periods before, during, and 1 h after the end of CPB. Splanchnic oxygen extraction increased during hypothermia and particularly during rewarming and warm CPB. JMP increased during hypothermia (26%), rewarming (31%), and warm CPB (38%) and was higher 1 h after CPB (42%), compared with pre-CPB control. The gastric-arterial PCO(2) difference was slightly increased (range 0.04-2.26 kPa) during rewarming and warm CPB as well as 1 h after CPB, indicating a mismatch between gastric mucosal oxygen delivery and demand. None of the patients produced lactate during CPB. We conclude that jejunal mucosal perfusion appears well preserved during CPB and moderate (34 degrees C) hypothermia; this finding is in contrast to previous studies showing gastric mucosal hypoperfusion during CPB. Implications: Jejunal mucosal perfusion increases during mild hypothermic cardiopulmonary bypass (CPB). Intestinal laser Doppler flowmetry, gastric tonometry, and measurements of splanchnic lactate extraction could not reveal a local or global splanchnic ischemia during or after CPB. A mismatch between splanchnic oxygen delivery and demand was seen, particularly during rewarming and warm CPB.