EFFECT OF TEMPERATURE DURING CARDIOPULMONARY BYPASS ON GASTRIC-MUCOSAL PERFUSION

The purpose of our study was to prospectively study the splanchnic res ponse to hypothermic and tepid cardiopulmonary bypass (CPB) using alph a-stat management of arterial blood-gas tensions. Twenty-four patients for elective CABG surgery were allocated randomly to tepid (35-36 deg rees C) or hypothermic (30 degrees C) bypass groups, Measurements were made at four times: (1) baseline, (2) stable during CPB (inflow tempe rature = nasopharyngeal temperature) 30 degrees C for hypothermic pati ents, bypass +20 min for tepid patients, (3) 10 min before the end of bypass, (4) after bypass, skin closure. Both groups demonstrated a sig nificant reduction in gastric intramucosal pH (pH(im)) from time 1 to time 4 and there was no difference in the incidence of a low pH(im) be tween the tepid and cold groups (4/12 vs 3/12; ns) at time 4. pH(im) w as significantly lower in the tepid group at time 3 (P = 0.03) but thi s discrepancy may have been because of an artefactually high pH(im) in the cold group. There was a significantly higher incidence of postope rative non-cardiac complications in patients who had a low pH(im) at t ime 4 (P = 0.0008) Therefore, we conclude that although the temperatur e during CPB had a transient effect on pH(im) it is unlikely to be a m ajor determinant in the pathogenesis of gut mucosal hypoperfusion afte r bypass.