Analysis of factors related to jugular venous oxygen saturation during cardiopulmonary bypass

Objective: To investigate preoperative clinical conditions and/or intraoper ative physiologic variables related to jugular venous oxygen saturation (Sj O(2)) during cardiopulmonary bypass (CPB). Design: Prospective study. Setting: General hospital, single institution. Participants: One hundred forty patients (52 women, 88 men) who underwent c oronary artery bypass grafting. Measurements and Main Results: The authors measured SjO(2) at five times du ring surgery. Multiple stepwise regression analysis showed a significant co rrelation of SjO(2) with (1) arterial carbon dioxide partial pressure (PaCO 2) before CPB (standard regression coefficient [(SC)] = 0.435), (2) cerebra l perfusion pressure (CPP) during initiation of CPB (SC = 0.259), (3) PaCO2 , tympanic temperature (TT), bubble oxygenator, and cerebral small infarcti ons (CSIs) during hypothermic CPB (SC = 0.507, -0.237, -0.192, and -0.189, respectively), (4) CPP, PaCO2, CSIs, and bubble oxygenator during rewarming (SC = 0.476, 0.294, -0.220, and -0.189, respectively), and (5) PaCO2 after CPB (SC = 0.480; p < 0.01), Correlation coefficients between SjO(2) and CP P during rewarming were 0.40 (0.46 without CSI and 0.37 with CSI; p < 0.01) . These results indicate that the relationship between CPP and SjO(2) was s ignificant in patients with CPP less than 40 mmHg during rewarming. Conclusion: During rewarming, when cerebral perfusion and oxygen demand cha nge abruptly, but not during stable hypothermic CPB, CPP was a significant factor related to SjO(2). Copyright (C) 1999 by W.B. Saunders Company.