Time course of changes in jugular venous oxygen saturation during hypothermic or normothermic cardiopulmonary bypass in patients with diabetes mellitus

Background: Preexisting diabetic mellitus is a risk factor determining postoperative neurological disorders. The present study assesses the effects of normothermic and hypothermic cardiopulmonary bypass (CPB) on jugular venous oxygen saturation (SjvO(2))in patients with preexisting diabetic mellitus. Methods: Sixteen diabetic patients who underwent elective coronary artery bypass grafting surgery were randomly divided into two groups: Group DN (n=8, diabetic patients) underwent normothermic CPB (> 35 degreesC), and group DH (n=8, diabetic patients) underwent hypothermic CPB (32 degreesC). Controls were 16 age-matched non-diabetic patients (normothermic group, CN: n=8; hypothermic group, CH: n=8). A 4.0 F fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to continuously monitor SjvO(2) values. Hemodynamic parameters and arterial and jugular venous blood gases were measured seven times. Results: Cerebral desaturation, which was defined as SjvO(2) values below 50%, was observed during normothermic CPB in diabetic patients (at the onset of CPB: 46 +/-3%, at 20 min after onset of CPB: 49 +/-3%, means +/- SD, respectively). No cerebral desaturation occurred in diabetic and control patients during hypothermic CPB. Conclusions: Patients with preexisting diabetes mellitus experienced cerebral desaturation during normothermic CPB.