Background: Deep hypothermic circulatory arrest may disturb neurological functions and therefore monitorization of neurophysiologic parameters during the operations incorporating circulatory arrest is important. This study was intended to monitor jugular venous oxygen saturation during profoundly hypothermic cardiopulmonary bypass and to evaluate this parameter as an indicator of cerebral supression before the initiation of circulatory arrest.

Methods: Between August 1999 and March 2002, 33 patients underwent deep hypothermic circulatory arrest. Among these, jugular venous oxygen saturation was monitored during cardiopulmonary bypass in 18 patients. Indications for operations were ascending aortic aneurysm (n = 15) and acute aortic dissection (n = 3). Hypothermic cardiopulmonary bypass (mean 233 ± 60 min), cardioplegic arrest (mean 105 ± 37 min) and deep hypothermic circulatory arrest (mean 22 ± 7 min) were utilized. Cardiac procedures included coronary artery bypass graft surgery in 8 patients.

Results: Jugular venous oxygen saturation was inversely related to body temperature during hypothermic cardiopulmonary bypass. Mean values for jugular venous oxygen saturation at 32, 28, 24, 20, 11-14°C during cooling were 70% ± 11%, 80% ± 8%, 87% ± 5%, 95% ± 2%, 98% ± 1%, respectively, and were 87%, 89%, 80%, 76%, 69%, 54% at 16, 20, 24, 28, 32, 36°C during rewarming respectively. All patients were considered neurologically normal and discharged in good condition (mean 14 ± 7 days) from the hospital.

Conclusion: Jugular venous oxygen saturation is inversely related to the body temperature in patients undergoing hypothermic cardiopulmonary bypass. At 11 to 14°C, jugular venous oxygen saturation equal to or beyond 97% may be indicative of a uniform cerebral cooling and a safe period of circulatory arrest up to 30 minutes.

Keywords : Deep hypothermic circulatory arrest, jugular venous oxygen saturation