[Cerebral oxygen desaturation during rewarming in retrograde cerebral perfusion with total circulatory arrest]

To evaluate cerebral oxygen desaturation during retrograde cerebral perfusion with total circulatory arrest (RCP), we measured cerebral oxygen extraction (O2 Ext), and arterio-venous oxygen differences (AV DO2) during and after RCP and compared the results with usual cardiopulmonary bypass (CPB) using continuous jugular blood saturation (SjO2) monitoring. In the RCP group, 7 patients underwent aortic arch replacement with RCP and in the CPB group, 4 patients underwent valvular surgery with CPB. A 5.5 Fr oximetric catheter was placed in the jugular bulb and cerebral venous and radial arterial blood were sampled. Oxygen partial pressure and saturation were measured at six intervals from cerebral venous and radial arterial blood. Measurements were taken at the following phases: phase I: before ECC was established, phase II: immediately after ECC started; phase III: at hypothermia (18 degrees C in the RCP group and 28 degrees C in the CPB group), phase IV: during rewarming (30 degrees C), phase V: after rewarming (36 degrees C), phase IV: immediately after weaning from ECC. All 11 patients survived without neurological complications. The minimum SjO2 of continuous monitoring during rewarming in the RCP group was significantly lower than in the CPB group. AVDO2 in the RCP group was also significantly higher than in the CPB group during rewarming. O2 Ext in the RCP group was significantly higher than in the CPB group during and after rewarming. Differences in glucose utilization during and after rewarming were also detected. Moreover, to determine factors that influence SjO2 during and after rewarming, we evaluated correlations with arterial PaCO2, arterial pH, and rewarming duration. There were significant (p < 0.05) correlations between SjO2 and PaCO2 in phase IV and phase V, between SjO2 and pH, and between SjO2 and rewarming duration. In conclusion, continuous SjO2 measurements reflected cerebral oxygen desaturation during and after rewarming in RCP. In RCP, significantly greater desaturation during and after rewarming was detected than in CPB. Therefore we suggest that relatively slow rewarming, higher PaCO2, and more acidic pH strategies were advantageous for preventing desaturation during and after rewarming in RCP.