Cerebral oxygen saturation during pulsatile and non-pulsatile cardiopulmonary bypass in patients with carotid stenosis.

Pulsatile and non-pulsatile cardiopulmonary bypass (CPB) flows may have different impact on cerebral oxygen saturation in patients with restricted cerebral arterial blood supply. Twenty patients, ten diagnosed with carotid stenosis (CS, n = 10) and ten without known carotid disease (Controls, n = 10), were subjected to one period of pulsatile and one period of non-pulsatile flow (6-8 min each) during CPB at 32 degrees C. Cerebral oxygen saturation was registered by near-infrared light spectroscopy (NIRS). The mean arterial pressure (MAP) was significantly lowered by pulsatile CPB flow. The NIRS tissue oxygenation index (TOI) tended to decrease in the CS group and increase in the Controls during pulsatile flow compared with non-pulsatile; however, the changes were not statistically significant. No significant correlations were seen between the changes in MAP and TOI across the observation periods. In conclusion, pulsatile CPB flow caused slightly decreased mean arterial pressure while the effect on cerebral oxygenation was unclear. Pulsatile flow was not found superior to non-pulsatile flow in patients with or without carotid stenosis.