Regional Cerebral oxygen saturation during electroconvulsive therapy: Monitoring by near-infrared spectrophotometry

Electroconvulsive therapy (ECT) increases neuronal energy consumption and alters systemic hemodynamics. We examined the effects of ECT on regional cerebral oxygen saturation (rSo(2)) using a near-infrared spectrophotometer. Heart rate (HR), mean arterial blood pressure (MAP), and rSo(2) were continuously monitored throughout ECT under general anesthesia in 43 patients. In all subjects, rSo(2) changed in a consistent pattern during ECT, initially decreasing (-9.4% +/- 0.9%) just after application of the electrical current and subsequent increasing (8.7% +/- 0.9%) beyond the pre-ECT value. A close correlation was demonstrated between the increase in rSo(2) and the mean blood pressure after the electrical shock (r(2) = 0.832, P < 0.0001). We conclude that ECT initially may increase cerebral metabolic rate of oxygen more than cerebral blood flow and that rapidly increasing blood pressure transiently may overwhelm cerebral pressure autoregulation.