Cerebral Oxygen Saturation During Electroconvulsive Therapy: A Secondary Analysis of a Randomized Crossover Trial

Electroconvulsive therapy (ECT) causes acute changes in cerebral perfusion and oxygenation. Near-infrared spectroscopy is a novel, noninvasive technique to assess cerebral oxygen saturation (cSO2). We hypothesized that cSO2 increases during ECT and more so with atropine premedication and decreases when systemic desaturation (peripheral oxygen saturation <90%) occurs during ECT.

We performed a secondary analysis of a randomized trial of patients undergoing ECT for psychiatric illness during a 6-month period. During the second ECT session, patients were randomly assigned to receive either 0.01 mg/kg IV atropine or no atropine. During the third ECT session, patients were crossed over. Standard anesthetic management was performed. Data with regard to heart rate, blood pressure, peripheral oxygen saturation, and cSO2 were collected at baseline and continuously examined for 5 minutes from delivery of ECT stimulus.

Forty-one patients underwent 82 ECT sessions. ECT resulted in significant increase in cSO2 during both the atropine and the no-atropine sessions (P<0.001 for both) but no between-session difference was observed (mean difference, 1.9±2.0; 95% confidence interval, -2.0, 5.9; P=0.337). The cSO2 values were lower in patients who developed systemic desaturation when compared with the cSO2 values in those who did not (mean difference, 5.0±2.6; 95% confidence interval -0.1, 10.2; P=0.054). However, the mean cSO2 was >60% at any measured time point, even in those with systemic desaturation.

ECT increased cSO2 irrespective of atropine premedication. cSO2 was lower when systemic desaturation occurred. Future studies should explore the effect of cerebral oxygenation changes during ECT on outcome of psychiatric conditions.