New Evidence for Seizure Quality Improvement by Hyperoxia and Mild Hypocapnia

Abstract

Preoxygenation and hyperventilation (with oxygen) in electroconvulsive therapy (ECT) may improve not only safety but also seizure quality. We retrospectively examined transcutaneous tissue partial pressure of oxygen (tcpO2) and carbon dioxide (tcpCO2) in 441 ECT sessions of 37 consecutive patients. All patients received standard face mask airway management. In parallel, seizure quality markers such as seizure duration, seizure amplitude, central inhibition, interhemispheric coherence, and sympathetic activation were documented and used to build up a seizure quality sum score. Mean (SD) tcpO2 was 289 (123) mm Hg and for tcpCO2 41 (11) mm Hg. A multivariate repeated measurement regression analysis revealed that the ratio of tcpO2/tcpCO2 had a significant influence on the seizure quality sum score (P = 0.033). Furthermore, a corresponding regression analysis with charge ("stimulation energy") as a dependent variable showed a significant influence of tcpO2 (P = 0.019) and of tcpO2/tcpCO2 (P = 0.03), too. We observed, in our typical clinical ECT sample of 37 patients, a significant and synergistic influence of tcpO2/tcpCO2 on seizure quality. Partial pressure of oxygen covaried with lower stimulation energy. The ratio tcpO2/tcpCO2 was associated with lower stimulation energy and still better seizure quality.