Pre-Oxygenation Study From Japan: The Green Gas is Good

Out on PubMed, from researchers in Japan, is this study:

Adequate Oxygenation State Maintained during Electroconvulsive Therapy in Nonobese Patients Using the Oxygen Reserve Index: A Pilot Study.

Kadoi Y, Ohta J, Sasaki Y, Saito S.Case Rep Anesthesiol. 2023 Nov 6;2023:7807693. doi: 10.1155/2023/7807693. eCollection 2023.PMID: 37965073

The abstract is copied below:

Some controversial reports have observed oxygen desaturation (defined as percutaneous oxygen saturation (SpO2) < 90%) during electroconvulsive therapy (ECT). The purpose of this pilot study was to examine oxygenation states in eight patients during ECT. In addition to the usual hemodynamic monitors and pulse oximeter, the oxygen reserve index (ORi) was monitored using a pulse oximeter. Patients received either no preoxygenation or preoxygenation with 100% oxygen via a tight-fitting mask for 1 or 3 min before induction of anesthesia. ORi increased after preoxygenation. ORi differed significantly between 3 min of preoxygenation and the other two methods before restarting mask ventilation. SpO2 was significantly increased with all methods before stopping manual mask ventilation or before restarting manual mask ventilation compared with that before preoxygenation. No oxygen desaturation was observed at any time with any treatment methods. In nonobese patients, the adequate oxygenation state as shown by SpO2 and ORi was maintained during ECT even without preoxygenation.

The paper is here.

And from the text:

The green gas is good; oxygen is what makes an ECT seizure a safe event; you can never have too much oxygen in ECT.

I am a big fan of research seeking to optimize anesthetic management during ECT; this is a small, but interesting study. The oxygen reserve index (ORi) is new to me (as are the fancy pulse oximeters from Masimo):

This study demonstrated no hypoxia even without pre-oxygenation, but pre-oxygenation and hyperventilation are almost always a good idea.

I take issue with the authors' contention that ventilation cannot be continued during the seizure for fear of contaminating the EEG tracing; with reasonable care, this should not be a problem.

Kudos to our Japanese anesthesia colleagues for this intriguing contribution to the ECT anesthesia literature.