Cerebral tissue oxygen saturation at defibrillation and return of spontaneous circulation in out-of-hospital cardiac...

We examined the association between cerebral tissue oxygen saturation (SctO₂) at each patient's first defibrillation after in-hospital monitoring began and return of spontaneous circulation (ROSC) after that defibrillation in patients requiring continued resuscitation after out-of-hospital cardiac arrest (OHCA).

We included adult patients with out-of-hospital cardiac arrest who underwent SctO₂ monitoring during ongoing CPR and received in-hospital defibrillation for ventricular fibrillation or pulseless ventricular tachycardia. The first monitored defibrillation per patient was analyzed using multivariable Firth penalized logistic regression. All 194 monitored defibrillations were analyzed secondarily using a logistic generalized linear mixed-effects model (GLMM) with a patient-level random intercept. Both models adjusted for site.

Nineteen patients achieved ROSC after the first monitored defibrillation. Median SctO₂ was 48.8% [interquartile range, 47.2-53.6] with ROSC and 38.1% [33.8-41.8] without ROSC. After adjusting for site, arrest-to-defibrillation time, and epinephrine within 2 min, the odds ratio (OR) was 1.48 for each 1% increase in SctO₂ (95% confidence interval [CI], 1.22-1.80; P < 0.001). The area under the receiver operating characteristic curve was 0.961 (95% CI, 0.917-0.991). At an SctO₂ cut-off of 44.5%, the sensitivity was 94.7% (18/19; 95% CI, 74.0%-99.9%) and the specificity was 89.7% (61/68; 95% CI, 79.9%-95.8%). In the adjusted GLMM of all 194 defibrillations (41 followed by ROSC), the association remained consistent (OR, 1.56; 95% CI, 1.34-1.82; P < 0.001).

In this selected population, higher SctO₂ at defibrillation was associated with ROSC. This indirect marker and exploratory cutoff need external validation and should not delay guideline-directed defibrillation.