BACKGROUND The association between perfusion index (PI) and out-of-hospital cardiac arrest survival outcomes is unknown. The American Heart Association suggested the need to improve the monitoring of cardiopulmonary resuscitation and chest compression quality. We hypothesized that higher event-average perfusion index values are associated with higher probability of return of spontaneous circulation, better survival and neurological outcomes.

METHODS In this prospective cohort study of index out-of-hospital cardiac arrests attended from January 2022 through October 2024, we analyzed the association of the event-average perfusion index value with sustained return of spontaneous circulation. Secondary exposures included survival to hospital admission, favorable neurological outcome (Cerebral Performance Category ≤3 or no change from baseline) and associations between epoch-average PI and CPR quality metrics.

RESULTS We included 98 index out-of-hospital cardiac arrests (mean [Standard Deviation]) age 62.1 years [17.6], 32% female, 9.2% shockable rhythm. Median event-average perfusion index was 0.29 ([Q1, Q3], 0.11, 0.92). Events with sustained return of spontaneous circulation had a higher event-level average perfusion index (0.92 [0.44, 1.73] mmol/L versus 0.19 [0.09, 0.55]; P<0.001). The receiver operating characteristic analyses of PI, as a predictor of sustained return of spontaneous circulation, identified an area under the curve of 0.77 [95% CI, 0.68– 0.86]) with an optimal cut point at 0.61 (sensitivity 0.67, specificity 0.81). After adjusting for confounders, PI was associated with higher relative risk of sustained ROSC (adjusted odds ratio, 2.6 [95% CI, 1.3–5.1]; P<0.001). Event-average PI was also associated with higher relative risk of survival to hospital admission (adjusted odds ratio, 2.1 [95% CI, 1.2–3.7]; P=0.001) while it was not associated with higher relative risk of neurological intact survival (adjusted odds ratio, 4.0 [95% CI, 0.8– 19.4]; P=0.085). Higher epoch-average PI was independently associated with higher chest compression fraction (P=0.003).

CONCLUSIONS Higher event-average PI was associated with higher probability of sustained return of spontaneous circulation. Event-average PI was associated with higher adjusted probability of return of spontaneous circulation, but not with neurological intact survival. Epoch-average PI was positively correlated with chest compression fraction.

The authors have declared no competing interest.

NCT05383885

This work was supported by the Association André Vésale. The funding sources had no role in the study design, collection, analysis, and interpretation of data, the writing of the report, or the decision to submit the article for publication.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Review board of the CHU Saint-Pierre hospital approved the study (CE/21-11-01)

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Data will be available from the corresponding author upon reasonable request