Reevaluating basic life support termination criteria using post-arrival data in Japanese out-of-hospital cardiac arrest patients.

Objective: Termination of resuscitation (TOR) rules for out-of-hospital cardiac arrest (OHCA) are applied worldwide. However, in some Asian countries, TOR is restricted by law or practice. We assessed the benefits of including post-arrival variables on the accuracy of the basic life support (BLS)-TOR rule in eligible patients. Design: A multicenter retrospective cohort study. Setting: A nationwide Japanese OHCA registry. Participants: We evaluated 81,234 patients recorded in a nationwide Japanese OHCA registry between 2014 and 2021 who were transported to 161 emergency hospitals. After applying exclusion criteria, 59,114 patients were included in the analysis. Among these, 43,737 patients fulfilled the BLS-TOR criteria. Main outcome measures: The primary outcome was 30-day survival and the secondary outcome was a favourable neurological status, defined as a cerebral performance category score of 1 or 2 at 30 days. Results: The 30-day survival and favourable neurological outcome rates were 0.9% and 0.1%, respectively. Multivariate analysis identified serum potassium as the strongest predictor of poor outcomes (adjusted odds ratio for survival: 0.45; 95% confidence interval: 0.42-0.49). When serum potassium thresholds were added to the BLS-TOR criteria, survival rates declined progressively-0.72, 0.40, and 0.21% at ≥5.0, ≥6.0, and ≥7.0 mEq/L, respectively. At ≥7.0 mEq/L, specificity for predicting 30-day mortality reached 0.99, and the positive predictive value was 1.00. Conclusions: Incorporating post-arrival in-hospital variables provides a novel approach to guide TOR. Serum potassium, a readily measured arrival marker, is one promising candidate.