When should on-scene CPR be terminated in OHCA patients?: Prognostic Models for Outcomes Based on Duration of On-Scene CPR in OHCA

Background Out-of-Hospital Cardiac Arrest (OHCA) is a leading cause of mortality worldwide, with approximately 30,000 cases managed annually by Emergency Medical Services (EMS) in South Korea. Prolonged on-scene Advanced Life Support (ALS) in OHCA patients has demonstrated potential for prehospital return of spontaneous circulation (ROSC) and neurological improvement. However, the optimal timing for terminating on-scene CPR in patients who do not achieve ROSC remains challenging. This study aims to develop and validate a predictive model for patient outcomes based on the duration of on-scene CPR in OHCA patients using data from the Smart ALS (SALS) protocol in South Korea. Methods A multi-regional observational study was conducted from August 2015 to December 2022, involving 19 fire stations and nine academic tertiary hospitals across seven provinces. Data were sourced from the SALS database, including EMS prehospital care reports, SALS intervention logs, and hospital patient records. The study focused on non-traumatic OHCA patients who underwent SALS, excluding those with obvious signs of death, those under 18 years old, those who refused on-scene CPR, or those with a DNR status. Statistical analyses were performed using R software, employing logistic regression models to predict prehospital ROSC, survival to discharge, and favorable neurological outcomes. Results Out of 98,569 OHCA patients evaluated, 34,989 were eligible for SALS, and 16,052 received SALS. Significant predictors of prehospital ROSC included younger age, male gender, arrest occurring in public places, witnessed arrest, bystander CPR, and initial shockable rhythm. Logistic regression models for patients who did not achieve prehospital ROSC showed that longer on-scene CPR duration negatively impacted the probability of ROSC, survival to discharge, and neurological outcomes. The predictive model for ROSC had an AUC of 0.730, for survival to discharge AUC of 0.838, and for favorable neurological outcome AUC of 0.917. Conclusions This study emphasizes the critical role of prehospital ROSC in improving survival and neurological outcomes in OHCA patients. The predictive models can aid in making informed decisions about the cessation of on-scene CPR. Further research is needed to validate these models and explore their application in different EMS settings. Trial registration Retrospectively registered.