A simple decision rule predicts futile resuscitation of out-of-hospital cardiac arrest.

Aim: Resuscitation of cardiac arrest involves invasive and traumatic interventions and places a large burden on limited EMS resources. Our aim was to identify prehospital cardiac arrests for which resuscitation is extremely unlikely to result in survival to hospital discharge. Methods: We performed a retrospective cohort analysis of all cardiac arrests in San Mateo County, California, for which paramedics were dispatched, from January 1, 2015 to December 31, 2018, using the Cardiac Arrest Registry to Enhance Survival (CARES) database. We described characteristics of patients, arrests, and EMS responses, and used recursive partitioning to develop decision rules to identify arrests unlikely to survive to hospital discharge, or to survive with good neurologic function. Results: From 2015-2018, 1750 patients received EMS dispatch for cardiac arrest in San Mateo County. We excluded 44 patients for whom resuscitation was terminated due to DNR directives. Median age was 69 years (IOR 57-81), 563 (33.0%) patients were female, 816 (47.8%) had witnessed arrests, 651 (38.2%) received bystander CPR, 421 (24.7%) had an initial shockable rhythm, and 1178 (69.1%) arrested at home. A simple rule (non-shockable initial rhythm, unwitnessed arrest, and age 80 or greater) excludes 223 (13.1%) arrests, of whom none survived to hospital discharge. Conclusion: A simple decision rule (non-shockable rhythm, unwitnessed arrest, age >= 80) identifies arrests for which resuscitation is futile. If validated, this rule could be applied by EMS policymakers to identify cardiac arrests for which the trauma and expense of resuscitation are extremely unlikely to result in survival.