Resuscitation Enhancement to Avoid Rearrest Through Evidence-based Strategies in Prehospital Post-resuscitation Care

Out-of-hospital cardiac arrest (OHCA) remains a leading global emergency condition with low survival to hospital discharge despite advances in cardiopulmonary resuscitation. Return of spontaneous circulation (ROSC) rates have improved; however, 30-50% of patients experience rearrest after ROSC, which is associated with significantly reduced survival. Preventable physiologic factors related to prehospital care - including hypoxia, hypotension, and hyperventilation - are frequently identified prior to rearrest. Evidence-based post-ROSC clinical bundles exist mainly for in-hospital settings, while structured prehospital post-resuscitation care protocols are limited, particularly in resource-constrained environments. The RE-ARREST project aims to develop, implement, and evaluate an evidence-based prehospital post-resuscitation care protocol designed for paramedic-led Emergency Medical Services. The intervention includes structured monitoring, tailored oxygenation and ventilation targets, vasopressor use criteria (norepinephrine), fluid management decision support, teamwork communication, and operational training workshops using simulation. This is a quasi-experimental pre-post interventional study conducted at the Siriraj Emergency Medical Service (SiEMS), Thailand. The study compares outcomes from retrospective pre-implementation cases with prospective post-implementation cases, including both patient-centered outcomes and provider compliance. Adult OHCA patients with ROSC achieved prehospital and transported to Siriraj Hospital are eligible. The estimated sample size is 318 participants (pre-intervention 212; post-intervention 106) over two years. The primary outcome is the incidence of rearrest within 1 hour after ROSC during prehospital care and initial emergency department management. Secondary outcomes include protocol compliance, survival-to-admission, and survival-to-hospital-discharge. The protocol emphasizes feasibility, safety, and replicability to inform