Resuscitation of out-of-hospital cardiac arrest victims in Austria's largest helicopter emergency medical service: A retrospective cohort study

Background: Helicopter emergency medical services (HEMS) play a fundamental role in prehospital care. However, the impact of HEMS on survival of patients with out -of -hospital cardiac arrest (OHCA) is widely unknown. Therefore, the purpose of this study was to assess demographics, treatment, and outcome of patients with OHCA attended by physician-staffed helicopters. Methods: Retrospective cohort study enrolling OHCA patients treated by HEMS during a ten-year period (2010-2019) in Austria. Patients were identified using electronic mission records of 13 HEMS bases run by the Austrian Automobile, Motorcycle and Touring Club (OEAMTC), and subsequently matched with the national register of deaths to determine 30 -day and one-year survival rates. Results are reported according to the 2015 Utstein Style. Multivariable logistic regression analysis was used to identify factors associated with patient outcome. Results: In total, 9344 presumed OHCA missions were identified. Cardiopulmonary resuscitation was attempted or continued by HEMS in 3889 cases. Approximately 32.2% of patients achieved return of spontaneous circulation (ROSC) and 22.5% sustained ROSC until arrival at the emergency department. Thirty-day and one-year survival rates were 14.0% and 12.4% respectively. HEMS response time, on-scene time, age, pathogenesis, arrest location, witness-status, first monitored rhythm, bystander automated external defibrillator (AED) use, airway type and administration of adrenaline were independent predictors of 30 -day survival. Conclusions: This study provides an extensive insight into the management of OHCA in an almost nationwide HEMS sample. Thirty-day and oneyear survival rates are high, indicating high-quality care and systematic selection of patients with favorable prognosis.