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.