title: Out-of-hospital cardiac arrest-review of demographics in South Australia to inform decisions about the provision of automatic external defibrillators within the community.
abstract: BACKGROUND
  Sudden, out-of-hospital cardiac arrest (OHCA) has an annual incidence of approximately 50 per 100,000 population. Public access defibrillation is seen as one of the key strategies in the chain-of-survival for OHCA. Positioning of these devices is important for the maximization of public health outcomes. The literature strongly advocates widespread public access to automated external defibrillatiors (AEDs). The most efficient placement of AEDs within individual communities remains unclear.
  
  
  METHODS
  A retrospective case review of OHCAs attended by the South Australia Ambulance Service in metropolitan and rural South Australia over a 30-month period was performed. Data were analyzed using Utstein-type indicators. Detailed demographics, summative data, and clinical data were recorded.
  
  
  RESULTS
  A total of 1,305 cases of cardiac arrest were reviewed. The annual rate of OHCA was 35 per 100,000 population. Of the cases, the mean value for the ages was 66.3 years, 517 (39.6%) were transported to hospital, 761 (58.3%) were judged by the paramedic to be cardiac, and 838 (64.2%) were witnessed. Bystander cardiopulmonary resuscitation (CPR) was performed in 495 (37.9%) of cases. The rhythm on arrival was ventricular fibrillation (VF) or ventricular tachycardia (VT) in 419 (32.1%) cases, and 315 (24.1%) of all arrests had return of spontaneous circulation (ROSC) before or on arrival at the hospital. For cardiac arrest cases that were witnessed by the ambulance service (n=121), the incidence of ROSC was 47.1%. During the 30-month period, there only was one location that recorded more than one cardiac arrest. No other location recorded recurrent episodes.
  
  
  CONCLUSIONS
  This study did not identify any specific location that would justify defibrillator placement over any other location without an existing defibrillator. The impact of bystander CPR and the relatively low rate of bystander CPR in this study points to an area of need. The relative potential impact of increasing bystander CPR rates versus investing in defibrillators in the community is worthy of further consideration.
authors.affiliation: St John Ambulance Aust SA Inc., Unley, SA, Australia. kmzeitz@onaustralia.com.au
authors.forename: Kathryn
authors.initials: K
authors.lastname: Zeitz
authors.forename: Hugh
authors.initials: H
authors.lastname: Grantham
authors.forename: Robert
authors.initials: R
authors.lastname: Elliot
authors.forename: Chris
authors.initials: C
authors.lastname: Zeitz
mesh_terms: D047548:Defibrillators; D004632:Emergency Medical Services; D006801:Humans; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000628:therapy*; D013021:South Australia; D016896:Treatment Outcome