title: Defibrillation before EMS arrival in western Sweden.
abstract: BACKGROUND
  Bystanders play a vital role in public access defibrillation (PAD) in out-of-hospital cardiac arrest (OHCA). Dual dispatch of first responders (FR) alongside emergency medical services (EMS) can reduce time to first defibrillation. The aim of this study was to describe the use of automated external defibrillators (AEDs) in OHCAs before EMS arrival.
  
  
  METHODS
  All OHCA cases with a shockable rhythm in which an AED was used prior to the arrival of EMS between 2008 and 2015 in western Sweden were eligible for inclusion. Data from the Swedish Register for Cardiopulmonary Resuscitation (SRCR) were used for analysis, on-site bystander and FR defibrillation were compared with EMS defibrillation in the final analysis.
  
  
  RESULTS
  Of the reported 6675 cases, 24% suffered ventricular fibrillation (VF), 162 patients (15%) of all VF cases were defibrillated before EMS arrival, 46% with a public AED on site. The proportion of cases defibrillated before EMS arrival increased from 5% in 2008 to 20% in 2015 (p<0.001). During this period, 30-day survival increased in patients with VF from 22% to 28% (p=0.04) and was highest when an AED was used on site (68%), with a median delay of 6.5min from collapse to defibrillation. Adjusted odds ratio for on-site defibrillation versus dispatched defibrillation for 30-day survival was 2.45 (95% CI: 1.02-5.95).
  
  
  CONCLUSIONS
  The use of AEDs before the arrival of EMS increased over time. This was associated with an increased 30-day survival among patients with VF. Thirty-day survival was highest when an AED was used on site before EMS arrival.
authors.affiliation: Department of Medicine, Centre for Resuscitation Science, Karolinska Institute, SE-171 77 Stockholm, Sweden. Electronic address: andreas.claesson@ki.se.
authors.forename: A
authors.initials: A
authors.lastname: Claesson
authors.affiliation: Department of Acute and Prehospital Care and Medical Technology, Prehospen - Centre for Prehospital Research, Prehospital Research Centre of Western Sweden, University of Borås, SE-501 90 Borås, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Herlitz
authors.affiliation: Department of Medicine, Centre for Resuscitation Science, Karolinska Institute, SE-171 77 Stockholm, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Svensson
authors.affiliation: Institute of Medicine, Department of Molecular and Clinical Medicine, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Ottosson
authors.affiliation: Institute of Medicine, Department of Molecular and Clinical Medicine, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Bergfeldt
authors.affiliation: Department of Clinical Sciences, Karolinska Institute, Danderyd Hospital, SE-182 88 Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Engdahl
authors.affiliation: Institute of Medicine, Department of Molecular and Clinical Medicine, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Ericson
authors.affiliation: Institute of Medicine, Department of Molecular and Clinical Medicine, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Sandén
authors.affiliation: Department of Acute and Prehospital Care and Medical Technology, Prehospen - Centre for Prehospital Research, Prehospital Research Centre of Western Sweden, University of Borås, SE-501 90 Borås, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Axelsson
authors.affiliation: Department of Acute and Prehospital Care and Medical Technology, Prehospen - Centre for Prehospital Research, Prehospital Research Centre of Western Sweden, University of Borås, SE-501 90 Borås, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Bremer
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation / Q000379:methods; D047548:Defibrillators / Q000706:statistics & numerical data; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy*; D015996:Survival Rate / Q000639:trends; D013548:Sweden / Q000453:epidemiology; D014693:Ventricular Fibrillation / Q000401:mortality / Q000628:therapy*
keywords: Automated external defibrillator; Emergency medical services; First responder; Out-of-hospital cardiac arrest