title: Survival in ventricular fibrillation with emphasis on the number of defibrillations in relation to other factors at resuscitation.
abstract: Mortality after out of hospital cardiac arrest (OHCA) is high and a shockable rhythm is a key predictor of survival. A concomitant need for repeated shocks appears to be associated with less favorable outcome.
  
  
  
  To, among patients found in ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT) describe: (a) factors associated with 30-day survival with emphasis on the number of defibrillatory shocks delivered; (b) the distribution of and the characteristics of patients in relation to the number of defibrillatory shocks that were delivered.
  
  
  
  Patients who were reported to The Swedish Register for Cardiopulmonary Resuscitation (SRCR) between January 1 1990 and December 31 2015 and who were found in VF/pVT took part in the survey.
  
  
  
  In all there were 19,519 patients found in VF/pVT. The 30-day survival decreased with an increasing number of shocks among all patients regardless of witnessed status and regardless of time period in the survey. In a multivariate analysis there were 12 factors that were associated with the chance of 30-day survival one of which was the number of shocks that was delivered. For each shock that was added the chance of survival decreased. Factors associated with an increased 30-day survival included CPR before arrival of EMS, female sex, cardiac etiology and year of OHCA (increasing survival over years). Factors associated with a decreased chance of 30-day survival included: increasing age, OHCA at home, the use of adrenaline and intubation and an increased delay to CPR, defibrillation and EMS arrival.
  
  
  
  Among patients found in VF/pVT, 7.5% required more than 10 shocks. For each shock that was added the chance of 30-day survival decreased. There was an increase in 30-day survival over time regardless of the number of shocks. On top of the number of defibrillations, eleven further factors were associated with 30-day survival.
authors.affiliation: Dept. of Prehospital and Emergency Care, Dept. of Anesthesiology and Intensive Care, Sahlgrenska University Hospital, Gothenburg, Sweden; Dept. of Pediatric Anesthesia and Intensive Care, The Queen Silvia Children's Hospital, Sahlgrenska University Hospital, Gothenburg, Sweden Institute of Medicine, Sahlgrenska University Hospital, Sweden. Electronic address: johan.holmen@vgregion.se.
authors.forename: Johan
authors.initials: J
authors.lastname: Holmén
authors.affiliation: Center for Resuscitation Science, Dept. for Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Jacob
authors.initials: J
authors.lastname: Hollenberg
authors.affiliation: Center for Resuscitation Science, Dept. for Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Andreas
authors.initials: A
authors.lastname: Claesson
authors.affiliation: Departament of Nursing, Universitat Rovira i Virgili, Spain.
authors.forename: Maria Jiménez
authors.initials: MJ
authors.lastname: Herrera
authors.affiliation: Sistema Emergències Mèdiques de Catalunya, Spain.
authors.forename: Youcef
authors.initials: Y
authors.lastname: Azeli
authors.affiliation: The Centre of Pre-hospital Research in Western Sweden University College of Borås and Institute of Medicine, Sahlgrenska University Hospital, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Herlitz
authors.affiliation: The Centre of Pre-hospital Research in Western Sweden University College of Borås and Institute of Medicine, Sahlgrenska University Hospital, Sweden.
authors.forename: Christer
authors.initials: C
authors.lastname: Axelsson
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation / Q000379:methods / Q000706:statistics & numerical data; D004554:Electric Countershock / Q000379:methods / Q000401:mortality / Q000706:statistics & numerical data; D004632:Emergency Medical Services / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006331:Heart Diseases / Q000453:epidemiology*; D006801:Humans; D008297:Male; D058687:Out-of-Hospital Cardiac Arrest / Q000209:etiology / Q000401:mortality; D010043:Outcome and Process Assessment, Health Care; D011237:Predictive Value of Tests; D011379:Prognosis; D018570:Risk Assessment / Q000379:methods; D012737:Sex Factors; D016019:Survival Analysis; D013548:Sweden / Q000453:epidemiology; D014693:Ventricular Fibrillation / Q000401:mortality / Q000628:therapy
keywords: Cardiac arrest; Defibrillation; Number of defibrillations; Resuscitation; Survival in out of hospital cardiac arrest; Ventricular fibrillation