title: The effect of time to defibrillation and targeted temperature management on functional survival after out-of-hospital cardiac arrest.
abstract: BACKGROUND
  Cardiac arrest physiology has been proposed to occur in three distinct phases: electrical, circulatory and metabolic. There is limited research evaluating the relationship of the 3-phase model of cardiac arrest to functional survival at hospital discharge. Furthermore, the effect of post-cardiac arrest targeted temperature management (TTM) on functional survival during each phase is unknown.
  
  
  OBJECTIVE
  To determine the effect of TTM on the relationship between the time of initial defibrillation during each phase of cardiac arrest and functional survival at hospital discharge.
  
  
  METHODS
  This was a retrospective observational study of consecutive adult (≥18 years) out-of-hospital cardiac arrest (OHCA) patients with initial shockable rhythms. Included patients obtained a return of spontaneous circulation (ROSC) and were eligible for TTM. Multivariable logistic regression was used to determine predictors of functional survival at hospital discharge.
  
  
  RESULTS
  There were 20,165 OHCA treated by EMS and 871 patients were eligible for TTM. Of these patients, 622 (71.4%) survived to hospital discharge and 487 (55.9%) had good functional survival. Good functional survival was associated with younger age (OR 0.94; 95% CI 0.93-0.95), shorter times from collapse to initial defibrillation (OR 0.73; 95% CI 0.65-0.82), and use of post-cardiac arrest TTM (OR 1.49; 95% CI 1.07-2.30). Functional survival decreased during each phase of the model (65.3% vs. 61.7% vs. 50.2%, P<0.001).
  
  
  CONCLUSIONS
  Functional survival at hospital discharge was associated with shorter times to initial defibrillation and was decreased during each successive phase of the 3-phase model. Post-cardiac arrest TTM was associated with improved functional survival.
authors.affiliation: Rescu, Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada; Institute of Medical Science, Department of Medicine, University of Toronto, Toronto, ON, Canada; School of Health and Wellness, Georgian College, Barrie, ON, Canada. Electronic address: DrennanI@smh.ca.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Drennan
authors.affiliation: Rescu, Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada; Division of Emergency Medicine, Department of Medicine, University of Toronto, Toronto, ON, Canada. Electronic address: LinS@smh.ca.
authors.forename: Steve
authors.initials: S
authors.lastname: Lin
authors.affiliation: Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; Applied Health Research Centre, St. Michael's Hospital, Toronto, ON, Canada. Electronic address: Kevin.Thorpe@utoronto.ca.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Thorpe
authors.affiliation: Rescu, Li Ka Shing Knowledge Institute, St. Michael's Hospital, University of Toronto, Toronto, ON, Canada; Institute of Medical Science, Department of Medicine, University of Toronto, Toronto, ON, Canada; Division of Emergency Medicine, Department of Medicine, University of Toronto, Toronto, ON, Canada. Electronic address: MorrisonL@smh.ca.
authors.forename: Laurie J
authors.initials: LJ
authors.lastname: Morrison
mesh_terms: D000328:Adult; D000368:Aged; D001833:Body Temperature Regulation; D003266:Continuity of Patient Care; D016208:Databases, Factual; D004554:Electric Countershock / Q000379:methods* / Q000401:mortality; D004632:Emergency Medical Services / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D017052:Hospital Mortality; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods* / Q000401:mortality; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009864:Ontario; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality* / Q000628:therapy*; D010351:Patient Discharge / Q000706:statistics & numerical data; D012189:Retrospective Studies; D018570:Risk Assessment; D015996:Survival Rate; D017741:Survivors; D061665:Time-to-Treatment / Q000592:standards* / Q000639:trends
keywords: Neurological outcome; Out-of-hospital cardiac arrest; Post-cardiac arrest care; Targeted temperature management