title: Association Between Duration of Resuscitation and Favorable Outcome After Out-of-Hospital Cardiac Arrest: Implications for Prolonging or Terminating Resuscitation.
abstract: BACKGROUND
  Little evidence guides the appropriate duration of resuscitation in out-of-hospital cardiac arrest, and case features justifying longer or shorter durations are ill defined. We estimated the impact of resuscitation duration on the probability of favorable functional outcome in out-of-hospital cardiac arrest using a large, multicenter cohort.
  
  
  METHODS
  This was a secondary analysis of a North American, single-blind, multicenter, cluster-randomized, clinical trial (ROC-PRIMED [Resuscitation Outcomes Consortium Prehospital Resuscitation Using an Impedance Valve and Early Versus Delayed]) of consecutive adults with nontraumatic, emergency medical services-treated out-of-hospital cardiac arrest. Primary exposure was duration of resuscitation in minutes (onset of professional resuscitation to return of spontaneous circulation [ROSC] or termination of resuscitation). Primary outcome was survival to hospital discharge with favorable outcome (modified Rankin scale [mRS] score of 0-3). Subjects were additionally classified as survival with unfavorable outcome (mRS score of 4-5), ROSC without survival (mRS score of 6), or without ROSC. Subject accrual was plotted as a function of resuscitation duration, and the dynamic probability of favorable outcome at discharge was estimated for the whole cohort and subgroups. Adjusted logistic regression models tested the association between resuscitation duration and survival with favorable outcome.
  
  
  RESULTS
  The primary cohort included 11 368 subjects (median age, 69 years [interquartile range, 56-81 years]; 7121 men [62.6%]). Of these, 4023 (35.4%) achieved ROSC, 1232 (10.8%) survived to hospital discharge, and 905 (8.0%) had an mRS score of 0 to 3 at discharge. Distribution of cardiopulmonary resuscitation duration differed by outcome (P<0.00001). For cardiopulmonary resuscitation duration up to 37.0 minutes (95% confidence interval, 34.9-40.9 minutes), 99% with an eventual mRS score of 0 to 3 at discharge achieved ROSC. The dynamic probability of an mRS score of 0 to 3 at discharge declined over elapsed resuscitation duration, but subjects with initial shockable cardiac rhythm, witnessed cardiac arrest, and bystander cardiopulmonary resuscitation were more likely to survive with favorable outcome after prolonged efforts (30-40 minutes). After adjustment for prehospital (odds ratio, 0.93; 95% confidence interval, 0.92-0.95) and inpatient (odds ratio, 0.97; 95% confidence interval, 0.95-0.99) covariates, resuscitation duration was associated with survival to discharge with an mRS score of 0 to 3.
  
  
  CONCLUSIONS
  Shorter resuscitation duration was associated with likelihood of favorable outcome at hospital discharge. Subjects with favorable case features were more likely to survive prolonged resuscitation up to 47 minutes.
  
  
  BACKGROUND
  URL: http://clinicaltrials.gov. Unique identifier: NCT00394706.
authors.affiliation: From Department of Emergency Medicine, Michigan State University College of Human Medicine, Grand Rapids (J.C. Reynolds); Department of Emergency Medicine, University of British Columbia, Vancouver, BC, Canada (B.E.G.); Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA (J.C. Rittenberger); Department of Emergency Medicine, Beaumont Health System Royal Oak, MI (K.N.S.); and Department of Emergency Medicine, University of Alabama School of Medicine, Birmingham (M.C.K.). reyno406@msu.edu.
authors.forename: Joshua C
authors.initials: JC
authors.lastname: Reynolds
authors.affiliation: From Department of Emergency Medicine, Michigan State University College of Human Medicine, Grand Rapids (J.C. Reynolds); Department of Emergency Medicine, University of British Columbia, Vancouver, BC, Canada (B.E.G.); Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA (J.C. Rittenberger); Department of Emergency Medicine, Beaumont Health System Royal Oak, MI (K.N.S.); and Department of Emergency Medicine, University of Alabama School of Medicine, Birmingham (M.C.K.).
authors.forename: Brian E
authors.initials: BE
authors.lastname: Grunau
authors.affiliation: From Department of Emergency Medicine, Michigan State University College of Human Medicine, Grand Rapids (J.C. Reynolds); Department of Emergency Medicine, University of British Columbia, Vancouver, BC, Canada (B.E.G.); Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA (J.C. Rittenberger); Department of Emergency Medicine, Beaumont Health System Royal Oak, MI (K.N.S.); and Department of Emergency Medicine, University of Alabama School of Medicine, Birmingham (M.C.K.).
authors.forename: Jon C
authors.initials: JC
authors.lastname: Rittenberger
authors.affiliation: From Department of Emergency Medicine, Michigan State University College of Human Medicine, Grand Rapids (J.C. Reynolds); Department of Emergency Medicine, University of British Columbia, Vancouver, BC, Canada (B.E.G.); Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA (J.C. Rittenberger); Department of Emergency Medicine, Beaumont Health System Royal Oak, MI (K.N.S.); and Department of Emergency Medicine, University of Alabama School of Medicine, Birmingham (M.C.K.).
authors.forename: Kelly N
authors.initials: KN
authors.lastname: Sawyer
authors.affiliation: From Department of Emergency Medicine, Michigan State University College of Human Medicine, Grand Rapids (J.C. Reynolds); Department of Emergency Medicine, University of British Columbia, Vancouver, BC, Canada (B.E.G.); Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA (J.C. Rittenberger); Department of Emergency Medicine, Beaumont Health System Royal Oak, MI (K.N.S.); and Department of Emergency Medicine, University of Alabama School of Medicine, Birmingham (M.C.K.).
authors.forename: Michael C
authors.initials: MC
authors.lastname: Kurz
authors.affiliation: From Department of Emergency Medicine, Michigan State University College of Human Medicine, Grand Rapids (J.C. Reynolds); Department of Emergency Medicine, University of British Columbia, Vancouver, BC, Canada (B.E.G.); Department of Emergency Medicine, University of Pittsburgh, Pittsburgh, PA (J.C. Rittenberger); Department of Emergency Medicine, Beaumont Health System Royal Oak, MI (K.N.S.); and Department of Emergency Medicine, University of Alabama School of Medicine, Birmingham (M.C.K.).
authors.forename: Clifton W
authors.initials: CW
authors.lastname: Callaway
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D024201:Bystander Effect; D016887:Cardiopulmonary Resuscitation; D004562:Electrocardiography; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy*; D010351:Patient Discharge; D013997:Time Factors
keywords: cardiopulmonary resuscitation; heart arrest; resuscitation