title: Progressing from initial non-shockable rhythms to a shockable rhythm is associated with improved outcome after out-of-hospital cardiac arrest.
abstract: BACKGROUND
  Cardiac arrest patients with initial non-shockable rhythm progressing to shockable rhythm have been reported to have inferior outcome to those remaining non-shockable. We wanted to confirm this observation in our prospectively collected database, and assess whether differences in cardiopulmonary resuscitation (CPR) quality could help to explain any such difference in outcome.
  
  
  METHODS
  All out-of-hospital cardiac arrest (OHCA) cases in the Oslo EMS between May 2003 and April 2008 were retrospectively studied, and cases with initial asystole or pulseless electrical activity (PEA) were selected. Pre-hospital and hospital records, Utstein forms, and continuous ECGs were reviewed. Quality of CPR and outcome were compared for patients who progressed to a shockable rhythm and patients who remained in non-shockable rhythms.
  
  
  RESULTS
  Of 753 cases with initial non-shockable rhythms 517 (69%) had asystole and 236 (31%) PEA. Ninety-eight (13%) patients progressed to a shockable rhythm, while 653 (87%) remained non-shockable during the entire resuscitation effort (two unknown). Hands-off ratio was higher in the shockable than the non-shockable group, 0.21+/-0.12 vs. 0.16+/-0.10 (p=0.000) with no significant difference in compression and ventilation rates. Overall survival to hospital discharge was 3%; 7% in the shockable and 2% in the non-shockable group (p=0.014). Based on a multivariate logistic analysis young age, initial PEA, and progressing to a shockable rhythm were associated with better outcome.
  
  
  CONCLUSIONS
  Progressing from initial non-shockable rhythms to a shockable rhythm was associated with improved outcome after OHCA. This occurred despite more pauses in chest compressions in the shockable group, probably related to defibrillation attempts.
authors.affiliation: Institute for Experimental Medical Research, Ulleval University Hospital, N-0407 Oslo, Norway. t.m.olasveengen@medisin.uio.no
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Olasveengen
authors.forename: Martin
authors.initials: M
authors.lastname: Samdal
authors.forename: Petter Andreas
authors.initials: PA
authors.lastname: Steen
authors.forename: Lars
authors.initials: L
authors.lastname: Wik
authors.forename: Kjetil
authors.initials: K
authors.lastname: Sunde
mesh_terms: D000368:Aged; D018450:Disease Progression; D004554:Electric Countershock / Q000379:methods*; D004632:Emergency Medical Services / Q000379:methods; D005260:Female; D006323:Heart Arrest / Q000150:complications* / Q000473:pathology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D011379:Prognosis; D011674:Pulse; D012189:Retrospective Studies; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000209:etiology* / Q000628:therapy*