title: Perishock Pause Intervals and Rearrest after Out-of-Hospital Cardiac Arrest.
abstract: BACKGROUND
  The loss of pulses after successful return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA) is known as rearrest (RA). The causes of RA are not well understood.
  
  
  OBJECTIVE
  To investigate the association between shock pause intervals and RA.
  
  
  METHODS
  Data from treated OHCA with ROSC and one or more defibrillation attempts were obtained from one site of the Resuscitation Outcomes Consortium. All analyses were conducted internally. Data available for analysis included cases spanning 2006-2008 and 2010-2011. Defibrillator tracings were used to calculate both components of the perishock pause (PSP) interval: the pre- (preSP) and the postshock pauses (postSP). RA and no-RA shock pauses were compared and independent associations between shock pause intervals, patient characteristics, and RA were assessed with the appropriate statistical tests.
  
  
  RESULTS
  Analysis included 241 shocks from 101 cases. Forty-one cases (41%) had RA. RA vs. no-RA median (interquartile range) shock pauses in seconds were: preSP 13.5 (6.0-18.0) vs. 15.0 (10.9-21.5) (p = 0.121); postSP 6.0 (3.5-8.2) vs. 8.7 (4.5-13.9) (p = 0.053); and PSP 18.0 (12.3-24.0) vs. 24.0 (16.7-30.2) (p = 0.022). Considering all possible shock pause durations, shock pause lengths and various patient characteristics were not associated with RA. If 30 s or shorter, the preSP (odds ratio [OR] 0.90, 955 confidence interval [CI] 0.82-0.98) and postSP (OR 0.89, 95% CI 0.79-0.99) were related to RA.
  
  
  CONCLUSIONS
  Shock pause length was inversely associated with RA when shock pause intervals were limited to 30 s or less. Shock pauses and RA were not associated when all durations of shock pauses were considered.
authors.affiliation: Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: Allison C
authors.initials: AC
authors.lastname: Koller
authors.affiliation: Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: David D
authors.initials: DD
authors.lastname: Salcido
authors.affiliation: Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
authors.forename: James J
authors.initials: JJ
authors.lastname: Menegazzi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016887:Cardiopulmonary Resuscitation; D004554:Electric Countershock / Q000379:methods*; D004632:Emergency Medical Services / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000628:therapy*; D012008:Recurrence; D013997:Time Factors
keywords: cardiac arrest; cardiopulmonary resuscitation; emergency medical services; prehospital intervention; shock pause interval