title: Outcome of out-of-hospital postcountershock asystole and pulseless electrical activity versus primary asystole and pulseless electrical activity.
abstract: OBJECTIVE
  In the prehospital setting, countershock terminates ventricular fibrillation (VF) in about 80% of cases. However, countershock is most commonly followed by asystole or pulseless electrical activity (PEA). The consequences of such a countershock outcome have not been well studied. The purpose of this investigation was to compare the outcome of prehospital VF victims shocked into asystole or PEA with that of patients whose first documented rhythm was asystole or PEA (primary asystole or PEA).
  
  
  METHODS
  Observational, retrospective study conducted over 5 yrs (1995-1999).
  
  
  METHODS
  A municipal hospital with a catchment area of >200,000.
  
  
  METHODS
  Consecutive adult patients with out-of-hospital nontraumatic cardiopulmonary arrest of cardiac origin. Patients found in VF who developed asystole or PEA after countershocks (group 1) and patients found in asystole or PEA (primary asystole or PEA) (group 2) were included if the reported downtime was <10 min.
  
  
  METHODS
  None.
  
  
  RESULTS
  Study end points included restoration of circulation (defined as a pulse for any duration), survival to hospital admission, and survival to hospital discharge. Ratios were determined, 95% confidence intervals were calculated, and observed differences were compared. For group 1 patients (n = 101), 61% of patients had a bystander-witnessed collapse and 34% received bystander cardiopulmonary resuscitation. For group 2 patients (n = 140), collapse was bystander witnessed in 71% and 45% received bystander cardiopulmonary resuscitation. These differences were not statistically significant. Restoration of circulation was significantly more frequent in group 2 than group 1 (42% vs. 16%, p <.001) as was survival to hospital admission (36% vs. 11%, p =.001). Survival to hospital discharge was greater in group 2 patients, but the difference failed to achieve statistical significance (10% vs. 3%, p =.062).
  
  
  CONCLUSIONS
  Countershock of prolonged VF followed by a nonperfusing rhythm has a worse prognosis than primary asystole or PEA and may be related to myocardial electrical injury.
authors.affiliation: UCLA School of Medicine, the Department of Emergency Medicine, Harbor-UCLA Medical Center, Torrance, CA, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Niemann
authors.forename: S J
authors.initials: SJ
authors.lastname: Stratton
authors.forename: B
authors.initials: B
authors.lastname: Cruz
authors.forename: R J
authors.initials: RJ
authors.lastname: Lewis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016887:Cardiopulmonary Resuscitation; D004554:Electric Countershock / Q000009:adverse effects*; D005260:Female; D006323:Heart Arrest / Q000209:etiology* / Q000401:mortality / Q000628:therapy*; D006801:Humans; D015141:Los Angeles / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000401:mortality / Q000628:therapy*