title: Evaluating the effectiveness of dispatch-assisted cardiopulmonary resuscitation instructions.
abstract: OBJECTIVE
  To determine the frequency of agonal breathing during cardiac arrest (CA), its impact on the ability of 9-1-1 dispatchers to identify CA, and the impact of dispatch-assisted cardiopulmonary resuscitation (CPR) instructions on bystander CPR rates.
  
  
  METHODS
  A before-after observational study enrolling out-of-hospital adult CA patients where resuscitation was attempted in a single city with basic life support with defibrillation/advanced life support tiered emergency medical services. Victim, caller, and system characteristics were measured during two successive nine-month periods before (control group) and after (intervention group) the introduction of dispatch-assisted CPR instructions.
  
  
  RESULTS
  There were 529 CAs between July 1, 2003, and December 31, 2004. Victim characteristics were similar in the control (n = 295) and intervention (n = 234) period; mean age was 68.3 years; 66.7% were male; 50.1% of CAs were witnessed; call-to-vehicle stop was 6 minutes, 37 seconds; ventricular fibrillation/ventricular tachycardia occurred in 29.9%; and the survival rate was 4.0%. Dispatchers identified 56.3% (95% confidence interval [CI] = 48.9% to 63.0%) of CA cases; agonal breathing was present in 37.0% (95% CI = 30.1% to 43.9%) of all CA cases and accounted for 50.0% (95% CI = 39.1% to 60.9%) of missed diagnoses. Callers provided ventilations in 17.2% and chest compressions in 8.3% of cases as a result of the intervention. Long time intervals were observed between call to diagnosis (2 minutes, 38 seconds) and during ventilation instructions (2 minutes, 5 seconds). Bystander CPR rates increased from 16.7% in the control phase to 26.4% in the intervention phase (absolute rate, 9.7%; 95% CI = 8.5% to 11.3%; p = 0.006).
  
  
  CONCLUSIONS
  This trial demonstrates an increase in bystander CPR rate after the introduction of dispatch-assisted CPR. Agonal breathing occurred frequently and had a negative impact on the recognition of CA. There were long time intervals between call initiation and diagnosis of CA and during mouth-to-mouth ventilation instructions.
authors.affiliation: Ottawa Health Research Institute, Ottawa, Ontario, Canada. cvaillancourt@ohri.ca
authors.forename: Christian
authors.initials: C
authors.lastname: Vaillancourt
authors.forename: Aikta
authors.initials: A
authors.lastname: Verma
authors.forename: John
authors.initials: J
authors.lastname: Trickett
authors.forename: Denis
authors.initials: D
authors.lastname: Crete
authors.forename: Tammy
authors.initials: T
authors.lastname: Beaudoin
authors.forename: Lisa
authors.initials: L
authors.lastname: Nesbitt
authors.forename: George A
authors.initials: GA
authors.lastname: Wells
authors.forename: Ian G
authors.initials: IG
authors.lastname: Stiell
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016887:Cardiopulmonary Resuscitation / Q000193:education* / Q000706:statistics & numerical data; D017028:Caregivers / Q000193:education* / Q000706:statistics & numerical data; D004631:Emergency Medical Service Communication Systems / Q000706:statistics & numerical data; D005260:Female; D006323:Heart Arrest / Q000175:diagnosis / Q000453:epidemiology / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D010043:Outcome and Process Assessment, Health Care; D012135:Respiratory Sounds / Q000175:diagnosis; D017216:Telemedicine / Q000379:methods / Q000706:statistics & numerical data; D016896:Treatment Outcome