To describe the patient characteristics, circumstances and community response in cases of out-of-hospital cardiac arrest; to evaluate the effect on survival of the introduction of prehospital defibrillation; and to identify factors that predict survival.
Population-based before-and-after clinical trial.
Five Ontario communities: London, Sudbury, the Greater Niagara region, Kingston and Ottawa.
A consecutive sample of 1510 primary cardiac arrest patients who were transported to hospital by ambulance over 2 years.
The use of defibrillators by ambulance attendants.
Patient characteristics (sex and age), circumstances of arrest (place, whether arrest was witnessed and cardiac rhythm), citizen response (whether cardiopulmonary resuscitation [CPR] was started by a bystander, time to access to emergency medical services and time to initiation of CPR), emergency medical services response (ambulance response time, time to initiation of CPR and time to rhythm analysis with defibrillator) and survival rates.
A total of 92.1% of the patients were 50 years of age or older, and 68.3% were men. Overall, 79.6% of the arrests occurred in the home. The average ambulance response time for witnessed cases was 7.8 minutes. The overall survival rate was 2.5%. The survival rates before and after defibrillators were introduced were similar, and the general functional outcome of the survivors did not differ significantly between the two phases. Factors predicting survival included patient's age, ambulance response time and whether CPR was started before the ambulance arrived.
The survival rate was lower than expected. The availability of prehospital defibrillation did not affect survival. To improve survival rates after cardiac arrest ambulance response times must be reduced and the frequency of bystander-initiated CPR increased. Once these changes are in place a beneficial effect from advanced manoeuvres such as prehospital defibrillation may be seen.
Notes
Cites: Can Med Assoc J. 1978 Jul 8;119(1):25-9679096
Cites: JAMA. 1979 May 4;241(18):1905-7430772
Cites: Ann Intern Med. 1979 May;90(5):737-40434671
Cites: Lancet. 1976 Oct 2;2(7988):702-461390
Cites: Am J Med. 1980 Apr;68(4):568-767369235
Cites: Can Med Assoc J. 1980 Feb 9;122(3):297-3007370825
Cites: N Engl J Med. 1980 Jun 19;302(25):1379-837374695
Cites: Acta Med Scand. 1982;212(4):247-517148520
Cites: Am J Public Health. 1983 Jul;73(7):766-96859360
Cites: Ann Emerg Med. 1983 Aug;12(8):478-816881643
Cites: Am J Cardiol. 1984 Jan 1;53(1):68-706691281
Cites: Am J Pathol. 1926 Jan;2(1):15-18.119969683
Cites: N Engl J Med. 1988 Sep 15;319(11):661-63412383
Cites: Am J Emerg Med. 1988 Mar;6(2):113-92833285
Cites: Br Med J (Clin Res Ed). 1987 May 2;294(6580):1133-53107727