Modifiable Factors Associated With Improved Cardiac Arrest Survival in a Multicenter Basic Life Support/Defibrillation System: OPALS Study Phase I Results☆,☆☆,★,★★,♢
Section snippets
INTRODUCTION
Thirty years ago, Pantridge and Geddes1 introduced the concept of providing advanced cardiac life support (ACLS) care to cardiac arrest victims outside of hospitals with mobile intensive care vehicles in Belfast. Many European and North American EMS responders provide out-of-hospital defibrillation and in some cases intravenous drug therapy and advanced airway techniques to cardiac arrest victims. Despite these advances, cardiac arrest survival remains poor in most jurisdictions, ranging from
MATERIALS AND METHODS
Overall, the OPALS Study incorporates a multiphase before-after design with the unit of study being all eligible cardiac arrest patients seen during each of 3 distinct phases. The current study, phase I, represents an observational cohort study conducted from 1991 through 1994 when all communities provided an ambulance automated defibrillation (BLS-D) program. The study was conducted in 21 Ontario urban/suburban communities ranging in population from 16,000 to 750,000. The study communities
RESULTS
Table 1 shows the characteristics of the 5,335 cardiac arrest cases from the study communities during phase I (July 1, 1991–January 31, 1995).
Characteristics Patients (n=5,335)* Mean age (y; SD) 68 (13.9) Range 16–102 Male sex (%) 3,610 (67.7) Community population size (%) <30,000 (n=5) 293 (5.5) 30,000 to 100,000 (n=5) 1,141 (21.4) 100,000 to 200,000 (n=6) 963 (18.1) 200,000 to 500,000 (n=4) 1,970 (36.9) >500,000 (n=1) 968 (18.1) Winter season (%) 1,467 (27.5) Witnessed arrest (%)
DISCUSSION
The OPALS Study represents the largest multicenter BLS-D study of prehospital cardiac arrest yet conducted. Our data clearly show that improved survival is associated with younger age and a witnessed event. Neither of these factors, however, can be improved on or optimized in an EMS system. We found 3 other independent factors associated with improved survival that are amenable to EMS system optimization. Survival may be enhanced by minimizing EMS response intervals, particularly the “call
Acknowledgements
We thank the OPALS Study Group investigators from the following base hospital programs: Burlington—Matthew W Stempian, MD, CCFP (EM), and Rose-Ellen G Rollins, RN; Cambridge—David Waldbillig, MD, CCFP (EM), Donald J Stewart, MD, MCFP (EM), and Bruce D Jermyn, RN, BScN, MBA; Kingston—Gordon J Jones, MD, FRCPC, Brian J Field, EMA III, and Thomas Bedford; London—Jonathan F Dreyer, MDCM, FRCPC, and Kenneth A Boyle, EMCA, EMT, RRT, CMA; Niagara—Douglas P Munkley, MD, MCFP (EM), and Lorraine G
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Cited by (0)
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Supported by grant 09194N from the Emergency Health Services Branch of the Ontario Ministry of Health, Ontario.
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Dr Stiell is a career scientist of the Medical Research Council of Canada.
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Address for reprints: Ian G Stiell, MD, MSc, FRCPC, Clinical Epidemiology Unit, Ottawa Hospital Loeb Research Institute, 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9; 613-798-5555 ext 8688, fax 613-761-5351.
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