The Ontario Prehospital Advanced Life Support (OPALS) Study: rationale and methodology for cardiac arrest patients

The Ontario Prehospital Advanced Life Support Study represents the largest prehospital study yet conducted, worldwide. This study will involve more than 25,000 cardiac arrest, trauma, and critically ill patients over an 8-year period. The study will evaluate the incremental benefit of rapid defibrillation and prehospital Advanced Cardiac Life Support measures for cardiac arrest survival and the benefit of Advanced Life Support for patients with traumatic injuries and other critically ill prehospital patients. This article describes the OPALS study with regard to the rationale and methodology for cardiac arrest patients.

Cost-effectiveness analysis of a rural/urban first-responder defibrillation program

OBJECTIVE

To analyze the cost-effectiveness of a proposed first-responder defibrillation program in a small rural area in comparison with a recently initiated first-responder program in an adjoining urban center in southwestern Ontario. The purpose of the analysis was to quantify the expected benefits of the proposed program to determine whether the costs are justified.

METHODS

This analysis was conducted on the city of Waterloo (population 80,000 over 25 square miles) and the adjoining rural township of Wellesley (population 8,000 over 105 square miles). The township has volunteer fire department first responders with basic life support (BLS), and basic life support/defibrillation (BLS-D) ambulances as the second tier; whereas the city's full-time fire department has recently adopted a first-responder defibrillation (BLS-D) program backed up by the same BLS-D ambulance service. The most relevant costs identified were the capital costs of the defibrillators, ancillary equipment, and biomedical service for preventive maintenance and routine nonwarranty work. Response intervals and percentage of patients found in ventricular fibrillation were projected and sensitivity analysis was applied.

RESULTS

The projected cost per life saved is $6,776 (C) in the urban area and $49,274 (C) in the rural area using an incremental save rate of 6%. Applying sensitivity analysis to the data, the save rate varied from 2% to 10%, resulting in a cost per life saved of $20,328 (C) and $4,066 (C), respectively, in the urban community. For the rural area, the cost per life saved ranged from $147,821 (C) (2%) to $29,564 (C) (10%). Even the worst-case save rate for the urban center [2%; $20,328 (C)] is significantly less than the best-case save rate [10%; $29,564 (C)] for the rural area.

CONCLUSIONS

The cost per life saved for a rural first-responder defibrillation program is significantly more expensive than one for an urban center. However, the cost per life saved is still economical compared with common treatments for other life-threatening illnesses.

Response interval comparison between urban fire departments and ambulance services

OBJECTIVE

To measure the response intervals of fire departments compared with ambulance services in three urban centers to determine whether defibrillators should be added to fire vehicles.

METHODS

A prospective sample of 1,882 code 4 (life-threatening) tiered calls were collected over a six-month period from March 1, 1994, to August 31, 1994. A matched pairs experimental design compared the response interval of the fire department with that of the ambulance service for each call. This emergency medical services (EMS) system encompasses three urban centers with populations of 80,000, 95,000, and 170,000.

RESULTS

In two of three of the urban centers, the fire department arrived on scene more than a minute sooner than the ambulance service: Cambridge (n = 571, mean = 2.22 min, p < 0.0001); Kitchener (n = 1,011, mean = 1.24 min, p < 0.003); and Waterloo (n = 300, mean = 0.69 min, p < 0.98).

CONCLUSIONS

The shorter response interval of fire departments suggests placing defibrillators on fire response vehicles in an effort to decrease the time to defibrillation for cardiac arrest victims in this EMS system.

Reduction of the call-response interval with ambulance base paging

OBJECTIVE

To determine whether the call-response interval for an emergency medical services (EMS) system would be decreased through the introduction of ambulance base paging.

METHODS

The study community included a mixture of urban and rural areas with a total population of approximately 400,000. The EMS system is composed of two ambulance services and one central ambulance communication center with computer-aided dispatching capabilities. Approximately 30,000 calls are responded to yearly by the combined ambulance services. A before-and-after study design was used. In a retrospective review of one ambulance service, there were 224 calls collected in the period before base paging and 200 calls collected in the period after base paging was introduced. In the other ambulance service, there were 571 calls captured in the period before base paging and 515 calls captured in the period after base paging.

RESULTS

The call-receipt-to-crew-notified interval was reduced from the before period to the after period in both ambulance services: Cambridge--61.8 to 49.8 seconds (p < 0.0001); Kitchener--66.6 to 46.2 seconds (p < 0.0001). The crew-notified-to-vehicle-mobile interval was reduced from the before period to the after period in both ambulance services: Cambridge--91.8 to 73.2 seconds (p < 0.0001); Kitchener-80.4 to 66.0 seconds (p < 0.0001).

CONCLUSIONS

The introduction of ambulance base paging reduced components of the call-response interval in this EMS system. Overall, the reduction in time was approximately 30 seconds, which was found to be statistically significant.