Dispatcher-assisted telephone CPR: common delays and time standards for delivery. STUDY OBJECTIVES: To determine the rate of bystander CPR before and after implementation of a telephone CPR program in King County; to determine the reasons for dispatcher delays in identifying patients in cardiac arrest in delivering CPR instructions over the telephone; and to suggest time standards for delivery of the telephone CPR message. DESIGN: An ongoing cardiac arrest surveillance system to calculate the annual bystander CPR rates from 1976 through 1988. Two hundred sixty-seven taped recordings of calls reporting cardiac arrests to nine emergency dispatch centers during 1988 were reviewed and timed. SETTING: King County, Washington, excluding the city of Seattle. PARTICIPANTS: Two hundred sixty-seven persons with out-of-hospital cardiac arrests receiving emergency medical services. Arrests in doctors' offices, clinics, or nursing homes were excluded. INTERVENTIONS: Dispatcher-assisted telephone CPR. MEASUREMENTS AND MAIN RESULTS: The rate of bystander CPR increased from 32% (1976 through 1981) to 54% (1982 through 1988) after implementation of the dispatcher-assisted telephone CPR program, although an increase in survival could not be demonstrated. The median time for dispatchers to identify the problem was 75 seconds; to deliver the early protocols, 19 seconds; to deliver the ventilation instructions, 25 seconds; and to deliver compression instructions, 30 seconds. The total time to deliver the entire CPR message was 2.3 minutes. The most frequent cause for delay was unnecessary questions (57%) with questions about patient age asked most frequently (32%). Other causes included the caller not being near the patient (29%) and deviations from protocol (22%). CONCLUSION: In a metropolitan emergency medical services system, a dispatcher-assisted telephone CPR program was associated with an increase in bystander CPR. Delays in proper delivery of telephone CPR can be minimized through training. 