• L L Culley, D K Henwood, J J Clark, M S Eisenberg, and C Horton.
• King County Emergency Medical Services Division, Seattle-King County Department of Public Health.
• Ann Emerg Med. 1994 Nov 1; 24 (5): 867-72.

Study ObjectivesTo determine whether criteria based dispatch (CBD) improved the efficiency of the emergency medical services system.DesignA before and after design was used to measure effects of CBD. Data were reviewed from medical reports from January 1986 through June 1992.SettingKing County, Washington, excluding the city of Seattle.ParticipantsResidents who called 911 to report a medical emergency.InterventionsEmergency medical dispatching (EMD), basic life support (BLS), and advanced life support (ALS).ResultsFindings show a decrease in ALS responses for two tracer conditions that medical control physicians determined not require ALS intervention. The percentage of febrile seizures in which paramedics responded decreased from 41% to 21% (P < .001). The percentage of cerebrovascular accidents in which paramedics responded decreased from 41% to 28% (P < .001). CBD led to a decrease, from 4.7% to 3.8% (P < .001), in frequency of requests by BLS units for dispatch of ALS units. There was no increase in the time required to dispatch each call.ConclusionCBD increased the efficiency of the EMS system by significantly reducing ALS responses to incidents not requiring ALS intervention and reducing requests by BLS units for dispatch of ALS units while maintaining a consistent time from receipt of call to dispatch.

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