The use of emergency medical dispatch protocols to reduce the number of inappropriate scene responses made by advanced life support personnel.

OBJECTIVES: To determine whether implementation of an emergency medical dispatch (EMD) system would reduce the rate of inappropriate advanced life support (ALS) utilization, and enable more accurate identification of those patients requiring ALS care.
METHODS: An emergency medical services (EMS) site providing basic life support (BLS) and ALS care to a population of 200,000 served as the study site for calendar year 1996. This study compared the prospective identification of patients as ALS or BLS using EMD with that using chief complaint-based dispatch criteria. Each patient served as his or her own control. The ALS or BLS priority was assigned using both chief complaint and EMD criteria. Chief complaint-based dispatching meant that all patients with preestablished chief complaints received ALS without further triage questions, while EMD allowed the dispatchers to question callers using a scripted set of questions. The outcome measures included the number of calls categorized as ALS or BLS, the number of calls cancelled by BLS, and the number of ALS calls released to BLS care. Yates-corrected chi-square was used for statistical analysis.
RESULTS: There were 11,174 patients enrolled. The use of EMD was associated with a significant decrease in the proportion of calls designated as ALS (44.7% vs 55.8%, p < 0.0001), as well as a significant decrease in the number of ALS responses cancelled by BLS (9.2% vs 23.8%, p < 0.0001) and patients released to BLS by medical control (4.7% vs 7.3%, p < 0.0001).
CONCLUSIONS: Implementation of an EMD system significantly decreased inappropriate ALS dispatching, as defined by decreased rate of ALS cancellations and BLS releases. Further study is needed to see whether other EMD dispatch models may further refine ALS dispatch.