Validation of Low-Acuity Emergency Medical Services Dispatch Codes

Abstract

Background. Computer-aided dispatch systems are used to assess the severity of a 9-1-1 caller's complaint andthen assign an appropriate level of emergency medical services (EMS) response. Objective. To evaluate a group of low-acuity codes (defined as requiring advanced life support [ALS] intervention in fewer than 10% of cases) that has been derived andvalidated in one community. Methods. All of the 9-1-1 medical calls assigned to these predetermined emergency medical dispatch codes between January 1, 2004, andJuly 1, 2004, were analyzed. ALS care was defined as receiving one or more of the following: pulse oximetry measurement, blood glucose measurement, cardiac defibrillation, administration of any medication, airway maneuvers, or the placement of an intravenous (IV) catheter. A more restrictive definition of ALS care (use of IV fluid bolus, medication administration, intubation, or defibrillation) was also calculated. Results. A total of 1,799 calls were assigned low-acuity dispatch codes, and1,597 met inclusion criteria. None of the 26 dispatch codes were found to be low-acuity by the study definition. Fifty-six percent of these patients received ALS care. Placement of an IV-catheter was the ALS intervention used most frequently (45% of cases), followed by pulse oximetry measurement (32%), glucose measurement (22%), medication administration (11%), intubation (0.13%), anddefibrillation (0%). The medication administered most frequent was morphine. When using the more restrictive definition of acuity, patients in 19 of the 28 categories received ALS intervention less than 10% of the time. Patients in the other seven categories were considered high-acuity 13% to 36% of the time. Conclusion. Dispatch codes that had previously been determined to be low-acuity were found not to be so in this community. The variation in clinical practice is likely explained by a more precautionary approach to care in this EMS system andthe increased use of analgesics. This study demonstrates the need to define the optimal subset of prehospital patients who would benefit from these treatments. Key words: ambulances; cardiopulmonary resuscitation; emergencies; emergency medical service communication systems; emergency medical services; retrospective studies; risk assessment; triage; acuity; wounds andinjuries; dispatch codes.