Unexpected ALS Procedures on Non-Emergency Ambulance Calls: The Value of a Single-Tier System

Abstract Background: In a single-tier, advanced-life-support (ALS) emergency medical service (EMS) system, ALS-trained staff in ALS-equipped vehicles respond to all ambulance calls. In some two-tier systems, basic life support (BLS) vehicles respond to calls which are determined initially to be non-emergency based on dispatcher triage. I emergency requiring ALS is discovered (or recognized) by BLS personnel, then a subsequent ALS response can be requested. Purpose: The purpose of this study was to determine the frequency of ALS care provided on ambulance calls initially dispatched as non-emergency. Setting: A single-tier, all-ALS provider, EMS system, serving an urban population of 475,000 with an annual response volume of 45,000 calls. Methods: A retrospective review of all prehospital transports initially dispatched as non-emergency from 1 January 1989 to 1 January 1990 that resulted in an ALS intervention being performed was conducted. An ALS intervention was defined as, “administration of a medication, endotracheal intubation, attempted IV insertion, and/or ECG monitoring.” Results: A total of 6,362 non-emergency calls were identified; of these 309 (5%) were upgraded to emergency while the responding unit was in route. Of 6,053 non-emergency calls remaining, 710 (11.7%) involved the provision of one or more ALS interventions. Of these, 296 (42%) received an IV, 24 (3%) a medication, and three (0.4%) were intubated. Calls that were upgraded by dispatchers required one or more interventions in 144/309 calls (46.6%). This was statistically significantly different than for the non-upgraded calls. Conclusion: Despite the use of strict dispatching protocols, 11.7% of patients prioritized as non-emergent unexpectedly received ALS care after evaluation by ALS personnel. These results add support for the use of a single-tier, ALS ambulance system.