How to evaluate an emergency medical dispatch system: a Belgian perspective.

In order to evaluate the local emergency medical dispatch centre, 4601 calls were analysed. Information was obtained from the tape recordings of the dispatch centre and standardized reports from the basic life support (BLS) teams, advanced life support (ALS) teams and the emergency departments of all receiving hospitals in the study area. The need for prehospital ALS care was assessed 'post hoc', based on the clinical findings at the scene and in the emergency department. The accuracy of the medical dispatch was evaluated by comparing the level of care actually sent with the real medical needs of the patient. The 4601 medical problems reported led to 4446 interventions: a BLS team only in 82% (n = 3627), an ALS team and BLS team simultaneously in 14% (n = 623), and a BLS team followed somewhat later by an ALS team in 4% (n = 196). In the 633 cases judged 'post hoc' to require prehospital ALS care, an ALS team was not sent in 260 (41%) or sent with some delay in 112 (18%). Of the 819 interventions of the ALS teams, 446 (54%) dealt with cases not requiring that level of care. With regard to the role of the dispatchers in the mismatches between the medical needs of the patients and the level of care sent, underestimation and overestimation of the severity of the emergency by the dispatchers was found in 31% and 22% cases respectively.