Safety of Tiered-Dispatch for 911 Calls for Abdominal Pain

Many dispatch systems send Advanced Life Support (ALS) resources to patients complaining of abdominal pain even though the majority of these incidents require only Basic Life Support (BLS). With increasing 911-call volume, resource utilization has become more important to ensure that ALS resources are available for time-critical emergencies. In 2015, a large, urban fire department implemented an internally developed, tiered-dispatch system. Under this system, patients reporting a chief complaint of abdominal pain received the closest BLS ambulance dispatched alone emergency if located within three miles of the incident. The objective of this study was to determine the safety of BLS-only dispatch to abdominal pain by determining the frequency of time-sensitive events.

This was a retrospective review of electronic health records of one emergency medical service provider agency from May 2015-2018. Inclusion criteria were a chief complaint of abdominal pain from a first- or second-party caller, age over 15, and the patient was reported to be alert and breathing normally. The primary outcome was the prevalence of time-sensitive events, including cardiopulmonary resuscitation (CPR), defibrillation, or airway management. Secondary outcomes were hypotension (systolic blood pressure < 90 mmHg); or a prehospital 12 lead-electrocardiogram (ECG) demonstrating ST-elevation myocardial infarction (STEMI) criteria or a wide complex arrhythmia. Descriptive statistics were used.

During the study period, there were 1,220,820 EMS incidents, of which 33,267 (2.72%) met inclusion criteria. The mean age was 49.9 years (range 16-111, standard deviation [SD] 19.6); 14,556 patients (56.2%) were female. Time-sensitive events occurred in seven cases (0.021%), mean age was 75.3 years (range 30-86, SD18.7); 85.7% were female. Airway management was required in seven cases (0.021%), CPR in six cases (0.018%), and defibrillation in one case (0.003%). Two of the seven (28.6%) cases involved dispatch protocol deviations. Hypotension was present in 240 (0.72%) cases; six (0.018%) cases had 12-lead ECGs meeting STEMI criteria; and no cases demonstrated wide complex arrhythmia.

Among adult 911 patients with a dispatch chief complaint of abdominal pain, time-sensitive events were exceedingly rare. Dispatching a BLS ambulance alone appears to be safe.