Related Experiment Video
Updated: Aug 16, 2026

Ultrasonographic Assessment During Cardiopulmonary Resuscitation
Published on: October 24, 2020
Can basic life support personnel safely determine that advanced life support is not needed?
1Department of Surgery, Yale University School of Medicine, New Haven, Connecticut, USA. david.cone@yale.edu
Objective:
To determine whether firefighter/emergency medical technicians-basic (FF/EMT-Bs) staffing basic life support (BLS) ambulances in a two-tiered emergency medical services (EMS) system can safely determine when advanced life support (ALS) is not needed.
Methods:
This was a prospective, observational study conducted in two academic emergency departments (EDs) receiving patients from a large urban fire-based EMS system. Runs were studied to which ALS and BLS ambulances were simultaneously dispatched, with the patient transported by the BLS unit. Prospectively established criteria for potential need for ALS were used to determine whether the FF/EMT-B's decision to cancel the ALS unit was safe, and simple outcomes (admission rate, length of stay, mortality) were examined. In the system studied, BLS crews may cancel responding ALS units at their discretion; there are no protocols or medical criteria for cancellation.
Results:
A convenience sample of 69 cases was collected. In 52 cases (75%), the BLS providers indicated that they cancelled the responding ALS unit because they did not feel ALS was needed. Of these, 40 (77%) met study criteria for ALS: 39 had potentially serious chief complaints, nine had abnormal vital signs, and ten had physical exam findings that warranted ALS. Forty-five (87%) received an intervention immediately upon ED arrival that could have been provided in the field by an ALS unit, and 16 (31%) were admitted, with a median length of stay of 3.3 days (range 1.1-73.4 days). One patient died.
Conclusion:
Firefighter/EMT-Bs, working without protocols or medical criteria, cannot always safely determine which patients may require ALS intervention.
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