Canceled Air Ambulance Trauma Scene Calls: A Prospective Observational Study of Causes and Outcomes of Trauma Auto-launch Cancellations

Published:August 09, 2022DOI:


      • Helicopter auto-launch calls are sometimes canceled by land emergency medical services after dispatch.
      • Patients may still meet the trauma criteria and later undergo interfacility transfer.
      • 76.2% of calls were canceled for not meeting the trauma bypass criteria.
      • 16.5% of these were later transferred to a trauma hospital.
      • A multidisciplinary approach needed to reduce the undertriage of trauma patients.



      Direct transport, occasionally by helicopter, to a trauma hospital for severely injured patients is associated with decreased mortality. This study sought to determine causes for air ambulance trauma response cancellations and secondarily to identify patients who underwent secondary transfer to a trauma center after a canceled air ambulance dispatch.


      This prospective cohort study used administrative databases from August 2020 to August 2021 to collect data related to canceled trauma calls. Frequencies of cancellation reasons and transferred patients were summarized, and the estimated delay to trauma center arrival was calculated. Subsequent probabilistic matching was performed to identify patients who underwent secondary transfer.


      Of 3,232 trauma calls, 1,924 were canceled for reasons including the trauma bypass criteria not being met, patient brought to trauma center, and patient refused transfer. Of the 1,117 patients for whom an air ambulance was canceled because they did not meet the trauma bypass criteria, 184 (16.5%) were later transferred to a lead trauma hospital, with a median delay of 4.12 hours (interquartile range = 2.57-7.35 hours).


      Most scene call cancellations were due to patients not meeting the trauma bypass criteria; yet, 16.5% of these patients were later transported to a trauma center. Interventions are needed in education, adherence, and modification of the trauma bypass criteria.
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