Spotlight on Research

Air ambulance tasking: which dispatch method is best?Despite their wide use throughout the UK, air ambulances remain a scarce resource but, as yet, there is no consensus on the best method to identify when they should be dispatched, especially in relation to patients with major trauma.This London-based, retrospective review of existing data (January 2008–December 2010) set out to demonstrate which of three dispatch methods was the most effective and accurate when identifying patients with serious injury. The three methods used by London's Air Ambulance include dispatch by a flight paramedic based on mechanism of injury (MOI), paramedic telephone interrogation of the caller (INT), and land ambulance crew request (REQ) once they have arrived on-scene.There are differences in the UK in relation to MOI criteria and what triggers dispatch of air ambulances but, for London's Air Ambulance there are six current criteria: fall over 6 metres, ejection from a vehicle, death of another person in the same vehicle, amputation (above ankle or wrist), entrapment under a vehicle (not motorcycle), person under a train.London's Air Ambulance dispatch paramedic screens the calls coming in to the London Ambulance Service NHS Trust (LAS) call centre and if any of these six criteria are identified, then the air ambulance will be dispatched immediately. Other traumatic calls (such as assault, stabbing, drowning, road traffic incident etc.) are triaged by the flight paramedic in the control room, who may need to gather further information by telephoning the original caller prior to initiating dispatch of the air ambulance. If there is insufficient information or the call is missed, then the LAS land crew can request air ambulance assistance once they have assessed the situation on-scene.ISTOCK/ALEXANDERCHERThe primary outcome for this study was accurate dispatch, which was defined as calls needing escort from the scene by the medical team to a major trauma centre, or where the air ambulance team carried out resuscitation on-scene. Inaccurate dispatch included calls where the air ambulance was stood down en-route or where the patient ultimately was left in the care of the land crew.During the study period, 2 203 helicopter dispatches were initiated: 417 by MOI, 1 375 after paramedic interrogation of the call (INT), and 411 after requests by the land crews (REQ). Results found that MOI dispatch was appropriate in 58.7% (245) of cases, paramedic interrogation in 69.7% (959) of cases, and crew request in 72.2% (297) of cases.No significant difference in accuracy was found between crew requests and paramedic interrogation of the caller (p=0.36). However, crew requests and paramedic interrogation were both significantly more accurate than MOI (p<0.0001).Mean time to dispatch was 4 minutes (range 1–34) for MOI, 8 minutes (range 1–56) for paramedic interrogation, and 21 minutes (range 2–61) for land crew requests.When dispatch criteria were applied away from the scene (MOI and INT), 80.2% of seriously injured patients were correctly identified, although this study identified an overtriage rate of 32.8% and an undertriage rate of 19.7%.The authors clearly identify the limitations of their study including the retrospective nature of the research, the missing data for 147 cases, and the reliance on the tasking paramedic to consistently document criteria for dispatch. Additionally, they highlight that when land crews cancelled the air ambulance team once it was en-route, this was classified as an inappropriate dispatch. However, no information was collected as to the reasons for the cancellations. Therefore, there was ambiguity as to whether the original dispatch was appropriate or not, for example, the initial decision to deploy the air ambulance may have been appropriate but the patient may have died after it had been dispatched.In conclusion, these findings support other studies which found that on its own MOI was found to be the least accurate method of tasking. This evaluation found that using a dedicated helicopter tasking desk staffed by a flight paramedic who interrogates calls was as accurate as land crew referrals, but has the added benefit of enabling faster dispatch of the air ambulance. However, overtriage still remains an issue with all methods and this requires further investigation.Spotlight on Research is edited by Julia Williams, principal lecturer, paramedic science, University of Hertfordshire, Hatfield, Hertfordshire, UK. To find out how you can contribute to future issues, please email her at‘On its own MOI was found to be the least accurate method of tasking’

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