This study has devised an algorithm based on easily obtainable variables. The data-driven algorithm may be remembered by the acronym “APEX” and can help emergency service providers on scene to determine the preferred method of extrication for patients who are trapped after a road traffic collision. This has the potential to decrease entrapment time and may contribute to a better outcome for these patients.

The proposed algorithm has several strengths. First, it is derived from real data. Unlike other extrication algorithms (i.e. for self-extrication), this algorithm was not derived in a Delphi procedure and/or based on expert-opinion, but variables included were derived from a real patient population of 920 trauma patients. Second, variables included are easy to measure, and limited clinical knowledge is required to interpret the algorithm. The algorithm will support healthcare providers in their decision on whether expedited or controlled extrication is warranted for patients entrapped in an RTC.

The study revealed that patients who were “alert” upon arrival of the HEMS team were unlikely to receive HEMS interventions post-extrication. These patients are generally not time-critical and can inform medical personnel reliably about any neurological deficits [3, 8]. Hence, a controlled extrication strategy or even self-extrication should normally be advocated in these patients. It should be noted however, that especially when these patients are seen early after their moment of injury there still is a potential for deterioration, so repeated evaluation and, if necessary, amendment of the extrication plan is warranted, as 3% of these patients still require HEMS interventions early after extrication.

The algorithm derived is most useful for patients responding to “voice”. This is a heterogenous group of patients, some of whom will require HEMS interventions and others not. In these patients, the presence of a (partially) occluded airway and absence of a radial pulse should be independently regarded as evidence for the need for expedited extrication. Extrication is required to perform critical interventions such as PHEA and blood product transfusion, and to facilitate expedited transport to definitive care (26). In support of this, evidence highlights that increased mortality is associated with a longer scene time [14, 15]. The need for spinal precautions for this group of patients should be weighed against the presence of the features mentioned above. When there are neurological deficits and when the airway is patent, and radial pulse is present, a controlled extrication technique may be preferred, whereas otherwise expedited extrication may be the approach of choice. It should be noted though that if a controlled extrication technique is chosen for this group, frequent clinical re-evaluation is mandatory, as even when they have a patent airway and a radial pulse, one or more HEMS interventions post-extrication are needed in 17% of the patients.

Patients who were only responsive to pain or were “unresponsive” almost invariably needed cardiopulmonary resuscitation and/or HEMS interventions. For these patients, rapid extrication is commonly warranted. However, sometimes to prevent the patient from dying before extrication is completed, immediate interventions whilst still entrapped are needed, such as opening the airway, gaining IV access, and starting a blood product transfusion. Whether or not these interventions should take place remains largely a dynamic risk assessment, wherein the risk of withholding these should be weighed between the risk associated with the medical professional offering these interventions, and the risk of prolonging the time to extrication. Further, the majority of unresponsive patients had a cardiac arrest and for these patients the need for rapid extrication is obvious. However, the merit of the algorithm for unresponsive patients is twofold: [1] It stresses the importance of rapid extrication of these patients when not in CA (29% of unresponsive patients), and [2] It emphasizes that for these patients sometimes interventions are needed before extrication.

The APEX algorithm allows for early decision making about the preferred extrication strategy before critical care teams such as HEMS arrive on scene. As previous studies have demonstrated entrapment after an RTC is associated with an increased mortality, decreasing entrapment time may affect outcome in this patient cohort, by shortening the time from the accident until critical (HEMS) interventions can take place. The authors hope the APEX algorithm will support those early on scene to make safe, clinically driven, evidenced based decisions for extrication and improve collaborative working between all emergency service agencies in working towards better outcomes for patients involved in RTCs. Pre-hospital systems are currently exploring the use of novel live-streaming technologies from scene using bystanders’ mobile devices [16]. These technologies can be used alongside the algorithm to ensure input from a Critical Care Dispatcher and/or Critical Care Paramedic who may be able to clinically guide the extrication in order to further improve outcome for these patients.

Our study has several limitations. First, although the APEX algorithm is data-driven, some aspects still rely on common sense and expert opinion: no data will be available to support recommendations on patients experiencing neurological symptoms or patients with obvious critical injuries decision making follows common sense in the instances. Second, generalisability of our study findings is potentially compromised by the fact that data were collected from one HEMS only and no data were collected from incidents with entrapment where no HEMS team attended. Third, population composition, incident types and EMS systems may differ from region to region, which may limit the external validity of the study’s findings. Further, extrication timestamps are not included on the electronic patient clinical record and therefore the relation between entrapment time and outcome could not be investigated. Finally, although the study has derived an algorithm to support decision making for extrication of trapped critically injured patients, the study has not validated the effectiveness of this algorithm in prospective practice. Therefore, multiagency services research is needed to evaluate the implementation and impact of the proposed algorithm.