• ACS Highlight: Trauma Team Activation: Optimizing Prehospital Triage of the Injured Patient

    Dr. Morgan Schellenberg

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    Trauma Team Activation: Optimizing Prehospital Triage of the Injured Patient

    The American College of Surgeons (ACS) Committee on Trauma (COT) provides a set of trauma team activation (TTA) criteria, intended to be applied in the prehospital setting to identify trauma patients who would benefit most from highest level trauma activation. These criteria include physiologic parameters, such as systolic blood pressure <90 mmHg and heart rate >120 beats per minute, as well as mechanism variables including gunshot wound to the torso1. When trauma patients meet one or more of these criteria, personnel and resources are mobilized at the receiving trauma center in advance of patient arrival.

    The concept behind TTA criteria is clear: to allow a few moments to prepare for the needs of the severely injured trauma patient so that there are no delays in care delivery and preventable morbidity and mortality are avoided. An ideal set of criteria would be succinct and capture all patients who truly require the highest level of trauma activation and none of those who do not. Practically speaking, it is exceedingly challenging if not impossible to design a manageable list with perfect sensitivity and specificity with which to screen trauma patients in the field. To avoid missing patients who require heightened trauma services, the ACS COT TTA criteria allow for the over-capture of patients who do not need such resources. Patients who needlessly trigger TTA and those who may benefit from TTA but do not meet TTA criteria are referred to as the over-and undertriage, respectively.

    Overtriage occurs when a patient without major trauma triggers TTA criteria1. Excessive levels of overtriage strain hospital systems as resources are expended unnecessarily, with one study demonstrating a cost exceeding $130 million from overtriage2. At the extreme, significant levels of overtriage may also negatively impact patient care, wherein a system becomes overwhelmed by such patients and is unable to effectively deliver patient care. Although the ACS COT does not define acceptable levels of overtriage, it suggests they are typically in the range of 25-35%1.

    Undertriage is more concerning than overtriage because it is more likely to jeopardize patient care. Undertriage occurs when patients with major trauma do not meet TTA criteria and therefore arrive to hospital without advanced mobilization of the trauma system. Because of the potential risk to life that may result from being undertriaged, the ACS COT defines acceptable rates of undertriage as <5%1 and monitors these rates among ACS-verified trauma centers as part of the Verification, Review, and Consultation (VRC) Program. The literature demonstrates a clear negative impact from being undertriaged. Trauma patients who have sustained major trauma and do not trigger TTA are at increased risk for mortality3, delayed time to intervention4, and potentially preventable complications.

    Consider a patient with a stab wound to the superficial femoral artery with a short transport time to hospital and/or a tourniquet or direct pressure application by bystanders5 or emergency medical technicians. Without significant prehospital blood loss, this patient may have relatively normal vital signs in the field and may therefore not trigger TTA. However, it is clear this patient will require trauma center resources including trauma-trained physicians, nurses, and other health care personnel; blood transfusion; and immediate access to the operating room. The receiving trauma system will be better able to quickly deliver these resources to the patient if they are mobilized from the field in advance of patient arrival to hospital.

    At our institution, we review all undertriaged patients for any potential clinical impact from the undertriage and identify a small number of such patients per year. These tend to be patients who may have had shorter times to surgical intervention or angioembolization or decreased blood transfusion requirements if they had met the criteria for TTA. In a one-year study of undertriaged patients at our center, we found an overall undertriage rate of 16%6. However, only 14% of all undertriaged patients were deemed to be high-risk, as defined by the need for emergency surgery, angioembolization, and/or those who died in hospital.

    The discrepancy between the number of patients who are technically undertriaged and those who sustain a potential clinical effect from being undertriaged may reflect limitations of the current definition of major trauma in prehospital triage. Resources for the Optimal Care of the Injured Patient defines major trauma as patients with an Injury Severity Score (ISS) of ≥16, and therefore, undertriage as patients with ISS ≥16 who do not meet TTA criteria1. However, there are known limitations of the ISS in terms of quantifying injury burden and the potential need for resources including immediate operative intervention, blood transfusion, and intensive care unit admission. Particularly after penetrating trauma, in which injuries tend to be more localized and therefore accumulate lower ISS scores, ISS may not be an accurate reflection of that patient’s burden of injury. The New Injury Severity Score (NISS) is a modified ISS which addresses this limitation by representing the three most severe injuries, even if they occur within a single body cavity7. Additionally, the inherent severity or lethality of injuries may change as our care of the injured patient improves, and therefore current Abbreviated Injury Scale (AIS) scores, on which the ISS calculation is predicated, may not reflect contemporary injury burden8.

    To further illustrate why the ISS alone may not be an ideal metric to quantify major trauma, consider a patient with minor to moderate injuries in multiple body regions such as a patient after a motor vehicle collision with three rib fractures, an American Association for the Surgery of Trauma (AAST) grade III solid organ injury, and a tibial fracture. This patient is likely to meet the current definition of major trauma with an ISS ≥16 but would not be expected to need enhanced trauma center resources.

    New scoring systems have been proposed to quantify major trauma in a different way than the ISS, with a heavier emphasis on the need for rapidly mobilized hospital resources than on injury severity in and of itself. These include the Need For Trauma Intervention (NFTI) score9, which is more strongly associated with outcomes after trauma than the ISS, and the Need for Emergent Intervention within 6 hours (NEI-6) score10. An excellent recent review article examines the impact on triage of these novel scoring systems and others in more depth11. Defining major trauma in a way more aligned with the need for trauma center resources may permit improved identification of patients who elude the current prehospital triage system and are therefore at risk for preventable morbidity and mortality. Definition of such patients may then allow for modification of existing TTA criteria to reduce or even eliminate clinically relevant undertriage.

    Several variables have been proposed as novel or modified TTA criteria. These include advanced age12-13, Glasgow Coma Scale (GCS) score of 9-124, narrow pulse pressure14, Prehospital Assessment of Blood Consumption (phABC) score15, and others. Despite reducing undertriage, inclusion of many of these variables as TTA criteria may increase overtriage, although further study is needed. Particularly because TTA criteria must remain concise in order to be practical, the trauma community may need to decide if a higher level of overtriage is tolerable in order to diminish undertriage.

    Moving forward, further validation of novel injury scoring tools and refined examination of clinically relevant undertriage may allow us to better tailor our definitions of major trauma and thereby improve the prehospital triage of the injured patient.


    1. American College of Surgeons Committee on Trauma. Resources for Optimal Care of the Injured Patient, 6th Ed. Chicago, IL: American College of Surgeons, 2014.
    2. Newgard CD, Staudenmayer K, Hsia RY, Mann NC, Bulger EM, Holmes JF, Fleischman R, Gorman K, Haukoos J, McConnell KJ. The cost of overtriage: more than one-third of low-risk injured patients were taken to major trauma centers. Health Aff (Millwood). 2013;32(9):1591-9.
    3. Tignanelli CJ, Vander Kolk WE, Mikhail JN, Delano MJ, Hemmila MR. Noncompliance with American College of Surgeons Committee on Trauma recommended criteria for full trauma team activation is associated with undertriage deaths. J Trauma Acute Care Surg. 2018;84(2):287-294.
    4. Schellenberg M, Benjamin E, Owattanapanich N, Inaba K, Demetriades D. The impact of delayed time to first CT head in traumatic brain injury. Eur J Trauma Emerg Surg. 2021;47(5):1511-1516.
    5. American College of Surgeons. Stop the Bleed Program. 2021. Available at http://stopthebleed.org [Accessed Oct 1, 2021].
    6. Schellenberg M, Benjamin E, Bardes JM, Inaba K, Demetriades D. Undertriaged trauma patients: Who are we missing? J Trauma Acute Care Surg. 2019;87(4):865-869.
    7. Osler T, Baker SP, Long W. A modification of the injury severity score that both improves accuracy and simplifies scoring. J Trauma. 1997;43:922–926.
    8. Schellenberg M, Owattanapanich N, Grigorian A, Lam L, Nahmias J, Inaba K. Surviving Nonsurvivable Injuries: Patients Who Elude the 'Lethal' Abbreviated Injury Scale (AIS) Score of Six. J Surg Res. 2021;268:616-622.
    9. Roden-Foreman JW, Rapier NR, Foreman ML, Zagel AL, Sexton KW, Beck WC, McGraw C, Coniglio RA, Blackmore AR, Holzmacher J, Sarani B, Hess JC, Greenwell C, Adams CA Jr, Lueckel SN, Weaver M, Agrawal V, Amos JD, Workman CF, Milia DJ, Bertelson A, Dorlac W, Warne MJ, Cull J, Lyell CA, Regner JL, McGonigal MD, Flohr SD, Steen S, Nance ML, Campbell M, Putty B, Sherar D, Schroeppel TJ. Rethinking the definition of major trauma: The need for trauma intervention outperforms Injury Severity Score and Revised Trauma Score in 38 adult and pediatric trauma centers. J Trauma Acute Care Surg. 2019;87(3):658-665.
    10. Morris R, Karam BS, Zolfaghari EJ, Chen B, Kirsh T, Tourani R, Milia DJ, Napolitano L, de Moya M, Conterato M, Aliferis C, Ma S, Tignanelli C. Need for Emergent Intervention within 6 Hours: A Novel Prediction Model for Hospital Trauma Triage. Prehosp Emerg Care. 2021; 18:1-10.
    11. Morris RS, Karam BS, Murphy PB, Jenkins P, Milia DJ, Hemmila MR, Haines KL, Puzio TJ, de Moya MA, Tignanelli CJ. Field-Triage, Hospital-Triage and Triage-Assessment: A Literature Review of the Current Phases of Adult Trauma Triage. J Trauma Acute Care Surg. 2021;90(6):e138-e145.
    12. Bardes JM, Benjamin E, Schellenberg M, Inaba K, Demetriades D. Old Age With a Traumatic Mechanism of Injury Should Be a Trauma Team Activation Criterion. J Emerg Med. 2019;57(2):151-155.
    13. Benjamin ER, Khor D, Cho J, Biswas S, Inaba K, Demetriades D. The Age of Undertriage: Current Trauma Triage Criteria Underestimate The Role of Age and Comorbidities in Early Mortality. J Emerg Med. 2018;55(2):278-287.
    14. Schellenberg M, Owattanapanich N, Getrajdman J, Matsushima K, Lam L, Inaba K. Prehospital Narrow Pulse Pressure Predicts Need for Resuscitative Thoracotomy and Emergent Intervention after Trauma. J Surg Res. 2021;268:284-290.
    15. Kalkwarf KJ, Goodman MD, Press GM, Wade CE, Cotton BA. Prehospital ABC Score Accurately Forecasts Patients Who Will Require Immediate Resource Utilization. South Med J. 2021;114(4):193-198.

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