Is mechanism of injury alone a useful predictor of major trauma?
Introduction
Following the report of the Victorian Ministerial Task Force on Trauma and Emergency Services (VMTFTES) in 1999, two significant pre-hospital care questions remained unresolved.4 The first, is mechanism of injury alone a useful predictor in pre-hospital trauma triage? And secondly, what is the appropriate triage strategy for patients who deteriorate severely at the scene or during transport? This study set out to answer the first question.
The presence of any one of the physiological or anatomical abnormalities included in the pre-hospital potential major trauma criteria for the purpose of primary triage is less contentious. Triage in physiologically stable trauma patients where only mechanistic criteria are present has a high potential for over triage, however, a degree of over triage is unavoidable and necessary to consistently detect potentially serious injuries.
However, the presence of only high risk mechanism of injury or co-morbid factors placing the patient at risk of potential major trauma is controversial and potentially disruptive to the efficiency of a state-wide trauma system. “This group of patients should be triaged to a designated trauma service for assessment but whether this needs to be a Major Trauma Service (MTS) or other trauma service will remain at the discretion of the attending ambulance officer”.4 Validation of the predictive value of the mechanistic criteria alone has been limited in Victoria and Australia whilst the international literature varies considerably.
A review of all Emergency Medical Service (EMS) trauma data has not been previously attempted in Victoria or nationally, this is probably due to none of the Australian states or territories having, at the time of the study, an electronic data capture and data repository for complete EMS clinical data. The review of trauma data from the Victorian State Trauma Outcome Registry and Monitoring Group (VSTORM) is restricted as the dataset contains only those patients who have sustained major trauma, a subset of the total trauma incidents.
Only five international studies have previously reviewed the ability of the mechanism of injury to provide the only criteria to predict hospital defined major trauma or for trauma team activation. All these studies, had less than 1000 patients with mechanism of injury alone, did not include all age groups, did not report the outcome in the same manner, and at best had only two criteria that could be compared across all studies.3, 5, 6, 10, 12 These studies collectively suggest that the mechanism of injury criteria alone are not useful predictors of hospital defined major trauma or useful for trauma team activation.
Ethics approval for the project was obtained from the Monash University Standing Committee for Ethics in Research on Humans and the Victorian Department of Human Services Ethics Committee.
The objective of the study was to undertake an analysis of trauma patients who have suffered mechanism of injury (MOI) only trauma and establish sensitivity, specificity, and predictive values for each of the MOI criteria as identified by the VMTFTES.4 The major outcome was the number of patients who had MOI only trauma and whether they subsequently had hospital defined major trauma.
Section snippets
Study design
A retrospective cohort study was undertaken of all trauma patients who were transported by Victorian emergency ambulances during 2002 that presented with mechanism of injury only.
Population and setting
The study was conducted in Victoria, a south eastern state of Australia. Victoria covers approximately 227,590 km2 with a population of approximately 4.9 million people during the study period (49% males and 51% females).2 The Metropolitan Ambulance Service (MAS) provides the EMS for the greater Melbourne metropolitan
Results
Victorian EMS transported 4571 patients classed as MOI only in the 12-month period from 1st January to 31st December 2002. This amounts to approximately 8.6% of the total trauma incidents (n = 53,039) for that time period. The MAS attended approximately 69% of the total trauma incidents whilst RAV attended to approximately 31%.
The gender distribution was 62.5% males, 37.3% females, there were missing data for the remaining 0.2%. The mean age was 32.3 years with a standard deviation of 16.81
Mechanism of injury and predictability of major trauma
Only two of the ten criteria where patients had hospital defined major trauma provided statistically significant results. They were, patients falling from a height greater than 5 m, RR 10.86, CI 4.47–26.42, P < 0.0001, and patients trapped in a motor vehicle greater than 30 min, RR 9.0, CI 2.92–27.70, P = 0003. The major trauma predictability criteria for all mechanisms are listed in Table 3.
Discussion
This study is the first in Australia, and one of few internationally, to use a complete state EMS dataset, and not data from a specific trauma registry, to investigate the characteristics of patients who have mechanism of injury only trauma over a 12-month period. Only two criteria demonstrated statistical significance, a fall greater than 5 m and a patient trapped in a vehicle greater than 30 min.
International studies often covered a small geographical area, normally a catchment area for a
Conclusions
In conclusion, data from this study confirms that individual mechanism of injury only criteria, that is, patients who are not physiologically distressed nor have a significant pattern of injury but have a mechanism of injury criteria present, are not good predictors of patients who will go on the have hospital defined major trauma. Consequently, individual mechanism of injury criteria have no clinical or operational significance in pre-hospital trauma triage of patients who have an absence of
Conflict of interest
There are no conflicts of interest.
Acknowledgements
We gratefully acknowledge the support of the Metropolitan Ambulance Service and Rural Ambulance Victoria for their assistance in providing the EMS Patient Care Records for this study. We are indebted to the Victorian Department of Human Services and the State Trauma Registry for their time and assistance involved with the data linking. We also acknowledge the research assistants who manually reviewed the Patient Care Records and entered the data into the study database.
We gratefully acknowledge
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2015, Journal of Surgical ResearchCitation Excerpt :In a similar way, mechanism of injury is also useful as a predictor in prehospital triage schemes [23]. Although the low specificity and sensitivity of mechanism of injury are known in this setting [24], mechanism of injury is easily obtained and is useful when more accurate anatomic or physiological variables are not obtainable or are unreliable. In this setting, mechanism of injury may provide additional information about the severity of injury and potential patient outcomes that is incompletely conveyed by other observable information.
Accuracy of the field triage protocol in selecting severely injured patients after high energy trauma
2014, InjuryCitation Excerpt :It appears that not all mechanism triage criteria are equally sensitive and specific. A study performed by Boyle et al. found only a fall > 5 m and trapped in a vehicle > 30 min to be predictive for severe injury [27]. Another study performed by Cox et al. found a fall from > 3 m, prolonged extrication (>30 min), pedestrian impact, motor/cyclist collision > 30 km/h, motor vehicle collision > 60 km/h to be significant predictors in severe injury.
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