Columns, Patient Care

Mechanism of Injury & Outcomes

Determining and understanding the energy involved in mechanism of injury has been the starting point of evaluating the potential for injury in trauma patients throughout the history of organized EMS training. In recent years challenges have been made as to whether mechanism alone is enough to determine treatment priorities or if it’s a reliable predictor of injury potential.

Most of us were taught that mechanism alone was the push off point and in a sense; the patient had to prove that they weren’t severely injured once the mechanism points in the direction of high index of suspicion. Recent studies have looked at the reliability of mechanism in predicting injury — which can be of more importance if the treatment given is not benign — having the potential to cause discomfort or harm. With this in mind, researchers are trying to get a handle on what works and what doesn’t work in predicting severity of injury in trauma patients.

A study published in the April issue of the Journal of Trauma Injury, Infection and Critical Care looked specifically at the relationship between mechanism of injury and outcomes in pediatric trauma patients.

In the article titled “Evaluation of the Relationship Between Mechanism of Injury and Outcome in Pediatric Trauma”, Randall S. Burd, MD, PhD; Tai S. Jang, MS; and Satish S. Nair, PhD looked at the records of pediatric patients in the National Pediatric Trauma Registry from 1995 to 2001.

They identified 42,966 injured children with an average age of 6.8 (plus or minus 4.2 years). Of the children, 63.6% were male. Of the almost 43,000 children, 63% were transported directly to the hospitals in the study and not transferred from other facilities, and 93.1% of the injuries were blunt trauma, 6,7% penetrating with the remaining categorized as other (0.2%). The majority (93.1%) of the injuries were unintentional with 5.8% caused by assault and 0.2% intentionally self-inflicted.

Of these children, 1,232 died; the majority of them were male and younger than the average age of 6.8 years. The leading cause of death was central nervous system injury. In order of frequency, the other leading causes were hypoxia, hemorrhage and multiple organ failure.

The researchers then looked at the relationship between mechanism of injury and mortality. Among their findings were that, when compared against the entire injured group, blunt and penetrating trauma had lower mortality rates and death occurred later than in other injury types. They also found that unintentional injuries had lower mortality rates than self-inflicted injuries and those caused by assault.

In looking at the care given to the injured children, the researchers found that, when compared with penetrating trauma, the children with blunt trauma were more severely injured, and required more care and rehabilitation. However, penetrating trauma victims required immediate or delayed surgical intervention more often than the blunt trauma patients.

In their discussion, the authors looked at the challenges presented to setting triage protocols. They showed that the variety of injuries that children received had variable outcomes and need of trauma center resources. They also stressed that the availability of resources was a factor to be included in any triage tool.

In their paper, they presented a matrix for predicting injury severity and resource utilization. Using the data they collected and fitting it into the matrix, such injuries as suffocation and gunshot wounds had high mortality potential, and these patients should be taken to a trauma center if available. On the other hand, a fall on the stairs or a cut or piercing injury had a lower mortality potential and could range in care from non-trauma transport to delayed or immediate transfer, based on condition and availability.

As in other recent studies, the authors concluded that “mechanism of injury cannot and should not be viewed as a stand alone triage criteria.” They went on to recommend that mechanism along with anatomic and physiologic factors be used to guide trauma triage protocols to ensure that patients are appropriately transported to the facilities best able to care for them. In making this recommendation they called for further study into the interaction between these factors and their independent predictive capacities.

This study, along with the research that has recently guided such protocols as indications for spinal immobilization, seems to lead us in the same direction. That is to say that mechanism is a piece of the puzzle of evaluating the potential for life threatening injuries in our patients, but we need to look at all of the pieces (anatomic and physiologic) and evaluate our ability to assess and identify the patients that need trauma centers to give them their best chance at survival.