Discussion
GSWB have high rates of mortality and morbidity. Our current understanding of these lethal injuries is primarily extrapolated from lessons learnt through military experiences, which tend to report improved outcomes with more aggressive management.8 Prospective civilian studies are sparse and often contain lower levels of evidence. Thus, there is no standard approach to treating these injuries in the published literature. In effort to address this deficit, our current effort was to identify specific factors associated with patient outcome—namely survival or organ donation. In this study, we report several resuscitative practices that are associated with survival to hospital discharge or organ donation in patients with GSWB who subsequently underwent CPR (tables 3 and 4).
An interesting parallel between our study and others with similar patient populations is the effect—or lack thereof—of age, race, and intent on outcome. Our study population had large disparities between these groups; assault was more common among black patients (235 black vs. 64 white) whereas suicides were more frequent in white patients (212 white vs. 42 black). Additionally, black patients in our study were significantly younger (mean 29.8 years vs. 45.0 years in white patients). Despite these differences, neither age, race, nor intent was predictive of survival. Similarly, Crutcher et al
9 reported disparities in injury intent between races, but intent and race were not predictive of survival in this study either.
With regard to specific factors associated with survival, various items have been previously identified. In a 2016 study, Jesin et al
10 concluded that mortality was related to increasing ISS and age. Lee et al
11 found GCS, AIS head, and age to be associated with survival in isolated head trauma but did not focus on penetrating injuries. In contrast, the strongest factors associated with outcome in our study were signs of life (SOL) on arrival, receipt of tranexamic acid (TXA), and transfer to a higher level trauma center. Patients who arrived at a trauma center with SOL were 8.3 times more likely to survive. We could not find any other published literature that documented SOL as a statistically significant predictor of outcome for this specific injury.
We found that receipt of TXA had a significant effect on survival (OR 7.90, p=0.0001). A meta-analysis12 of the two largest randomized controlled trials13 14 on TXA in traumatic brain injury (TBI) found a significant reduction in intracranial hemorrhage expansion (relative risk (RR)=0.72) and mortality (RR=0.63) when TXA had been given. Yet unpublished, the results of the Clinical Randomization of an Antifibrinolytic in Significant Head Injury-3 trial, an international multicenter randomized trial studying the effects of TXA in TBI, are expected to provide novel and clinically significant information. Our third strongest predictor of survival, transfer to a trauma center, has been associated with lower risk of death in prior studies.15 16 In this study, patients transferred to trauma centers were 6.6 times more likely to survive. Similarly, Sugerman et al
17 reported an improved survival rate when patients with severe TBI were transferred to a trauma center.
As discussed above, a wide range of survival-associated factors have been identified—both in our study and previous reports. Without significant overlap of results, the interpretation of data and application of specific management is challenging. Muehlschlegel et al
18 have attempted to combine several predictors into the Surviving Penetrating Injury to the Brain (SPIN) score, a logistic regression-based clinical risk stratification scale estimating survival after penetrating TBI. Components of the SPIN score include motor GCS, pupillary examination, whether the injury was self-inflicted, transfer status, gender, ISS, and INR. Although the SPIN score does not address CPR, it does include transfer and ISS, which were both significant predictors in our study. Further identification of similar threads across studies may reveal that certain predictors are more consistent and significant than others.
A particularly noteworthy area is hormone replacement therapy. In our study, patients who received at least one hormone (methylprednisolone, insulin, vasopressin, and/or thyroid hormone) during the initial resuscitation had significantly improved survival or greater rates of successful organ donation. However, the overall donation rate was very low at 10.3% of non-survivors. This is lower than other reported rates in the literature, which range from 26.1% to 34.7% in patients with GSWB.19 20 This is likely because our study focused on patients in extremis at the time of presentation, and thus, the least likely to be salvageable. The findings of this study and numerous other retrospective reports2 21–24 on the benefits of hormone replacement therapy have provided the basis for a future prospective, randomized trial.