Outcomes of prehospital traumatic cardiac arrest managed by helicopter emergency medical service personnel in Japan: a registry data analysis.

BACKGROUND

Traumatic cardiac arrest (TCA) is associated with poor outcomes. Helicopter emergency medical services (HEMSs) are often used to transport critically ill patients to hospitals. However, the role of HEMS in the treatment of TCA remains unclear. Therefore, in this study, we aimed to determine the current status of patients with prehospital TCA managed by HEMS personnel in Japan and compare the outcomes of patients who experienced TCA before and after the arrival of HEMS.

METHODS

The Japanese Society for Aeromedical Services registry data of patients managed by HEMS personnel from April 2015 to March 2020 were analyzed in this retrospective cohort study. HEMS arrival and physicians' interventions at the scene were the variables of interest. The survival rate and neurological outcomes at 28 days after injury were analyzed.

RESULTS

Of the 55 299 registered patients, 722 who experienced prehospital TCA were included in the analysis. The distribution of first-witnessed TCA was as follows: pre-emergency medical service (EMS) arrival (n = 426/722, 60.3%), after EMS arrival (n = 113/722, 16.0%), and after HEMS arrival (n = 168/722, 23.8%). The 28-day survival rate was 6.2% (n = 44/706), with a cerebral performance category of 1 or 2 in 18 patients. However, patients who experienced TCA after receiving interventions provided by physicians before HEMS arrival had the worst outcomes, with only 0.6% of them surviving with favorable neurological outcomes. Multivariable analysis revealed that securing the intravenous route by the EMS team (adjusted odds ratio: 2.43, 95% confidence interval [CI]: 1.11-5.30) and tranexamic acid infusion by the HEMS team (adjusted odds ratio: 2.78, 95% CI: 1.16-6.64) may have increased the return of spontaneous circulation (ROSC) rate.

CONCLUSIONS

The results of our study were similar to those reported in previous studies with regards to the use of HEMS in Japan for transporting patients with TCA. Our findings suggest that in patients with severe trauma, cardiac arrest after initiation of HEMS, the highest level of prehospital medical intervention, may be associated with an inferior prognosis. Tracheal intubation and administration of tranexamic acid by the EMS team may increase the rate of ROSC in TCA.