Keyword-Based Early Request for Helicopter Emergency Medical Services in Acute Aortic Dissection: A Registry-Based Study

Abstract

ObjectiveAcute aortic dissection (AAD) is a life-threatening condition that necessitates rapid medical intervention. In Japan, helicopter emergency medical services (HEMS) are deployed using either keyword-based early requests or standard requests from ground emergency medical services (GEMS). This study evaluates the impact of these request methods on patient outcomes. MethodsWe conducted a retrospective cohort study using data from the Japanese Society for Aeromedical Services registry from April 2015 to March 2020. A total of 342 AAD patients transported by HEMS were analyzed, excluding those with out-of-hospital cardiac arrest. Patients were categorized based on whether HEMS was requested using a keyword method or after initial GEMS contact. We compared the groups on time intervals, prehospital interventions, and outcomes including Cerebral Performance Category. ResultsThe time from GEMS awareness to HEMS contact was significantly shorter in the keyword methods group compared with the control group (median 27 vs. 33 minutes, respectively; P < .001). No significant difference was observed in the time from contact to departure from the scene. Patient characteristics, vital signs at HEMS staff contact, and medical interventions provided by HEMS staff showed no statistically significant differences. Changes in vital signs from HEMS staff contact to hospital arrival included a significant decrease in the respiratory rate and systolic blood pressure. Patients in the keyword methods group had a significantly higher proportion of favorable outcomes in terms of Cerebral Performance Category compared with the control group (77.2% vs. 66.5%, P = .03). However, logistic analysis did not show significant differences (odds ratio = 1.007; 95% confidence interval, 0.987-1.016; P = .814). ConclusionKeyword methods for early HEMS requests may appear to reduce time to specialty care and suggest improvement of outcomes for patients with AAD.