Introduction:
Acute aortic syndromes (AAS) are part of the main cardiovascular emergencies. They result from serious aortic impairment that may lead to death even if treated promptly and adequately. Consequently, AAS management includes a rapid diagnosis, optimal medical treatment, and urgent surgical consultation. The mortality associated with these impairments and the difficulty in recognizing them have led multiple scientific societies and in particular cardiovascular experts to focus on clear guidelines for better management. (1, 2)
Helicopter transfer is a well-established practice in Switzerland that allows saving time in all sorts of situations. Some concerns about helicopter transfer for AAS patients have been raised. Factors such as altitude rise, air depression, shocks and vibrations were considered as risk factors for aortic rupture during transfer. This study aims to provide data to confirm that it’s a safe and acceptable practice.
Methods:
We compared ground ambulance with medical staff on board (EMS) with helicopter transferred patients (HEMS). Patients all had AAS. Inclusion period was from 01.01.2015 to 31.12.2019. Primary end point was Modified Shock Index (MSI) evolution during transfer. We used MSI as assessment tool for hemodynamic state evaluation during transfer. MSI was calculated at departure from transfer protocols and at arrival from the emergency room protocols. Secondary endpoint was in-hospital mortality difference between each group. In-hospital mortality was defined as death occurring during hospital stay or 30 days after discharge.
Results:
Our study showed an intratransport MSI of 0.88±0.36 for EMS group and 0.77±0.23 for HEMS group, no significant difference was shown at departure condition (P-value=0.27).
Arrival MSI was 1.05±0.53 for EMS group and 0.79±0.22 for HEMS group, no significant difference between each group (P-value=0.09).
When using valid pairs, no significant MSI difference was found from departure upon arrival for patients whether they were transported with an ambulance or helicopter (EMS group: P- value=0.09/HEMS group: P-value=0.31)
In-hospital mortality was 21% (9/44 patients) with no significant difference between both groups (P-Value=0.72).
Conclusion:
Our study showed no significant difference between EMS vs. HEMS transport in regard of hemodynamic stability of patients suffering from an AAS. This result is consistent with our hypothesis that helicopter transfer is an acceptable practice for those patients and the concerns about an increased risk of aortic rupture because of altitude rise, air depressurization, vibrations and shocks endured when the helicopter is landing doesn’t seem justified.
Three major cardiovascular events were recorded during transport, they all happened in the EMS group, suggesting that HEMS transfer doesn’t represent an increased risk of deterioration. Moreover, we found no significant difference in terms of in-hospital mortality for patients whether they were transported by EMS or HEMS.
In addition, patients transferred with HEMS traveled a significantly higher distance than those transferred with EMS.