Advanced medical care delivered by helicopter is increasingly linked to improved survival rates for patients with life-threatening injuries, according to recent analyses of data from a regional air ambulance service in South East England. The findings, published in Emergency Medicine Journal, suggest that pre-hospital intervention by Helicopter Emergency Medical Services (HEMS) may be saving lives beyond what was previously understood.
Challenges in Assessing HEMS Effectiveness
Historically, determining the precise impact of HEMS on trauma survival has been difficult. Researchers have faced challenges due to inconsistencies in study methodologies, limited patient numbers in individual studies, and a lack of standardized definitions for measuring outcomes. Identifying which patient populations benefit most from this rapid response system has also remained an open question.
A Decade of Trauma Data Analyzed
To address these challenges, researchers undertook a comprehensive review of outcomes for 3,225 trauma patients who received pre-hospital care from a single HEMS team operating across Kent, Surrey, and Sussex. The data spanned a ten-year period, from to . A statistical method known as Ws analysis was employed to estimate each patient’s probability of survival, accounting for variations in injury severity and individual patient characteristics. This analysis also identified factors associated with mortality within 30 days of the injury.
Unexpected Survival Rates
The analysis revealed that 2,125 patients (85%) survived at least 30 days after their injury, compared to an expected survival rate of 81%. This difference translates to approximately five additional survivors for every 100 severely injured patients treated by the HEMS team. Based on the service’s typical caseload, this could equate to as many as 115 additional lives saved annually.
Identifying Patients Who Benefit Most
The study identified specific patient groups who experienced the most significant benefits from pre-hospital air ambulance care. Patients with severe injuries and a moderate predicted chance of survival (25-45%) showed substantial gains, with 35% surviving for 30 days despite initial predictions to the contrary. Similarly, patients with a low probability of survival (less than 50%) also demonstrated higher-than-expected survival rates, with 39% surviving for at least 30 days.
Key Factors Associated with Improved Survival
Several factors were independently linked to improved survival outcomes. Younger age and a higher initial Glasgow Coma Scale (GCS) score – a 3 to 15 point measure used to assess consciousness after a brain injury – were strong predictors of unexpected survival. Perhaps most significantly, pre-hospital emergency anesthesia, delivered by the advanced medical teams on the HEMS, was independently associated with improved survival rates in severely injured patients. This intervention involves placing patients into an induced coma.
Traumatic Cardiac Arrest Outcomes
Researchers also examined outcomes among patients who experienced traumatic cardiac arrest – when the heart stops beating following severe injury, such as major bleeding or chest trauma. Among 1,316 patients who experienced traumatic cardiac arrest, 356 (27%) experienced a return of spontaneous circulation (ROSC) – meaning their heartbeat was restored – while being transported to the hospital. Of the 356 patients who initially survived, 30-day outcome data were available for 185 (52%). Of those, 46 (25%) were still alive after 30 days, while 139 died after arriving at the hospital. Notably, the likelihood of ROSC increased by 6% each year between and .
Study Limitations and Future Research
The researchers acknowledge that their findings demonstrate survival rates that were higher than statistically predicted, rather than definitively proving that HEMS caused the improved outcomes. They also note that their estimates rely on the assumption that patient characteristics and the quality of care remained consistent throughout the study period, which may not always be the case.
Despite these limitations, the research team emphasizes the potential clinical benefits demonstrated by their findings, aligning with previous studies that have shown economic and social benefits associated with HEMS. They conclude that the findings “provide supportive evidence for continued investment in HEMS, particularly for severely injured patients, though comparative studies with alternative care pathways are needed to establish causal effectiveness.”
As of today, , these findings contribute to a growing body of evidence suggesting that rapid access to advanced pre-hospital care, delivered by air ambulance teams, plays a critical role in improving survival rates for patients with major trauma.
