A Cochrane review [Abstract] 1 included 29 non-randomized studies with a total of 163748 subjects. The effect of helicopter emergency medical services (HEMS) for mortality due to major trauma was assessed.
Five studies out of 9 using multivariate regression to adjust for confounding indicated a statistically significant increase in odds of survival associated with HEMS. There was no decreased risk of death with HEMS (RR 1.02; 95% CI 0.85 to 1.23) based on five studies that focused on traumatic brain injury. There were 4 studies where HEMS was used to transfer patients to higher level trauma centers and all the studies suggested a positive benefit. The review stresses the importance of triage criteria since the benefits of HEMS may be greatest for patients with serious but potentially survivable injuries.
Effect of HEMS is likely due to some combination of crew expertise, prehospital interventions, and timely access to a high-level trauma. Some studies included helicopter teams that had specialized physicians on board whereas other helicopter crews were staffed by paramedics and nurses. Furthermore, patients transported by helicopter or ground emergency medical services had varying numbers and types of procedures en route to the trauma centre. The use of some of these procedures, such as the placement of a breathing tube, may have helped improve survival in some of the studies.
The heterogeneity of results across studies may reflect the fact that in most European HEMS programs physicians are mandatory crew members, whereas in the United States most HEMS programs are staffed by critical care nurses and paramedics. Moreover, in Europe the helicopter is used in many systems to transport the treatment team to the scene of the injury, and in countries such as the Netherlands the helicopter is rarely used for patient transport.
Date of latest search: 2012-01-24
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