Air Ambulance and Medical Flights – The Trauma System

The “Golden Hour” concept provides that along the route to the surgeon’s knife in that first hour, a patient should benefit from an organized EMS system which provides increasingly advanced care (e.g. BLS to ALS to the physician-level care provided by air medical crews). The complete EMS trauma subsystem must include: Rapid discovery of the injured patient and notification of EMS. Fast response of BLS EMS. Early activation by trained and authorized requesters. Timely availability of ALS resources. Rapid access to physician level intervention through HEMS response or the closest Emergency Department. Rapid transport to identified trauma centers. Inter-hospital transfer to needed specialty care by critical care ground ambulance helicopter or fixed wing air ambulance as needed. Excellent planning and coordination of EMS resources. Quality assessment of each component in the combined air and ground emergency response. A recent paper cites the Maryland system as having these components in place and organized well, and calls upon other systems to emulate it. It has been well demonstrated that organized trauma systems with trauma centers save lives.

In the early 1980’s, the first analytical attempts to determine the life-saving impact on mortality by HEMS response to injury scenes began to appear, largely demonstrating reductions in mortality compared with ground systems.18-20, 38 Since the ‘80’s, there have been many published medical studies which have attempted, through a variety of means, to assess HEMS’ impact on trauma mortality and morbidity for both scene and interfacility flights. Overall, these studies have demonstrated the power of HEMS to affect improvements in trauma-related mortality and morbidity.

As a part of an organized trauma system, HEMS cuts the injury-tooperating- room time significantly. Medical helicopters, dispatched simultaneously with ground EMS, can give over 54% of the US population access to a full-service trauma center within 60 minutes that they otherwise would not have.

Medical helicopters also discourage time-costly intermediate stops at small, non-trauma center hospitals. Such stops have been shown to be detrimental to trauma patients, even where HEMS is called from that hospital for the final leg of the trip.

In the future, improvements in cell phone technology and automatic crash notification (ACN) technology in cars may cut the time required to discover and report a crash injury to almost zero. Using “urgency” indicators generated by automatic crash notification data sent from crashed cars to dispatch centers, along with special medical protocols for assessing the probability of severe injury from the crash, will soon provide a rational and effective way for helicopters to be launched within minutes of an accident, no matter ho remote, thereby further improving the speed of EMS response to patients.

Examples of recent study findings demonstrate that: s Patients severely injured enough to require inter-facility transfer were four times more likely to die after the HEMS serving that area was discontinued. HEMS reduced injury mortality by 24% in a multi-center study with some 16,000 patients in Boston. Even injury patients in urban areas experienced a transport-time benefit by HEMS in 23% of the cases.

Traumatic brain injury (TBI) is frequently associated with events causing severe, multiple trauma in patients, and is the leading cause of death and disability in children and in adults in their most productive years. As with other major injury, treatment of traumatic brain injury is time-critical. Outside of urban areas, the reduced availability of the neurosurgical services required to treat traumatic brain injury has posed a challenge to EMS. Recent studies indicate that early advanced care by air medical crews and air transport to definitive care by a neurosurgeon can overcome this challenge, resulting in significant improvement to moderately and severely traumatic brain injured patients.

HEMS is generally effective in trauma care circumstances such as when: There is an extended period required to access or extricate a remote (e.g. injured hiker, snowmobiler, or boater) or trapped patient (e.g. in a crashed car) which depletes the time windo to get the patient to the trauma center by ground. Distance to the trauma center is greater than 20 to 25 miles. The patient needs medical care and stabilization at the ALS level, and there is no ALS-level ground ambulance service available within a reasonable time frame. Traffic conditions or hospital availability make it unlikely that the patient will get to a trauma center via ground ambulance within the ideal time frame for best clinical outcome. There are multiple patients who will overwhelm resources at the trauma center(s) reachable by ground within the time window. EMS systems require bringing a patient to the nearest hospital for initial evaluation and stabilization, rather than by-passing those facilities and going directly to a trauma center. This may add delay to definitive surgical care and necessitate HEMS transport to mitigate the impact of that delay. There is a mass casualty incident.

In rural and frontier areas, HEMS and fixed wing aircraft play a particularly important role.  Where the nearest ground ambulance is further, by traveltime, from the scene of injury than the nearest HEMS, the air medical service may be the primary ambulance for critically ill and injured patients in that area. Where the nearest ALS-capable medical facility is further, by travel-time, from the scene of the injury than is a HEMS or a fixed wing provider, the air medical service may be the primary ALS provider for critically ill or injured patients in that area. Where blood supplies or availability of other medical supplies or equipment are limited or non-existent, jeopardizing the care of the patient, the air medical service can bring these resources to the hospital with the patient.

The air medical service can transport specialized medical staff (surgical, emergency medicine, respiratory therapy, pediatric, neonatal, obstetric, and specialized nursing staff) to assist with a local mass casualty event or to augment the rural/frontier hospital’s staff in stabilizing patients needing special care before transport.


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