Air medical transport consists of helicopter (or rotor-wing) and airplane (or fixed-wing) transport and is an important component of EMS systems for prehospital care and interfacility transport. These specialized vehicles offer fast speeds, ranging from 100 to 200 miles per hour for helicopters to >500 miles per hour for airplanes. However, planning for appropriate vehicle use involves many other logistic factors in addition to speed. Although many ill and injured patients can be transported safely by ground, air medical transport provides added medical assessment and care capabilities beyond those of the paramedic-staffed ground ambulance. Guidelines for the use of air medical transport exist, but field EMS personnel and physicians involved in transfer decision making should be able to consider situational circumstances to determine the appropriate transportation mode.

With the occasionally important exception of ground transport legs (e.g., from a landing zone to the patient or from an airport to the hospital), air transport modalities are not limited by traffic or road quality. Weather can be an operational limitation, particularly for helicopters. The radius of service differs between helicopters and fixed-wing craft, but, as a general rule, fixed-wing transport is considered when weather conditions are poor or when transport distances exceed 150 to 200 miles.

The complexity of air transport far exceeds the simple act of loading a patient on an airborne vehicle. National organizations such as the Air Medical Physician Association, the Committee on Accreditation of Medical Transport Systems, and the National Association of EMS Physicians have published texts, position statements, and guidelines covering aspects of air medical transport. The Air Medical Physician Association (http://www.ampa.org) Air Medical Physician Handbook is a particularly helpful resource for medical issues. The Committee on Accreditation of Medical Transport Systems (http://www.camts.org) accreditation standards address medical, aviation, organizational, and operational issues. The National Association of EMS Physicians (http://www.naemsp.org) has created detailed position statements and guidelines addressing helicopter EMS trauma and nontrauma triage criteria, as well as training of physicians involved as air medical crew or medical directors.

The effectiveness of air medical services is enabled by attention to a myriad of factors that come into play before, during, and after actual patient transport. The transport service should disseminate protocols guiding appropriate triage, and the program’s communications personnel (as well as its physician consultants) should be versed and available for rapid decision making as to appropriate vehicle use. Ongoing training of referring agencies should occur to ensure safe and efficient operations during air transport service arrival (e.g., securing of landing zones) and transition of patient care to the flight crew (e.g., loading of patients onto the aircraft). Rigorous training programs, covering both cognitive and procedural skills, enable flight crews to provide a high level of intratransport care. In-flight communications capabilities should include the ability of the air medical crew to speak with medical control physicians, as well as arrange for any change of plan (e.g., direct transport to the operating suite) necessitated by patient condition.

AVIATION ISSUES

Individual hospitals, hospital systems, or private for-profit enterprises run most U.S. civilian air transport programs. Because helicopters are expensive (ranging from $750,000 to more than $5 million each) and other aviation needs (e.g., maintenance, pilot training) are also resource intensive, most hospital-based programs lease their helicopters from vendors. The air medical program typically provides and equips communications and medical personnel, whereas the aircraft vendor supplies the helicopters, pilots, and maintenance personnel. Although costs vary depending on geographic region, patient case mix, equipment and aircraft used, and even the methods used for their calculation, annual operating costs for a rotor-wing service typically exceed $2 million.

Safety is an overriding consideration for air transport. Optimization of safety begins well before an actual air transport, with training of the flight crew and of those who interact with them at scenes and hospitals. Training is especially important for scene responses, in which the helicopter may be landing in an unknown area with more nearby obstacles (e.g., wires, trees) than the hospital helipad. Scene setup (depending on the aircraft, an area of up to 100 × 100 ft is required) and demarcation, as well as safety of nearby personnel, must be taught to ground EMS services and others who call for helicopter EMS transport. In addition to providing training for referring agencies, helicopter EMS pilots and medical crew should undergo both initial and recurrent safety training. For added protection, most helicopter EMS programs have followed the lessons of the military experience and adopted injury-prevention maneuvers such as the use of helmets and fire-resistant clothing. As another safety issue, the pilot should be “blinded” to the nature of the call during mission planning; this eliminates the introduction of acuity-related subjectivity as the pilot considers whether the mission should be accepted.

Safety is partially behind the transition of helicopter EMS programs from single-engine helicopters with visual flight rules capability to twin-engine helicopters that can fly under instrument flight rules conditions. The latter aircraft have greater lifting capacity, range, and speed and usually can execute controlled landings in the event of failure of one engine. A visual flight rules aircraft can fly only during good visibility, whereas instrument flight rules aircraft operate safely in poorer conditions; both comply with visibility limitations imposed by the Federal Aviation Administration, but the instrument flight rules helicopter has fewer restrictions. If the pilot unexpectedly encounters bad weather during a flight, an instrument flight rules helicopter (as compared with a visual flight rules aircraft) has a better chance of completing the mission successfully and safely. Due to the complexity of instrument flight rules operations, some programs (especially those with frequent bad weather periods) have elected to use two-pilot instrument flight rules.

Air medical programs operate under rules established by the national aviation authority—in the United States, the Federal Aviation Administration. Additionally, the industry itself has set forth stringent standards under the auspices of the Committee on Accreditation of Medical Transport Systems. On request, the Committee on Accreditation of Medical Transport Systems performs site visits of air medical programs to certify that they comply with strict safety and operational (as well as clinical) standards. As of January 2012, 148 U.S. transport programs were accredited by the Committee on Accreditation of Medical Transport Systems.

AIR MEDICAL CREW

The primary considerations regarding medical members of the flight crew are crew configuration and training. Although there are few absolutes with regard to optimal configuration, initial and recurrent training are at least as important as the credentials of the flight team members.

The air medical team can have multiple compositions: nurse–paramedic, nurse–nurse, nurse–physician, or nurse–respiratory therapist. These differences may be one reason that the literature has failed to answer definitively the seemingly simple question of whether a physician should be on board the helicopter. Studies done outside the United States, where physician staffing is more prevalent, have failed to show outcome improvement associated with physician staffing of helicopter EMS programs.^1,2 Most U.S. programs agree that physicians are not a necessary component of helicopter EMS crews, and individual program staffing configurations generally have remained stable during the ongoing debate on optimal team makeup.

For a number of reasons, it is unlikely that further efforts to define the optimal crew configuration will result in a consensus. The capabilities of most U.S. nonphysician crews represent an extended scope of practice. For instance, flight paramedics and/or nurses frequently are credentialed to perform such procedures as neuromuscular blockade–assisted endotracheal intubation and cricothyrotomy. This example of extended practice scope is important, given the importance of prehospital airway considerations and the fact that flight crews represent a highly trained group with particular expertise in this area. Reported success rates for nonphysicians are as high as 94.6% for drug-assisted and 97.7% for rapid sequence intubation–assisted endotracheal intubation and 90.9% for surgical cricothyrotomy.³ The ability of nonphysicians to perform advanced procedures—and to perform them well—blurs the procedural skills demarcation between physician and nonphysician crew. Physician cognitive contributions are inherently difficult to quantify or associate with patient survival.^1,2

At this time, the best recommendation with regard to crew configuration is for programs to continue to do what works for them, as the literature does not report the superiority of a particular model. Most U.S. programs perform a variety of scene and interfacility missions for trauma and nontrauma indications, so the nurse–paramedic configuration, combining the complementary skills of prehospital and hospital-based practitioners, is most popular in the United States. Some transport population heterogeneity can be addressed by the accommodation of extra crew members (e.g., neonatal nurses, intra-aortic balloon pump technicians) when logistics allow. Regardless of the background of the air medical crew, initial and recurrent training in both cognitive and procedural skills is necessary to ensure an optimal level of care.

ENVIRONMENTAL FACTORS OF AIR TRANSPORT

Patient care in any transport vehicle differs from that provided while the patient is on a hospital stretcher. Vehicle vibrations, bumpy rides, noise, physiologic stress, ergonomic constraints (Figure 3-1), and motion sickness are among the factors that can affect monitoring and interventions.

The impact of most vehicle-related issues in helicopter EMS can be eliminated, or at least reduced. Some solutions are easy (e.g., visual rather than aural alarms on ventilators), but flight crews must learn to “work around” other limitations (e.g., perform preflight intubation on patients who appear likely to deteriorate). Some problems will be specific to a service’s particular aircraft, mission profile, or crew background. Individual program patient care protocols should take into account the service’s equipment and personnel-related capabilities and limitations.

One transport-related issue that cannot be avoided is the question of altitude and its potential effects on the patient and the crew. In fact, altitude considerations vary with location—a Denver-based program has concerns that are different from those of a Miami service. Environmental conditions also have an impact on altitude considerations, because aircraft operating under instrument flight rules frequently fly at higher altitudes than those operating under visual flight rules. Of course, fixed-wing transports have more pronounced altitude considerations.

Helicopter (or fixed-wing) altitude and environment have potential effects on patient pathology as well as the crew’s ability to monitor and care for the patient. Helicopters generally transport patients at about 1000 to 3500 ft above ground level (not necessarily sea level), although sometimes these altitudes are increased for instrument flight rules flights or for clearing of obstacles or terrain. Therefore, altitude-related problems such as hypoxemia, dehydration, and low temperature tend to be mild or relatively easily to overcome. However, geographic differences are important. Some western U.S. programs fly with supplemental oxygen for the medical crews.