High in the Sky: An Overview of Helicopter EMS

While helicopters have been used to evacuate injured servicemembers dating back to World War I, the war in Vietnam saw the first medical treatments taking place in helicopters, marking the dawn of modern-day helicopter EMS (HEMS) operations—the often-overlooked but critical link in the EMS chain for patients with life-threatening emergencies.

Zachary Matuzsan, DO, physician at Lehigh Valley Health Network in Allentown, PA, and associate medical director for Lehigh’s aeromedical MedEvac program, presented “High in the Sky: An Overview of Helicopter EMS” on Feb. 24, 2024, at the NCEMSF Annual Conference in Baltimore.

HEMS systems operate under one of three system models, according to Matuzsan:

• Traditional. Hospitals provide the medical staff and a national air medical provider handle the helicopter and maintenance of the equipment.
• Community based. A private company separate from a hospital or health system provides the equipment and personnel—akin to a private ground ambulance company.
• Governmental, i.e. state police.

The FAA is the governing body for all aviation aspects of HEMS, Matuzsan explained. Federal Aviation Regulations Part 91 cover general operations and flight rules, while Part 135 regulates pilot rest, training, helicopter maintenance and other considerations.

Helicopter flight medicine generally covers a range of less than 150 miles and between 1000 and 5000 feet of altitude. Longer-range transports are generally handled by fixed-wing aircraft.

Most helicopter systems operate under visual flight rules (VFR), meaning pilots must visually see conditions to operate the aircraft. Conditions must include at least one-mile visibility and a minimum of 500 feet of clear conditions below the cloud cover ceiling.

Roughly 95% of air medical helicopters in the U.S. are staffed by a flight nurse (CFRN) and certified flight paramedic (FP-C) at minimum. The air medical team also consists of a pilot, communications technician, mechanics, leadership and a medical director.

Patients transported by HEMS today are either being transported from a scene (i.e. 9-1-1 transport) or between facilities for specialized care such as pediatric care, burn care, high-risk OB, comprehensive stroke care, toxicology, medical-surgical, etc. About 70 percent of helicopter EMS transports today are interfacility.

The Airbus EC 135 is one of the most common helicopter models in use in the United States today. Larger EC 145s are more expensive, but provide more room for patients and EMS crew.

Pertaining to patient care in the air, HEMS brings specific considerations, continued Matuzsan. The decreased pressure at altitude makes gases expand, which has effects on health conditions and treatments administered—for example, pneumothorax will worsen and any treatment equipment with air chambers will be affected, he explained.

Matuzsan concluded his talk with a discussion of recent high-profile HEMS accidents and the risks of helicopter transport. Safety risks must be evaluated before a helicopter lifts off, said Matuzsan, and all staff on board perform a safety check of the aircraft. HEMS follows the rule of “Three to go, one to say no.” All crew members staffing the aircraft must agree that it’s safe to fly—and that includes not only weather concerns and equipment considerations but also crew fatigue.