Chapter 40 Helicopter Rescue and Aeromedical Transport*

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Rapid provision of appropriate definitive care to acutely ill and injured patients is a major goal of all emergency medical services (EMS) systems. The ability to rapidly transport and initiate treatment of severely ill or traumatized patients is important in decreasing morbidity and mortality. This is particularly germane to wilderness and environmental emergencies, for which medical resources are scarce, transport times to definitive care facilities are often prolonged, and terrain and weather conditions are inherently difficult. Aeromedical transport crews can deliver emergency medical care at the scene, and the time to definitive care can be greatly decreased. This maximizes the patient’s chance for a successful recovery.

Aeromedical Evolution

Rapid evacuation of trauma victims from an injury scene to the location of definitive care is a modern concept with roots in antiquity. The New Testament documented an early instance of prehospital care and transport: “A certain Samaritan … went to him and bound up his wounds, pouring oil and wine, and set him on his own beast and brought him to an inn, and took care of him.”⁹⁰

The greatest impetuses to the advancement of emergency care and transportation have been epidemics and wars.⁶⁵ Before the classical Greco-Roman period, injured soldiers were often left on the battlefield to die. Later, Homer described the use of chariots to evacuate fallen warriors during the Trojan War.⁴⁸ Napoleon’s forces devised horse-drawn carriages, or ambulances volantes, for the same purpose.⁵⁵ North American Indians devised the travois, a litter that could be pulled by a person or animal to transport ill or injured persons.⁶³ The U.S. Army began a similar practice during the Seminole War of 1835-1842 and used it again in the Civil War. Major Jonathan Letterman established the process of rapidly clearing wounded soldiers to a point behind the battle line where they could be further triaged to an expectant area for persons with mortal wounds, a local treatment area for the “walking wounded,” or a hospital if definitive care was feasible. The central concept was efficient access to surgery for victims of trauma.

These developments were soon followed by invention of flying machines. In France, Richet had predicted the potentials of air transport in 1869.⁶⁵ This was before the first balloon airlift. The prediction was validated the following year during the Franco-Prussian War, when the first documented aeromedical evacuations took place. During the Prussian siege of Paris, 160 wounded soldiers were evacuated and transported by hot air balloon over enemy lines.⁹²

In the United States, air evacuation took place soon after the Wright brothers flew in 1903.³⁹ Grossman and Rhoades presented their idea of air transport of patients to the War Department in 1910, but the government refused to fund them. It was not until World War I that the U.S. military began to use aircraft to carry injured soldiers, and this occurred only rarely. However, the French transported patients as early as 1912 aboard Dorland ARII fighters converted to carry litters, despite the government’s objection to the concept of aeromedical transport: “Are there not enough dead in France today without killing the wounded in airplanes?”³⁹

The United States began using its first dedicated air ambulances in 1920, using the de Havilland DH-4A, followed by the Cox-Klemin XA-I. World War II saw widespread application of fixed-wing aircraft for evacuation. More than 1.4 million patients were transported from front-line hospitals to tertiary care facilities, with only 46 deaths en route.⁹⁶ During this time, the concept of medical care during transport was implemented. In November 1942, the War Department began to train flight surgeons and flight nurses and enlisted medical personnel for aeromedical transport.³⁹ Also during 1942, Igor Sikorsky produced a rotary-wing aircraft, called a “helicopter,” which the army configured with external litters. It was used in an air evacuation for the first time in 1944 in Burma.³⁶

Helicopters did not enjoy widespread use until more reliable and powerful machines became available. The Sikorsky S-51 and later the Bell 47-B were deployed over the rugged terrain and uncertain roads of Korea with great success to provide wide-scale evacuation of wounded soldiers to Mobile Army Surgical Hospital (MASH) units. Although only 11 dedicated medevac helicopters were used, more than 17,700 casualties were evacuated. For the first time, injury victims could travel directly from the point of injury to definitive surgical care.

This set the stage for Army helicopter evacuation (“Dust Off”) operations in Vietnam in 1962. With the Bell UH-1A Iroquois (“Huey”) under the leadership of Major Charles Kelly, the Army’s 57th Medical Detachment became known for the courage and hard work of flight crews, who flew despite darkness, adverse weather, and enemy fire. Later, the Bell model UH-1H was used to evacuate up to nine patients at a time by hoist from above a dense jungle canopy. By 1967, about 94,000 injured men had been evacuated.⁷⁷

As air evacuation matured, the time from wounding to definitive care declined from 18 hours in World War I to between 1 and 2 hours in Vietnam.⁹⁸ Although medical advances have contributed to improved survival, battlefield mortality has steadily declined from 18% in World War I to 1.8% in Vietnam, perhaps more because of rapid aeromedical transport to definitive care (Table 40-1).

TABLE 40-1 Mortality Rates and Evacuation Times During Major Wars

Conflict	Evacuation	Mortality
Conflict	Time (hr)	Rate (%)
World War I	18-30	18.3
World War II	4-6	3.3
Korea	2-4	2.4
Vietnam	1-2	1.8

From Stewart RD: Prehospital care of trauma, Trauma Q. May: 1, 1985.

Unfortunately, emergency medical care for civilians greatly lagged behind the developments in the military. In the late 1960s, rescue efforts were more organized, skilled, and rapidly performed for a man shot in the Vietnam conflict than for a civilian injured on a U.S. highway.⁶⁵ Civilian ambulances were said to be no faster than taxis.⁸⁹

Civilian transport began to change dramatically in the United States in 1966, when the National Academy of Sciences–National Research Council put forth the white paper “Accidental Death and Disability: The Neglected Disease of Modern Society” (U.S. Department of Health, Education, and Welfare), which outlined the inadequacies of prehospital emergency care, including the observation that “helicopter ambulances have not been adapted to civilian peace-time needs.” This document was the impetus for improving EMS systems through the country, and soon the civilian sector began to emulate the military model.

The first U.S. civilian aeromedical program was begun in 1969 as a joint effort between the Maryland State Police and the University of Maryland Center for the Study of Trauma (now the Maryland Institute for Emergency Medical Service Systems). Certain hospitals were designated as trauma centers, and victims of highway and other trauma were flown by police pilot–paramedic teams in a primary response role at the accident scene.⁹⁴

The 1980s saw rapid growth in helicopter EMS (HEMS) programs, both in terms of the number of services and helicopters (Figure 40-1, online). In 1980, there were only 32 HEMS programs with 39 helicopters flying 17,000 patients. By 1990, this system grew to 174 services with 231 helicopters flying 160,000 patients. In 2009, the Atlas and Database of Air Medical Services (ADAMS) database project identified 307 air medical services providing 867 dedicated rotary-wing aircraft and 309 fixed-wing aircraft. The National Transportation Safety Board (NTSB) estimates nearly 400,000 rotary-wing aircraft transports annually, with an additional 150,000 patients flown by fixed-wing aircraft.³² The distribution of the air medical services programs is graphically depicted by the ADAMS database (Figure 40-2, online).

FIGURE 40-1 Growth of helicopter emergency medical services: number of services and helicopters per year.

FIGURE 40-2 Distribution of air medical services.

The Commission on Accreditation of Medical Transport Systems (CAMTS; http://www.camts.org) is an independent, nonprofit agency that, since 1991, has established standards for critical care transport systems. CAMTS is made up of representatives from 19 different organizations, including the American College of Emergency Physicians, American College of Surgeons, Aerospace Medical Association, International Association of Flight and Critical Care Paramedics, and Air and Surface Transport Nurses Association. As of July 2009, there were 152 air medical services accredited by CAMTS, which represents approximately 50% of the HEMS programs in the United States. Although CAMTS accreditation is voluntary, several states have adopted CAMTS accreditation as a requirement for licensure of air medical services. Several other states have adopted CAMTS standards as their own standards for air medical service licensure. CAMTS reviews its standards on a routine basis and released the eighth edition of the standards for accreditation on February 25, 2011.

The modern-day U.S. Air Force (USAF) aeromedical evacuation system has its origins in the Vietnam War, during which more than 406,000 wounded troops were aeromedically evacuated. Current USAF aeromedical evacuation crews are composed of flight nurses and aeromedical evacuation technicians. Experienced nurses and medical technicians are trained to be aeromedical crews at the USAF School of Aerospace Medicine. This 5-week course includes aircraft configuration, air and ground safety, patient flight physiology, and aeromedical nursing considerations. Aeromedical evacuation crews are trained to move stable patients by fixed-wing aircraft over distances ranging from a few miles to transoceanic flights. Physicians do not normally accompany aeromedical evacuation flights; patient care and medication are provided by prior physician orders and written protocols.

U.S. military operations in Afghanistan and Iraq have led to significant changes in the USAF aeromedical evacuation system. Changes in military doctrine have resulted in the need to move seriously ill but stabilized patients over great distances by air. The requirement has led to development of dedicated critical care air transport (CCAT) teams, which fly with aeromedical evacuation crews to provide care for critical patients. CCAT teams include a critical care physician, critical care nurse, and cardiopulmonary technician. A formal training course in CCAT is given at the USAF School of Aerospace Medicine.^11,⁸² The trend toward formal CCAT teams has been mirrored throughout the world, with countries such as Great Britain, Germany, Japan, Australia, and Colombia developing and fielding CCAT capabilities.^11,^49,⁵⁴

With the development of faster and more powerful helicopters, reconfiguration of fixed-wing aircraft for aeromedical needs, enhanced knowledge of aeromedical physiology, and experience accumulated over more than 50 years of transport experience, acceptance, utilization, and success of aeromedical transport are universal. The role of aeromedical transport in the wilderness setting continues to evolve as its importance is recognized in providing rapid emergency medical care and evacuation to sick and injured patients.

Types of Aeromedical Transport Programs

Hospital-Based Programs

At one time, the most ubiquitous type of aeromedical transport program was hospital-based. Helicopter service is often provided in primary (to the accident scene) and secondary (to the community hospital emergency department) response roles. In addition, many hospitals provide fixed-wing transport in a secondary response role for long-distance transports or when transport by helicopter is impractical.

In a hospital-based transport program, the hospital frequently leases the helicopter from a vendor, who also supplies the pilots, maintenance, and fuel. The hospital has the responsibility for providing the medical crew and determining its configuration. The program directors are responsible for medical control and quality improvement.

The hospital may choose to own the aircraft and contract with a vendor for operations or employ its own pilots and mechanics. In most cases, the helicopter resides on a helipad atop or near the hospital, and the crew, which may consist of a specially trained flight nurse, flight paramedic, and physician, is quartered in the hospital, ready for immediate launch (see Flight Crew, later).

Non–Hospital-Based Programs

Non–hospital-based service is provided by an entity that may be supported by a consortium of hospitals, or it may be an independent corporation, ambulance service, or aviation fixed-base operator. The aircraft may be owned or leased by the entity or by an aviation contractor. This is not a common model for helicopter services in the United States, although many fixed-wing services operate in this manner. Use of the community-based model of HEMS has increased remarkably over the last 10 years and is now commonly seen in the United States. As of early 2009, Air Methods, a large HEMS company, operated a fleet of 335 aircraft at 254 bases in 43 states. About 60% of their operations are hospital based and 40% are community based.⁷⁶ A corporate airplane with its interior reconfigured may be provided on demand for use in an air ambulance mode, or a dedicated airplane may be provided with a custom-made air ambulance interior configuration, usually under a supplemental type certificate (STC).

Public Safety, Police, or State Services

The aircraft (usually a helicopter) may be owned and operated by a governmental agency, such as the state highway patrol, and operated under part 135 of the Federal Aviation Regulations (FAR). As in the Maryland model, flight personnel typically include police pilots and emergency medical technician (EMT)-paramedics.

the Military Assistance to Safety and Traffic Program

The Military Assistance to Safety and Traffic (MAST) program was established to supplement the civilian EMS systems. Under this program, air medical evacuation services are supplied by active-duty military medical units to the extent allowed by their training budgets, provided they can use actual patient transports instead of training exercises. The MAST mission is “secondary”; it is available only when its personnel and equipment are not being used in support of the unit’s primary mission. MAST may be requested by the local EMS or disaster management agency. Typical aircraft include the Bell UH-1 and Sikorsky UH-60 (Black Hawk). The medical crew usually consists of medical corpsmen. The MAST program may not compete with similar civilian services.

Other Military Resources

The USAF provides aeromedical transport in support of U.S. military operations and some disaster situations. The formal aeromedical evacuation system run by the USAF is the largest in the world, able to move large numbers of stable and critical-stabilized patients over intercontinental distances. In calendar year 2009, the USAF aeromedical evacuation system moved 21,538 patients (4543 of whom had battle injuries); 9-1-1 patients were critically ill and required CCAT team support during flight.⁹⁹

Other available resources include the Air National Guard and the U.S. Coast Guard. Many states and some counties have organizations (e.g., California Department of Forestry, Los Angeles County Sheriff’s Department) that may be called on to assist in search and rescue (SAR) operations in preparation for aeromedical transport. Many other countries have analogous units. The Israel Air Force, for example, operates a squadron that provides civilian and military rescue and evacuation services.

Patient Mission Types

Aeromedical transports have varying mission profiles, with the majority (70%) of flights being interfacility transports and 30% flights from the scene.⁵⁰

Primary Response

In a primary response role, the aeromedical transport service responds to an accident scene or field location, usually at the request of police, fire, or local EMS personnel, and serves as the initial and sole mechanism of transport to the hospital. In this instance, the aeromedical crew may function as “first responders.” Helicopters are most suited to a primary response role. The required response times must be short (less than 10 minutes from call to takeoff); thus the flight crew must be stationed at or near the launch site 24 hours a day. The service radius (“stage length”) is short (typically less than 50 miles), and crews need to be experienced in techniques for landing in proximity to obstacles, under poor conditions, and on uncertain surfaces. In prehospital situations, patients’ conditions vary widely, and often little or no assessment or stabilization is performed before arrival of the flight crew. Medical personnel must possess a high degree of training and experience and should possess at a minimum EMT skills required for patient extrication and stabilization at the scene. It must be kept in mind that the availability of helicopter transport, particularly for on-scene response, may not affect the outcome of the patient. Several studies have found that helicopter transport does not significantly improve outcomes in areas where ground ambulance transport is readily available.^10,^17,^80,⁸¹ The possible benefit to the patient must be measured against the risk to the helicopter crew, especially in poor weather conditions or during the night.

Secondary Response

In the secondary response role, a patient has already been transported by other means to a hospital, where some degree of stabilization may have occurred. The aeromedical service transports the patient in the early stages of care from the emergency department of a hospital to a facility better equipped to offer definitive care. Response times required for this type of mission must be competitive with one-way ground transport times. Stage lengths are short to intermediate (up to 241.4 km [150 miles]). The transport vehicle is typically a helicopter, although in some remote and wilderness areas, fixed-wing services are also suited to this role. Flight crews used in a secondary response vary depending on the needs of the patient (see Medical Mission Types). The responding aeromedical service typically consists of flight nurses, paramedics, and in some cases flight physicians.

Tertiary Response

In a tertiary response, an inpatient requiring specialized services unavailable at the current facility or requesting relocation is transported to a new facility. Tertiary transports may involve helicopters or fixed-wing aircraft, depending on the level of urgency, stage length, and cost of transport. Commercial entities throughout the world specialize in this type of service.

Medical Mission Types

The needs of different patient types may be categorized by medical problem; this in turn dictates the requirements of the aeromedical transport service. In most hospital-based helicopter programs, most patients transported are categorized as adult trauma, cardiac, or medical noncardiac. A number of programs offer or specialize in pediatric, neonatal, perinatal, and organ transplantation services, for which specialized crews and equipment may be required. In addition, aeromedical transport programs that provide SAR operations require specialized equipment and training.

Trauma Patients

Trauma patients transported in the primary or secondary response modes may account for 20% to 60% of a hospital-based helicopter service’s transport activity, depending on the hospital’s function and capability as a trauma center and the relationship between the aeromedical service and the community EMS and public safety network. A study of one urban setting noted that 20% of helicopter missions were to injury scenes, which were located at a mean distance of 1.6 km (14.4 miles) from the hospital. Of patients transported, 19% had penetrating trauma and 81% blunt trauma (66% from motor vehicle crashes). The most common organ system injuries involved the head (65%), extremities (39%), chest (31%), and abdomen (27%). The overall mortality rate of transported patients was 24%. The most common procedures required at the scene were endotracheal (ET) intubation (41%) and cardiopulmonary resuscitation (CPR) (18.7%). The most common life-threatening conditions were cardiac arrest (18.7%), airway obstruction (5.1%), cardiac tamponade (3.2%), and tension pneumothorax (1.7%).³⁵

A multicenter study of blunt trauma victims transported by helicopter aeromedical services from both urban and rural environments found a mean trauma score of 13 (of 16), mean age of 29 years, and overall mortality rate of 15%.¹⁰

A retrospective analysis of 10,314 patients with moderate to severe traumatic brain injury indicated that aeromedical response and transport were associated with better outcomes than was ground transport, even after adjustment for multiple influential factors. Patients with more severe injuries appeared to derive the greatest benefit from aeromedical transport.²³

These and other studies indicate the need for skilled crews in the transport of trauma patients.¹⁰² Medical personnel must have the ability to assess the patient adequately to detect frequent in-flight complications and to intervene with appropriate procedures, including intravenous (IV) cannulation, ET intubation, CPR, chest decompression, and at times a surgical airway (Box 40-1).

In wilderness areas, the flight crew must be skilled at victim extrication and operating in rugged terrain. They must be familiar with standard trauma care and the range of clinical entities most frequently seen in the wilderness setting. In addition, because resources may be limited and backup unavailable, they may be required to function semiautonomously. For this reason, protocols and standing orders are valuable. Most important are training, skill, and judgment.

Patients with Cardiac Disease

Patients with cardiac disease are most often transported in a secondary or tertiary response role, by either helicopter or fixed-wing aircraft. They typically account for 20% to 50% of an aeromedical service’s transport activity. The condition of these patients is often medically complex. Technologically sophisticated treatment modalities may include antiarrhythmics, vasopressors, inotropes, vasodilators, thrombolytic agents, cardiac monitoring, arterial and central venous pressure monitoring, pacemakers, implantable defibrillators, and intra-aortic balloon counterpulsation devices.^24,^28,^37,⁵² The flight crew must have sophisticated knowledge, expertise, and experience and may include a cardiac critical care nurse and a physician.

Patients with Medical, Noncardiac Conditions

Patients with medical noncardiac conditions, including those with underlying cardiac disease, are most often transported in the secondary or tertiary response mode by either helicopter or fixed-wing aircraft. This group consists largely of patients with acute neurologic disease or shock or those who require assisted ventilation.⁴² The spectrum of potential in-flight challenges includes cardiovascular problems, arrhythmias, hypotension, respiratory difficulties requiring acute airway management, seizures, and alterations in level of consciousness. The flight team must be able to manage an airway and operate a ventilator. Additional considerations relate to the cabin environment and need for pressurization if hypoxemia is present, if barotrauma is likely, or if trapped gas exists, as well as the need to predict the requirement for and manage finite oxygen resources in flight.

Pediatric Patients

Pediatric patients may have traumatic or medical conditions.^13,⁴⁴ In a study of 636 pediatric patients transported by air in the Salt Lake City area, 57.5% were transported by helicopter and 37.5% by fixed-wing aircraft, with a mean stage length of 207 miles (helicopter, 82 miles; fixed-wing, 452 miles). Less than 1% of flights were from the scene. The patient ages ranged from 3 weeks to 16 years, with 45% younger than 1 year. Trauma was the most common diagnosis (15.3% had head injury, 9.3% multiple injuries), followed by neurologic illness (24.2%), respiratory failure or infection (20.1%), gastrointestinal or genitourinary problems (10.2%), metabolic disease (9.2%), cardiovascular disease (6%), and general pediatric surgical problems (5.7%). The overall mortality rate was 7%.⁶⁴ Many of the considerations for pediatric transport are similar to those for adults, especially with older children. Infants may require an incubator, however, and flight crews must be experienced in caring for infants and children. Specifically, knowledge of pediatric advanced cardiac life support skills, including pediatric drug dosages, airway sizes, and fluid management, is essential.

Perinatal Patients

The need for expedient evaluation, preparation, and transport of the obstetric–gynecologic patient is increasing. Types of problems include ectopic pregnancy, pelvic inflammatory disease, toxic shock syndrome, abnormal fetal presentation, multiple gestation, diabetes in pregnancy, placenta previa, abruptio placentae, disseminated intravascular coagulation, preeclampsia–eclampsia, and preterm labor. The decision to transport patients in advanced preterm labor should be based on such factors as distance between hospitals, time required to cover the distance, personnel available for the transport, gestational age, and speed with which labor has progressed. The flight crew must be knowledgeable about these problems and comfortable with their treatment in order to ensure favorable outcomes for both mother and child.

Neonates

Neonates have unique anatomy and physiology, and the diseases that affect them require specific knowledge and skills by those involved in their transport. Specific issues include newborn assessment, including assignment of an Apgar score, airway clearance, temperature, homeostasis, and familiarity with neonatal resuscitation.^4,⁴⁰ Access to references concerning neonatal emergency drug dosages should be available.^3,³³

The ability to perform umbilical vein catheterization is an important skill for any member of the transport team involved in neonatal care. In addition, knowledge of fluid, electrolyte, and glucose requirements is essential.^49,⁵⁷ The flight crew involved in the transport of a neonate often includes a neonatal nurse and neonatologist.

Search and Rescue

Wilderness SAR is a unique aspect of aeromedical care and transport that requires significant training and expertise. Most dedicated aeromedical aircraft in the United States are not well suited for SAR operations (see Aircraft for Search and Rescue, later). Most standard aeromedical crews are not trained in SAR techniques. Many aeromedical helicopters and some fixed-wing aircraft become involved in SAR activities, however, and it is important to be familiar with SAR techniques. In addition, outside the United States, persons providing aeromedical transport are frequently involved in SAR activities (see Chapter 37).

The keys to a successful SAR operation include proper communications, transport, evacuation, and medical treatment, along with favorable weather conditions and topography. Helicopters are helpful in various SAR activities, including low-altitude search activity, search area evaluation, and movement of supplies and equipment. Fixed-wing aircraft are also useful for search and can provide secondary transport, especially when long distances are involved. A helicopter with hoist or short-haul capability may be the only means of extrication and rescue from the scene. These are external human load operations in which the rescuer or patient is carried by cable for either insertion or extraction. A hoist uses a cable attached to a harness or basket that can be lowered or raised with the person, whereas a short haul is a fixed length of line attached to the helicopter. The helicopter, equipped with a hoist and winch, is one of the most effective means of providing SAR in the wilderness setting and is essential in mountainous regions. These systems enable extrication and rescue of patients from terrain that may otherwise entail a complex and dangerous ground evacuation. Patients with critical illness may not be able to sustain a long delay between the time of the accident and the call for assistance before adversely affecting patient outcome.

The U.S. Air Force routinely uses helicopters and fixed-wing aircraft for long-distance SAR operations. Fixed-wing aircraft often arrive at the scene first and may deploy para-rescue specialists (“PJs”) by parachute. If the rescue site is over water, the aircraft may also deploy an inflatable boat with motor and rescue equipment. The PJs and their survivors are then recovered by surface vessels or by rescue helicopters that have been refueled aerially in order to reach the rescue site (Figure 40-3). This capability permits rapid deployment of rescuers while allowing the most expeditious recovery of survivors and their delivery to definitive care. These services were on alert for all space shuttle launches to provide SAR support in the event of a mishap.

FIGURE 40-3 MH-60G Pave Hawk hoisting a para-rescuer during a search and rescue exercise. A variant of the UH-60 Black Hawk, the Pave Hawk is flown by U.S. Air Force rescue squadrons. Modifications include forward-looking infrared equipment, night vision–compatible cockpit lighting, terrain and navigation radar, air-refueling probe, auxiliary fuel tanks, and hoist.

(Courtesy U.S. Air Force.)

In the United Kingdom, the Royal Air Force operates a helicopter SAR service that flew 1490 missions from 1980 to 1989, almost all of which involved vacationers along the coasts or in the mountains.⁵⁹ The Danish helicopter rescue service was founded in 1966 and uses a Sikorsky (S-61) helicopter. Since 1973, its crew has included a physician trained in aerospace medicine and helicopter transport. From 1973 to 1989, it flew 5733 missions, 2075 of which involved direct medical intervention. The most frequent problems were abdominal trauma and cardiopulmonary diseases.¹⁰⁶

In the high Alps, more than 90% (3000 per year) of all rescues are performed using helicopters.⁵ Of these, 5% are combined rescues; that is, the helicopter carries the rescuers below cloud level, near the site of the accident. Only 5% of mountain rescues are purely ground rescues, mainly necessitated by visibility.⁸⁸ Currently, a network of SAR systems extends throughout the Alps. In some countries (France, Italy, Germany, Austria, and Spain), air rescues are managed partially or totally by the army or the state. The aircraft most often used for this purpose are the Alouette III, Lama, Ecureuil (French), Bolkow¹⁰⁰^,117 (German), Agusta AK¹¹⁷ (Italian), and Bell (U.S.). In Switzerland, the rescue system in remote terrain is managed by the Swiss Alpine Club and three air rescue companies, Swiss Air-Rescue (REGA), Air Glaciers, and Air Zermatt. Switzerland may be unique in that its 18 strategically placed helicopter rescue bases allow an aircraft to reach any accident scene within 15 minutes of takeoff. Since the foundation of REGA in 1952, more than 150,000 patients have been transported by either fixed-wing aircraft or helicopter.

Up to 8000 patients (5500 from accident scenes) are transported by helicopter every year. Twenty percent of these rescues require a winch, with one-third of all winch operations occurring in accident sites that are difficult to reach.²⁶ More than 75% of all persons rescued by winch were thought to have injuries requiring physician assistance at the scene. Eighty percent of all Swiss air rescue missions are physician assisted, and 20% have a paramedic in charge. All the physicians and rescue crews are physically fit and trained in alpine techniques, because two-thirds of all rescue missions performed from 1990 to 1993 were in topographically remote and difficult terrain (Figure 40-4).

FIGURE 40-4 Helicopter rescue in extremely difficult terrain.

(Courtesy P. Bärtsch, MD, and the Swiss Alpine Club.)

Difficult helicopter SAR operations are those that involve low visibility, strong winds, night missions, high-angle rescues, and long-line hoist operations (extension of the hoist cable up to 120 m [394 feet]). In addition, in mountainous regions, power cables and transport cables present considerable risks. In all cases, the risks to the flight crew (as well as to the patient) must be weighed against the degree of injury and risk for further morbidity. The U.S. Air Force, Army, Navy, and Coast Guard equip and train groups to operate in these hostile rescue environments. Helicopters are frequently equipped with precision navigation systems and night vision, forward-looking infrared (FLIR), and thermal imaging equipment. The intense training and specialized equipment permit rescue operations under much more demanding conditions than those encountered by civilian services. Of the military services, only the U.S. Coast Guard has a primary mission of civilian SAR; Army, Navy, or Air Force groups may be requested to assist in civilian rescues in areas in which they are available.

An increasing number of people participate in alpine sports, including mountain climbing, downhill skiing, mountain biking, and paragliding.²⁸ A typical representation of the type of mountaineering accidents experienced in the Swiss Alps is shown in Table 40-2. In addition to SAR in mountainous regions, aeromedical rescue presents great challenges to the medical and flight crews involved in rescues from sea and white water, floods, vertical rock faces, and avalanches.

TABLE 40-2 Mountaineering Accidents in the Swiss Alps, 1992 (N = 1844)

Activity	Patients Rescued (n)
Delta gliding	18
Paragliding	196
Off-slope skiing	35
Ski touring	238
Mixed climbing	456
Rock climbing	178
Hiking	723

From Dürrer B, Hassler R, Mosimann U: Mountaineering accidents in the Swiss Alps and rescue activities of the Swiss Alpine Club, 1992.

Medical treatment of the survivors should begin immediately at the site of the accident unless weather conditions are deteriorating or the scene is inherently unsafe. If a hoist extraction is needed, the patient with potential multisystem trauma should be evacuated by a rescue net or basket (Stokes) litter with careful spinal immobilization. A tag line attached to the litter prevents spinning during hoist operations. The tag line should be attached with a weak link so that the tag line will break away if the litter becomes uncontrollable. Persons with minimal or isolated injuries may be hoisted by a jungle penetrator (Figure 40-5), rescue basket, or other dedicated hoist device. If a hoist device is not available, the victim may be hoisted by climbing harnesses or rescue belts.²⁷ The climbing harness or belt should be carefully inspected to make sure that it has not been damaged in the mishap, that it will withstand the strain of the hoist operation, and that it can be safely attached to the hoist cable.

FIGURE 40-5 A, Jungle penetrator used as a hoist device on most military rescue helicopters. The streamlined shape allows it to slip through dense tree canopies to reach the ground. A foam flotation collar can be attached, making the penetrator buoyant. B, Jungle penetrator rigged for hoist. The seats are flipped down, and the safety straps are pulled out from their stowed position and passed over the head and under the arms of the victim, who then straddles one of the seat paddles. Although the penetrator has three seats, usually only one or two persons are hoisted at a time.

(Courtesy Robert C. Allen.)

The extent of medical treatment rendered on site before extraction depends on many factors, including the victim’s condition, scene safety, medical supplies available, medical skill of the rescuers, weather conditions, aircraft loiter time, and flight time to definitive care. Good communication between the flight crew and the rescue team is essential to the decision-making process. Aeromedical crews involved in mountain rescue need to have a thorough understanding of the unique medical problems frequently found in high-altitude rescue situations.

Hoist Operations

If the helicopter is not able to land at a mishap scene and has a rescue hoist installed, hoist operations may be the only means of evacuating the patient. In most circumstances, a helicopter crew member rides the hoist down to the site to rig the survivor into the rescue device and to oversee the hoist operation, using the following guidelines:

• It is critical that personnel on the ground not touch the hoist, rescue device, or cable until after it has touched the ground (or water). Helicopters can build up a very powerful static electricity charge that will be grounded through whatever the hoist touches first. This has been known to knock rescuers and survivors off their feet.

• Once the rescue device and cable have touched the ground, put the patient into the rescue device, taking care to keep the hoist cable clear of all personnel. Do not allow the hoist cable to loop around any personnel or around the rescue device, because serious injury is possible when the cable slack is taken up.

• Make sure that the patient is properly secured in the rescue device, with all safety straps tightened.

• When the patient is secured, move away from the rescue device and signal “up cable.”

• If the rescue device is a basket (Stokes) litter, use a tag line with a properly installed weak link to prevent the litter from spinning during the hoist.

International Aeromedical Evacuation

A growing segment of aeromedical evacuation is evacuation of international travelers from the point of injury or illness to their home country. This growth is fueled by increasing travel to remote areas of the world, the increase in the age (and concomitant decrease in health) of travelers, and to some extent, risk-taking behavior on the part of travelers. The vast majority of international travelers complete their journeys without incident, with fewer than 0.5% of travelers requiring medical evacuation. However, when one considers the huge number of people who travel by air each year (1 to 2 billion per year by some estimates), even this small percentage adds up to thousands of people requiring international aeromedical evacuation.¹⁰⁰

There are multiple companies that specialize in fixed-wing movement of patients over medium- to long-range distances. Some operate their own fleet of aircraft and have full-time medical personnel, others charter aircraft as required and fit medical transport equipment and personnel as required for a specific transport.

One daunting factor in these evacuations is the large cost associated with international aeromedical transport. It is not unusual for these transports to cost upward of $50,000 to $100,000.¹⁰⁰ Frequently this cost is not covered by medical insurance. Several of these companies offer “memberships,” where for a relatively small yearly fee, the member will be provided aeromedical evacuation from just about anywhere on the globe to their home of record.

Long-range transport in relatively small aircraft presents some unique challenges, including having adequate space to provide care, oxygen supply, power supply, and the possibility of patient deterioration en route. Unlike the relatively short-range, short-duration flights done by HEMS services, international aeromedical evacuation flights very frequently have aeromedically trained physicians as members of the flight crew.

Flight Crew

Crew Configuration

The ideal medical flight crew composition varies with the mission profile. When the aircraft is involved in a primary response to the accident scene, inclusion of an EMT may be beneficial. Transport of patients whose illness or injuries are complex or whose clinical conditions are extremely unstable may benefit from the presence of a physician. Interfacility transport of a patient on mechanical ventilation may benefit from inclusion of a respiratory therapist as part of the flight crew. All aeromedical transport programs include one or more of the providers below in the transport medical crew. In a 2010 survey of 300 critical care transport programs, none of the responding programs flew either fixed-wing or rotary-wing missions with a single medical crew member.³⁸ The most common crew configuration was a two-person crew, with a nurse and an EMT-paramedic making up the crew 84% of the time in rotary-wing missions and 69% of the time in fixed-wing missions. Two-nurse crews were uncommon (8% rotary-wing and 9% fixed-wing). A respiratory therapist made up the second crew member in relatively few rotary-wing transports (5%); however, they were more common in fixed-wing transport (22%). Nurse–physician crews were relatively uncommon, making up only 3% of the rotary-wing crews and none of the fixed-wing crews. Three-person crews were less common and usually involved adding a respiratory therapist to an RN/EMT–paramedic crew.³⁸

Emergency Medical Technician–Paramedic

EMTs are increasingly members of the aeromedical flight team. In 1993, 71% of rotary-wing transport programs reported using an EMT–paramedic as a member of the flight team, compared with 44% in 1988.¹⁸ EMTs vary in their level of training, depending on the state in which they work, but usually follow Department of Transportation (DOT) guidelines, which include three levels of certification. EMT-basic provides basic ambulance, rescue, and first-aid skills. EMT-intermediate may include IV and intubation skills. The EMT-paramedic level involves such skills as intubation, IV techniques, medication administration, defibrillation, and arrhythmia recognition and treatment. For an aeromedical flight team member, additional training relating to the aeromedical environment is desirable.^49,^93,¹⁰³

EMTs can be of particular value in operations that necessitate frequent interaction with ground EMS. In some regions, HEMS service is integrated into the regional primary response network, so that the helicopter and crew arrive at the accident scene before ground units; therefore flight team members experienced in scene assessment and victim extrication are essential. The Association of Air Medical Services (AAMS; http://www.aams.org) has published Guidelines for Air Medical Crew Education, which gives templates for initial training of advanced life support skills for EMT-paramedics, nurses, and respiratory care personnel in advanced techniques that may be required in the aeromedical environment. The International Association of Flight and Critical Care Paramedics (http://www.flightparamedic.org) offers flight paramedic review courses. The Board for Critical Care Transport Paramedic Certification offers an examination for paramedics to become certified flight paramedics (FP-C).

Flight Nurse

At least one flight nurse is part of almost all aeromedical transport programs; in 1993, 21% of rotary-wing programs reported using two flight nurses as the sole team members.¹⁸ In 2010, 100% of 77 rotary-wing transport programs reported using an RN as part of the flight team. As noted earlier, only 8% used a dual-RN crew.³⁸ Critical care or emergency nursing experience is usually a prerequisite, with additional training that includes patient assessment, advanced cardiac life support, a trauma life support course, and prehospital care skills, including certain procedures such as ET intubation, advanced IV cannulation techniques, and in some cases needle thoracostomy, venous cutdown, cricothyrotomy, and other specialized skills. The flight nurse often is also a certified EMT. The Air and Surface Transport Nurses Association (http://www.astna.org), in association with the Board of Certification for Emergency Nursing, offers a certification in flight nursing, leading to the credential of certified flight registered nurse (CFRN).

Flight Physician

The experience and training of physicians involved in aeromedical transport depend on their role. Those who function as the online medical control physician communicate via radio or 800-MHz radiotelephone with the flight crew, monitor care, and give necessary orders. In the United States, physicians fly as a component of the flight team in a minority of aeromedical transport programs; in 1993, only 3% of all rotary-wing transport programs reported the routine use of a physician, compared with 10% in 1988.¹⁸ As has been noted earlier, very few helicopter EMS flights have physicians as members of the flight crew; this varies, depending on the individual organization. In HEMS operations, an emergency physician or trauma surgeon may be appropriate, whereas with long-range fixed-wing transport of intensive care unit patients, an intensivist may be of value.

Physicians functioning in this role must have a current level of skill and expertise sufficient to address a wide range of clinical problems. They must also possess additional training relative to the airborne medical environment, including flight physiology, aircraft operations, and prehospital care (Box 40-2). Most important, they must function in this role with sufficient frequency so as to maintain their skills and remain safe and comfortable within the aeromedical setting. In doing so, they become an asset to the flight team rather than a distraction or liability. The National Association of EMS Physicians has written a position paper on the core training it considers necessary for the flight physician.⁶⁹ The Air Medical Physician Association has a three-part core curriculum recognized and recommended by CAMTS as background training for the medical director of a critical care transport program applying for accreditation or reaccreditation.

BOX 40-2 Specialized Training for Aeromedical Transport

Aviation physiology

Atmospheric pressure changes with altitude

Gas expansion with altitude

Changes in partial pressure of oxygen with altitude

Effects of motion and acceleration

Effects of noise and vibration

Changes in temperature and humidity

Aircraft safety

Aircraft systems and equipment operations

In-flight emergency procedures

Survival techniques

Patient extrication and immobilization

Patient loading and handling aboard an aircraft

Patient care techniques in the aeromedical environment

Respiratory support and ventilation aboard the aircraft

Pertinent Federal Aviation Administration regulations and procedures

Familiarity with the local emergency medical services system

Radio communications skills and techniques

Hazardous materials response procedures

Record keeping and documentation in aeromedical transport

Preflight, in-flight, and postflight procedures

Clinical procedures

Cardiopulmonary resuscitation aboard the aircraft

Defibrillation aboard the aircraft

Intravenous cannulation

Endotracheal intubation

Tube thoracostomy

Needle thoracotomy

Cricothyrotomy

Central vein catheterization

Pericardiocentesis

Nasogastric tube insertion

Bladder catheterization

Intraosseous line placement

Umbilical vein catheterization

Studies during the late 1980s and early 1990s attempted to determine whether a physician crew member has an effect on the outcomes of patients transported by helicopter.^8,⁹ Some studies concluded that a physician crew member had a positive impact on patient outcome, whereas others found no difference in outcome between similar cohorts of patients transported by flight crews with two nurses or a nurse and a paramedic.^40,⁸⁷ The cost of using a physician crew member is substantially higher than that of a nurse–nurse or nurse–paramedic crew configuration. Some argue that this higher cost would be offset by the decrease in hospital stay or lost person-years that would occur if a physician were a standard member of the flight crew. With advanced training in critical procedures and treatment protocols, combined with online medical direction, a nonphysician flight crew usually functions as well as a crew that includes a physician. No objective evidence supports the benefit of a physician as a standard flight crew member in helicopter transports.

USAF CCAT teams, U.S. Army burn transport teams, and other military transport teams designed to move critically ill or injured patients over long distances will almost invariably have a specially trained physician (intensivist or burn specialist) as part of the team. Given the long duration of intercontinental missions and the difficulty of diverting transoceanic flights, the presence of a specialist physician onboard is vital to safe transport.^11,^49,^82,⁸⁶

Crew Member Stress

By its nature, aeromedical transport involves moving a gravely ill patient into an adverse environment with limited resources. Under these conditions, a medical crew of only two or three persons must perform complex tasks, solve difficult problems, and make life-or-death decisions. They must perform in a physically confining space that may be uncomfortable, and they must do so under time pressure and with little or no physical assistance. In some cases, rescuers’ lives may be at risk. This scenario occurs in few other arenas of civilian medical care.

The term stress describes an array of adverse physiologic and psychological reactions that occur when a person perceives a threat to existence. Although stress may not diminish performance, it may be responsible for errors, faulty judgment, and uneven manual skill performance. It may also affect the physical and psychological health and satisfaction of the flight crew member.¹⁹

When measured during patient flights, the level of anxiety among aeromedical crew members was significantly higher than during a baseline period on the ground.⁹⁷ Factors that correlate with high in-flight anxiety levels include adverse weather conditions (e.g., low ceilings, high winds), severity of the patient’s medical condition, complexity of illness or injuries, and the crew member’s fatigue.

Efforts should be made to minimize stress among crew members. This includes frequent and adequate training; continuing education and feedback; adequate medical backup, including online medical direction, written protocols, and treatment guidelines that can aid in difficult decisions; a supportive rather than an intimidating or critical quality assurance program; adequate rest; and safe weather minimums. Routine mission debriefing and critical incident stress debriefing should be integral parts of all transport programs.⁶⁷

Appropriate Use of Aeromedical Services

Aeromedical transport combines skilled treatment and stabilization capability with rapid access to definitive care, but not without risk, and at high cost. (In 1986, it was estimated that aeromedical transport costs were $1 to $2 million per year for a program, or about $2000 per transported patient, which is about 400% higher than ground transport. This cost has gone up considerably; it is not unusual for an HEMS run to cost over $8000. Long-range international transports can cost upward of $100,000.^17,¹⁰⁰ However, the comparative risk of aeromedical transport must be placed in perspective against the risk for patient death from nonreferral or from less timely ground transport with limited medical capability en route.

Although not proved, advanced provider skill levels during prehospital care are considered beneficial, especially in severely ill or injured patients.⁵¹ In rural and wilderness environments, advanced life support services may be made more readily available by EMS helicopters. This is especially true in areas that are difficult or impossible to reach by ground.

The speed of access to definitive care is another consideration in choosing the mode of transport. In isolated rural or wilderness locations, a helicopter may be the only means of expedient access. Prolonged victim extrication allows time for a helicopter to arrive at the scene, decreasing total transport time and thereby increasing the advantage of helicopter transport.

Patient comfort also must be considered, especially on long transports over rough roads. Although a helicopter moves in three dimensions, fore-and-aft acceleration is usually steady, without the starting and stopping motions present during ground transport. However, helicopters typically travel within 914 m (3000 feet) of the ground’s surface and are more subject to turbulence than are high-flying fixed-wing aircraft.

Whether aeromedical transport reduces mortality when compared with ground transport has not been definitively determined. An uncontrolled national multicenter study of trauma patients transported by helicopter showed a 21% reduction in mortality from that expected based on predictions from the trauma revised injury severity score (TRISS) methodology and national normative trauma outcome data.¹⁰

A similar study using the TRISS methodology compared actual mortality with helicopter versus ground transport and showed a 52% reduction from expected mortality when patients were transported by air, compared with no reduction in expected mortality when transport occurred by ground.⁷ Another study using TRISS methodology found a benefit of aeromedical transport only in patients with severe trauma (a probability of survival of less than 90%).¹⁵

As has been noted earlier, a retrospective analysis of 10,314 patients with moderate to severe traumatic brain injury indicated that aeromedical response and transport was associated with better outcomes than was ground transport, even after adjustment for multiple influential factors. Patients with more severe injuries appeared to derive the greatest benefit from aeromedical transport.²³

In 1990, the AAMS issued a position paper on the appropriate use of emergency air medical services. In 1992, these recommendations were accepted by the California Medicaid provider as reasonable criteria for the use of air medical transport. In a review of 558 consecutive patient transports, 98% had met at least one of the AAMS criteria.⁸⁰ The aeromedical triage criteria were updated by the National Association of EMS Physicians in the position paper “Guidelines for Air Medical Dispatch” in 2003. These guidelines have been endorsed by the AAMS and Air Medical Physician Association (AMPA).^2,⁷⁰

The risk of aeromedical transport can be placed in perspective if the overall risk for death using ground transport, estimated from the trauma score, is compared with the risk when patients are transported by air. Assuming a reduction in risk of between 21% and 52% when transport is by air, the additional risk for death from crashes (1.18 per 100,000 transports) is negligible in comparison with the benefits. This is probably true, however, only for patients with moderate to severe, but nonmortal, injuries (i.e., trauma scores between 5 and 14). Those having minor injuries, with near 100% likelihood of survival, are unlikely to gain additional benefit; those having mortal injuries, with little hope of survival, are unlikely to be saved by any means attempted or employed.

The decision to transport a patient by air requires judgment and a realistic appraisal of the risks. A patient should be transported by air only if he or she is so ill that transport is necessary; if ground transport is unavailable, delayed, or unable to reach the patient; or if aeromedical transport would reduce the risk for death by permitting more rapid access to definitive care, providing greater medical skill en route, or both.⁸¹

Box 40-3 gives some of the indications for aeromedical transport. A more detailed list can be found in the AMPA position statement: “Medical Condition List and Appropriate Use of Air Medical Transport.”² Box 40-4 is from the National Association of EMS Physicians position paper “Guidelines for Air Medical Dispatch.” These questions can be used to assist in determining appropriate transport modes.⁷⁰

BOX 40-3

Medical Conditions That May Require Aeromedical Evacuation

Acute neurologic, vascular, surgical, or cardiac emergencies requiring time-sensitive intervention

Critical conditions in patients with compromised hemodynamic or respiratory function

Critical conditions in obstetric patients whose time of transfer must be minimized to prevent complications in the patient or fetus

Critical conditions in neonatal or pediatric patients with compromised hemodynamic or respiratory function, metabolic acidosis more than 2 hours after delivery, or sepsis or meningitis

Electrolyte disturbances and toxic exposures requiring immediate lifesaving intervention

Organ failure requiring transplantation

Conditions requiring treatment in a hyperbaric oxygen unit

Burns requiring treatment in a burn treatment center

Any injury that is potentially threatening to life or limb, including penetrating eye injuries

Data from Teichman PG, Donchin Y, Kot RJ: International aeromedical evacuation, N Engl J Med 356:262, 2007.