Evacuation Flow and Medical Regulating 

As a general rule, casualties are evacuated rearward, using assets of the next higher medical echelon. For example, casualty evacuation from point of injury to an echelon I treatment facility (e.g., BAS) is usually accomplished using battalion vehicles. Casualties are then typically evacuated from the BAS to a second echelon medical company or PCRTS by division ambulances or ship vessels/aircraft. Before this movement, or any subsequent evacuation, the originating facility must ensure that patients are stabilized within the limits of its ability. As a minimum, an open airway must be established, bleeding must be controlled, shock must be treated, and fractures must be splinted. For the most part, evacuation from the point of injury through echelon II flows automatically using established service channels. It is the responsibility of the component surgeons to ensure that a mechanism exists to exchange or replenish medical equipment (litters, litter straps, blankets, etc.) lost in the evacuation process. This is can be readily accomplished using property exchange points and ambulance backhaul. 

The movement of patients from echelon II facilities to echelon III hospitals requires additional coordination. This coordination is accomplished for a service component surgeon by the component’s Medical Regulating Office (MRO). MROs may set up a prearranged flow from specific echelon II facilities to specific echelon III hospitals; however, they must also monitor bed status to ensure that no hospital becomes overcrowded or underused. To preclude this, the service component surgeons may direct their MROs to coordinate all evacuations between echelon II facilities to echelon III hospitals. MROs must coordinate with the JPMRC/TMPRC if their hospitals are overcrowded or have patients who require treatment in another component’s facilities. Evacuation from echelon II facilities to echelon III is usually provided by ground, rotary-wing, or fixed-wing assets assigned within the third echelon. Again, the JTF Surgeon must ensure service component surgeons have effective medical equipment exchange or replenishment systems 

To coordinate the evacuation of patients out of theater, MROs must coordinate with the JPMRC/TPMRC, which, in turn, coordinates evacuations out of theater. Although, patients traditionally are only evacuated out of theater after admission and treatment in an echelon III hospital, it may be necessary in Military Operations Other Than War (MOOTW) or low-intensity conflict operations to evacuate wounded from an Echelon II facility directly to an echelon IV or V hospital after only minimal stabilization. If this is planned, it does not relieve regulating officers at all levels or their responsibilities. Unregulated patient movement is to be avoided.

The Aeromedical Evacuation System 

Whenever possible, patients are evacuated rearward from echelon III hospitals using fixed-wing aircraft. When regulating and evacuation coordination is completed, echelon III hospitals are instructed to move their evacuees to a specific Mobile Aeromedical Staging Facilities (MASF), usually collocated at a theater airfield. It is the responsibility of the losing facility to ensure that patients arrive at the specified time since the MASF is not staffed, equipped, or supplied to care for patients for longer than several hours. Casualties are expected to have with them sufficient meals-ready-to-eat (MRE), medications, and dressings to last the duration of their stay in the aeromedical evacuation system. Additionally they must be provided with Patient Movement Items (PMI) to include litters, blankets, and specialized medical equipment. The Air Force has been tasked to develop a PMI exchange system that will ensure replenishment of the property lost by medical facilities when they turn patients over to the aeromedical evacuation system. 
Unless otherwise specified, the expected stay for patients in the intratheater aeromedical evacuation system is three days and five days for intertheater moves. Nursing services are provided in-flight, however if physician supervision is needed, it must be provided by the losing medical treatment facility. Generally, flights from echelon III facilities take no more than four hours and use C-9, C-130, C-141, or C-17 aircraft. If mission duration exceeds four hours, crew augmentation will likely be required and aircraft will be limited to C-141 or C-17. 
The Theater Aeromedical Evacuation System (TAES) requires a mix of components to operate successfully. The bare essentials required for low-intensity conflict are as follows: 

• Aeromedical advance echelon (ADVON). The ADVON provides a cadre of about eight people to arrange initial support, begin establishing the theater aeromedical evacuation system, and provide planning advice to the supported commander.
• Support cell. The support cell augments the ADVON with about five more staff members to sustain operations.
• Aeromedical evacuation control center/element (AECC/AECE). The AECC/AECE consists of up to 19 personnel and provides overall control of the aeromedical evacuation process. Whenever possible it makes maximum use of the on-scene airlift command and control system and equipment.
• AELT. AELTs, consisting of six personnel, are located at key service component medical facilities and pass patient airlift requirements to the AECE/AECC at the same time that regulating information is passed by the MRO to the JPMRC.
• MASF. A MASF is staffed with 39 personnel and provides patient holding capability at forward airfields. The facility is designed to hold up to 50 litter patients for short periods and can manage surges of up to 150 patients per day.
• Aeromedical evacuation crews and a crew management cell. Sufficient crews and a crew management cell are assigned and located or staged at the AECC/AECE, MASF, forward operating base, or aircraft hangars.

Patient Preparation and Stabilization 

In addition to requiring that support materials and PMI accompany patients during evacuation, the JTF Surgeon should ensure that components receive current Air Force guidelines and requirements. Excerpts from the 1st Aeromedical Evacuation Squadron (now the 23rd Aeromedical Evacuation Squadron) Primer published in 1992 follow. 

• When entering the aeromedical evacuation (AE) system, patients should be stable enough to tolerate a trip of 1 to 24 hours with a high probability of not incurring complications. Degree of stabilization is dependent upon the operational situation. Theater missions are normally short; intertheater missions often last up to fourteen hours.
• Abdominal injuries. Patients with abdominal injuries should be carefully evaluated by a general surgeon prior to flight. Use of nasogastric (NG) and/or rectal tubes should be considered in order to avoid distention frequently encountered with a nonfunctioning bowel.
• Airway management. Endotracheal tubes should be used if the patient requires assisted ventilation. Balloon cuffs should be filled with normal saline instead of air, since gas expansion at altitude may cause tracheal damage.
• Cardiac patients. Patients with severe cardiovascular disease usually have reduced tolerance to hypoxia, but they generally do well during flight if provided supplemental oxygen. Patients with recent myocardial infarctions (MI) can usually be moved by airlift with appropriate preparation and monitoring. Unstable patients requiring cardiac monitoring in flight will be moved with a medical attendant, and the referring hospital must provide an AE-approved monitor. Note that patients should be at least ten days post MI and pain-free for five days before movement. If monitored, patients must be accompanied by a physician.
• Chest tubes. Chest tubes should be left in place. However, they will require a Heimlich valve and an underwater drainage system approved for AE use.
• Circular casts. Ideally, casts on recent fractures should be at least 48 hours old. All casts should be bivalved unless that would jeopardize the stability of the fracture.
• Colostomy patients. Extra colostomy bags should accompany the patient. Drainage is more profuse in flight because of gas expansion.
• Crutches. Patients using crutches should travel by litter because of safety factors involved in moving about on unstable aircraft. Crutches should accompany the patient and will be stowed aboard the aircraft.
• Dressing changes. As a rule, dressings will be reinforced but not changed during flight due to the relatively unclean inflight environment. Serious complications such as bleeding, increased pain, or swelling may require wound inspection. Routine dressings will be provided by the AE crews, however unique dressings or dressings for patients with excessively draining wounds should be provided by the losing hospital.
• Drug or alcohol abuse patients. These patients should undergo three to five days of detoxification before they are airlifted. An AE mission is not equipped to deal with acute withdrawal symptoms.
• Eye injuries. Penetrating eye wounds and/or surgery can sometimes introduce air into the globe of the eye, making it susceptible to oxygen deficiency and decreased barometric pressure. An altitude restriction is recommended for such cases except for patients with retinal detachments.
• Hematologic problems. Ideally, patients should have a preflight hemoglobin (HGB) of 10 grams and a hepatocrit (HCT) of 25 percent. However, severely traumatized patients may have readings below those levels, and supplemental oxygen may be required. Note that HGB can be below 8.5 grams if the condition is chronic and stable and not due to bleeding.
• Intravenous (IV) fluids. Some patients not requiring IV fluids on the ground may require them during the flight due to the excessively dry aircraft environment. Catheter function should be assessed prior to transport to ensure the catheter is securely in place. Patients requiring antibiotics without fluid replacement should be switched to a heparin lock with heparin flushes provided. A three-day supply of IV fluids should accompany patients.
• Maxillofacial injuries. Due to the increased potential for nausea and vomiting, patients with wired, immobilized upper and lower jaws must have quick release mechanisms applied or have easy access to wire cutters. Premedication with an antiemetic should be considered, especially if the patient is prone to motion sickness.
• NG Tubes. NG tube insertion is recommended for patients with abdominal wounds, abscesses or obstructions, paraplegia or quadriplegia, or the potential for paralytic ileus. Limited suction capabilities are available, however the distal end of the tube may be left to gravity drain into a glove or bag.
• Neurological patients. The decreased partial pressure of oxygen in flight can cause increased intracranial pressure in head-injury patients. Low-flow oxygen and an altitude restriction should be considered. Noise, vibration, and thermal stresses can precipitate seizures, so adequate antiseizure medication levels should be established before flight. Patients should not perform the Valsalva maneuver if at risk for increased intracrainal pressure. Preflight decongestants and polyethylene (PE) tube insertion should be considered, especially for comatose patients. Craniotomy patients should be at least 48 hours post surgery, awake, and alert. Subtle changes in neurological status, normally discovered during routine checks, are difficult to detect during flight; patients requiring close observation are poor candidates for aeromedical evacuation. Stable, comatose patients can be transported. Decreased humidity in flight dictates that patients with a loss of corneal blink reflex be provided with bilateral eye patches and eye ointment or liquid tears. Intraventricular monitoring cannot be accomplished during flights.
• Oxygen requirements. Supplemental (humidified) and emergency therapeutic oxygen are available on all AE missions.
• Psychiatric patients. Each severe psychiatric patient requires a litter, leather wrist and ankle restraints, and sedation. Each intermediate severity psychiatric patient requires a litter and sedation and must have wrist restraints available. All litter psychiatric patients must be searched, and all sharp objects, such as razor blades and pocket knives, must be removed.
• Stryker frames. These frames are generally indicated for paraplegia, quadriplegia, cervical fractures, severe burns, and those patients require total assistance. Patients having cervical injuries and wearing halo traction may be transported on a regular litter or they may be transported as ambulatory patients if stabilized. All components of the Stryker frame must be present to allow continuity of patient care and turning of patients throughout the evacuation.
• Thermal injuries. Thermal injuries should be covered with occlusive dressings. Escharotomies are required for full-thickness circumferential burns. Extra burn dressings for in-flight reinforcement should be provided. Limited infusion pumps and poor in-flight refrigeration capabilities preclude the use of total parenteral nutrition. D10W with necessary electrolytes should be ordered as a short-term substitute. Phosphorous injuries should be covered with saline-soaked dressings. Large vesicles and bullae should be protected through use of large, bulky dressings.
• Tracheostomy patients. Tracheotomy tubes should be changed before flight and an extra tube should be sent with the patient.
• Traction patients. Free-swinging weights for traction are unacceptable for flight. Cervical traction is available via a Collins traction device, however a physician must be present when the device is applied.
• Urinary catheters. Indwelling catheters and drainage bags in use before transport should be left in place during evacuation or inserted preflight if urinary retention is a problem. The internal balloon should be filled with sterile, normal saline instead of air to avoid gas expansion during flight.
• Vascular Injuries. Vascular repairs should be clearly recorded. If casts are applied and they are less than 48 hours old, they should be bivalved and windowed over the injured area in case excessive swelling occurs during flight.

Ventilators. Ventilator-dependent patients will be accompanied by a respiratory therapist or other appropriate medical attendant from the losing facility.

Evacuation vehicle and aircraft capacities

Table 8. Some Evacuation Vehicle and Aircraft Capacities