Aeromedical Transport
Because aeromedical transport involves medical care delivered in a hostile environment, the patient and crew are at risk for injury or death in the event of a mishap. Flight crew training must emphasize safety. A helicopter mountain rescue operation is a high-risk endeavor for the pilot and crew, as well as for the patient. Dangerous mistakes are easy to make around working helicopters. Therefore, aeromedical transport is not always the proper choice for rescue. Any decision to use aeromedical resources must be weighed against the lower risk associated with ground-based rescue or evacuation. One should consider the severity of the patient’s condition, desired level of out-of-hospital care, access to ground transportation, weather conditions for helicopter flight, and if local receiving hospitals have the capacity to land helicopters. Specific medical conditions may be more appropriate for aeromedical transport (Box 58-1).
Common Aeromedical Transport Problems
1. Once the decision is made to transport a patient by air and the appropriate aeromedical service is contacted, preparations must be made to ensure safety and comfort and to aid the flight crew in patient care.
2. To minimize delays, pretransport preparations should be made for patients of acute trauma (Box 58-2).
Patient Movement
1. Patient handling and movement can contribute to morbidity and mortality in unstable persons.
2. All transported patients should be adequately secured to the stretcher with safety straps to prevent sudden shifting of position or movement of a secured fracture.
3. During transport from the ground to the aircraft cabin, attempts should be made to limit sudden pitching of the stretcher.
4. U.S. Department of Transportation guidelines recommend design of cabin access such that no more than 30 degrees of roll and 45 degrees of pitch may occur to the patient-occupied stretcher during loading.
5. The stretcher, in turn, should be adequately attached to the floor.
6. Motion sickness in the patient may be treated with an antiemetic such as promethazine (25 mg PO, IV, or IM) or prochlorperazine (5 to 10 mg PO, IV, or IM).
7. Transdermal scopolamine patches are useful for prolonged flights and do not require parenteral or oral administration. Scopolamine’s antiemetic effects are not always uniform and may not occur until 4 to 6 hours after application of a patch. Patches may best be used to decrease motion sickness in the flight crew because they are nonsedating.
8. A novel approach to prevention of airsickness that does not induce excessive sedation is to give 25 mg of promethazine orally along with 200 mg of caffeine.
Oxygen Availability for Flight
1. In general, enough oxygen should be provided for the flight, plus a 30- to 45-minute reserve.
2. Sufficient oxygen should be carried to allow for ground handling time at either end.
3. The amount of oxygen required can be obtained by multiplying the desired flow rate in liters per minute (L/min) by the total duration of transport, including patient loading and unloading.
4. Table 58-1 lists the capacities of various types of oxygen tanks and their respective weights.
Table 58-1
Aluminum Oxygen Tank Specifications and Approximate Endurance
*Fill pressure of 139 bar (2016 psi).
†Fill pressure 153 bar (2219 psi).
From Luxfer Gas Cylinders. http://www.luxfercylinders.com/products.
5. Some portable ventilators have a gas-driven logic circuit that requires additional air or oxygen. Electrically powered ventilators have a lower requirement for oxygen but carry the additional need for a power inverter.
6. Most patients are transported with oxygen supplied by nasal cannula (1 to 6 L/min). A single E-sized oxygen cylinder is adequate for short flights, although backup cylinders are usually carried.
7. Patients intubated and maintained on 100% oxygen, as well as those ventilated on long flights, will quickly exceed the capacity of an E cylinder; several E cylinders or an H cylinder will be required.
Noise
1. Noise can be avoided with hearing protectors, which are devices similar to headphones but without internal speakers.
2. Inexpensive hearing protectors are available as moldable foam earplugs. In some cases, headphones may be used in the awake patient if the crew wants the patient to be able to communicate on the intercom system.
Cold
1. For winter and cold weather operations, remember that rotor wash can produce wind speeds of 80 mph under the rotor.
2. Always adequately dress or protect the patient from freezing rotor wash when loading under power (“hot loading”) or for winch or short-haul operations (patient outside the aircraft).
3. Use goggles to protect from blowing snow, along with full head and hand protection.
Eye Protection
1. Serious eye injuries can result from debris blown into the air.
2. When a patient is loaded onto or off a helicopter with the rotors turning, the patient’s eyes must be protected.
3. The eyes must be protected even if the patient is unconscious.
4. Lightweight skydiver goggles (“boogie goggles”) or ski goggles are effective and inexpensive.
5. Taping temporary patches over the eyes is also effective.
Respiratory Distress
1. Persons with respiratory disease or distress should have immediately treatable conditions addressed before takeoff.
2. Endotracheal (ET) intubation is essential if airway patency is threatened or if adequate oxygenation cannot be maintained with supplemental oxygen.
3. It is better to err on the side of caution when making a decision about a patient’s airway.
4. During flight it is easier to treat restlessness in an intubated person than airway obstruction or apnea in a nonintubated person.
5. Nearly all patients should receive supplemental oxygen.
6. Fraction of inspired oxygen (FIo2) should be increased with increasing cabin altitude to maintain a stable partial pressure of oxygen (Po2).
7. When oxygen saturation monitoring is unavailable and pretransport arterial oxygen content unknown, 100% oxygen may be administered throughout the flight to ensure adequate oxygenation.
8. Persons with chronic lung disease who are prone to hypercapnia may undergo deterioration in condition if the hypoxic drive is eliminated. In these patients, the least oxygen necessary to maintain saturation above 90% is advisable.
9. Close in-flight monitoring is essential, preferably by continuous pulse oximetry. Portable end-tidal CO2 monitoring is now relatively easy to accomplish and should be used for intubated/ventilated patients whenever possible.
10. Altitude changes may affect ET cuff volume, so cuff pressure must be checked frequently.
11. If any other air-bladder devices (e.g., cuffed tracheostomy tubes, laryngeal mask airways, air splints) are present on the patient, they must also be adjusted during flight to avoid increased volume/pressure problems. Check these frequently.
Transport of Dive-Related Injuries (e.g., Decompression Sickness, Arterial Gas Embolism)
1. Aircraft selection is crucial because the stricken diver should not be exposed to a significantly lower atmospheric pressure in the aircraft.
2. Ideally, transport only by pressurized aircraft.
3. For nonpressurized aircraft (i.e., helicopter), the flight altitude must be maintained as low as possible, not to exceed 305 m (1000 feet) above sea level, if possible.
Cardiopulmonary Resuscitation and Cardiac Defibrillation
1. Cardiopulmonary resuscitation (CPR) in an aircraft is difficult. The rescuers must perform several tasks simultaneously while ventilating the lungs or compressing the chest, all in a physically confining space.
2. There should be no concern with airborne defibrillation if all electronic navigational equipment on the aircraft has a common ground, as mandated by Federal Aviation Agency standards.
