Weapons and Ammunition
You must understand that a patient’s weapons and ammunition will be a concern for you when trying to get your patients onto the aircraft. The easiest way to avoid controversy with the AE crew and the other aircrew members is to anti-hijack the individual yourself. To “anti-hijack” the patient, do the following:
- Separate the ammunition from the weapon; the loadmaster (if no loadmaster, check with Aircraft Commander, or Medical Crew Director, or Flying Crew Chief) will secure the ammunition. Make sure the weapon has been CLEARED! If time permits, label the weapon CLEARED and identify the owner.
- Secure any explosives prior to entry to the plane (aircraft and explosives are a bad combination). Make sure to check the patients’ uniform pockets for C-4, detonators, grenades, ammunition, etc. - Secure knives with the loadmaster or designated individual in a similar fashion as the ammunition - Search bags and rucksacks for ammunition, knives and explosivesl; take appropriate action as described above.
- If possible, leave ammo/explosives with the remaining SOF unit if possible.
- Civilian air ambulance companies will not take weapons, ammunitions or explosives. The unit is responsible for securing these or arranging to leave behind.
General Principles of Flight Physiology/Gas Laws. The temperature, pressure, volume and relative mass of a gas influence the body’s response to barometric pressure changes as the aircraft changes altitude. Barometric/atmospheric pressure is the pressure exerted against an object by the atmosphere.
Boyle’s Law: The principle of gas expansion. The volume of a gas is inversely proportional to the pressure. Increasing altitude decreases barometric pressure. An example is a balloon expanding at altitude. If there is free air in the chest or cranium, the expanding air pressure will cause increased pressure inside the structure. An altitude restriction is required. Consult the PMCC.
Dalton’s Law: The law of partial pressure. As altitude increases, barometric pressure decreases. However, oxygen partial pressure/concentration remains 21% of the total air regardless of altitude. Consequently, as altitude increases, the partial pressure of oxygen decreases. The actual available oxygen to the tissues decreases with altitude because oxygen molecules move farther apart. This can result in hypoxia, or lower levels of oxygen to the tissues and cells.
Charles’ Law: When the mass of a gas is kept under constant pressure the pressure will increase or decrease as the temperature of the gas increases or decreases. As an example, the pressure reading in a tire or an oxygen tank decreases as the temperature decreases.
Henry’s Law: The solubility of gases in liquids. The weight of a gas dissolved in a liquid is directly proportional to the weight of the gas above the liquid. An example is shaking a can of soda and
opening it immediately. The balance of pressure is altered, releasing the bubbles of gas in the soda. The release of nitrogen bubbles into the blood after a flight or diving decompression causing the bends is another example. An altitude restriction is required. If the patient has conducted scuba diving operations 24 hours prior to entry into the AE system, inform the AE crew.
Graham’s Law: The law of gaseous diffusion. Gases flow from higher pressure (or concentration) to a region of lower pressure (or concentration). Simple diffusion or gas exchange at the cellular level is an example.
Physiological Stresses of Flight. Patients in the AE environment are more susceptible to the physiologic stresses encountered at altitude. Clinical factors include patency of the respiratory passages, neuromuscular function, rate and depth of respiration, adequate blood flow and diffusion of oxygen at the alveolar and cell level, an adequate hemoglobin level and a functioning respiratory center.
Decreased Partial Pressure of Oxygen (pa02). The effects of higher altitudes plus the patient’s condition can lead to hypoxia. There are four types of hypoxia requiring in-flight oxygen:
1. Hypoxic hypoxia or altitude hypoxia: If oxygen is required on the ground, it may be necessary to increase the O2 flow rate to maintain oxygen saturation levels at 90%.
2. Histotoxic hypoxia or tissue poisoning: affects the tissues ability to utilize oxygen. Caused by carbon monoxide poisoning, cyanide and alcohol.
3. Hypemic hypoxia or reduced oxygen carrying capacity of the blood: Caused by hemorrhage, anemia, sickle cell anemia, cyanide and carbon monoxide (which has 200% greater bonding affinity to hemoglobin than O2).
4. Stagnant hypoxia or reduced cardiac output: due to pooling of blood and reduced flow to the tissues caused by respiratory failure, shock, PEEP, tourniquets, embolus, and heart failure. Barometric Pressure Changes. On ascent, gas expands and on descent gas contracts. Trapped or partially trapped gases in body cavities (GI tract, lungs, skull, middle ear, sinuses and teeth) expand. Untreated gas expansion in the abdominal cavity can cause diaphragmatic crowding resulting in decreased lung volume and expansion. This can be relieved with a vented NG tube. Additionally, the ear and sinuses must adjust as the cabin pressure changes. Flying with a cold, sinus infection or facial or head injuries can require decongestants or an altitude restriction.
Thermal Changes. Aircraft cabin temperature can fluctuate considerably. Temperatures can range from freezing up to 90° while on the ground. In-flight temperatures tend to be cooler. Hyperthermia and hypothermia are seen in burns and frostbite. Both conditions increase the body’s oxygen requirements.
Decreased Humidity. When air is cooled, it loses its ability to hold moisture. Air at altitude is cold and dry. After two hours of flying time, relative humidity is 5% and after four hours, it is less than 1%. Oxygen needs humidification.
Noise. Unprotected exposure to noise can interfere with effective communication, produce temporary threshold shifts (auditory fatigue), permanent threshold shifts (sensorineural hearing loss) and varying levels of fatigue. Wear hearing protection when the aircraft’s engines are running.
Vibration. The mechanical energy of aircraft vibration is transferred to the tissues and increases muscle activity, especially if in direct contact with the aircraft fuselage. Extra padding of suspected injuries can diminish pain.
Fatigue. All of the stresses of flight induce fatigue to some degree.
Gravitational Forces (G-Forces). When the aircraft accelerates or decelerates, the body responds by moving in the same direction as the aircraft. Severe head injuries can sustain further damage if the head of the litter is not elevated or if the aircraft produces sudden movement, such as during carrier takeoffs and landings.
Special Considerations
A thorough primary and secondary preflight assessment, documentation and communication will improve patient outcomes.
Airway: Secure with C-Spine precautions as needed.
Glasgow Coma Scale (GCS) less than 8 can indicate hypoxia and the patient may need to be intubated prior to flight.
Endotracheal or tracheostomy tubes are the best choice. Use sterile water or saline instead of air to inflate the balloons. Document the amount of fluid used.
Report tube size to PMRC
Breathing: Give humidified oxygen to maintain 90% saturation Rule out tension pneumothorax. Use a Heimlich valve on chest tubes Circulation: Control bleeding
Maintain IV fluids; keep track of intake and output.
Immobilized fractures. Do not use air splints or MAST trousers in-flight. Disability: Documented baseline GCS and vital signs preflight are essential. Head Injuries:
Secure the airway. Use caution with facial fractures Elevate the head and torso to 30°, if not contraindicated. Dress wounds
Check pupils, verbal response, clear drainage from ears or nasal passages Secure the cervical area, as necessary
Thorax:
Check breath sounds Check for flail chest
Check for a mediastinum shift
Rule out hemothorax/pneumothorax or ruptured diaphragm; securely tape Heimlich value on chest tube, (the AE crew can provide one)
Report blood loss to TPMRC and AE crew Dress wounds as appropriate
Abdomen and Perineum:
Dress wounds. In the event of exposed bowel, cover with saline dressing and reinforce (if available). Do not insert bowel back into the abdominal cavity. Do not change dressings in-flight. Prior to inserting a Foley catheter, inspect for obvious or suspected abdominal injury. Males: check the rectum/prostate for potential urethral tear. Females: check for obvious vaginal bleeding. Use sterile water or saline instead of air to inflate the balloons.
Extremities:
Stop hemorrhage, apply pressure dressings, elevate the limb. Dress and splint as appropriate
Perform circulation and neuro checks; reapply dressings and splints as needed.
Altitude Restrictions:
The following injuries will require an altitude restriction to decrease the likelihood of any further injury/complications. (When air is introduced into a cavity, it will expand at altitude, potentially causing further injury):
Head injuries Eye injuries
Traumatic chest and abdominal injuries
Decompression injuries (will require destination field elevation and 100% oxygen) Injuries/complications involving the heart if severely compromised.
Note: It is important to note that if there is an altitude restriction, the flight time will be lengthened. Inform the PMCC of the likelihood of an altitude restriction.
In the event that you feel there is a requirement to have specialized medical personnel to augment the AE crew, inform the PMCC.