Briefly discuss the problems specific to aeromedical transport of a critically ill patient.
• Transport by any means involves risk to staff and patients
• Need to be familiar with the use of the transport vehicle’s O2, suction, communications,and other equipment systems.
• Reduction in partial pressure of oxygen with altitude, critically ill patients who are already dependent on high FiO2 may be further compromised.
• Expansion of trapped gases – pneumothoraces, intracranial air from injuries
• Expansion of air containing equipment – ET tube, Sengstaken tube. ET cuff pressures will need to be adjusted
• IABP difficult to transport
• Risk of hypothermia
• As water partial pressure falls, risk of dehydration through resp losses and passive humidification important
• Auscultation is difficult.
• The ventilated patient is placed in the Trendelenburg and the reverse Trendelenburg positions during take off and landing respectively. This can impact on perfusion and oxygenation.
• Potential for pacemaker malfunction due to avionic interference.
• Staff doing air transport should refrain from compressed gas diving for at least 24 hrs prior to transfer.
• Physical problems: cold, noise, lighting, access to patient, motion sickness, acceleration injuries (eg head to front of plane to avoid increased ICP on takeoff)
This answer would benefit from a systematic approach:
Limitations of the aircraft
- Little space for large equipment (eg. ECMO, IABP)
- Little space for gas reserve (O2)
- Less equipment available
- Little room for CPR
- Changes in aircraft tilt place the patient in Trendelenberg and reverse Trendelberg positions
- Hypothermia can develop in the cold cabin
- The aircraft is noisy
- The lighting is sub-optimal
- Turbulence can cause injuries to the poorly restrained patient
Dangers of altitude: changes in the behaviour of gases
- ETT cuffs expand
- Gas-filled cavities expand (eg. bowel, pneumothorax, pneumoencephalus)
- Partial pressures of gas mixtures is lower (100% FiO2 at 2100m, the standard "cabin altitude" of commercial aircraft, is only 597mmHg)
- Evacuation by air of those who have bee deep-sea diving is best avoided for about 24 hours- decompression sickness may result.
Dangers of altitude: changes in fluid behaviour
- Decreased boiling point at altitude increases the rate of evaporative loss
Dangers of aircraft operation
- Avionics may interfere with pacemakers
- Noise may interfere with equipment alarms
- Vibration interferes with examination of the pulse
- Auscultation is practically impossible
- Motion sickness may cause vomiting and aspiration (it would suck to be intubated purely because of motion sickness)
Parsons, Chris J., and Walter P. Bobechko. "Aeromedical transport: its hidden problems." Canadian Medical Association Journal 126.3 (1982): 237.
CICM "Minimum Standards for Transport of Critically Ill Patients" (IC-10, 2010)