TRANSFER BY AIR

Patients, with dysfunction or failure of one or more organs can be categorised as critically ill patients. They depend on advanced monitoring and therapy to sustain their lives.When equipments, personnel or other facilities are not available or insufficient to deal with the critically ill patients, they should be transferred to a tertiary centre. Since these patients have reduced physiological reserves, even short trips can cause signi ficant adverse effects. Movements in the vehicle, temperature and pressure changes also affect them badly. The other problems to be faced are vehicle accidents and stress related health problems for the transporting personnel. Modes of transport that are available range from family car to fixed-wing aircraft. Here we are discussing the problems in transportation  by air with special referrance to helicopter or aircraft. Air lifting is appropriate if the transportation distance exceeds over 150 miles.Consider the following factors when air transportation is planned.

• Weather and climatic conditions, whether suitable or not.
• The time required >; to arrange the aircraft, to get permission to cross the borders of  a neighboring country, to arrange the staff and equipments.
• The risk benefit ratio.
• The condition of the patient, means the physiological tolerance
• The cost effectiveness

The advantages of air transport are

• Rapid transport (30-50% time of ground transport, 120-180 MPH covering up to 150 miles)
• Easy access to difficult locations
• Smoother flight
• Decreased incidence of accident, unless the craft is faulty

The disadvantages are

•    Helipad or aerodrome needed
•    Space and weight limits
•    Patient access limited
•    Increased noise level (90-110 dB)
•    Motion sickness 
•    Incorrect NIBP and SPO2 measurement due to movement and vibration
•    Weather restrictions
•    Altitude effects (>8000 ft) (mentioned below)
•    Cost to operate

A lower barometric pressure at high altitude can cause a reduction in the partial pressure of the oxygen in the alveoli. At 1500 meters Pao2 is about 75 mm of Hg. Also noise and vibration can cause autonomic dysturbances leading to nausea, vomiting, hypertension or tachycardia.Air contained in closed spaces and body cavities will get expanded due to low atm pressure. These problems are more with a helicopter and can be reduced significantly, if transportation is done by fixed wing aircraft as the cabin is pressurised to atmospheric pressure. The aircraft can offer more space, is fast, and can manage bad weather, cause less noise and vibration but are expensive.The other problems of air lifting include vibration leads to failure and inaccuracy of NIBP, limited Access to the patient ,accelaration and decelaration,hypothermia,etc. Pulse oxy meters may be un reliable in cold and moving patients.

How to manage transport?

• Increase fio2 if cabin is open
• Drainage of pneumothoraces
• All tubes eg, NG tube should be kept open
• Split plaster casts, as these may cause ischemic injury of the limb due to swelling up of tissues

According to General Surgeon, Neel, (commanding officer of the helicopter, medical evacuation program in Vietnam) The helicopter must be incorporated into an integrated medical system. Such a system must include centralized control, adequate, reliable communications, methods for locating and reporting casualties, and skilled medical personnel to provide attention at the site of the injury, during flight, and at the arrival of the the hospital.

Thanx to: Dr.Babji Kalapati, Anaesthetist, ARMED FORCES HOSPITAL, MUSCAT, for sharing the information

Ref:   Oxford handbook of critical care, 3rd edition page 648