Mike and Chris sent me this nice up to date review article of critical care air transport. Its mainly North American focussed but covers the broad base of literature on the topic:
Wilcox S, Tollefsen W. Air Transport Of The Critically Ill Emergency Department Patient. EM Critical Care, Vol 2 Num 4, 2012 [Abstract]
Here is the usual LITFL Q&A format to for a quick review of this topic.
Q1. What is the most common work of air transport teams and helicopter ambulances in Australia and USA?
In one review, 80% of critical care transport team missions were interfacility transfers. Fixed wing and helicopter ambulances undertake the bulk of long distance interfacility transport work in Australia and USA.
Q2. What conditions benefit the most from air transport and critical care transport team management?
Trauma by far and away carries the best evidence for benefit with up to a 33% reduction in trauma related death for the more severely injured patient compared with ground transport. STEMI and air transport to a PCI capable hospital appears to be beneficial as opposed to immediate thrombolysis as long as its timely, although more ALS interventions are needed with air transport within first 24hrs of STEMI.
Q3. Unstable patients are prone to deterioration during air transport due to a number of environmental and physical reasons. What principles can be applied to adequately prepare the critical patient for air transport?
Take a systematic ABCDE approach and consider that interventions during flight are more difficult than on the ground. Stabilise the patient’s physiology as much as possible. All lines, tubes and drains must be secured for considerable movement. Adequate analgesia and/or sedation is crucial for patient comfort as they will be moved multiple times. A systematic clinical handover tool is the single most effective measure in all patient transport scenarios.
Q4. Which patients should not fly?
There are few absolute contraindications but clearly the maxim should be that air transport should provide a reasonable measure of benefit to the patient.
Cardiac arrest patients are unlikely to benefit from air transport but the growing use of mechanical automatic CPR devices may change this notion! Actively labouring pregnant women are considered a strong contraindication to flying but this is dependant upon the local health care facilities and staffing and effective tocolysis may allow air transport to occur without delivery. Agitated combative patients are considered a strong contraindication to flying and careful stabilisation, sedation and restraint need to be applied prior to taking such patients into the air.
Q5. Boyles law tells us that any volume of gas will expand with decrease in ambient pressure. Traditionally this has meant considering endotracheal tube cuffs being filled with saline as opposed to air. Why is this a retrieval medicine myth?
Endotracheal cuffs are designed to be inflated with air. They are tested prior to sale with air. Despite your best attempts, it is almost impossible to remove all the residual air in the cuff. When filled with saline, the residual air will expand and the cuff will grow in volume. Certainly it will not expand as much as if all air is used to fill the cuff. The smart thing to do is measure the cuff pressure regularly during air transport with a portable cuff manometer. It is impossible to do this accurately with a saline filled cuff.