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Rescue
Transport of the critically ill
Is there a doctor in the helicopter?
MJA 1998; 169: 610-611
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In this issue
of the Journal, Bartolacci, Munford and
coworkers1 present
an Australian perspective on major controversies in aeromedical
transport. The controversies revolve around two central questions:
the benefit of helicopter as opposed to ground transport, and the
benefit (or otherwise) of a doctor as part of the transport team. While
articles on these aspects of patient transport have been published
since the early 1970s, good research is lacking. This largely
reflects the difficulty of conducting controlled trials in an
extremely complex field with many uncontrolled variables.
The article by Bartolacci et al illustrates some of these problems: comparison groups were not randomised and data being compared (eg, admission versus scene data) were not directly comparable. This emphasises the need for a more scientific approach to this form of research. Even the often-quoted landmark studies by Baxt and Moody,2,3 which concluded that medical staffing of a helicopter rescue service significantly improved outcome, had similar drawbacks. They used scene data to calculate trauma scores for the cohort of patients treated by doctors (as part of a helicopter team) and compared outcomes with scores calculated from admission data for the group of patients treated by paramedics. Another study came to the opposite conclusion. Nicholl and colleagues4 found that the London HEMS (Helicopter Emergency Medical Service) made little impact on survival, except perhaps in the most severely injured patients. They used complex statistical manoeuvres in an attempt to artificially separate the effect of the helicopter team's intervention from that of the helicopter transfer and of the major trauma service receiving the patient. Even when the methodological flaws of these studies are overlooked, the conclusions reached are often specific to the system studied, and therefore have little external validity. For example, like Bartolacci et al, Dalton and colleagues concluded that a doctor was of benefit on a HEMS, as he or she could perform procedures that paramedics were not trained to do, such as orotracheal intubation.5 This may apply to the London HEMS, but other systems train non-physician flight staff to perform orotracheal intubation with or without muscle relaxants.6,7 A further concern is that most of the published work to date, like that of Bartolacci et al, focuses on trauma patients, and particularly on scene response. While trauma is important and rapid access of patients to definitive care has been demonstrated to be of benefit, it accounts for only about a third of patient transfers to hospitals (by all modes) for provision of specialised care. Several studies of all forms of interhospital transfer of critically ill non-trauma patients support the view that in such cases not only is it beneficial to have a doctor as part of the transport team, but that the doctor must be highly experienced in the management of critically ill patients -- junior doctors provide no benefit.7-9 While it will not be possible to make valid, universally applicable conclusions until detailed databases are established to act as a basis for integrated transport research, the work conducted to date suggests that the presence of an appropriately trained physician on a helicopter may make a significant impact on the outcome of patients in some circumstances: stable patients with cardiac problems, for example, may not require medical treatment during transport, whereas patients with complex critical illnesses may require an experienced clinician.
Despite the limitations and difficulty interpreting studies to date, some aspects of a critical care transport system seem from first principles to be beyond debate.
Minimum standards for such transport are detailed in the joint policy document of the Australasian College for Emergency Medicine (ACEM) and the Australian and New Zealand College of Anaesthetists (ANZCA),10 the essential principles being that transport should aim to improve patient care, and that "management during transport should equal or better management at the point of referral". In the debate about the benefit of helicopters as opposed to ground transport, helicopter transport is more expensive, but has the advantage of being able to collect patients from the roadside or referring hospital and deliver them more rapidly to the receiving institution. However, patients less than 30 minutes by road from hospital generally do not benefit from helicopter transport. Similarly, beyond 300 km, or when helicopter flight time exceeds one hour, the question becomes whether the greater air speed of fixed-wing aircraft can overcome the delays inherent in transferring patients between hospitals and airports. The actual point at which the balance favours fixed-wing aircraft probably depends on the conditions, patient needs and the type of aircraft used.11 It is clear that methodologically sound systems research is scarce in the field of critically ill patient transport, but that medical staffing is required for optimal management of some critically ill patients. Peter A Cameron Salomon Zalstein
©MJA 1998
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