This paper was published in the British Medical Journal as one of their fortnightly review series
Dr Tony Goodwin
In-flight medical emergencies are attracting increasing levels of interest from the media, travelling public, aviation industry and medical profession. Reasons for this are discussed and the magnitude of the problem estimated from available data. Methods for preventing these emergencies and present facilities for dealing with them are listed and future requirements considered.
Search of recent literature for conference presentations Refs (1) + (2) statistics made available by Virgin Atlantic Airways (VAA).
The provision of medical care in the air is attracting increasing levels of interest both from the travelling public, the aviation industry and now the medical profession. As older, less healthy, passengers wish to fly often considerable distances, there is the expectation that the airlines will look after them should problems arise. Similarly those with known illnesses or disability expect no discrimination and that special facilities should be provided to make their journeys possible. The gap between air ambulances and well-equipped commercial aircraft is narrowing! Nearly 300 patients were repatriated by Virgin in 1998, often after pressure from the repatriation companies acting on behalf of insurers as well as the patients themselves for an early return to the safe (and cheap!) care of the NHS care. In fact, carrying ill passengers can be quite lucrative for the airline who sell 12 seats for a stretcher, as well as adding a doctor and nurse to the passenger list! Each year Virgin take around 50 such cases, but limit the number of non-ambulatory passengers to 10 on a Jumbo and 6 on an Airbus.
Air travel can precipitate or contribute to medical problems in a number of ways. The stress of getting to and through a modern airport is not the most relaxing way to start a day. Uncertainty due to delay compounds the anxiety and, may mean too long spent at the bar. 75% of medical emergencies occur while travellers are still on the ground. (3)
Once in the air the drop in pressure (the cabin is kept at the equivalent of 6-8000 ft altitude) causes gas expansion and less oxygen to be available. Middle ears and sinuses blocked by catarrh feel as if they will explode as the air inside expands by some 30% and are even more painful on the descent. Decongestants, analgesics, swallowing and Val Salva are all the doctor can offer. The effect on pneumothorax has been well publised! The reduced partial pressure of oxygen should not effect the healthy passenger due to the nature of the oxygen dissociation curve, but those with compromised cardiovascular or respiratory systems or blood disorders may suffer. (4) Shortness of breath may be due to myocardial insufficiency, lung disease or hyperventilation (there is no shortage of paper bags).
As the journey proceeds the dry cabin atmosphere irritates mucous membranes. Drinking extra fluid helps, but alcohol has the opposite effect as its intoxicating properties are enhanced at altitude and often contribute to "air rage". Time zone changes and altered meal times can confuse insulin dependent diabetics into hypoglycaemia, though diabetic meals can be provided. Passengers on other strict drug regimes may also fall foul of this, especially when they have packed their medication in the hold! Restricted space in most seats encourages musculo-skeletal aches which should be relieved by regular stretching exercises and walks to the toilets! Scalds are quite frequent as hot drinks are served in a crowded area and so are head injuries. Finally, problems on the individual flight can cause medical emergencies and though rapid decompression of the cabin is thankfully rare, turbulence is much less so. One passenger was killed and nearly a third of them injured in such an incident (not a Virgin flight!) two years ago.
The size of the problem and the risks involved are hard to estimate. Airlines are not required to monitor medical incidents, less still notify a central register. Indeed there is a difficulty in definition of an "incident" or "emergency" in any case. Does it include diarrhoea and vomiting, shortness of breath, a faint? For these are the most commonly occurring conditions in flight for which medical help is sought.
Diversions for genuine medical emergencies must depend on the routes operated and the possible ports with medical and aviation facilities. As aircraft get larger, presumably the choice will diminish. The commonest reasons for diversion worldwide are continuing unconsciousness, acute breathing difficulties, severe and uncontrollable pain, uncontrolled bleeding, major injury with shock, impending birth and uncontrollable mental disturbance. Emergencies on Virgin flights over the last two years are shown in table 1. You can see that Virgin diverted ten times for such cases in 1997 and eight times in 1998. It is unfortunate that confidentiality prevents the airline from learning the outcome of all these cases, and audit must largely be based on percentage of hospital admissions.
The figures for in-flight deaths are similar vague, varying around the world between 0.1 (5) and 1.0 (6) deaths per million passengers carried or one death between 1.5 - 4.7 billion passenger miles flown. (7) But how accurate are they? There is a suspicion that death rates are under reported because of bad publicity and, as on the ground, the patient will sometimes not be declared dead until arrival at hospital. This can circumvent a lot of red tape. Good news then that at least all deaths in America aircraft must now be reported to the FAA. (8)
It should be possible to avoid many in-flight emergencies by careful screening of passengers with pre-existing medical conditions. Unfortunately we only get to hear of these if the passenger requests some extra facility, or declares them if taking out holiday insurance. The information is usually provided on the IATA 'Medif' form, filled in by both client and doctor. The form is badly designed and the information frequently unintelligible. I often end up having to phone the doctor concerned, which is a nuisance for both. It's also interesting how the story can change when the passenger realises that their clever attempt to get their seat upgraded for medical reasons could suddenly threaten their acceptance to travel! I dealt with over 1300 such clearances last year and the total number of passengers with a medical request increased by 55% from 1997 to 1998. Luck has been on my side and the only case of medical emergency causing diversion of which I had any prior knowledge concerned an epileptic who failed to take the regular medication.
Sometimes a check-in supervisor suspects a passenger is unwell and 'phones for advice. This is always difficult to deal with at a distance, as the passenger is usually loathe to abandon their trip on a telephone decision and few airports have a doctor available at short notice. No criteria for refusing or accepting a passenger are set in stone. For instance, advice on when it is safe to fly after an uncomplicated heart attack varies from 10 days (9) to 24 weeks. Some even suggest trial by treadmill (10) first! New challenges such as the current "peanut allergy" dilemma also command attention. Precluding mothers 34 or more weeks pregnant has denied us the challenge of delivery on board so far. New babies I considered fine to fly after 24 hours until a certain professor linked it with cot deaths, so now I have to put the onus on the obstetricians.
However, the majority of medical emergencies in the air (table 1) happen unexpectedly in a traveller who is perhaps not planning to have a heart attack that day, or (after dosing with large portions of grape juice) falls into a deep sleep with legs crossed and suffers a pulmonary embolism. (11)
Cabin Staff Training
Of all our onboard facilities, the most valuable are the cabin staff. All airlines are required to give some first aid training, but Virgin's AVMED system is particularly comprehensive, the initial course lasting five long days followed by a practical and a multiple choice written exam. It covers all aspects of first aid as well as practical advice from jet lag to positioning the deceased. The annual refresher course and CPR practice lasts a day and again is followed by an examination. Flight deck crew undergo a day's initial course and a half day recurrent, dealing with prevention of food poisoning to deciding to divert. Training 1,800 cabin staff cost Virgin a quarter of a million pounds in 1997.
On-board medical professional
Despite this training, the announcement "Is there a doctor on board?" often booms from the PA, and apparently one is available on between 8 and 86 percent of flights worldwide. (12) On Virgin flights in 1997 only 4 times was one not available when requested, 8 in 1998 (table 1) As only one of the defence unions will support us while working over American or Canadian airspace, (13) Virgin took out an insurance policy indemnifying anyone who comes forward to help. However, I believe the recent US Medical Assistance Act liability clause (14) should make these precautions unnecessary. Other offers of help to Virgin have come from a Spanish team who proposed to place a doctor and nurse on every aircraft, to more recently the concept of telemedicine, possible now that Satellite telecommunications can transmit digital data. Three different systems are at present being assessed by Virgin.
A recent innovation used by Virgin and several other airlines is Medlink, a direct communication between the cabin crew and Medaire, a medical facility in Phoenix Arizona. Attached to the ER of the Good Samaritans Regional Medical Centre the doctors have studied the problems of in-flight emergencies and are available to give instant advice on how to proceed. Up to date lists of airports suitable for diversions with details of medical facilities are also available. Provided the communication is clear this facility gives confidence to crew and any on-board doctor, and once contacted relieves the doctor of liability. Medaire's insurance covers this as well as the cost of any subsequent diversion. However, it is the captain who makes the decision of whether to divert or not, and he is instructed in case of dispute to follow Medaires' advice over that of any onboard doctor or nurse.
Of all the requests I receive for extra facilities, oxygen for COPD or a heart problem is the commonest. The market for in-flight therapeutic oxygen apparently grows by 10 to 12 percent per year worldwide, but in Virgin, where we provide it free to individual passengers, the demand in 1997 trebled! The facility was provided 425 times in 1998 and continues to rise. Oxygen-driven nebulisers can also be provided if requested by the passenger's doctor in advance.
Supplementary oxygen is available in 240 litre cylinders, providing a flow rate of 2 or 4 litres per minute; used continuously they will last for a couple of hours at the lower rate and ten are carried on Virgin's Jumbos and Airbus. The logistics of carrying so many oxygen cylinders have led to interest in new ways of providing oxygen on aircraft and a variety of concentrators and generating devices are "in the pipeline". Virgin has tried one of the concentrators but as yet it is reserved for stretcher cases. As for the generators, the suspicion that one might have contributed to the Valuejet crash brings their safety under special scrutiny.
Emergency medical kits (EMKs)
The provision of first aid equipment onboard aircraft varies considerably worldwide. Until recently the US FAA required little more than a simple kit as carried by our cabin staff, compared with the new regulations (15) that become mandatory in the European Community this year. "Unfortunately, there is little information available regarding in-flight medical events and medical kit usage. These data are vital if the airlines are ever going to design a standardised list based upon relevant information rather that the educated guess", a comment by the Director of the Aerospace Medical Association that neatly defines the problem (16)
A balance has to be found between possible medical requirements and storage space, training, security, shelf-life, and cost effectiveness. It is easy to put in too many items. It became clear some time ago that the Emergency Medical Kit (EMK) carried by Virgin, though apparently satisfactory at its introduction, was not ideal. 17 of the 27 drugs were rejected and 11 new ones added. The kit does now I believe achieve that correct balance. In 1998 it was opened 144 times (table 2) The most commonly used medications were IV glucose, Diazepam and Sodium Chloride, IM Metoclopramide, and Ventolin via nebuliser. An additional source of medication is from the passengers themselves who will often produce a small chemists' shop if invited over the PA!
Automatic External Defibrillators (AEDs)
Virgin was the first airline to carry AEDs and the present Physio-Control Lifepak 500s are simple to use with clear audio instructions. They include ECG storage for subsequent review.
They cost around £2,500 each and an extra £20,000 is spent annually on training the 440 pursers and in-flight supervisors (IFSs) in their use. They were applied five times in 1997, twice to passengers with terminal cancer, twice for cardiac arrest without fibrillation when no shock was advised; all died.
The fifth application was on a 73 year old man on a flight from Heathrow to Miami in December. Six hours into the flight he clutched his chest in pain and became unconscious. When the electrodes were placed on his chest by the IFS the AED analysed no fibrillation and advised CPR. After one minute a second analysis was called for, and suddenly the heart went into ventricular fibrillation. The AED voice prompted 'Shock Advised - Stand Clear', and the first shock was delivered, just 17 seconds after onset of fibrillation, and the fibrillation ceased. Fibrillation resumed three times before the fourth and final shock restored normal rhythm. A consultant anaesthetist on board administered Hydrocortisone, Frusemide, Adrenaline and Dextrose from the EMK and advised diversion. The Jumbo's captain put it down into Charlestown Airport some 25 minutes later and the passenger was escorted to the local Hospital by paramedics and the Sheriff. He had a defibrillator implanted and was back home for Christmas.
Provision of AEDs onboard aircraft has always been controversial, though QANTAS too have had success over the years. (17) Recent litigation however, has helped increase their popularity and now British Airways as well as most major American long-haul carriers are getting equipped with them and will have cabin staff trained in their use on every flight.
With all the above equipment and facilities it should be possible to deliver primary care more promptly and at least as adequately as on the ground.
In-flight medical emergencies are likely to increase as air travel continues to expand and the population's life expectancy lengthens. Provisions made by the airlines continue to improve in response to this demand and to changing medical technology and practices, but commercial, financial and practical considerations have to be taken into account. The role of the on-board doctor has never been easy, working often in isolation with limited facilities in a hostile environment. Recent changes in attitude by the airlines should make the task easier, safer and more professionally rewarding for any doctors who come forward to help and act within their normal capabilities.
Tables (not in this version)
In-flight medical emergencies present additional challenges to those on the ground.
Drop in cabin pressure at altitude means less oxygen and gas expansion.
In-flight emergencies will increase as more elderly passengers fly greater distances.
Data on emergencies and deaths worldwide is scarce, but Virgin figures for 1997 & 1998 are given.
On-board facilities including oxygen, defibrillator and medical kit contents are listed.
Hopefully, good primary care facilities and removal of legal liability concerns will encourage on-board doctors to come forward.
Airport Medical Services Limited