Lung Patients Should Be Careful On Flights

Main Category: Respiratory / Asthma
Article Date: 27 Nov 2007 - 1:00 PDT

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Up to 10% of in-flight medical emergencies involve lung disease, according to major airlines' statistics. In the USA, it is the third most common medical reason for emergency landings, after cardiac and neurological problems.

And it is not only the patients themselves who suffer when they experience respiratory complications during a flight. Other passengers are affected too, and there are economic losses: emergency landings of this kind cost almost $100,000 in just one year in the USA.

In this context, the original study published in the forthcoming issue of the European Respiratory Journal (ERJ) by Robina Coker and her team (Department of Respiratory Medicine, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK) provides some reassurance. It shows that careful pre-flight examination of the patient and good in-flight monitoring, with oxygen therapy if needed, should prevent adverse events for most lung patients.

The growing trend for long-distance travel and the ageing population mean that the proportion of air passengers with health problems will inevitably rise. This has its dangers, and the risk of medical emergencies increases further on longer flights. Out of all travellers with health issues, lung disease sufferers are a special category because of the air pressure in aircraft cabins. As Coker mentions in her ERJ article, commercial aircraft, even when flying at a height of 10,000-12,000 metres, are designed to have cabin pressure equivalent to an altitude of 2,438 metres. It is not unusual to find pressure equivalent to an altitude of 2,700 metres.

Lack of recommendations

In these conditions, partial pressure of oxygen (PaO2), which reflects the quantity of oxygen transported in the blood, falls very markedly. In healthy subjects, it can easily fall from 100 mmHg (normal pressure) to as little as 53-64 mmHg. While this drop in PaO2 is harmless for most people, it can have a significant impact on lung patients, who have a relatively low PaO2, even at sea level. There are recommendations in the USA and Europe for air travel by lung patients - as the article's authors emphasise - but they generally apply only to those with chronic obstructive pulmonary disease (COPD). Only the UK has published guidelines for other lung conditions.

Over 600 patients monitored

To identify the risks associated with air travel for various lung conditions and the potential benefits of in-flight oxygen therapy, Coker and her team conducted a large prospective study. The subjects had to be monitored by a lung specialist and be planning a flight on a commercial airline. During the examination conducted in the three months leading up to the flight, each patient was given at least two additional tests: pulse oximetry and lung function testing (FEV1 or forced expiratory volume in one second).

The participants then took their flights, after which they were invited to complete a questionnaire and return it within two weeks of coming home. In total, the study included 616 patients recruited from 37 respiratory medicine clinics. They had various diseases, most commonly asthma and COPD, which accounted for a total of 54% of patients. Almost a quarter (23%) had interstitial lung disease.

Approximately half (275 patients) underwent a hypoxia test, and half of those tested were recommended for in-flight oxygen therapy.

Various consequences

The results reported in the ERJ contain a rather surprising finding: just over 10% of patients did not, in the end, take their flight. Of those, 31 did not travel for health reasons, often on medical advice. For ten others, the problem was the recommended oxygen therapy (either they did not want it or the airline refused to allow it) or the prohibitive cost of insurance. Seven patients died before the date of their flight, almost all from respiratory problems. The remaining non-travellers simply changed their minds for personal reasons.

Of the 431 subjects who did travel and returned their questionnaires, almost one-fifth (18%) suffered respiratory symptoms either on the outward or return flight, or both. Increased breathlessness (77%), cough (44%) and chest pain (23%) were the most frequently encountered symptoms. Their intensity, however, was usually moderate. "Five patients did need medical attention during the flight," Coker emphasises, "but only one of those was for a respiratory exacerbation. What's more, there was no need for emergency landings or repatriation and none of the patients died during the flight." It should be noted, however, that five patients died within the month following the flight.

A low death rate

"The death rate in the thirty days post-flight was below one per cent", Coker and her team point out. However, they note that, of the 81 patients who visited the doctor in the four weeks following their return, 65% were prescribed antibiotics for a lower respiratory tract infection. "That could be a complication resulting from the flight, but it needs to be confirmed by other studies," the authors explain.

This major multicentre prospective study thus proves that even a severe lung condition is not a contra-indication for flying, as long as the patient undergoes a thorough medical examination beforehand. "Patients should also check before flying that they have insurance cover and, if necessary, obtain extra cover for oxygen," Coker adds. "But even if all precautions are taken, there can be no absolute guarantee that everything will go well."

The European Respiratory Journal is the peer-reviewed scientific publication of the European Respiratory Society (more than 8,000 specialists in lung diseases and respiratory medicine in Europe, the United States and Australia).

European Respiratory Society