Medical Matters: Medical students need to be taught more about aviation medicine, according to Dr Moosajee Bhamjee, the former Labour Party TD and consultant psychiatrist in Ennis, Co Clare, writes Dr Muiris Houston.
Prompted by his experience of an in-flight medical emergency, Dr Bhamjee feels airlines should become more involved in educating doctors. "With the increased amount of flying, more complications will develop at airports or in the aeroplane - to be forewarned is to be forearmed," he wrote in a recent edition of Irish Medical News.
It is a view I agree with. Singapore Airlines has just announced what will be the world's longest commercial flight. The transpacific journey, from Singapore to Los Angeles, will take 18.5 hours. It is a long time to remain within the narrow confines of an aircraft.
One of the biggest aviation-related health scares of the past few years was the suggestion that air travel was associated with an increased risk of deep- venous thrombosis, or DVT.
The first reported case was in 1954, but studies since then had failed to establish a definitive level of risk. So a recent landmark paper on the subject in the British Medical Journal is most welcome.
Doctors from Canberra and Perth in Australia looked at the medical records of 5,400 patients admitted to hospital with DVT and matched them with data for international flight arrivals between 1981 and 1999.
The research was made possible by the fact that Australia has kept electronic data on the arrivals and departures of international travellers since 1970.
In addition, flight times from Perth, in Western Australia, to other airports are long, giving the researchers the opportunity to define a relationship between DVT and the length of a flight.
As a result, they established that an increased risk of a serious clot lasted for two weeks after a long-haul flight. The annual risk of DVT is increased by 12 per cent if a passenger takes one long-haul flight a year.
It is important to look at what the absolute risk of a clot is, however, rather than just focus on the percentage increase. Of just under 10 million people landing in Perth over an 18-year period, 246 developed venous thromboembolism within 14 days. This represents a small increase in absolute risk.
Significantly, the individual risk of death from a flight-related DVT for people with certain existing medical conditions is greater than the average risk of one in two million flights. So if you are taking the contraceptive pill, smoke cigarettes, had recent surgery or have cancer your risk is elevated.
Death from DVT is the result of the clot travelling to the lungs, causing pulmonary embolism. The incidence of pulmonary embolism is greater among passengers travelling more than 10,000 kilometres on a single flight. Singapore Airlines' new non-stop journey to Los Angeles covers 14,700 kilometres.
The Australian research is based on good records and large numbers of travellers, so we now have a much clearer picture of the risk of DVT among air passengers. At one in two million passengers, the absolute risk is not something that should concern a healthy person on a long-haul flight.
That said, it is still prudent for all passengers to move about the cabin as much as possible and to do the exercises outlined in most in-flight magazines.
Research is also continuing into the effects of jet lag. A study of US business travellers in which the participants used an actigraph - a watch-like device that monitors the wearer's movements - found that business travellers think they perform better and sleep more than they do. An objective assessment of their performance showed it dropped by 20 per cent while travelling.
The volunteers also reported getting an hour's more sleep than they actually did.
Exercise was the most effective way to increase performance. And the research found that travellers performed best in the afternoons rather than in the mornings.
The study looked at just 25 people who travelled across at least two time zones for a business trip of two to four days' duration.
Unlike the Australian DVT research, its results cannot be rated as definitive. Nevertheless, it provides an interesting insight into the challenges facing those who strive for peak performance on long-distance business trips. You can e-mail Dr Muiris Houston at mhouston@irish-times.ie. He regrets he cannot answer individual queries