DVT can kill

The Maltese love travel; long distance flights to North America and Australia are common and on the increase. There are several risks associated with air travel and one risk, not very obvious, but one which can have serious consequences, has to be kept in mind.

Public awareness of the dangers of deep vein thrombosis (DVT) was low until Emma Christofferson, 28, died soon after a 12,000-mile journey from Australia to London in 1999.

Another death which made the headlines last Christmas was that of Alayne Wake, also 28, who felt unwell near the end of her journey from Singapore to London; she collapsed in the cabin and never regained consciousness.

Many cases of DVT remain symptomless and undetected or they are diagnosed days after the journey, so estimates of the extent of the problem vary but it is generally accepted that passengers flying for eight hours or more stand a 10 per cent risk of developing DVT. It has been claimed that flight-induced blood clots are killing 2,000 passengers each year in the United Kingdom. However inaccurate these figures may be it is worth remembering that the risk is a real one and needs to be taken seriously.

DVT is the result of the formation of blood clots which can block a vein in a stagnant or sluggish circulation. The clot can travel to the lungs to give rise to a life threatening condition, or it can cause a swollen, discoloured and painful leg. Because of the cramped conditions on most commercial jets, DVT has become known as the 'economy class syndrome'. DVT can strike at any age and irrespective of the state of physical fitness, so every long distance air traveller is at risk.

In the early stages of a blood clot there is tenderness in the affected calf, followed by a feeling of warmth and a noticeable swelling which may be accompanied by a mild fever. DVT is more likely to form in the leg after a period of inactivity, illness or surgery. Every long distance traveller is at risk but those who are at special risk include those who travel in very cramped conditions, in which the veins at the back of the knees are compressed against the edge of the seat, older passengers, women who are pregnant or on the contraceptive pill, those who have a medical history of blood clots, the overweight and those who have a genetic clotting abnormality found in 10 per cent of the population.

Passengers who have a family history of thrombo-embolism and who frequently travel long distances by air would do well to see their medical adviser for medical screening.

It is reassuring that long distance air travellers can make use of several measures to reduce the risk of DVT. One should drink enough water and juices to avoid dehydration. Intake of alcohol as well as of tea and coffee should be reduced. When permitted one should get up and take a few steps down the aisle. Clothing should be worn loose. 75mg tablets of aspirin can be taken, two before the flight and one about 12 hours into the flight if approved by a medical adviser. Wearing elastic compression stockings reduces the risk of DVT in hospital patients so wearing specially measured stockings during long distance flights may help. Frequent flexing of the calf muscles will improve venous blood flow.

A simple method of exercising the legs while seated has been developed. Both legs are lifted on the ball of the foot, then both feet are lifted on the heel of the foot; the ankles are then flexed to turn the sole of the foot inward and flexed again to turn the sole of the foot outward. Each manoeuvre is carried out 10 times and the whole exercise repeated every hour.

To help with these essential exercises manufacturers have come up with an anti-DVT cushion. This simple device is inflated and placed under the feet when exercising; it is claimed that the use of the cushion can increase the blood flow to the legs ten fold.

For passengers with a known thrombotic abnormality, a low molecular weight Heparin injection will lower the risk. Additionally, there is a new drug which is said to reduce the DVT risk by 50 per cent, but any medication should only be taken after seeking medical advice.

The risk of DVT on long distance flights is genuine but it is at least reassuring that preventive action can be taken to minimise the risk and make the journey safer and trouble-free.

Dr Franco Grima is a retired Royal Air Force Group captain and a former RAF consultant in occupational medicine.