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When a PYT (pretty young thing) steps off an aeroplane and drops dead minutes later, DVT (deep vein thrombosis) makes news. Others, probably less attractive and older, who develop DVT two or three weeks after travelling, are forgotten.
DVT occurs if the legs remain stationary, causing the blood to remain stagnant in the legs. Enforced immobility occurs in the cramped spaces of planes, buses, vans, cars or trains, and in offices.
Prolonged immobility causes the blood to stagnate in the veins of the legs. The blood is not able to negotiate the acute angle at the bent knee, especially if the feet are also crossed. Blood thickens and this results in “thrombosis”, another word for clot formation.
Undetected thrombi are very common. They form after a journey lasting four hours or more in one in 10 people. Many of these small clots dissolve spontaneously. Some large ones migrate, causing “thrombo-embolism” (a moving clot). As these travel through the body, they may become wedged and block blood vessels. This can result in stroke, heart attack (myocardial infarction) or fatal pulmonary embolism.
DVT is more likely to occur in people who are very tall (more than 190cm) or very short (less than 152cm). The risk rises steadily after the age of 40 years. Children being fidgety, rarely develop DVT. Young people can also develop DVT if they are obese, have a family history of clots, have had cancer or heart failure or have varicose veins. Women are generally more prone to it, especially if they are pregnant, have delivered in the preceding six weeks or are on hormone treatment. The risk for DVT increases if there is immobility for four hours.
Multiple short journeys, too, are dangerous. The waiting periods must be added to the travel time. Frequent travel increases the risk as the effects of a journey take about four weeks to wear off.
DVT can be present with redness and warmth, pain, discolouration and sometimes swelling of one leg. It can be totally asymptomatic and diagnosed in retrospect after an embolus has occurred. The diagnosis is confirmed with Doppler studies and blood tests. But by that time it may have been too late.
Airlines advocate exercises during long flights. Passengers are advised to get up, stretch and walk in the plane every hour. However, this is not very practical. The planes are cramped and crowded, and the aisles blocked with moving food and drink trolleys. Balance may be a problem while attempting to stretch or walk in a moving train. On long bus journeys, remaining seated and immobile is probably the only option. So, to prevent DVT,
• The foot should be rotated and the toes wiggled 20 times every half an hour.
• Those driving should break journey and stretch every hour.
• Alcohol adds to the soporific effects of the journey and contributes to the inactivity. Avoid it.
• Wear loose fitting clothes.
• Avoid socks with elastic bands. Special compression stockings are available which help to keep the blood flowing.
• Shoes should be loose.
• High risk individuals can take aspirin for a few days before and after a journey under medical supervision.
The treatment of DVT involves injections of anticoagulants like heparin, followed by tablets of warfarin. They prevent the extension of the clot and formation of new ones but do not dissolve the ones that are already present. If there has been recurrent DVT, treatment may have to be continued lifelong. A high price to pay for not wiggling your toes!
Sources: The Telegraph (Kolkata, India)