After a tiring trans-Atlantic flight in January, a senior manager with a top outsourcing firm, returning to Bangalore, woke up next morning to discover his calves swollen and his legs feeling heavy. By the time he'd had breakfast, the veins around his ankles were quite prominent.
The 45-year-old had spent the past few days working continually on contract negotiations in the United States. After a drink and a heavy dinner, he had slept through his flight, except for a quick layover in Europe, and woken up only to stagger home.
But when he visited a hospital a few days later, the swelling of his legs was diagnosed as deep vein thrombosis or DVT - an ailment where the veins get clogged by blood clots, and which can potentially lead to a pulmonary embolism, or blockage of the main artery of the lung. Business travellers, cooped up in offices and conference rooms or aboard flights, with little exercise and consequently poor blood circulation, are in the highest risk bracket. "It is now confirmed that sitting in the same position for a long time and consumption of alcohol aggravate the onset of DVT," says Dr U.V. Rao, a vascular surgeon at Bangalore's Manipal Health Enterprises.
1. DVT occurs when blood clots form in the vein of the leg
2. Sitting cooped up for long periods is a common cause
3. Chances of DVT increase with age
4. Walking in the aisle during flights and drinking red wine in moderation lessen the risk of DVT
The likelihood of DVT increases with dehydration, consumption of alcohol and being cooped up in a tight seat - not just on a long-distance flight, but even on a train or a bus overnight. "Since planes are pressurised chambers, the previous claim that high altitude was a key contributor to DVT is now contentious," says Rao.
Frequent travellers, aware of this threat, try to fend off DVT in different ways. Sleeping on flights, say some doctors, may worsen the condition, since inactivity can catalyse clot formation. Some say they try to sleep as little as possible - difficult on long flights - and instead take regular strolls down the aisle. Others avoid the temptation of hard drinks in mid-air and instead gulp water or isotonic drinks to keep themselves hydrated.
The onset of DVT is closely linked to age, with older people more prone. In 2001, the last time such a study was conducted, the medical journal Lancet estimated that there were around one million cases of the ailment worldwide. Up to five per cent of frequent flyers can develop the disease, say various studies.
The detection and treatment of DVT has become simpler today. With the advent of third-generation ultrasound tests, a competent radiologist can easily locate these blocks. Administration of heparin, a blood thinning drug, eases the pain and also lowers the chances of more dangerous complications. But doctors say frequent travellers often ignore the early symptoms of DVT - ascribing them to stress or fatigue - and end up scrambling to a hospital only when they have no choice. "There is only a two per cent chance of DVT worsening into pulmonary embolism," says Rao. "Yet it is better to be safe than sorry."