The shocking and untimely death of Jonah Lomu, a day after flying home to New Zealand from the Rugby World Cup, highlights a lesser-known but well-established fact about DVT: size matters, with tall and large people at significantly higher risk.
Deep vein thrombosis (DVT) occurs when blood coagulates within the deep veins of the lower leg. A serious complication - pulmonary embolism - can follow when clots dislodge into the bloodstream and block blood flow through lungs, resulting in sudden death.
Who is most at risk?
Individual risk of DVT ultimately amounts to the sum of a multitude of possible contributing factors – from pre-existing medical conditions, clotting disorders, medication, recent surgery or injury, to immobility, dehydration and the cramped seating conditions with which long haul air travellers are all too familiar.
Jonah Lomu had chronic kidney disease, receiving a transplant in 2004, and his medical history would have undoubtedly contributed to his risk. However, at 6ft 5in and weighing in at 18½st, his formidable size would also have amplified his DVT risk five-fold or more, in comparison with a smaller man of average weight.
Even without the contributing effects of air travel, researchers have observed excess risks linked to size. A Norwegian study found that overweight men taller than 6ft have a 5.28x higher risk of clots; short overweight men have a 2.11x increased risk, and tall men of normal weight have an increased risk of 2.57x (though for some reason tall women of normal weight are not at increased risk). Overweight women taller than 5ft 6in have a 2.77x increased risk, and overweight short women have a 1.83x increased risk.
Air travel adds to the dangers. Airline seating is not height-adjustable, so without a footrest, passengers shorter than 5ft 3in experience increased pressure on the backs of their thighs; sitting in the same position during a long flight causes sluggish blood flow, and an increased tendency for blood to clot. At the top of the scale, tall or overweight passengers may be simply too large to fit comfortably into their allotted space, restricting limb movement and slowing blood flow to a point where clots more easily occur.
How can I reduce the risk?
We can’t control our height or many of the other factors that make us more vulnerable, but simple precautions can help:
- Travel in the roomiest class you can afford, avoiding crowded flights
- Wear comfortable, non-restricting clothing for the journey
- Keeping mobile gets blood flowing and prevents clots, so tense and relax your calf muscles frequently, and stand, stretch or walk around the cabin at least once every hour
- Avoid sitting in the same position for a prolonged period; set alarms to remind you to move about – don’t wait till the end of the movie!
- Avoid deep sleep, and don’t take sleeping pills unless you are able to sleep in a fully flat position
- Keep hydrated: drink a cup of water for every hour in the air, avoiding drinks containing caffeine or alcohol, which have a dehydrating effect – unless you drink extra water to compensate for them
- Consider wearing compression stockings during your flight
If you have pre-existing medical problems, an injury, have had recent surgery, a previous DVT, or believe you may be at increased risk, talk to your doctor about additional precautions: people at high risk can be prescribed a blood-thinning injection for their flight
What are the symptoms of DVT?
If you develop symptoms such as calf pain, leg swelling, or shortness of breath following a flight, seek prompt medical attention: DVT is treatable and complications can be prevented.
Dr Richard Dawood is a specialist in Travel Medicine at the Fleet Street Clinic (020 7353 5678). The DVT Risk Calculator on the Fleet Street Clinic website can help you understand your risk.
This article was first published on October 6, 2013, and updated in full on November 26, 2015
0 nhận xét:
Đăng nhận xét