Symptoms and prevention of DVT

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Sitting on a flight

Deep Vein Thrombosis is a clot of blood (a thrombosis) in the veins situated deep within the calf muscles of the lower leg or within the thigh muscles.

If part of the clot breaks off, it can travel to the lungs and form a pulmonary embolism, which can be fatal.

DVTs are associated with any type of long distance travel which involves sitting around immobile including by car, bus or train. Being immobile increases your risk of a blood clot developing. The combination of immobility, low humidity and dehydration in aeroplanes may help make the blood stickier and more likely to clot.

Who is at risk?

Anyone can develop a DVT when flying. Although for most people the risk is minimal, your risk will increase if you drink alcohol whilst sitting immobile for hours on end and then falling asleep in the same position.

Passengers most at risk are those who have a medical condition which raises their risk of developing blood clots in general. These include:

  • Anyone over 40 years of age
  • Smokers
  • People who are obese
  • Anyone who has a personal or family history of blood clots
  • People who are being or have been treated for cancer
  • Anyone who has had recent surgery
  • Pregnant women
  • Women taking oral contraceptives
  • Women taking HRT

    • Symptoms of DVT

    Symptoms of DVT could develop during a flight, but usually happen anything up to 4 weeks afterwards. Signs you may have DVT include pain and swelling in one leg compared with the other. The area may be red and tender particularly if it is situated at the back of the leg below the knee. Flexing your foot upwards may increase the pain. Other symptoms include a raised temperature, joint pain and a sudden cough or shortness of breath. You must contact your GP immediately.

    What you can do to reduce your risk of DVT?

    Before boarding a flight:

  • Wear loose clothing and comfortable shoes
  • Use the time to walk around
  • Avoid drinks containing alcohol or caffeine as these help cause dehydration

    • During a flight:

  • Give yourself as much room as possible; e.g. store your hand luggage in the overhead compartments
  • Keep hydrated by drinking plenty of fluids (not alcohol or caffeinated drinks)
  • Do not take any sleeping tablets
  • Avoid crossing your legs as this restricts blood circulation further
  • Move around every hour if possible
  • Wear graduated compression stockings, especially if you have varicose veins, to improve the blood flow. These are in addition to the DVT prevention exercises
  • Do DVT prevention exercises

    • DVT prevention exercises

    There are many exercises you can do whilst seated to improve blood flow. These heel and toe exercises are ideal. They contract the muscles of the lower leg, between the knees and the ankle joints, helping to squeeze the veins in the lower legs to move and pump the blood upwards towards the heart. This reduces the risk of the blood pooling and clotting, and so reduces the risk of DVT.

    Heel lifts:

    STEP 1 Whilst seated, raise your heels as high as possible keeping your toes on the floor. As you forcibly raise your heals from the floor, the calf muscles will tighten and squeeze the veins deep inside the calf muscles. Try to do heel lifts ten times or so each time.

    Not only do heel lifts tighten those calf muscles, they also lift your thighs off the edge of the seat. This is important as the seat exerts pressure on the back of the thighs compressing the blood vessels and may help slow blood flow.

    STEP 2 This time, keeping your heels on the ground bring your toes up as high as you can. This contracts the muscles at the front of the lower leg, between the knee and the ankle. Repeat ten times, after the heel lifts or alternate heel and toe lifts.

    Toe curls

    These are very simple. Keep your feet flat on the ground then curl and uncurl your toes. Repeat ten times.

    If you place a hands on your calf or the front of your leg as you carry out these exercises, you will feel the different muscles harden as they contract and pump blood upwards through the leg veins.

    How to get a flight upgrade

    August 2009