One of the common risk factors for developing DVT (Deep Vein Thrombosis) is long distance air travel. Air plane travel creates increased risks not only because of restricted mobility within the airplane but also because of lower oxygen levels (which may activate the clotting system) and lower humidity within airplane cabins (which increases risk of dehydration).
A DVT occurs when a blood clot forms in the deep veins of the legs, thighs or pelvis. It is of concern because in the short-term it can cause significant pain and swelling and in the long-term, in over 25% of cases, damage to the deep veins leads to chronic pain, swelling and skin changes, (the so-called post thrombotic syndrome). The other concern with DVT is that a blood clot can break away from the deep vein and circulate to block arteries in the lungs. This is called a Pulmonary Embolism (PE) and can be life threatening causing chest pain, palpitations, shortness of breath and even sudden death.
It has been estimated that the risk of DVT doubles with flights longer than four hours and is higher again for flights lasting 16 hours or longer.
Nearly all people who develop a travel related DVT have at least one of the following recognized risk factors:
- Previous DVT or PE
- Thrombophilia (inherited clotting disorder)
- Oestrogen medication (oral contraceptive, HRT)
- Active cancer (not in remission)
- Recent surgery or trauma in last 4 weeks (particularly to abdomen, pelvic region or legs)
- Older age (over 40)
- Varicose veins
- Extremes of height (taller than 1.9m, shorter than 1.6m)
- Immobilisation (limb in a cast)
- Serious medical illness (e.g. congestive cardiac failure, inflammatory bowel disease)
Our 5 point plan to reduce risk of DVT on long haul flights (over four hours) is:
1. Wear Compression Stockings
- Below the knee and open toe are adequate.
- Preference for 20-30 mm Hg compression rating but flight socks and skins with 15-20 mm Hg are beneficial. Put stockings on before leaving for the airport
2. Drink Plenty of Water
- Airplane cabins have low humidity which increases dehydration.
- Minimise alcohol, coffee and tea which can contribute to dehydration.
3. Regular Exercise
- Avoid sitting for long periods.
- Get up and walk around once an hour if possible.
- Perform heel and toe lifts hourly (e.g. three sets of 10)
4. No Sleeping Tablets
- Sleeping tablets can result in immobility for a prolonged period of time, often in an awkward cramped position.
- Recent studies support effectiveness of low dose Aspirin in reducing DVT risk.
- Recommend 100mg (e.g. CARTIA) with main meal, unless there is a contradiction to Aspirin such as history of allergy, gastritis or peptic ulcers. If unable to take aspirin use Fish Oil supplements (e.g. 5000mg).
High Risk Group
If individuals are at a high risk of DVT, then an injection of anticoagulant (CLEXANE) may be indicated 1-2 hours before departure. This can be prescribed by your doctor for you to administer or can be provided at an airport health clinic. High risk group includes previous DVT or PE, active cancer, recent major surgery in last 4 weeks, immobilization (limb in cast) and multiple other risk factors.