Be aware predisposing and risk factors

• Predisposing factors for DVT (in addition to the possible effects of prolonged immobility while travelling) are endothelial vascular lesions, hypercoagulabiltity of the blood and thrombophilia (including hereditary forms such as factor V Leiden)
• These factors may specifically include those over 60 years of age, smokers, previous (especially recent) DVT or pulmonary embolus, recent surgery or injury, pregnancy or less than 2 months post-partum, malignancy, cardio-respiratory disease, other chronic illnesses, oestrogen medication (contraceptive and hormone replacement), varicose veins. Symptoms can be delayed for several weeks after the flight. Cases of DVT may have an average of 3 factors.

Advice for those at minimal risk (nil or one predisposing factor)

• While further studies are undertaken preliminary advice for those at low risk could be to exercise the legs when possible, maintain hydration and limit alcohol consumption.

Advice for those at low or moderate risk (e.g. 2 or 3 predisposing factors)

• Exercise in the aircraft cabin wherever possible, maintain hydration and limit alcohol consumption, consider using below knee compression stockings. Possibly consider taking a daily dose of aspirin while at risk (so long as aspirin is not contra-indicated). The effective dose is unclear – perhaps 75-300mg.

Advice for those at high-risk (e.g. more than 3 predisposing factors)

• Exercise, compression pantyhose / stockings, maintain hydration and limit alcohol consumption. Possibly consider a subcutaneous injections of Minihep (sodium heparin 5000 IU twice daily) or low molecular weight heparin (e.g. dalteparin 2500 daily or enoxaparin 40mg daily) while at risk (so long as anticoagulation is not contra-indicated).