Những thông tin quan trọng về huyết khối tĩnh mạch sâu (DVT)

What causes DVT on a long-haul flight?

Sitting still for hours in a cramped position, combined with lower cabin pressure and limited movement, slows blood flow in the leg veins and allows blood to pool, which makes it easier for clots to form. Risk factors include flights of more than four hours, sitting in a window seat, taking several flights in one journey, dehydration, smoking, alcohol, use of oral contraceptives and any pre-existing blood clotting condition. According to a World Health Organisation report covered by the British Medical Journal, the risk of venous thromboembolism doubles after long haul air travel of more than four hours’ duration, and the risk increases with the duration of the travel and with multiple flights within a short period. For healthy travellers, the overall risk remains low. The report put the absolute risk among healthy individuals for a flight of more than four hours at 1 in 6000. The risk is considerably higher for people with additional risk factors.

Most flight-related clots can be prevented with simple habits. Walk up and down the aisle every hour or two when it is safe to do so. When seated, flex and point your ankles regularly to keep the calf muscles pumping blood back towards the heart. Drink plenty of water, limit alcohol and caffeine, and avoid sleeping for long stretches in a cramped position. If you choose your seat, an aisle seat makes moving around easier. Well-fitted graduated compression stockings can also help, particularly for travellers with additional risk factors. If you have had a blood clot before, have a clotting disorder, or have recently had surgery, see a vascular specialist before a long-haul trip. After landing, seek medical attention promptly if you develop swelling, pain, warmth or redness in one leg, or sudden breathlessness or chest pain. These can be signs of deep vein thrombosis or pulmonary embolism.

What symptoms should we watch for, and is it important to seek medical help quickly?

A lot of DVTs can be silent. Symptoms always start at the calf which can be a funny sensation or pain at the back of the calf and in worst cases you’ll also notice redness, increase in warmth and swelling on the affected leg. In very bad cases, the person can also struggle to walk. As DVT can progress to pulmonary embolism if left untreated, there can be serious consequences.

In less severe cases, if left untreated the clots can also destroy the valves inside the veins and cause long-term pain (post-thrombotic syndrome) and chronic leg swelling (deep venous reflux).

What are the non-surgical treatments for deep vein thrombosis?

Anticoagulants, or blood thinners, are vital in điều trị DVT. They prevent existing clots from enlarging and reduce the risk of new clots by inhibiting clotting factors. Though they don’t dissolve clots directly, they aid the body’s natural clot breakdown process. They help manage DVT and prevent complications like pulmonary embolism and post-thrombotic syndrome, which can lead to heavy and swollen limbs.

The main anticoagulants are heparin, which rapidly thins blood and is administered in hospitals; warfarin, an oral medication used long-term with close monitoring; and DOACs like apixaban and rivaroxaban, newer oral options that are as effective as warfarin but with fewer bleeding risks and no need for regular blood tests.

What are the surgical options for removing severe DVTs?

We perform surgery under local anaesthesia to remove large clots, especially if symptoms are severe. The procedure choice depends on clot location, severity, and patient health. Fresh clots are easier to remove via percutaneous thrombectomy, while older clots may need thrombolysis (clot busters) to aid breakdown before removal. Specialised devices physically remove the clot during this procedure.