For a patient preparing for a long flight, what is the most appropriate recommendation to prevent deep vein thrombosis?

Recommending walking frequently during the flight is the most appropriate recommendation for preventing deep vein thrombosis (DVT). Prolonged immobility during long flights can lead to venous stasis, a key factor in the development of DVT. Encouraging patients to get up, stretch, and walk periodically helps promote circulation in the legs, reducing the risk of clot formation.

Walking allows for calf muscle contraction, which acts like a "muscle pump," aiding venous return to the heart. This is especially important on long flights where passengers often remain seated for extended periods. Regular movement helps stimulate blood flow and can significantly mitigate the chances of forming a clot.

Other measures such as hydration and wearing compression stockings are also helpful, but walking remains one of the most straightforward and effective strategies to directly combat the risks associated with prolonged sitting.