What is the primary purpose of compression devices in long AE flights?

• A. To measure blood pressure noninvasively.
• B. To prevent motion sickness by stabilizing legs.
• C. To provide warmth.
• D. To reduce the risk of venous thromboembolism by promoting venous return in immobile patients.

Answer: (D)

When legs stay still for long periods on a flight, blood can pool in the leg veins, increasing the risk of blood clots. Compression devices counter this by cyclically squeezing the calves, which pushes blood back toward the heart and enhances venous return. This mimics the natural muscle-pump action of walking and reduces venous stasis, thereby lowering the chance of venous thromboembolism. The other options don’t address clot risk: measuring blood pressure uses a cuff, warmth isn’t the main function, and motion sickness isn’t related to venous return.