What causes swelling?

When we are moving around, the muscles of the legs—particularly the calf muscles—act as pumps, encouraging the main veins to pump fluids back to the heart. However, when the muscles have remained inactive for long periods, the blood becomes sluggish, and fluids leak from the vessels into the surrounding tissues.

Inactivity can also lead to deep vein thrombosis (DVT), although this is an uncommon event.

Deep vein thrombosis

Medical authorities have determined that sitting immobile for long periods is one of the contributing causes of DVT.

After long periods of remaining still, particularly in the sitting position, the deep veins can become compressed, narrowed or blocked. This makes it more difficult for the blood to travel back to the heart. The formation of a blood clot within deep veins results in partial or complete blockage of blood flow in the vein. The condition can be remedied if it is recognized and treated promptly. However, it can be fatal if the clot breaks off, travels to the lungs, and causes a pulmonary embolism.

Preventing swelling and DVT

Moving about will help prevent the pooling of fluids that can lead to swelling and DVT. This applies on short flights as well as longhaul flights. Try to move your calves, ankles and toes as  frequently as possible (a minimum of once per hour) for several minutes. Get up, walk the aisles, or stretch your legs out under the seat in front of you if you have room. You should also refrain from sleeping for long periods while flying, and avoid medication taken to make you drowsy.

Transport Canada recommends that shorter passengers whose feet don’t reach the floor, elevate the feet on luggage to prevent the seat edge from compressing the back of the thighs. Ensure you remain well hydrated. Drink plenty of water or juice and avoid caffeinated colas, tea and coffee, as well as alcohol. Finally, remember that very few passengers develop venous problems when flying. Transport Canada does however recommend that these guidelines be followed to minimize the risk of developing DVT.