What is a thrombosis?

The word "thrombosis" refers to the formation of a thrombus or blood clot inside a vessel. These clots most frequently form in the lower half of the body, such as in the leg veins. When one of these clots detaches and finds its way through the bloodstream into the lungs, it can get stuck in one of the lung vessels and lead to a life-threatening circulatory disorder in the lung. In this case, we refer to it as a "pulmonary embolism".How dangerous are long flights?.

Long flights that take several hours increase the risk of thrombosis formation. Because of the limitation on motion and the long period of sitting still in cramped quarters – especially in tourist class (which is why we speak of it as "Economy Class Syndrome") – the veins in the hollow of the knee and the groin become bent in two. This slows down the return flow of the blood.
Beyond this, the drop of pressure in the cabin causes a stretching of the vein walls, which also slows down the blood flow. The reduced humidity in the air causes a loss of fluid in the body, thus thickening the blood and making it easier for clots to form.

The interaction of these many different factors causes liquid to collect in the legs. Passengers often notice this when the skin on the lower legs stretches, the feet swell, and the shoes don’t seem to fit any more. The longer the flight, and the less frequently the passenger moves around, the more the bloodstream slows down, causing the blood to thicken and increasing the hazard of clot formation.

Risk groups

Travelers with an increased risk of thrombosis include especially patients with vein disorders (such as varicosis and phlebitis) or cardiac insufficiency, as well as senior citizens, pregnant women and recent surgical patients. Smoking, overweight and "the pill" represent additional risk factors. Studies have shown that travelers in these risk groups continue to be subject to an increased thrombosis risk up to five days after a long-distance flight. This is why they should continue to wear elastic stockings and, in certain cases, take appropriate medication throughout this period as instructed by their physician.

Proper preventive measures help

Walking is the most important factor

If at all possible, especially on long-distance flights, passengers should stand up frequently and take a walk up and down the aisles. This exercises the calf muscles, which in turn get the blood circulating. In this context we also speak of the "calf muscle pump".

Sufficient drinking

Because of the reduced humidity, the body needs an increased amount of liquid. Drinking mineral water, fruit and
vegetable juices makes it easier for the body to retain a balance of liquids and gives it helpful minerals and salts. Alcohol
expands the vessels and thus represents an increased risk factor.

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