Compression devices are plastic wraps that are placed around a patient's legs in order to decrease the chance of blood clot formation. They have compartments that inflate and deflate, gently squeezing the muscles of the legs. The stockings are connected to a small compressor that controls the timing of the inflation/deflation cycles. The squeezing action of the compression stockings improves the circulation in the leg veins, thus decreasing the chance of clot formation. Most ICU patients have an increased risk of blood clot formation and compression stockings are one of the measures used to decrease this risk. Unfortunately, no measure is 100% effective at preventing the formation of blood clots in the leg veins of ICU patients.