You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is An 85-year-old gentleman complaint of pain in leg while lying down, it lessens when he hangs the foot out of bed. What is the cause? and explain in detail?
In peripheral aerial occlusive disease, as the disease progress, perfusion to the leg may be so severely compromised that anaerobic respiration occurs even at rest, typically affecting the foot and/or calf. The pain is exacerbated by lying down or elevation of the foot due to loss of the gravitational effects on perfusion pressure in the foot. The patient characteristically describes the pain that is worse at night and may be lessened by hanging the foot out of bed or by sleeping in a chair (effects of gravity restored)Ref: Bailey and love pg: 943