Why do cirrhosis of the liver cause pulmonary edema?

Cirrhosis is general scarring of the liver. This restrics to a great extent the normal circulation of blood, causing backflow. This increases the pulmonary pressure hence causing pulmonary edema.

CAUSES 鈥?In most cases, the process of edema formation begins when fluid leaks from the body's smallest blood vessels, called capillaries, into the surrounding tissues. The leakage can occur because of changes in pressure in the capillaries, weakening of the capillary wall from disease, or other factors.

Usually, the leakage itself is not enough to cause noticeable edema. However, when the body senses that fluid is being lost from the capillaries, it signals the kidneys to hold on to sodium and water. This results in an increase in the volume of fluid circulating in the blood vessels, which, in turn, leads to additional leakage of fluid from the capillaries. It is typically at this point that edema can be seen.

CONDITIONS ASSOCIATED WITH EDEMA 鈥?A number of different problems can cause edema. Some of the most common are unrelated to any specific disease. For example, damage to the veins in the legs (venous insufficiency) can cause abnormal pooling or clotting of blood in these vessels, leading to edema. Pregnancy, drug effects, and problems with drainage in the lymphatic system can also cause peripheral edema. Diseases commonly associated with edema include kidney disease, heart failure, and cirrhosis of the liver.

Venous insufficiency 鈥?A common cause of peripheral edema in clinical practice is venous insufficiency, one cause of which is a syndrome that may occur after an episode of venous blood clots (called deep vein thrombosis). In this case, the edema is usually limited to the lower extremities (feet or ankles) and may affect only one side (the left or right); other conditions that cause edema usually cause swelling of both extremities.

Pregnancy 鈥?Pregnant women retain a significant amount of sodium and water. Some of this excess fluid is required by the fetus and placenta. Edema of the hands, feet, and face is commonly seen.

Premenstrual syndrome 鈥?Edema that appears in a cyclic pattern (usually once per month) may occur due to premenstrual syndrome (PMS). Diuretics are of no benefit for edema related to PMS. (See "Patient information: Premenstrual syndrome (PMS) and premenstrual dysphoric disorder (PMDD)").

Drugs 鈥?Edema can be a side effect of a wide variety of medications.