Accumulation of fluid in the lungs, which restricts oxygen and carbon dioxide exchange and causes shortness of breath and cyanosis. The condition is associated with gurgling respiration, the coughing up of pink, foaming fluid, chest pain and fever. The condition occurs when the small blood vessels in the lungs fail to retain fluid, which is then as it were ‘sweated’ out into the lungs. It can be caused by the inhalation of poisonous gases (such as chlorine if toilet cleaners are used incorrectly). It can also be the result of heart and blood vessel diseases associated with lung congestion such as heart failure and some abnormalities of the heart valves. Diagnosis is by means of the above symptoms and X-rays. Treatment is aimed at reducing the quantity of fluid and, where possible, its cause. The patient must be placed with the upper part of his body raised, to keep the upper parts of the lungs as free from fluid as possible. He must even sleep in a sitting position. Extra oxygen may be administered, and rest prescribed to restrict oxygen consumption. Possible medication includes diuretics, and drugs to strengthen heart and lung function. Corticosteroids may also be prescribed. Artificial respiration has to be used in serious cases.