[Non-cardiac pulmonary edema: an enigma today]

Pulmonary oedema is caused by an excessive accumulation of interstitial fluid in the lungs: in the case of left ventricular failure, oedema arises due to an increase in capillary hydrostatic pressure. Non-cardiac oedema, on the other hand, is brought about by a change in alveolar capillary membrane permeability. Although the causes are different, namely respiratory distress syndrome in adults, altitude-induced pulmonary oedema, oxygen toxicity, medication, metabolic changes, etc., the result is the same, i.e. damage to the alveolar capillary membrane. This damage appears to be brought about by two factors: complement activation and damage to the blood clotting mechanism. The difference between cardiac and non-cardiac pulmonary oedema is difficult to gauge. If pulmonary cone pressure is normal or low, and if the oedematous fluid/plasma protein ratio is greater than 0.7, the oedema is non-cardiac in origin. Treatment is carried out with the aim of repairing the alveolar capillary membrane and preventing extension of the damage. Respiratory insufficiency is treated by a mechanical respirator, applying positive pressure at the end of expiration. Fluid administration is adjusted according to pulmonary cone pressure levels. Opinions are still divided over whether to administer crystalline or colloidal solutions, steroids or protease inhibitors.