CAUSES OF EDEMA IN THE INTENSIVE-CARE UNIT

Patients in emergencies necessitating treatment in the intensive care unit (ICU) often develop generalized gross edema. The usual scenario i s that in the emergency situation characterized by hypotension and (im pending) organ failure, large amounts of fluids are administered that subsequently cannot be excreted adequately, even if the emergency situ ation subsides to a more stable condition. Three main factors underlie the inadequate restoration of volume balance: (1) impaired edema mobi lization, due to the negative influence on lymphatic flow of reduced m uscle activity and increased central venous pressure by mechanical ven tilation; (2) secondary renal sodium retention by circulatory impairme nt and hypotension caused by mechanical ventilation and by the cardiod epressant and vasodilatory effects of (endo-)toxemia; and (3) primary renal sodium retention by renal vasoconstriction and filtration impedi ment, due to a complex of systemic and intrarenal vasomodulator activa tion and intrarenal endothelitis, or acute renal failure. Edema itself , as far as impeding organ function and necessitating mechanical venti lation, may further perpetuate this difficult to handle and vicious ci rcle.