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.