[Crystalloids and colloids: fluid homeostasis and toxicity]

Fluid balance is crucial in critically ill patients because mechanisms to counteract fluid dysbalances are limited. Therefore, an extremely important task of ICU staff is to assess and maintain fluid status. Fluid overload has been shown to have deleterious consequences for patients. Infusion fluids may be divided into colloid and crystalloid solutions. Within the crystalloids, balanced solutions have been shown to be superior over 0.9% saline with respect to acidosis, acute kidney injury, and mortality. The most widespread used colloid is hydroyethyl starch (HES). Compared to crystalloids, HES has a much greater volume effect. Despite this advantage, precautions must be undertaken with the use of HES. Side effects such as anaphylactic reactions and acute kidney injury are not uncommon; thus, critically ill patients and those at risk of kidney dysfunction should only receive HES preparations after careful consideration.