Issues in contemporary fluid management

Fluid management strategies need to be guided by an understanding of the pa thophysiologic mechanisms underlying fluid imbalance. In the hypovolaemic p atient, reduced circulating blood volume and venous return and, in severe c ases, altered tissue perfusion may initiate a cascade of pathophysiologic p rocesses culminating in multiple organ failure. The objectives of fluid man agement are to maintain adequate blood pressure, tissue oxygenation and int ravascular fluid volume. Both crystalloids and colloids can be useful for t hese purposes. In the hypovolaemic patient with normal pulmonary function, the use of colloids to maintain colloid osmotic pressure can limit the deve lopment of peripheral as well as pulmonary oedema. However, choice of fluid is less important in states of increased lung capillary permeability. Furt her evidence is needed to broaden understanding of the optimal roles for pa rticular fluid management strategies. Experimental models can make an impor tant contribution in gathering such evidence. Rigorous pharmacoeconomic stu dies are also needed to define the benefits and costs of differing fluid re gimens.