Fluid resuscitation: colloids vs. crystalloids

The administration of intravenous fluids is perhaps the most common treatment given in the intensive care unit. According to biologic rationale, ongoing fluid losses should be replaced to maintain fluid homeostasis and relative or absolute deficiencies in circulating blood volume should be prevented or rapidly corrected. There is agreement that insensible fluid losses and isotonic fluid losses should be replaced with a judicious mixture of water and crystalloid solutions. There is, however, a great deal of controversy on which fluids should be used during the acute resuscitation phase to deal with acute relative or absolute hypovolemia. In particular, there is much controversy on whether colloidal or crystalloid solutions should be used. The controversy remains despite multiple meta-analyses. There are suggestions that albumin might increase mortality but the data supporting these concerns are weak. Starch solutions might adversely affect renal function. Crystalloids might be favored in trauma patients. These views remain inadequately supported by evidence. A randomized controlled trial now under way should increase the evidence base for practice in this area.