Physiology, pharmacology, and rationale for colloid administration for the maintenance of effective hemodynamic stability in critically ill patients.

The semisynthetic colloid solutions (gelatins, dextrans, and hydroxyethyl starches) are complex drugs. Their principal role in the care of the critically ill is as plasma volume expanders, but they may also affect hemorrheology, hemostasis, and inflammatory processes. The pattern of beneficial and detrimental effects varies between products. Understanding of the physiology of plasma volume expansion, as well as the nature and magnitude of these additional pharmacological qualities, is necessary for rational prescription of these commonly used products. The composition of the solute carrier solution can influence the clinical effects of colloid solutions. A large amount of data from laboratory and small clinical studies is available to inform this choice of colloid in a variety of situations. Significant patient outcome data from large studies has until recently been lacking, and clinicians have continued to prescribe a variety of crystalloids and colloids for the maintenance of effective hemodynamic stability in critically ill patients. The recently published Saline vs Albumin Fluid Evaluation Study demonstrates that albumin has an equivalent effectiveness and safety profile to 0.9% saline as a resuscitation fluid. The choice of clinical endpoints to guide dosage (infused volume) of colloids is probably therefore more important than the choice between individual products.