Plasma volume expanders: classification and characteristics of colloids

Abstract

Fluid therapy remains an important therapeutic maneuver in managing surgical, medical, and the critically ill intensive care patient. However, the ideal volume replacement strategy remains under debate. The debate on whether patients should be managed with crystalloids, colloids, or both has for many years been mainly a debate about effectiveness. The dispute over crystalloids versus colloids has been enlarged to a colloid versus colloid debate because of the varying properties of different colloids. The natural colloid albumin and artificial colloids such as gelatin, dextran, and hydroxyethyl starch continue to enjoy widespread usage for clinical fluid management. Colloid is an effective plasma volume expander and is able to restore the hemodynamic profile with less total volume than crystalloid. However, colloid is associated with coagulation abnormalities, renal impairment, and allergic reactions. Albumin is considered to be one of the safe colloids. However, due to its cost, albumin cannot be recommended for hypovolemia. Gelatin and dextran can also cause coagulation abnormalities and renal impairment. Dextran is not used any-more due to its high anaphylactic potency. Each hydroxyethyl starch has different properties by concentration, mean molecular weight, molar substitution, and its C-2/C-6 ratio. New hydroxyethyl starches with a lower mean molecular weight and molar substitution than the old hydroxyethyl starch may be promising by improving volume management therapy with lower risks of coagulation abnormalities and renal impairment. The selection of colloid for plasma volume expansion should be based on the patients' clinical conditions and the characteristics of each colloid.