Pharmacology of plasma expanders

Plasma expanders are used to restore the circulating volume of a hypovolaemic patient. Typically, colloids are used to expand the plasma volume, although combinations of hypertonic crystalloid and colloid have recently been used. The currently available colloids vary in their physicochemical, pharmacodynamics and pharmacokinetic properties. In particular, they differ in molecular weight, which partly determines their duration of action, and in their ability to expand the plasma volume. Dextran, hydroxyethyl starch and hypertonic colloid solutions improve oxygen flux within the microcirculation. Despite their benefits, the use of dextran and high-molecular-weight starches is limited by their negative impact on coagulation. In addition, these macro-molecules may also induce acute renal failure in susceptible patients. Current research focuses on the development of artificial oxygen carriers as plasma expanders. These substances, which include modified stromal-free haemoglobin and perfluorocarbon emulsions, are undergoing clinical trials.