Plasma volume changes after infusion of various plasma expanders.

In the immediate post-operative period after moderate surgical procedures, 1 litre of a colloid solution or saline was given intravenously. The plasma volume expansion after infusion of dextran 70 (Macrodex), hydroxyethylstarch (Volex), polygelatin (Haemaccel), albumin and saline was found to be between 790 and 180 ml. The most efficent plasma expander was dextran, followed by hydroxyethylstarch. Polygelatin and saline did not give full restitution, although twice the calculated loss was infused. Total plasma protein concentration was lowered in all groups in proportion to the dilution, except for the patients given albumin, in whom the concentration of total protein increased. Calculation of the total circulating protein mass showed no decrease during the period immediately after the infusion. This investigation has demonstrated that the most efficient plasma volume expander is dextran but that hydroxyethylstarch offers an almost equal alternative in terms of volume expansion. Dextran, however, exerts an advantageous effect on the microcirculation. As the metabolic pathways of hydroxyethylstarch have not yet been further explored, dextran is preferred when using artificial colloids. Judged by its secondary effects alone, including the influence on plasma protein patterns, albumin seems to be the compound of choice. Polygelatin and saline are not efficient expanders when hypovolaemia is to be corrected rapidly.