[Degree of substitution and volume expanding effect of various medium molecular weight hydroxyethyl starch solutions].

Hydroxyethylstarch (HES) is today one of the most frequently used artificial plasma substitutes in prehospital, as well as in clinical settings. However, there are no studies comparing the volume effect of different HES solutions. The goals of the present study therefore were to compare the volume effect of three HES solutions, which are similar with regard to mean molecular weight but different in concentration and degree of substitution. The obtained results enable guidelines for fluid resuscitation in hypovolemia to be laid down. In 30 patients fulfilling the ASA physical status classification I and II 500 ml of either 10% HES 200/0.5, 6% HES 200/0.5 or 6% HES 200/0.6-0.66 were infused within 30 min. The effect of each solution was evaluated using the mechanical oscillator technique (MOT). This technique measures precisely density changes of blood and plasma and allows-using standard formulae-calculation of blood and plasma volume changes. All 3 HES solutions showed similar effects in increasing plasma volume. Immediately after the end of infusion plasma volume was increased by about 800 ml with 10% HES and by about 650 ml with 6% HES 200/0.5. The volume expanding effect of 6% HES 200/0.6-0.66 amounted to 700 ml. The volume expanding effect of all starches decreased only slightly during the following two hours; an interesting detail observed was a second volume effect of HES (about 20% of the volume infused). We conclude that for the correlation of fluid deficits due to trauma, hemorrhage and shock HES solutions seem to be most effective artificial plasma substitutes.(ABSTRACT TRUNCATED AT 250 WORDS)