SUBSTITUTION DEGREE AND VOLUME EXPANDING EFFECT OF VARIOUS MEDIUM MOLECULAR-WEIGHT HYDROXYETHYLSTARCH SOLUTIONS

Hydroxyethylstarch (HES) is today one of the most frequently used arti ficial plasma substitutes in prehospital, as well as in clinical setti ngs. However, there are no studies comparing the volume effect of diff erent HES solutions. The goals of the present study therefore were to compare the volume effect of three HES solutions, which are similar wi th regard to mean molecular weight but different in concentration and degree of substitution. The obtained results enable guidelines for flu id resuscitation in hypovolemia to be laid down. In 30 patients fulfil ling the ASA physical status classification I and II 500 ml of either 10% HES 200/0.5, 6% HES 200/0.5 or 6% HES200/0.6-0.66 were infused wit hin 30 min. The effect of each solution was evaluated using the mechan ical oscillator technique (MOT). This technique measures precisely den sity 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 1 0% HES and by about 650 ml with 6% HES 200/0.5. The volume expanding e ffect of 6% HES200/0.6-0.66 amounted to 700 ml. The volume expanding e ffect of all starches decreased only slightly during the following two hours; an interesting detail observed was a second volume effect of H ES (about 20% of the volume infused). We conclude that for the correla tion of fluid deficits due to trauma, hemorrhage and shock HES solutio ns seem to be most effective artificial plasma substitutes. Our study demonstrates that differences in physicochemical properties of differe nt HES solutions do not significantly influence the volume effect of t hese solutions over the chosen period of observation.