[Effects of low molecular weight hydroxyethyl starch (HES 40) in comparison with Ringer solution on oxygen tension in skeletal muscles of infected patients]

Abstract

Volume expansion for the establishment of normal to slightly hyperdynamic systemic circulation has become part of a standard concept in the treatment of septicemic patients. The goal is an improvement of microcirculation with beneficial effects on tissue oxygen supply. This study investigates the effect of hydroxyethyl starch solution (HES 6%: mean molecular weight = 40,000) versus ringer's solution on tissue oxygen tensions in human skeletal muscle during periods of septicemia in 10 mechanically ventilated ICU-patients. Measurement of tissue oxygen tension was achieved by a polarographic pO2-sensitive flexible probe. After computer assisted analysis pO2-histograms were calculated out of 200 single pO2-values measured consecutively within a time period of 4 min. Infusions of 500 ml ringer's solution or 500 ml HES were given over 60 min in each patient in a randomized order. The second infusion was begun when the pO2-histogram had reproducibly regained control values as measured before treatment. Measurements were made every 30 min after starting the infusion for a total period of 150 min. As a result the median pO2 improved by 24.5% 90 min after the infusion of HES was begun with a simultaneous significant (30 to 150 min; p less than 0.05) drop in hematocrit from 34.3% to 32.4%. In contrast ringer's solution had no significant effect on tissue pO2 whereas the hematocrit was comparable to the HES group in the time period of 30-60 min. In both groups no linear correlation between hematocrit and pO2-tensions could be established. It remains unclear if pO2-tensions during and after HES infusion can be correlated to an improved capillary perfusion. However, as was clearly demonstrated, different types of solutions used for volume expansion may exert different effects on pO2-tissue tension in septic patients.