Interactions between the volume effects of hydroxyethyl starch 130/0.4 and Ringer\ub4s acetate

IntroductionThe turnover of Ringer\ub4s solutions is greatly dependent on the physiological situation, such as the presence of dehydration or anaesthesia. The present study evaluates whether the kinetics is affected by previous infusion of colloid fluid.MethodsTen male volunteers with a mean age of 22 years underwent three infusion experiments, on separate days and in random order. The experiments included 10 mL/kg of 6% hydroxyethyl starch 130/0.4 (Voluven™), 20 mL/kg of Ringer\u27s acetate, and a combination of both, where Ringer\ub4s was administered 75 minutes after the starch infusion ended. The kinetics of the volume expansion was analysed by non-linear least- squares regression, based on urinary excretion and serial measurement of blood haemoglobin concentration for up to 420 minutes.ResultsThe mean volume of distribution of the starch was 3.12 L which agreed well with the plasma volume (3.14 L) estimated by anthropometry. The volume expansion following the infusion of starch showed monoexponential elimination kinetics with a half-life of two hours. Two interaction effects were found when Ringer\ub4s acetate was infused after the starch. First, there was a higher tendency for Ringer\ub4s acetate to distribute to a peripheral compartment at the expense of the plasma volume expansion. The translocated amount of Ringer\ub4s was 70% higher when HES had been infused earlier. Second, the elimination half-life of Ringer\ub4s acetate was five times longer when administered after the starch (88 versus 497 minutes,