Abstract
IntroductionThe turnover of Ringer´s 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's acetate, and a combination of both, where Ringer´s 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´s acetate was infused after the starch. First, there was a higher tendency for Ringer´s acetate to distribute to a peripheral compartment at the expense of the plasma volume expansion. The translocated amount of Ringer´s was 70% higher when HES had been infused earlier. Second, the elimination half-life of Ringer´s acetate was five times longer when administered after the starch (88 versus 497 minutes, P <0.02).ConclusionsStarch promoted peripheral accumulation of the later infused Ringer´s acetate solution and markedly prolonged the elimination half-life.Trial registrationClinicalTrials.gov: NCT01195025
Highlights
The turnover of Ringers solutions is greatly dependent on the physiological situation, such as the presence of dehydration or anaesthesia
Kinetic analysis The kinetic models were successfully fitted to all experiments
HES, hydroxyethyl starch; Vc, size of central body fluid space at baseline and during fluid therapy; k12, rate constant for fluid passing from vc to vp; k21, rate constant for fluid passing from vp to vc; k10, rate constant for fluid leaving the system; T1/2, half-life
Summary
The turnover of Ringers solutions is greatly dependent on the physiological situation, such as the presence of dehydration or anaesthesia. Intravenous infusion of acetated or lactated Ringers solution and hydroxyethyl starch (HES) are therapeutic cornerstones in modern perioperative fluid therapy. The turnover of such crystalloid fluids has been studied both in conscious [1,2] and anaesthetised [3] volunteers and in patients undergoing surgery [4,5]. Key findings include that the distribution half-life of 7 to 8 minutes is fairly constantly stable under most conditions, while the rate of elimination is retarded by 70 to 80% by general anaesthesia and surgery [6]. The weight does not readily reflect the plasma volume expansion, as this is dependent on the number of molecules and not on their weight [8,9]
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