Dilutional acidosis following hetastarch or albumin in healthy volunteers

Background The intent of this study was to evaluate the impact of the commo nly used colloids-hetastarch and albumin-on in vivo acid-base balance. From this evaluation, a better understanding of the mechanism of dilutional aci dosis was expected. Methods: in a prospective, randomized fashion, 11 healthy volunteers were a dministered 15 ml/kg hetastarch solution, 6%, or 15 ml/kg albumin, 5%, intr avenously over 30 min. Four weeks later, the study subjects were administer ed the other colloid. Arterial blood gas and electrolyte parameters were me asured at baseline and at SO, 60, 90, 120, 210, and 300 min after colloid a dministration. Pre- and postlaboratory values were compared within groups u sing a paired t test and a Wilcoxon signed rank test and between groups usi ng repeated-measures analysis of variance and a Wilcoxon rank sum test. Results: Thirty min after infusion, subjects who were administered hetastar ch showed statistically significant changes (P < 0.05) in base excess (from 2.5 +/- 0.9 mEq/l to 0.7 +/- 1.1 mEq/l), HCO3- concentration (from 27 +/- 1.0 mEq/l to 25 +/- 1.3 mEq/l), Cl- concentration (from 108 +/- 2 mEq/l to 112 +/- 2 mEq/l), albumin concentration (from 4.4 +/- 0.2 g/dl to 3.5 +/- 0 .5 g/dl), and arterial carbon dioxide tension (Paco(2); from 40.8 +/- 2.3 m mHg to 39.2 +/- 3.2 mmHg), whereas only the albumin concentration (from 4.4 +/- 0.2 g/dl to 4.8 +/- 0.6 g/dl) changed significantly in the albumin-tre ated group. Conclusions: Decreases in base excess were observed for 210 min after hetas tarch administration but not after albumin. The mechanism for this differen ce is discussed.