Acid-base changes caused by 5% albumin versus 6% hydroxyethyl starch solution in patients undergoing acute normovolemic hemodilution: a randomized prospective study

Anesthesiology. 2000 Nov;93(5):1174-83 doi: 10.1097/00000542-200011000-00007.

Preoperative acute normovolemic hemodilution (ANH) is an excellent model for evaluating the effects of different colloid solutions that are free of bicarbonate but have large chloride concentrations on acid-base equilibrium.


In 20 patients undergoing gynecologic surgery, ANH to a hematocrit of 22% was performed. Two groups of 10 patients each were randomly assigned to receive either 5% albumin or 6% hydroxyethyl starch solutions containing chloride concentrations of 150 and 154 mm, respectively, during ANH. Blood volume (double label measurement of plasma and red cell volumes), pH, Paco2, and serum concentrations of sodium, potassium, chloride, lactate, ionized calcium, phosphate, albumin, and total protein were measured before and 20 min after completion of ANH. Strong ion difference was calculated as serum sodium plus serum potassium minus serum chloride minus serum lactate. The amount of weak plasma acid was calculated using a computer program.


After ANH, blood volume was well maintained in both groups. ANH caused slight metabolic acidosis with hyperchloremia and a concomitant decrease in strong ion difference. Plasma albumin concentration decreased after hemodilution with 6% hydroxyethyl starch solution and increased after hemodilution with 5% albumin solution. Despite a three-times larger decrease in strong ion difference after ANH with 6% hydroxyethyl starch solution, the decrease in pH was nearly the same in both groups.


ANH with 5% albumin or 6% hydroxyethyl starch solutions led to metabolic acidosis. A dilution of extracellular bicarbonate or changes in strong ion difference and albumin concentration offer explanations for this type of acidosis.

MESH HEADINGS: Acid-Base Equilibrium; Acidosis; Adult; Albumins; Blood Volume; Chlorides; Electrolytes; Erythrocyte Volume; Female; Hematocrit; Hemodilution; Humans; Hydrogen-Ion Concentration; Hydroxyethyl Starch Derivatives; Middle Aged; Plasma Substitutes; Prospective Studies; Solutions; Uterine Cervical Neoplasms
Study Details
Study Design: Randomised Controlled Trial
Language: English
Additional Material: Comment in: Anesthesiology. 2001 Sep;95(3):809; author reply 810-2; PMID: 11575564, Comment in: Anesthesiology. 2001 Sep;95(3):810-2; PMID: 11575565, Comment in: Anesthesiology. 2000 Nov;93(5):1167-9; PMID: 11046200
Credits: Bibliographic data from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine