The Effect of Volume Replacement on Serum Protein Concentration During Cardiopulmonary Bypass

Division of Clinical Perfusion Education, University of Nebraska Medical Center, School of Allied Health Professionals, Omaha, Nebraska

^* Address correspondence to: Scott A. Kmiecik, MPS, Saint Mary's/ Duluth Clinic Health System, Cardiothoracic Surgery/ Perfusion Department, 407 East Third Street, Duluth, MN 55805. Tel.: (218) 786-4463; e-mail: skmiecik@smdc.org

Received: 25 March 2001
Accepted: 10 October 2001

Abstract

Although controversy exists concerning the optimal total protein and colloid osmotic pressure that should be maintained during cardiopulmonary bypass (CPB), the primary volume expanders remain albumin and 6% hetastarch. The purpose of this study was to quantify the effect of adding boluses of volume replacement agents under various conditions to total serum protein values during CPB. A standard CPB circuit was utilized in eight 45-kg swine that had a priming volume (physiologic saline solution) of 2309 ± 245 mL. Volumetric alterations occurred throughout the CPB period by the addition of combinations of physiologic saline solution, 6% hetastarch or 5% swine albumin. Pre- and postadministration samples were assayed for total serum protein, total protein, and albumin throughout the CPB period and at pre- and postvolume administration times. There was a significant decline in total serum protein with the initiation of CPB (6.14 ± 0.49 g/dL vs. 3.40 ± 0.43 g/dL, p <.0001). Addition of 12.5 g of swine albumin (N = 5) to two different swine increased total serum protein significantly when compared to adding 500 mL of 6% hetastarch (N = 6) (swine albumin 12.4 ± 6.3% vs. hetastarch 3.3 ± 2.1%, p <.005). A reduction in total serum protein occurred after hemodilution with varying amount of physiologic saline solution: 250–450 mL (7.4 ± 4.5%), 451–650 mL (9.6 ± 5.6%), and 651–1050 mL (19.4 ± 4.0%). In summary, knowledge of total serum protein concentration and estimated circulating blood volume can be used to guide albumin and hetastarch administration following hemodilution.