Original Article

Ultrafiltration of the Waste Plasma Effluent from Cardiopulmonary Bypass Circuit Contents Processed with a Cell-Washing Device

University of Nebraska Medical Center, Division of Clinical Perfusion Sciences, Omaha, Nebraska

^* Address correspondence to: Chad P. Brady, B.S., University of Nebraska Medical Center, Division of Clinical Perfusion Education, 600 South 42nd Street, Omaha, NE 68198-5155

Abstract

Blood conservation methods are commonly practiced throughout most hospitals that conduct cardiothoracic surgery. In an effort to reduce patients' exposure to homologous blood products and due to cost effectiveness of blood conservation techniques, this present study combines autotransfusion of the remaining blood in the extracorporeal circuit and ultrafiltration of the plasma effluent, and describes the resulting product.

Seven patients, greater than 19 years of age, requiring cardiopulmonary bypass (CPB) were incorporated into this study. Exclusion criteria included age limitation. At termination of CPB, the remaining blood in the circuit was transferred to an autotransfusion machine and processed. Plasma (1054 ± 206 ml) effluent was collected directly from the centrifugal bowl and processed through a ultrafiltrator, with a constant flow rate and negative pressure, until the plasma effluent concentrated down to an end processed volume of approximately 150 ml. The following variables were either measured or calculated: plasma-concentrate volumes per three minute interval, inlet/outlet pressures of an ultrafiltrator, transmembrane pressure (TMP), plasma free hemoglobin, fibrinogen, total protein, and colloid osmotic pressure.

The average ultrafiltrate volume taken off from the plasma effluent was 828 ± 237 ml, with an average ultrafiltrate volume of 115 ml in every three minute interval. The TMP did not change over the first 15 minutes of processing but became significantly elevated at the 18th minute interval and continued to increase and reach a maximum TMP of 286.5 ± 2.1 mmHg at the end of concentration. Fibrinogen levels increased from pre-concentration values of 118.2 ± 64 to 317 ± 177 mg/dl (p=.03) along with increases in plasma free hemoglobin from 97.7 ± 46 to 402.1 ± 180 mg/dl (p=.0002). The total protein concentration increased by over 330% from baseline values.

Ultrafiltrating plasma effluent from autotransfused cell salvaged CPB circuit contents could prove beneficial, but further study is required to discover ways to separate unfavorable products, such as activated platelet-leukocyte products and reduced plasma free hemoglobin, and to lower heparin concentrations of the plasma-concentrate.