Membrane Plasma Separation

Abstract

Guest Editor's Introduction: This paper was presented at the first plasmapheresis symposium organized by ISAO and the International Center for Artificial Organs and Transplantation on April 3, 1982, Cleveland, Ohio. This paper was printed in the proceedings of this symposium, Plasmapheresis: Therapeutic Applications and New Techniques, edited by Y Nosé and PS Malchesky, JW Smith, and RS Krakauer, Raven Press, New York, 1983, p. 81–92. This paper describes the basic concept of membrane plasma separation. Consideration necessary for the usage of membrane plasma separators are also specifically described. The importance of transmembrane pressures and their maintenance for the lowest possible levels is stressed for the effective hemolysis‐free membrane plasma separation.

Membrane Processes for Plasma Separation and Plasma Fractionation: Guiding Principles for Clinical Use

“…Solomon and co‐workers (16) found that the filtration velocities prior to the onset of hemolysis were higher than predicted on the basis of deposition theory and the dependence of filtration velocity on wall shear rate was lower than the power 1.5 predicted. Similar findings were noted by Malchesky et al (15) in which the shear rate dependence varied as a function of membrane types:…”

“…Plasma viscosity is a function of the concentration of plasma solutes, particularly that of macromolecules. In the separation of plasmas containing high concentrations of immune complexes, cryoproteins, and total cholesterol, significantly higher transmembrane pressures are encountered, and therefore operation of membrane plasma separators must be carried out at reduced plasma flows (15).…”

“…Studies with membranes for plasma separation indicate that the plasma filtration coefficients for whole blood are one to two orders of magnitude less than that for saline (15,16). The filtration rate of cell‐free plasma has been shown to be related to the viscosity of the solution (11,17) and to the interactions (as by absorption) of plasma proteins with the membrane materials, which lead to pore narrowing (8,18,19).…”

Hemolysis in Double-Filtration Plasmapheresis

“…13 Operation should be at the lowest possible TMP and generally less than 50 mm Hg. 1,9 In our study, the TMP progressively increased throughout the entire course of plasmapheresis. In the NH group, the TMP remained below the ideal pressure of 50 mm Hg during 59% of the course.…”

“…8 For given membrane and module properties, the properties of blood and its concentrations of plasma solutes affect the limits of the filtration process. 9 Regarding the operating conditions during membrane plasmapheresis, Fok et al 5 reported that the vascular access through large veins, smooth blood flow, and constant plasma ultrafiltration flow were the major determinants for development of hemolysis. Our previous study on the hemodynamic effects of the different vascular access sites for DFP revealed that the central vein access group had a higher blood flow rate, a shorter duration of DFP treatment, and a lower dose of heparin.…”