title: Hydrodynamic characteristics of a membrane oxygenator: modeling of pressure-flow characteristics and their influence on apparent viscosity.
abstract: The viscosity obtained from pressure-flow characteristics of an oxygenator may help to detect factors that change oxygenator resistance. The objective of this study was to model pressure-flow characteristics of a membrane oxygenator with an integrated arterial filter and to quantify their influence on apparent viscosity of non-Newtonian fluids. One Newtonian fluid (glycerin solution) and two non-Newtonian fluids (whole bovine blood and a human red blood cell suspension) were perfused through an oxygenator and their pressure-flow characteristics examined systematically. Four resistance parameters for the pressure gradient characteristics approximation equation were obtained by the least squares method from the relational expression of pressure-flow characteristics and viscosity. For all three fluids, a non-linear flow to pressure change was observed with a coefficient of determination of almost 1 by exponential approximation. The glycerin solution had a higher pressure gradient (10-70%) than the other fluids; the apparent viscosity of the non-Newtonian fluids was around 35% lower than the static one measured by a torsional oscillation viscometer. Overall, our study demonstrated that the influence on the apparent viscosity of non-Newtonian fluids can be quantified by pressure gradient differences in a membrane oxygenator with an integrated arterial filter.
authors.affiliation: Department of System Cybernetics, Graduate School of Engineering, Hiroshima University, Hiroshima, Japan Department of Clinical Engineering, Hiroshima University Hospital, Hiroshima, Japan okahara@hiroshima-u.ac.jp.
authors.forename: S
authors.initials: S
authors.lastname: Okahara
authors.affiliation: Department of System Cybernetics, Institute of Engineering, Hiroshima University, Hiroshima, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tsuji
authors.affiliation: Department of Clinical Engineering, Hiroshima International University, Hiroshima, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ninomiya
authors.affiliation: Department of Clinical Engineering, Hiroshima University Hospital, Hiroshima, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Miyamoto
authors.affiliation: Department of Clinical Engineering, Hiroshima University Hospital, Hiroshima, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Department of System Cybernetics, Institute of Engineering, Hiroshima University, Hiroshima, Japan.
authors.forename: Z
authors.initials: Z
authors.lastname: Soh
authors.affiliation: Department of Cardiovascular Surgery, Hiroshima University Hospital, Hiroshima, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sueda
mesh_terms: D000818:Animals; D001794:Blood Pressure; D001809:Blood Viscosity; D002417:Cattle; D015199:Extracorporeal Membrane Oxygenation; D006801:Humans; D008955:Models, Cardiovascular; D010107:Oxygenators, Membrane
keywords: blood viscosity; cardiopulmonary bypass; oxygenator; pressure gradient; pressure-flow characteristics