title: Plasma Skimming in a Spiral Groove Bearing of a Centrifugal Blood Pump.
abstract: Plasma skimming is a phenomenon in which discharge hematocrit is lower than feed hematocrit in microvessels. Plasma skimming has been investigated at a bearing gap in a spiral groove bearing (SGB), as this has the potential to prevent hemolysis in the SGB of a blood pump. However, it is not clear whether plasma skimming occurs in a blood pump with the SGB, because the hematocrit has not been obtained. The purpose of this study is to verify plasma skimming in an SGB of a centrifugal blood pump by developing a hematocrit measurement method in an SGB. Erythrocyte observation using a high-speed microscope and a bearing gap measurement using a laser confocal displacement meter was performed five times. In these tests, bovine blood as a working fluid was diluted with autologous plasma to adjust the hematocrit to 1.0%. A resistor was adjusted to achieve a pressure head of 100 mm Hg and a flow rate of 5.0 L/min at a rotational speed of 2800 rpm. Hematocrit on the ridge region in the SGB was measured using an image analysis based on motion image of erythrocytes, mean corpuscular volume, the measured bearing gap, and a cross-sectional area of erythrocyte. Mean hematocrit on the ridge region in the SGB was linearly reduced from 0.97 to 0.07% with the decreasing mean bearing gap from 38 to 21 μm when the rotational speed was changed from 2250 to 3000 rpm. A maximum plasma skimming efficiency of 93% was obtained with a gap of 21 μm. In conclusion, we succeeded in measuring the hematocrit on the ridge region in the SGB of the blood pump. Hematocrit decreased on the ridge region in the SGB and plasma skimming occurred with a bearing gap of less than 30 μm in the hydrodynamically levitated centrifugal blood pump.
authors.affiliation: Graduate School of Science and Technology, Tokyo University of Science, Chiba, Japan.
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Murashige
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan. sakota.ao@aist.go.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sakota
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kosaka
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Nishida
authors.affiliation: Tokyo University of Science, Chiba, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kawaguchi
authors.affiliation: Graduate School of Engineering, Kobe University, Kobe, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamane
authors.affiliation: National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Maruyama
mesh_terms: D000465:Algorithms; D000818:Animals; D001243:Assisted Circulation / Q000295:instrumentation*; D002417:Cattle; D002498:Centrifugation / Q000295:instrumentation; D004867:Equipment Design; D004909:Erythrocyte Indices; D004912:Erythrocytes / Q000166:cytology*; D006400:Hematocrit / Q000379:methods*; D057446:Hydrodynamics; D055806:Microvessels / Q000502:physiology
keywords: Bearing gap; Centrifugal blood pump; Hematocrit; Plasma skimming; Spiral groove bearing