Plasma skimming efficiency of human blood in the spiral groove bearing of a centrifugal blood pump
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ORIGINAL ARTICLE Artificial Heart (Basic)
Plasma skimming efficiency of human blood in the spiral groove bearing of a centrifugal blood pump Daisuke Sakota1 · Kazuki Kondo1 · Ryo Kosaka1 · Masahiro Nishida1 · Osamu Maruyama1 Received: 19 May 2020 / Accepted: 13 October 2020 © The Author(s) 2020
Abstract This work investigates the plasma skimming effect in a spiral groove bearing within a hydrodynamically levitated centrifugal blood pump when working with human blood having a hematocrit value from 0 to 40%. The present study assessed the evaluation based on a method that clarified the limitations associated with such assessments. Human blood was circulated in a closed-loop circuit via a pump operating at 4000 rpm at a flow rate of 5 L/min. Red blood cells flowing through a ridge area of the bearing were directly observed using a high-speed microscope. The hematocrit value in the ridge area was calculated using the mean corpuscular volume, the bearing gap, the cross-sectional area of a red blood cell, and the occupancy of red blood cells. The latter value was obtained from photographic images by dividing the number of pixels showing red blood cells in the evaluation area by the total number of pixels in this area. The plasma skimming efficiency was calculated as the extent to which the hematocrit of the working blood was reduced in the ridge area. For the hematocrit in the circuit from 0 to 40%, the plasma skimming efficiency was approximately 90%, meaning that the hematocrit in the ridge area became 10% as compared to that in the circuit. For a hematocrit of 20% and over, red blood cells almost completely occupied the ridge. Thus, a valid assessment of plasma skimming was only possible when the hematocrit was less than 20%. Keywords Plasma skimming · Hydrodynamic bearing · Centrifugal blood pump · Hemolysis · Optics of blood
Introduction Understanding the blood flow dynamics in mechanical circulatory support devices is important for the development of more hemocompatible devices, with the aim of preventing thrombosis and hemolysis. Consequently, many researchers have investigated and simulated such dynamics using computational fluid dynamics (CFD) and particle image velocimetry [1–5]. However, these conventional studies have assessed blood flow solely on the macroscopic level.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10047-020-01221-9) contains supplementary material, which is available to authorized users. * Daisuke Sakota [email protected] 1
Artificial Organ Research Group, Health and Medical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1‑2‑1 Namiki, Tsukuba, Ibaraki 305‑8564, Japan
In fact, it is challenging to precisely simulate or even to directly visualize localized bearing areas in a rotary blood pump, which are likely the primary regions associated with the destruction of blood cells. As such, it would be helpful to have a better understanding of blood flow dynamics on the scale of individ
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