Simultaneous electrical online estimation of changes in blood hematocrit and temperature in cardiopulmonary bypass

Martin Wekesa Sifuna; Daisuke Kawashima; Katsuhiro Matsuura; Hiromichi Obara; Yusuke Nakajima; Masahiro Takei

doi:10.1007/s10047-022-01320-9

Simultaneous electrical online estimation of changes in blood hematocrit and temperature in cardiopulmonary bypass

J Artif Organs. 2022 Dec;25(4):305-313. doi: 10.1007/s10047-022-01320-9. Epub 2022 Mar 7.

Authors

Martin Wekesa Sifuna¹, Daisuke Kawashima², Katsuhiro Matsuura^{3

4}, Hiromichi Obara⁵, Yusuke Nakajima¹, Masahiro Takei⁶

Affiliations

¹ Department of Mechanical Engineering, Graduate School of Science and Engineering, Chiba University, 1-33, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan.
² Department of Mechanical Engineering, Graduate School of Science and Engineering, Chiba University, 1-33, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan. dkawa@chiba-u.jp.
³ VCA Japan Shiraishi Animal Hospital, 4 Chome-33-2, Saitama, Sayamadai, Sayama, 350-1304, Japan.
⁴ Department of Veterinary Medicine, Tokyo University of Agriculture and Technology, 3Chome-8-1, Harumicho, Fuchu, Tokyo, 183-8538, Japan.
⁵ Department of Mechanical System Engineering, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino-shi, Tokyo, 191-0065, Japan.
⁶ Department of Mechanical Engineering, Graduate School of Science and Engineering, Chiba University, 1-33, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan. masa2@chiba-u.jp.

PMID: 35254539
DOI: 10.1007/s10047-022-01320-9

Abstract

Two equations have been developed from multi-frequency measurements of blood impedance Z_b for a simultaneous electrical online estimation of changes in blood hematocrit ΔH [%] and temperatures ΔT [K] in cardiopulmonary bypass (CPB). Z_b of fixed blood volumes at varying H and T were measured by an impedance analyzer and changes in blood conductivity σ_b and relative permittivity ε_b computed. Correlation analysis were based on changes in σ_b with H or T at f = 1 MHz while H and T equations were developed by correlating changes in ε_b with H and T at dual frequencies of f = 1 MHz and f = 10 MHz which best capture blood plasma Z_p and red blood cell cytoplasm Z_cyt impedances respectively. Results show high correlations between σ_b and H (R² = 0.987) or σ_b and T (R² = 0.9959) indicating dependence of the electrical parameters of blood on its H and T. Based on computed ε_b, changes in blood hematocrit ΔH and temperature ΔT at a given time t are estimated as ΔH(t) = 1.7298Δε_b (f = 1 MHz) - 1.0669Δε_b (f = 10 MHz) and ΔT(t) = -2.186Δε_b (f = 1 MHz) + 2.13Δε_b (f = 10 MHz). When applied to a CPB during a canine mitral valve plasty, ΔH and ΔT had correlations of R² = 0.9992 and R² = 0.966 against H and T respectively as measured by conventional devices.

Keywords: Cardiopulmonary bypass; Hematocrit; Relative permittivity; Simultaneous online estimation; Temperature.

MeSH terms

Animals
Cardiopulmonary Bypass* / methods
Dogs
Electric Impedance
Hematocrit
Temperature