The effect of haematocrit on the resistivity of human blood at 37°C and 100 kHz

Hill, Dennis W.; Thompson, F. D.

doi:10.1007/bf02477725

Cited by 91 publications

(28 citation statements)

References 6 publications

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“…The electrical resistivity of whole blood, measured at low frequency (20 kHz), is highly dependent on hematocrit, because the isolating membranes of the RBCs are not conducting below 100 kHz [7,8]. Similar to blood viscosity, the electrical impedance of blood will increase at low shear rate because of RBC aggregation (rouleaux formation) [5], which diminishes the accessible conducting plasma volume.…”

Section: Introductionmentioning

confidence: 99%

On-Line Electrical Impedance Measurement for Monitoring Blood Viscosity during On-Pump Heart Surgery

Pop¹,

Backer²,

Jong³

et al. 2004

Eur Surg Res

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Background: The viscosity of blood (η) as well as its electrical impedance at 20 kHz at high shear rate depends on hematocrit, temperature, concentration of macromolecules and red cell deformability. The aim of our study was to investigate the relation between viscosity and electrical impedance in a heart-lung machine-like set-up, because during on-pump heart surgery considerable viscosity changes occur. Methods: Blood of 10 healthy volunteers was examined under temperature variation between 18.5 and 37°C at four different levels of hemodilution. Blood viscosity was examined with a golden-standard technique, i.e. a Contraves LS 30 Couette viscometer, and the results were compared with measurements of the electrical resistivity (R) at 20 kHz by a specially designed device in series with the tubing system of a heart-lung machine. All measurements were performed at a shear rate of 87 s^–1. Results: Using stepwise multiparameter regression analysis (SPSS) a highly significant correlation was found (r² = 0.882) between viscosity (η) and resistivity (R). Adding the variables sodium ([Na⁺]) and fibrinogen ([Fibr]) concentration the coefficient of correlation further improved to r² = 0.928 and the relation became: η = –0.6844 + 0.038 R + 0.038 [Na⁺] + 0.514 [Fibr]. All coefficients showed a statistical significance of p < 0. 001. Conclusions: Electrical impedance measurement is feasible in a heart-lung machine-like set-up and allows accurate continuous on-line estimation of blood viscosity; it may offer an adequate way to record and control viscosity changes during on-pump heart surgery.

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Section: Introductionmentioning

confidence: 99%

On-Line Electrical Impedance Measurement for Monitoring Blood Viscosity during On-Pump Heart Surgery

Pop¹,

Backer²,

Jong³

et al. 2004

Eur Surg Res

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“…Those of Kuhicek ( 17) and of Cictltlea and Sacllcr ( 1 1) arc exponential and wcrc derived from work with reconstituted time-expired bank hlood. The more recent relationship\ derived by Hill and Thompson ( 13) and Mohiipatrii and Hill ( 7 I ) are lineiir a n d are based on measurement\ made on fresh samples of blood drawn from adult patients from ;I renal dial!sis unit with hematocrits ranging from 16-52'> .…”

Section: Discussionmentioning

confidence: 99%

Cardiac Output in the Neonatal Period Using Impedance Cardiography

et al. 1977

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“…7). Hill et al and Niewiadomski et al found a linear relationship between the resistivity and the hematocrit value [8,9]. Both use measurement cells based on plate capacitors with a homogeneous electrical field.…”

Section: Detection Of Electrical Properties (Hematocrit Value)mentioning

confidence: 99%

Surface acoustic wave resonators as novel tools for multiparametric blood analysis

Guhr

Brunig

Schmidt

et al. 2010

2010 Annual International Conference of the IEEE Engineering in Medicine and Biology

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In this paper a new tool to assess viscoelastic and dielectric properties of human fluids is presented. Shear horizontal polarized surface acoustic waves (SH-SAW) are used to detect the viscoelastic properties of coagulating blood and blood plasma samples. One-port SAW resonators, with fundamental modes of 85, 170 und 340 MHz were developed. Additionally, their electrode structures can be used simultaneously to detect the dielectric behavior of the whole system by impedance spectroscopy while the frequency ranges from kHz to MHz. The combination of both methods offers the detection of clinical relevant blood parameters like the blood coagulation time and the hematocrit value within one measurement.

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The effect of haematocrit on the resistivity of human blood at 37°C and 100 kHz

Cited by 91 publications

References 6 publications

On-Line Electrical Impedance Measurement for Monitoring Blood Viscosity during On-Pump Heart Surgery

On-Line Electrical Impedance Measurement for Monitoring Blood Viscosity during On-Pump Heart Surgery

Cardiac Output in the Neonatal Period Using Impedance Cardiography

Surface acoustic wave resonators as novel tools for multiparametric blood analysis

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