Hematocrit Measurement by Dielectric Spectroscopy

Abstract

Based on permittivity changes, a new method to measure hematocrit (HCT) in extracorporeal blood systems is presented. Human blood samples were tested at different HCT levels pairing the values of permittivity change, obtained by means of a commercial impedance analyzer, with traditional centrifugation measurements. Data were correlated using both linear and nonlinear regression. When using the lineal model, the comparison yielded a high correlation coefficient (r = 0.99). Theoretical simplifications suggest that the method is independent of changes in the conductivities of the intracellular and extracellular compartments. The influence of osmolarity and conductivity of the extracellular compartment was analyzed. It is shown that HCT can be predicted within an error lower than 5% when those parameters changed as much as 1 mS/cm and 50 mOsm/kg, respectively. Thus, the method appears as valid and viable showing good possibilities in applications such as renal dialysis.

Dielectric properties of glucose in bulk aqueous solutions: Influence of electrode polarization and modeling

“…Significant advances have been reported in recent years on the development of dielectric spectroscopy-based devices, which are capable of in vivo, non-invasive glucose monitoring by measuring the dielectric properties of a subject's skin (Caduff et al, 2003(Caduff et al, , 2006Huber et al, 2007). Electrical properties of the plasma membrane and cytoplasm may be extracted from analyzing entire dielectric spectra of suspensions of cells, such as red blood cells (RBC) (Asami et al, 1989;Bordi et al, 2002), yeast (Raicu et al, 1996), and bacteria (Asami et al, 1980), while the volume fraction of cells in suspension (called hematocrit, in the case of RBC) can be easily inferred from simple measurements of conductivity at low frequencies (Cha et al, 1994;Treo et al, 2005;Asami and Yonezawa, 1996).…”

In vitro hematocrit measurement using spectrally encoded flow cytometry

“…In vitro measurement of HCT have also been demonstrated using various optical techniques, including measuring the reflectance from dried blood spots [9], analyzing light scattering from blood samples [10], and using low-coherence interferometry [11]. Non-optical techniques for measuring HCT in vitro include dielectric [12] and impedance [13] spectroscopy, conductivity-based measurements [14] and ultrasonic attenuation [15].…”

Hematocrit estimation using online sequential extreme learning machine

“…With modern lab equipment, it can be measured indirectly by an automated analyzer in which hematocrit is calculated by multiplying the mean cell volume by the red blood cell count. Treo et al proposed an approach for hematocrit estimation based on the dielectric spectroscopy, which is still complicated or requires special devices [7]. In our previous study, a neural network approach was developed for improving accuracy of the handheld glucose meters based on changing pattern of the transduced current curve [8].…”