electrical impedance of human blood with different anticoagulants submit

COLE-COLE PARAMETERS OF HUMAN BLOOD WITH DIFFERENT ANTICOAGULANTS Abstract: Impedance spectroscopy of blood samples with Acid Citrate Dextrose, Ethylene Diamine Tetra-acetic Acid, Lithium Heparin and Sodium Citrate anticaogulants, taken from 14 healthy male donors between ages 22-28, are performed in the frequency range 20Hz-1MHz, using the two probe method. However, only high frequency data (100kHz-1MHz) are used in fitting the Cole circle, where effects of electrode polarization are negligible. It is shown that this is acceptable si nce the characteristic f requency of the samples occurs around 1 MHz. Resistivitie s at low frequencies with plasma alone are calculated as 54.9 .cm: 65.9 .cm: 81.9 .cm and 96.9 .cm for EDTA, LH, SC and ACD respectively. At 100% hematocrit, the extracellular conductivity is zero and the intracellular resistances are 183.9 cm for EDTA; 180.0 cm for LH; 232.3 cm for SC and 140 cm for ACD. The rate of i ncrease in extracellular res istance with Ht is measured higher with LH and EDTA. In the physiological range of hema tocrit, R e is the highest with LH and lowest with SC; at h=0.6 LH samples are 34% higher than SC samples. The characteristic frequency f c changes with the type of anticoagulant; the frequency span at Ht=50% is from 0.8 MHz (LH) to 1.1 MHz (ACD). The angle of depression is highest with LH. Introduction Physiological measu rements of blood are time consumi ng and too expensive for routine studies . On the contrary, electrical measurements can be realized within few seconds at low cost. In a recent study, results indicated that the complex electrical impedance measurement might provide a useful method for investigating the storage lesions, and for tracking the q uality of red cells during storage b y monitoring the Cole-Cole parameters. When applying the relaxation theory to biological tissues (Figure 1), a plot (Cole-Cole plot) of negative reactance versus resist ance of the measured impedance (Z = R + jX) is a semicircle whose center is below x=0. The intersection of the Cole-Cole plot with the real axis provides R 0 and R . Capacitive e ffects of cell membr anes are usually lumped in a constant phase angle impedance CPA Z defined by: 1 1/ CPA Z K j (1) Figure 1 Equivalent electrical circuit of blood. The depressed semicircular locus is a representa tion of an impedance of the form given by Equation 2 where the angle of depression is equal to 2 / . radians. The Cole-Cole equation can be written as : 0 1 1 R R Z R j (2) The dc resistance value R 0 is equal to R e . R is given by the parallel combination of R e and R i and 1 2 / . c i e K f R R R e R i CPA

electrical impedance of human blood with different anticoagulants submit

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