Blood rheological and electrical properties and relationships with the microvascular tone regulation in patients with diabetes mellitus type 2

Aim. The study aims to evaluate impairment of the rheological and electrical properties of blood, plasma viscosity and blood conductivity in patients with type 2 diabetes mellitus (T2DM) in comparison with the data of the control group of healthy individuals. It also aims to investigate the changes of the skin blood flow responses to cold stress in T2DM patients through wavelet analysis of the peripheral skin temperature pulsations and to estimate their relationships with the blood viscosity and blood conductivity parameters, obtained from the simulation of experimental data with mathematical equations.Materials and methods. The whole blood viscosity was measured by Contraves LS30 viscometer (Switzerland) at a steady flow in 9 healthy individuals and in 13 patients with type 2 diabetes mellitus. Time variation of whole blood conductivity σ under transient flow at rectangular and trapezium shaped Couette viscometric flow and under electric field of 2 kHz was determined. The amplitudes of the skin temperature pulsations (ASTP) were monitored by «Microtest» device («FM-Diagnostics», Russia). To analyze the temperature fluctuations, wavelet transformation analysis of the low amplitude oscillations of skin temperature in accordance with myogenic (0.05–0.14 Hz), neurogenic (0.02–0.05 Hz), and endothelial (0.0095–0.02 Hz) control mechanisms of the vascular tone (WAST method) was applied.Results. Blood viscosity was increased in the T2DM patients’ group, while blood conductivity decreased in comparison to controls. Two sigmoidal equations were applied to describe the kinetics of blood conductivity. Both models include conductivity indices (σ1 , σ2 , σ3 ) and time indices too. The Pearson correlations between these parameters and the ASTP in the frequency ranges, corresponding to the myogenic, neurogenic and endothelial mechanisms of the microcirculation tone regulation were analyzed. The correlation analysis revealed good ASTP–(σ1 , σ2 , σ3 ) relationships in the neurogenic range 3 minutes after the cold test, while the ASTP–(σ1 , σ2 , σ3 ) correlation in the myogenic frequency range before the cold test was negative (r<–0.8, p<0.5).Conclusion. The results complement the studies of the microvascular regulatory mechanisms and endothelial dysfunction in patients with type 2 diabetes mellitus, as well as their relationships with the rheological and electrical properties of blood.

Influence of Measurement Principle on Total Hemoglobin Value

Background: Total hemoglobin measurement is indispensable for determining the stroke type (haemorrhagic vs. ischaemic) and need for blood transfusion. Conductivity- and absorbance-based measurement methods are used for blood gas analysis of total hemoglobin. For conductivity-based measurement, total hemoglobin is calculated after converting blood conductivity into a hematocrit value, whereas absorbance measurement is based on light absorbance after red blood cell hemolysis. We previously reported hemolysis observed after infusion or transfusion during veno-arterial extracorporeal membrane oxygenation, and total hemoglobin differed between conductivity and absorbance measurement methods possibly due to plasma electrolyte changes and hemolysis. Methods: In this study, test samples with controlled electrolyte changes and hemolysis were created by adding sodium chloride, distilled water or hemolysed blood to blood samples collected from healthy volunteers, and total hemoglobin values were compared between both methods. Results: Conductivity-based measurement revealed reduced total hemoglobin value (from 15.49 to 13.05 g/dl) following the addition of 10% sodium chloride, which was also reduced by the addition of hemolysate. Conversely, the addition of distilled water significantly increased total hemoglobin value than the expected value. In the absorbance method, there was no significant change in total hemoglobin value due to electrolyte change or hemolysis. Conclusions: The absorbance method should be used when measuring total hemoglobin in patients with expected blood conductivity changes. However, when using this method, the added contribution of hemoglobin from hemolysed erythrocytes lacking oxygen carrying capacity must be considered.

Measurement of cardiac output in small laboratory animals using recordings of blood conductivity

No method exists which enables easy, frequent, and, at the same time, reliable cardiac output (CO) measurements in mice. To validate a simple indicator-dilution method suitable for frequent measurements of CO in small laboratory animals, a 5% glucose solution was injected as a bolus into femoral veins of mice and rats. The corresponding blood conductivity was measured continuously between an intra-aortic and a rectal electrode. The resulting conductivity-dilution curves were used to calculate CO in mice during hypervolemia and hypovolemia and in conscious as well as halothane-anesthetized mice and rats. In rats, conductivity-dilution curves and time courses of plasma glucose concentration were recorded simultaneously. Compared with CO in awake animals, CO in both species was slightly, but not significantly, reduced during halothane anesthesia. CO was significantly and gradually reduced in hypovolemic mice (up to 58 ml blood/kg body wt), whereas hypervolemia (23 ml saline/kg body wt) had no significant effect. Simultaneous recordings of conductivity-dilution curves and time courses of plasma glucose concentration yielded corresponding values of CO ( P < 0.001). Measurement of blood conductivity appears to be a reliable, simple, and convenient method for quantification of CO in small animals.

An improved procedure for determination of cardiac output by a conductivity method

The applicability of the hematocrit dilution technique employing arterial blood conductivity changes to the determination of the cardiac output has been extended by a) electronic damping of the detecting circuits, which permits greater amplification of the signal without increasing the variability of the base line that occurs during each cardiac cycle, and by b) development of a solution isoosmolar and isoconductive with plasma that substitutes for autogenous plasma in the procedure. The preparation of the synthetic solution is described. It is shown that this solution gives results indistinguishable from those obtained with plasma. Values are given for the conductivity and osmolarity of dog plasma. Submitted on December 3, 1959

The Composition of the Blood of the Shore Crab, Carcinus Moenas Pennant, in Relation to Sex and Body Size

1. The influence of body size and sex on the total osmotic pressure (O.P.) and blood conductivity of the shore crab was investigated. 2. In both sexes the O.P. fell steadily as body weight increased. 3. At any body weight the O.P. of the blood of male crabs was significantly higher that that of females. 4. Blood conductivity increased in both sexes until a maximum was reached at a weight of about 35 g. Thereafter the conductivity fell as the weight increased. 5. There was no significant difference in blood conductivity between male and female crabs below 35 g. body weight. Above 35 g. the conductivity of males was significantly higher than that of females.

THE ELECTRICAL CONDUCTIVITY OF BLOOD

1. The factors influencing blood conductivity have been noted. 2. An accurate apparatus has been designed to measure blood and plasma conductivity. 3. A new cell has been designed to measure conductivity of blood. 4. Through studies on normal blood before and after dilution, a correlation has been shown to exist between blood conductivity and the red cell count. 5. The form factor for normal human red cells has been determined to be 1.393. 6. A mathematical equation is presented relating red cell count with conductivity for normal blood. See PDF for Equation 7. The factor C on the basis of 33 determinations has been calculated to be 10.80.