Development of Medical Sensor Systems in Pulmonology Based on Electrical Impedance Measurement.

In order to experimentally confirm the dependence of the bioelectrical impedance on the flow rate of charged aerosol particles and the composition of bronchial secretions in small airways, the electrical impedance of an aerosol of 0.9% NaCl solution in polyethylene tubes of various diameters was studied. The electrical impedance was also measured in cylindrical chambers of various diameters and volumes filled with a 0.9% NaCl solution or a gelatin solution. The studies were carried out at frequencies of alternating electric current from 20 Hz to 150 kHz. It was shown that the electrical current is not recorded in the absence of a flow of aerosol particles, and the impedance decreases with an increase in the flow velocity. The impedance modulus and the phase angle of the electrical impedance has an expressed dependence on the composition of the conductive medium, the impedance modulus increases in the gelatin solution medium, with a decrease in the diameter of the electric current conductor, and decreases with an increase in the frequency of the probing alternating current. The obtained results confirmed the hypothesis about the influence of the speed of salty aerosol particles flow and the composition of bronchial secretions on the results of measuring electrical impedance.

[Lung functional testing by electroimpedance spirometry: experimental and clinical study].

The aim of the study was to investigate 0.9% sodium chloride saline aerosol and airways electrical impedance including experiments with plastic tubes, healthy people and asthmatic patients examination using electrical impedance spirometry. The experimental part of the study consisted of measurements of the 0.9% NaCl aerosol particles size and their flow action on the electrical impedance measure in polyethylene tubes of different diameters. As a result reverse dependence between aerosol particles size, its flow intensity and electrical impedance value were revealed. In the clinical part of the study the mean values of the electrical impedance spirometry were detected in the children groups of different ages, healthy people and bronchial asthma patients. It was found that an active compound of electrical impedance spirometry was correlated with airways diameter and may be used as a criterion of bronchial obstruction syndrome. It was established that small airways disease is the basic mechanism of airways disorders in patients with control bronchial asthma, and small airways as well as large airways both are involved in not controlled bronchial asthma patients.