A DAQ-based virtual instrument for trans-thoracic impedance investigations

Impedance pneumography is a technique which allows the monitoring of respiratory activity through the measurement of variations in the impedance between two points located on the thoracic surface. In this paper, a low-cost, easily portable, and re-configurable measurement system is presented, suitable to perform impedance pneumography investigations. The system is based on a LabVIEW virtual instrument and employs only a data acquisition card. A preliminary metrological assessment of the system is performed, showing that the basic accuracy of the instrument is adequate for monitoring patients lying in a bed. Acquisitions made on several volunteers have evidenced the feasibility of the proposed system in monitoring the breath activity of a patient and in extrapolating the relevant diagnostic parameters. With the aid of suitable signal processing and hardware optimizations the instrument might become a truly portable and non-invasive breath rate monitoring system.