Movement artefact rejection in impedance pneumography.

Impedance pneumography is a non-invasive and a very convenient technique for monitoring breathing. However, a major drawback of this technique is that it is impossible to monitor breathing due to large artefacts introduced by the body movements. The aim of this project was to develop a technique for reducing these 'movement artefacts'. In the first stage of the project, experimental and theoretical studies were carried out to identify an 'optimum' electrode placement that would maximise the 'sensitivity' of measured thoracic impedance to lung resistivity changes. This maximum sensitivity was obtained when the drive and the receive electrode pairs were placed in two different horizontal planes. This sensitivity was also found to increase with increase in electrode spacing. In the second stage, the optimum electrode placement was used to record thoracic impedance during movements. Movement artefacts occurred only when the electrodes moved from their initial location along with the skin, during movements. Taking into consideration these observations, a strategy was decided for placing 4 electrodes in one plane so that movement artefacts could be reduced by combining the two independent measurements. Further studies showed that movement artefacts could be reduced using a strategic 6- electrode placement in three dimensions. It was also possible to detect obstructive apnoea, as the amplitude of the breathing signal was higher than that due to obstructive apnoea and this difference was statistically significant. In these studies, the main cause of movement artefacts was identified as the movement of electrodes with the skin. A significant reduction in movement artefacts was obtained using the 6-electrode placement. This advantage of the 6-electrode placement proposed in this project, can be of great use in clinical applications such as apnoea monitoring in neonates. Further studies can be carried out to determine an optimum frequency of injected current to achieve reduction in residual movement artefacts

Comparison between regional lung CT values and lung densities estimated using EIT

In this paper we report the results of our study in which we compared lung density values obtained from EIT and CT values (HU) within a region of interest. The purpose was to verify clinical use of lung density estimation using EIT data. Image resolution of CT images, which was originally 512*512 pixels, was changed to 16*16 pixels, to match that of the EIT images. The CT and EIT images were recorded from eight patients in an intensive care unit and the results showed a correlation coefficient of 0.66 (p<0.05) between the CT values (HU) and the lung density values (kg/m3) obtained from EIT

A Real time Data Acquisition and Monitoring Device for Medical Applications based on Android Platform

An android based real time data acquisition and monitoring device is presented here. The system finds its initial application in medical field.it serves as a remote monitor for measuring and analysing along with logging of data from patients. The system comprises of two parts. A data acquisition (DaQ) part connected to patient side and an android based display device on the receiving end. The Data Acquisition part contains sensors for picking up the vital signs from the patients, signal conditioning circuits and a Bluetooth transceiver to transmit data wirelessly to the display device. The Display Device then displays the data received from the transmitter in a readable form and also logs the data into a excel form so that it can be taken out digitally and analyzed