Journal of medical engineering & technology
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Increasing use of computerized ECG processing systems requires effective electrocardiogram (ECG) data compression techniques which aim to enlarge storage capacity and improve data transmission over phone and internet lines. This paper presents a compression technique for ECG signals using the singular value decomposition (SVD) combined with discrete wavelet transform (DWT). The central idea is to transform the ECG signal to a rectangular matrix, compute the SVD, and then discard small singular values of the matrix. ⋯ The technique has been tested on ECG signals obtained from MIT-BIH arrhythmia database. The results showed that data reduction with high signal fidelity can thus be achieved with average data compression ratio of 25.2:1 and average PRD of 3.14. Comparison between the obtained results and recently published results show that the proposed technique gives better performance.
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A unit has been designed which monitors newborn infants at risk of Sudden Infant Death Syndrome (SIDS) in a home environment. The unit monitors respiration, electrocardiogram (ECG) and haemoglobin oxygen saturation (SpO2) in combination, in order to detect any potentially life threatening event at an early stage. ⋯ An intelligent fuzzy logic algorithm is used to process the signals monitored and to implement several propositions concerning their status in order to determine the probability of an apnoea event and initiate the appropriate action. This has substantially reduced the number of false alarms and of undetected dangerous situations compared with previous units, which greatly improves the reliability and usefulness of such a monitor.
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Clinical Trial
Reliability of an infrared forehead skin thermometer for core temperature measurements.
The SensorTouch thermometer performs an infrared measurement of the skin temperature above the Superficial Temporal Artery (STA). This study evaluates the validity and the accuracy of the SensorTouch thermometer. Two experiments were performed in which the body temperature was measured with a rectal sensor, with an oesophageal sensor and with the SensorTouch. ⋯ The largest differences between the SensorTouch and the core temperature existed 15 minutes after the start of the exercise. During this period the SensorTouch was significantly higher than the core temperature. The SensorTouch did not provide reliable values of the body temperature during periods of increasing body temperature, but the SensorTouch might work under stable conditions.
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Photoplethysmography (PPG) is a common optical technique used to monitor peripheral pulsation. Studies have shown that minimal variability in phase characteristics is critical to attain accurate estimation of timing-related measurements, such as heart rate and pulse transit time. ⋯ This study investigates nominal fluctuations when different detection settings were used on the PPG signals. The results indicate that there can be differences in variations observed, and an appropriate detection setting can minimize phase-induced errors in clinical interpretation of timing-related physiologic measurements.
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This paper introduces a simple and efficient technique for compression of medical ultrasound (US) images in the wavelet domain. The statistics of subband wavelet coefficients are modelled using the generalized Gaussian distribution (GGD). By exploiting these statistics, a uniform scalar quantizer is designed which adapts very well to the changing statistics of the signal across various subbands and scales. ⋯ The operational R-D criterion used for joint optimization is derived in the minimum description length (MDL) framework. The experimental results show that the joint R-D optimization leads to significant improvement in the compression performance of the proposed coder, named JTQ-WV, over the best state-of-the-art image coder, SPIHT. For example, the coding of US images at 0.25 bpp by JTQ-WV yields a PSNR gain of 1.0 dB over the benchmark SPIHT.