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We examined the functionality and reliability of a wearable physiological monitoring system (LifeShirt) during normal daily activities and in a hospital operating room (OR) environment. The garment collects physiological data such as oxygen saturation, and stores them in a recorder from which it can be read afterwards. Ten normal subjects wore the shirt continuously for 8 h per day. Feedback from the testers was quite positive, although the collected data varied in quality. Ten hospital patients also wore the shirt during endoscopy. The data collected during the hospital stay were qualitatively adequate. Measuring respiratory function caused the biggest problems. The study showed that intelligent garment technology could be used in an OR environment for patient monitoring, albeit not in realtime. It may also be useful in home follow-up.

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Beat-to-beat heart rate variability analysis is a powerful tool for the diagnosis of neuropathy. Respiration-related heart rate variability (respiratory sinus arrhythmia, RSA) reflects the function of parasympathetic nervous system during spontaneous ventilation while awake. RSA is also claimed to monitor the depth of anaesthesia. Power spectrum analysis or various averaging techniques of the heart rate variability are usually applied. The current literature, however, does not usually interpret the ground rules and limitations of the method used, and this may sometimes lead to erroneous conclusions on the data. The aim of our study was to compare and analyse critically the performance of different methods of evaluating RSA during anaesthesia and positive pressure ventilation. Power spectrum analysis, the root mean square of the successive RR-interval difference (RMSSD), and two respiration related methods, RSA index and average phase RSA, were included in the comparison. To test these methods, 11 patients were anaesthetised with isoflurane and their lungs were ventilated mechanically with a frequency of 6 cycles min-1. Each patient received a bolus dose of atropine (20 micrograms kg-1) during the trial. Electrocardiogram, electroencephalogram and tracheal pressure signal from respirator were recorded and analyses were performed off-line. We demonstrated that general indices, such as RMSSD, may be strongly affected by heart rate level and other non-respiration related variations in heart rate. We also showed that the effect of unwanted fluctuations on RSA can be reduced with respiration dependent beat-to-beat methods. Furthermore we confirmed that in addition to the amplitude, also the pattern of respiratory sinus arrhythmia is of interest: the pattern is reversed in phase compared to spontaneous breathing while awake, as we have shown earlier. To analyse RSA during anaesthesia, we recommend the use of an average phase RSA method based on beat-to-beat variability that shows both the amplitude and pattern of RSA. Finally, no measure of RSA should be used without a presentation of the actual beat-to-beat heart rate curve.

A literature survey was carried out to identify papers describing teleconsulting applications. From 1259 potentially relevant articles identified through Medline, 128 articles were selected for review. The majority of these had been published in the Journal of Telemedicine and Telecare (50 articles, or 39%). We analysed different user groups, equipment and implementation issues, and the type of connections. In 101 studies (79%) the teleconsultations were between doctors, in 11 they were between patient and doctor, in seven between patient and nurse, and in nine between nurse and doctor. Studies of consultations between patients and health-care professionals were thus quite rare. Surgery was the most common specialty in which teleconsultation was described. The teleconsultations were realtime or mainly realtime in 72% of articles. In 39% of studies the primary focus was on videoconferencing. The most common means of connection was by ISDN digital lines (38%). There were very few mentions of how to ensure data protection or to maintain patient confidentiality. We conclude that, for the majority of teleconsultation needs, asynchronous communication is the most flexible and cost-effective approach. Realtime videoconferencing can be justified only in particular circumstances.

We have developed a consultation forum for clinical neurophysiology in Finland. The system connects local digital electroencephalography (EEG) recording and analysing networks using a high-speed asynchronous transfer mode (ATM) network. Clinicians can obtain a second opinion using interactive data and video consultations or using data-only consultations. In addition, the system can be used for off-line review of pre-recorded data. During a one-month evaluation, 66 EEG recordings were made altogether in Satakunta Central Hospital and consultations were required on 12 occasions. Nine of them were data-only consultations and three were data and video consultations. A data consultation lasted 15-20 min and a data and video consultation 35-45 min. Clinically, there were numerous benefits for the hospitals. The system established a link to a centre of excellence for second opinions or continuing education. It also helped with on-duty arrangements and enabled the construction of national data banks.

A nonlinear Hammerstein model is proposed for coding speech signals. Using Tsay's nonlinearity test, we first show that the great majority of speech frames contain nonlinearities (over 80% in our test data) when using 20-millisecond speech frames. Frame length correlates with the level of nonlinearity: the longer the frames the higher the percentage of nonlinear frames. Motivated by this result, we present a nonlinear structure using a frame-by-frame adaptive identification of the Hammerstein model parameters for speech coding. Finally, the proposed structure is compared with the LPC coding scheme for three phonemes /a/, /s/, and /k/ by calculating the Akaike information criterion of the corresponding residual signals. The tests show clearly that the residual of the nonlinear model presented in this paper contains significantly less information compared to that of the LPC scheme. The presented method is a potential tool to shape the residual signal in an encode-efficient form in speech coding.