Péter Várady

A novel method for the detection of apnea and hypopnea events in respiration signals

The monitoring of breathing dynamics is an essential diagnostic tool in various clinical environments, such as sleep diagnostics, intensive care and neonatal monitoring. This paper introduces an innovative signal classification method that is capable of on-line detection of the presence or absence of normal breathing. Four different artificial neural networks are presented for the recognition of three different patterns in the respiration signals (normal breathing, hypopnea, and apnea). Two networks process the normalized respiration signals directly, while another two use sophisticatedly preprocessed signals. The development of the networks was based on training sets from the polysomnographic records of nine different patients. The detection performance of the networks was tested and compared by using up to 8000 untrained breathing patterns from 16 different patients. The networks which classified the preprocessed respiration signals produced an average detection performance of over 90%. In the light of the moderate computational power used, the presented method is not only viable in clinical polysomnographs and respiration monitors, but also in portable devices.

An open architecture patient monitoring system using standard technologies

Computer-aided bedside patient monitoring is applied in areas where real-time vital function analysis takes place. Modern bedside monitoring requires not only the networking of bedside monitors with a central monitor but also other standard communication interfaces. In the paper, an approach to patient monitoring is introduced. A patient monitoring system was developed and implemented based on an existing industry standard communication network, using standard hardware components and software technologies. The open architecture system design offers scalability, standard interfaces, and flexible signal interpretation possibilities.

An advanced method in fetal phonocardiography

The long-term variability of the fetal heart rate (FHR) provides valuable information on the fetal health status. The routine clinical FHR measurements are usually carried out by the means of ultrasound cardiography. Although the frequent FHR monitoring is recommendable, the high quality ultrasound devices are so expensive that they are not available for home care use. The passive and fully non-invasive acoustic recording called phonocardiography, provides an alternative low-cost measurement method. Unfortunately, the acoustic signal recorded on the maternal abdominal surface is heavily loaded by noise, thus the determination of the FHR raises serious signal processing issues. The development of an accurate and robust fetal phonocardiograph has been since long researched. This paper presents a novel two-channel phonocardiographic device and an advanced signal processing method for determination of the FHR. The developed system provided 83% accuracy compared to the simultaneously recorded reference ultrasound measurements.

Wavelet-based adaptive denoising of phonocardiographic records

The various noise components make the diagnostic evaluation of phonocardiographic records difficult or in some cases even impossible. This paper presents a novel wavelet-based denoising method using two-channel signal recording and an adaptive cross-channel coefficient thresholding technique. The qualitative evaluation of the denoising performance has shown that the proposed method cancels noises more effectively than the other examined techniques. The introduced method can be used as preprocessor stage in all fields of phonocardiography, including the recording of fetal heart sounds on the maternal abdominal surface.

Detection of airway obstructions and sleep apnea by analyzing the phase relation of respiration movement signals

The authors introduce a novel diagnostic method of a sleep disorder, sleep apnea syndrome (SAS), which may cause numerous irreversible complications with severe consequences without treatment. The sleep laboratory test called polysomnography is the main aid to the experts to recognize and obtain the grade of SAS. A polysomnographic record consists of several channels such as nasal air flow, blood pressure, abdominal and thoracic excursion, blood oxygen saturation etc. Several well-known methods exist to analyze one or more of these signals. We present a method, which uses the phase relation information between the abdominal and thoracic respiration movements in order to detect the grade and type of SAS.

Distributed measurement system for heat metering and control

Measuring and charging heat consumption are not often worked out in the prevalent warm-water heating systems. The developed modern heat-meter device, which includes a microcontroller, is self-calibrating and self-testing; it uses several correctional algorithms in order to increase accuracy after authentication. Consumption data and information about the work-state events are logged and stored by the measuring unit. The discrete devices are connected to a local concentrator via M-bus. The concentrator is connected to the central supervisory system through a mobile communication channel. In this system, the meter devices respond to arising failures. The center collects information about measuring and usage. This solution highly increases the efficiency and the reliability of the system.

Patient monitoring on industry standard fieldbus

Currently approved medical communication standards exist only for the higher level of medical care, and not for low level communication between bed side measurement and diagnostic devices of patient monitoring systems. Our system is a new approach. Using a vendor-independent, open, broadly supported industrial fieldbus in the medical area makes possible to interconnect bed side devices via a simple two wire cable at an economical cost. The main goal in the system is to demonstrate the benefits of open system design, support the connection of existing medical devices to the fieldbus system and allowing the further extension for integration into the hospital information system (HIS) and telemedicine (telemonitoring) applications.

Design of glucose control via symbolic computation

Symbolic computation has been applied to the design procedure for blood glucose control of diabetic patients under intensive care. To design the multivariable modal control system based on nonlinear state-space model fully symbolically, MAPLE packages were employed. The model has been verified and tested in a clinical environment.

Distributed intelligent hierarchical system for heat metering and controlling

A key factor of rational energy consumption management is the accurate measurement. Measuring and charging heat consumption are rarely worked out in the prevalent warm-water heating systems. The developed modern heat-meter device, which includes micro-controller, is self-calibrating and self-testing. It uses several correction algorithms in order to increase accuracy after authentication. The discrete devices are connected to a local concentrator via M-bus. The concentrator collects calculated data from measured values and information about the state of the heat-meter. Consumption data and information about the work-state events are logged and stored by the measuring unit. The concentrator is connected to the central supervisory system through mobile communication channel (GSM). In this system, the meter devices respond to arising failures on the one hand with the help of their own algorithms, on the other hand based on information from the concentrator and from the center. The center is able to collect information about measuring and usage, based on requested information. This solution highly increases the speed and the accuracy of the system.

Biomedical engineering education in Hungary

In medical-biological research, the need for an exact mathematical method is being felt more and more. The Biomedical Engineering Education Programme (BMEEP) in Hungary includes all theoretical processes allowing one to describe the behaviour of a biological system by means of a mathematical model. This paper first deals with the objectives of biomedical engineering training (general principles, etc.); then the BMEEP curriculum is discussed.