Biomedical subjects

A Bolz

Publications and source records attributed to A Bolz.

At least 19 recordsLinked to original sources

PubMed2005

[The technical possibilities in telemonitoring of physiological parameters].

For decades, telemonitoring of vital parameters has been a recurring topic among experts. Because of its lack of economical advantages it has not established itself as a standard up to now. Thanks to novel wireless communication technologies such as Bluetooth or Zigbee, the enormous technological progress in mobile communication via GSM, GPRS, as well as UMTS and various radical medical changes within disease management programs, currently very promising new potentials for telemonitoring are appearing. This article summarizes the current technological developments, discusses their advantages and drawbacks, and deduces scenarios and technical requirements for future system architectures.

Blood Pressure Determination↗

PubMed2004

Newly explored electrical properties of normal skin and special skin sites.

Skin impedance measurements at various skin sites yield different impedance loci for normal skin and special skin sites. The results of skin impedance measurements taken at such sites with a two-electrode measurement system are presented herein. Some of these sites can be identified as acupuncture points. Data from 4 volunteers were acquired by means of a data acquisition board and a measuring system consisting of the measurement circuit, including several electrode types, and a power supply. The Cole model is a model for an equivalent electrical circuit of the skin-electrode system. The system was used to derive skin-typical parameters from the Bode plot of the whole system. These parameters are the fractional power a, the pseudo-capacity K, the parallel resistance Rp, and the serial resistance Rs of the equivalent electrical circuit. The results show that the measured parameters differ between normal skin and special skin sites. These effects have not previously been discovered by other authors, since there has been no systematic investigation of many acupuncture points to date, and there has been no apparent need for such an investigation. A number of necessary criteria for acupuncture point detection can be derived from the results obtained.

Acupuncture↗

PubMed2004

[Comparative analyses of the reliability of automatic external defibrillators].

Automatic external defibrillators are gaining increasing acceptance. Last year 6000 devices were installed in Germany. Since the average user has only limited medical knowledge, high demands have to be made on the automatic ECG diagnosis (fibrillation detection). Within the framework of this study a fully automatic test system that permits an objective comparison of the performance of the various devices available on the market was constructed. Older devices in particular do not always meet the requirements defined by international standards with regard to sensitivity and specificity. In addition, company philosophy appears to differ in terms of the preferential emphasis on sensitivity or specificity. Purchasers of such devices need take these findings into consideration.

Arrhythmias, Cardiac↗

PubMed2002

[Development of an optical 3-D position measuring system for simultaneous detection of 6 degrees of freedom].

A few years ago it became possible to carry out complicated surgical procedures in humans with the required precision by combining medical imaging (MRI, CT) with minimally invasive surgery. The confined space within these imaging systems and the resulting inaccuracies associated with the manual use of instruments increasingly make necessary the help of aids ranging from positioning systems to robotic devices, which themselves must be position controlled. A position sensor has been developed for a medical robotic system allowing the image-controlled insertion of injection needles and the simultaneous administration of different drugs. The 3D position coordinates are determined by a noncontact optical principle, which also enables simultaneous determination of all 6 basic degrees of freedom of the robotic system (3 translational, 3 rotational). On the basis of an area image sensor and the measurement of a geometrically defined structure in the path of the rays between sensor and light source, the position coordinates are calculated almost real time. Special emphasis was placed on designing the sensor system to cover a sufficiently large workspace to enable it to cover the entire intervention area. The sensor described herein determines the position coordinates in a volume of 10 x 10 x 10 cm at a resolution of up to 1 mm for translations and 1 degree for rotations.

Equipment Design↗

PubMed2002

Patient-dependent current dosing for semi-automatic external defibrillators (AED).

The improvements in semiconductors and modern circuitry allow new waveforms to be created for treating life-threatening heart fibrillation. A comparison of common waveforms shows that there is no definite optimal waveform. Especially in the case of early defibrillation by novices, the question of dosage should be re-discussed. While a physician may be able to dose the intensity of the therapeutic electric shock, one can't expect that from someone having no medical training. Common AEDs have predefined energy levels, that are delivered to a patient regardless of the patient's size and weight, etc. Current-based defibrillation provides a therapy matched to patient parameters, keeping the myocard stress as low as possible so that the heart has better chances of resuming a normal rhythm.

Cardiography, Impedance↗

PubMed2002

Kater-Karlsruhe Telemetry Test in Rescue Services.

The Karlsruhe Telemetry Test in Rescue Services (KATER) investigates the central role of the regional emergency dispatch center as the midpoint of the emergency medicine information network using ECG telemetry, in order to be able to draw conclusions for future development. Rescue centers today form the logistic center of the flow of information. Expanding this legally formulated role to data flows within a network is just beginning, however, since the introduction of EDP in pre-clinical emergency medicine is still in the pilot project stage. Legislators are tending toward big solutions due to economic reasons. The increasing complexity of this problem can only be handled by a networked infrastructure.

Computer Communication Networks↗

PubMed2002

Automated sleep stage detection with a classical and a neural learning algorithm--methodological aspects.

For classification tasks in biosignal processing, several strategies and algorithms can be used. Knowledge-based systems allow prior knowledge about the decision process to be integrated, both by the developer and by self-learning capabilities. For the classification stages in a sleep stage detection framework, three inference strategies were compared regarding their specific strengths: a classical signal processing approach, artificial neural networks and neuro-fuzzy systems. Methodological aspects were assessed to attain optimum performance and maximum transparency for the user. Due to their effective and robust learning behavior, artificial neural networks could be recommended for pattern recognition, while neuro-fuzzy systems performed best for the processing of contextual information.

Algorithms↗

PubMed2002

[Development of Bluetooth wireless sensors].

Wireless communication could help to overcome current obstacles in medical devices and could enable medical services to offer completely new scenarios in health care. The Bluetooth technology which is the upcoming global market leader in wireless communication turned out to be perfectly suited not only for consumer market products but also in the medical environment [1]. It offers a low power, low cost connection in the medium range of 1-100 m with a bandwidth of currently 723.2 kbaud. This paper describes the development of a wireless ECG device and a Pulse Oximeter. Equipped with a Bluetooth port, the measurement devices are enabled to transmit data between the sensor and a Bluetooth-monitor. Therefore, CSR's Bluetooth protocol embedded two-processor and embedded single-processor architecture has been used.

Electrocardiography↗

PubMed2002

Design aspects for novel, telemedical unattended diagnosis and therapy control systems for sleep disorders.

Medical research confirmed the relevance of diagnosis and therapy of sleep-related breathing disorders, revealing prevalence and patho-physiological mechanisms [1-10]. Reliable sleep assessment currently demands examinations in the sleep-lab, which is very technical and time-consuming. Thus, expanding the conventional procedure to meet capacity demands does not seem realistic regarding cost aspects. As a solution, the authors present telemetric system concepts for the unattended assessment of a patient's sleep profile and cardio-respiratory parameters. Taking initial experience with home polysomnography into consideration, the presented research work focuses on easily applicable sensors, the corresponding sleep profile assessment rules, wireless data recording, intelligent signal processing algorithms and telemedical information logistics to include sleep-labs in the diagnosis and treatment process as competence centers.

Algorithms↗

PubMed2002

Transmitting patient and device data via GSM--central management for decentral mobile medical devices.

Equipping medical devices with long range telemetry opens completely new possibilities for emergency response, home care and remote diagnosis. Mobile communications nowadays seem to be a generally accepted part of our modern world, but bridging the gap between new (consumer-) technologies and medical devices still is a challenge today. Providing a telemetry link (GSM) is just the trivial part--ensuring security, reliability and service management are the more critical tasks that need to be addressed. Therefore, a complete system concept consists of an automatic fleet management (e.g. periodic device-initiated service calls) as well as customer relationship management (CRM), including technical service and a trouble-ticket system.

Artificial Intelligence↗

PubMed2002

[Patient monitoring after discharge by teleconsultation].

The Televisite application is a post-stationary consulting method, whose main aim is to reduce the treatment time of inpatients. It provides a high quality home consultation after the patient has been discharged from the hospital. The technical handling and the validity of the new method of caring will be analysed--particularly the human-machine interface. In a prospective study case injured patients were attend using the Televisite. For communications with the consulting doctor they were supplied with a high resolution digital camera and a mobile PC with an integrated HCSCD cell phone. The doctor examined the data transmitted by the patient and remotely consulted the patient using the Televisite. Through a simple self-explaining user interface, a smooth information transfer was guaranteed.

Computer Systems↗

PubMed2002

Simulation methods for the online extraction of ECG parameters under Matlab/Simulink.

The classification of cardiac pathologies in the human ECG greatly depends on the reliable extraction of characteristic features. This work presents a complete simulation environment for testing ECG classification algorithms under Matlab/Simulink. Evaluation of algorithm performance is undertaken in full compliance with the ANSI/AAMI standards EC38 and EC57, and ranges from beat-to-beat analysis to the comparison of episode markers (e.g., for VT/VF detection algorithms). For testing the quality of waveform boundary detection, our own testing methods have been implemented in compliance with existing literature.

Algorithms↗

PubMed2002

[Hardware implementation in VT/VF detection algorithms for AED (automatic external defibrillators)].

The automatic external defibrillator (AED) should carry out the diagnosis of the patient in a cardiac emergency when medical professionals are not present. The decision about defibrillation should be made without the help of first responder. To fulfill these requirements special algorithms are needed. In this article the structure of such an algorithm and also hardware implementation problems are described.

Algorithms↗

PubMed2002

Mobile patient simulator for resuscitation training with automatic external defibrillators.

Resuscitation training has to be performed under most realistic conditions. This includes both usual CPR measures (breathing and chest compressions) and advanced measures, e.g. the usage of an Automatic External Defibrillator (AED). Almost all currently available simulators for ECG signals used in such trainings have a rather limited variety of available ECG signals. The trainer also has to change between different rhythms manually, resulting in a less realistic training environment. The development will result in mobile ECG simulator which can automatically react to events in the resuscitation process according to pre-programmed scenarios. It also has potential to simulate other physiological parameters like thorax impedance in the future.

Cardiopulmonary Resuscitation↗

PubMed2002

Development of a current-controlled defibrillator for clinical tests.

The work presented here is only a part of the development for a new current-controlled defibrillator. In the diploma thesis "Development and construction of a current-controlled defibrillator for clinical tests" the most important part was the control and safety of the defibrillator. To ensure a safe circuit design, a risk-analysis and a Failure Mode and Effects Analysis (FMEA) were necessary. Another major part was the programming of a microcontroller in embedded C and a programmable logic device in Very High Speed Integrated Circuit Description Language (VHDL). The circuit had to be constructed, and the defibrillator was optically decoupled from the laptop for safety reasons. The waveform-data can be transmitted to the microcontroller from the laptop, and the logged data is then transmitted back.

Electric Countershock↗

PubMed2002

Signalprocessing in transmission pulse hemometry.

Supplying organs and body tissues with sufficient oxygen is one of the most important vital human functions. Commercial pulse oximeters compute the functional oxygen saturation from relative values (reduced hemoglobin and oxyhemoglobin). Methemoglobin (MetHb) and carboxyhemoglobin (COHb) are not taken into account, since they are considered to be reduced hemoglobin and oxyhemoglobin (RHb, HbO2). The total hemoglobin concentration is not included, and is determined by invasive methods. In this work, a non-invasive pulse oximeter is developed, which finds the entire hemoglobin concentration photometrically, and measures the fractional oxygen saturation and pulse rate. The signal of transmitted light I is processed according to the Lambert-Beer-law. The signal decays exponentially with the thickness d of the irradiated sample and its absorption coefficient alpha (I = I0 e -alpha d), where I0 is the incident light intensity.

Fingers↗

PubMed2002

The wireless monitoring of vital parameters: a design study.

This project shows the way vital parameters can be transmitted and visualized with no connecting cables necessary to the PDA. This was realized using a sensor developed with an integrated Bluetooth interface and a PDA, also equipped with Bluetooth. This radio connection can span up to 10 m, and parameters, such as pulse frequency, oxygen saturation in blood, ECG measurements and plethysmograms, can be transmitted. Using the software introduced in this work, the transmitted measurements can be displayed numerically or graphically on the PDA. The software simultaneously checks for any limits and sends a warning message if these limits are exceeded. All received data are additionally documented.

Computer Graphics↗

PubMed2002

Miniaturized module for the wireless transmission of measurements with Bluetooth.

The wiring of patients for obtaining medical measurements has many disadvantages. In order to limit these, a miniaturized module was developed which digitalizes analog signals and sends the signal wirelessly to the receiver using Bluetooth. Bluetooth is especially suitable for this application because distances of up to 10 m are possible with low power consumption and robust transmission with encryption. The module consists of a Bluetooth chip, which is initialized in such a way by a microcontroller that connections from other bluetooth receivers can be accepted. The signals are then transmitted to the distant end. The maximum bit rate of the 23 mm x 30 mm module is 73.5 kBit/s. At 4.7 kBit/s, the current consumption is 12 mA.

Amplifiers, Electronic↗