Biomedical subjects

A Bolz

Publications and source records attributed to A Bolz.

At least 37 records · Page 2Linked to original sources

PubMed2002

XML-based synchronization of mobile medical devices.

Today, mobile computing provides enough resources to be used in medical applications. Patient treatment is a process that involves multiple partners. All those partners need access to common patient-data and need to make changes to the patients' health record. Therefore, data that the partners collect and change with mobile devices has to be synchronized on a central server to form the master patient record. Data conflicts resulting from the synchronization have to be solved automatically. Our project describes a solution for XML-based data replication and synchronization for mobile health applications.

Computers, Handheld↗

PubMed2002

Parameter extraction of ECG signals in real-time.

In order for a mobile ECG recorder to be able to classify a heart rhythm online, the significant parameters must be extracted. The relevant parameters are the beginning, peak and end of the QRS-complex, the P- and T-waves, the ST-segment and other significant intervals, such as the RR-interval. The aim of the development was, firstly, stable, real-time-capable QRS detection, which finally achieved values for sensitivity of 98.9% and a positive predictivity of 99.9% on standard ECG databases. Also, a filter-based detection of P- and T-waves was implemented, which can also be performed in real-time on a microcontroller platform.

Artifacts↗

PubMed2002

Evaluation and optimization of different spectral estimation methods for EEG signals.

The goal of this work was the evaluation of various spectral estimation methods with regard to their suitability for classifying EEG data. A test environment was implemented in which the algorithms are optimized and evaluated using various artificial and real EEG data. The methods are based on autoregressive approaches, as well as from FFT, wavelet, and matching pursuit-based spectral estimations. The evaluation showed that the quality of the results strongly correlate with the computational effort of the algorithm. The matching pursuit algorithm (MP) was implemented and further optimized since it had the best test result and had good scalability. Even under a sufficiently low runtime, it still gave good results.

Algorithms↗

PubMed2002

[Can costs be lowered by post-hospital patient management with telecare].

The idea of Televisite is to equip the patients with a camera and a communication panel at the time of their discharge from the hospital. In that way patients and physicians are able to continue the treatment and the rehabilitation program. An easy to handle interface helps the patient to answer simple questions or to send voice recordings, pictures or videos via a service centre to the doctor in attendance. This concept has the great advantage that the patients has to visit the physician in the office or in the hospital only when absolute required. Routine checks can be done by telecommunication. Thus the efficiency of the system may significantly contribute to lower costs in the health care system.

Computer Communication Networks↗

PubMed2002

Recording and transmission of digital wound images with the help of a mobile device.

The goal of this project is to develop a mobile device for transmitting images for the aftercare of surgical patients within the framework of the competence center TELTRA. After designing and evaluating different platforms and cameras, it was decided to develop for a compact flash camera card and an HSCSD modem which is based on and can be plugged into a pocket PC. The recorded images are sent with the help of a Java program from the pocket PC over an IrDA interface to the HSCSD mobile telephone, and then to the web server, where it is saved in a digital patient record.

Computer Communication Networks↗

PubMed2002

[New approaches in first aid for cardiovascular patients].

Sudden cardiac arrest is a major problem of our society. Ventricular fibrillation strikes without any warning. It leads to unconsciousness and death occurs within minutes. Every year at least 100,000 people die from sudden cardiac arrest in Germany alone. The following article is concerned with how todays rescue system can be improved in order to increase survival rates. The time which passes between occurrence of the ventricular fibrillation and the therapeutic defibrillation plays a major role. It is being observed that decentralizing the rescue system is of great advantage. The idea of the "first responder", involving laymen, family members, and company paramedics, reduces the rescue time extraordinarily. The introduction of a digital emergency health record which provides the doctor with all the important data on the patient briefly seems to be of equal importance. Hereby, delays based on false information can be reduced to a minimum. Optimizing the equipment by means of implementing automatic procedures which enable the application by laymen is just as important. But the key to medical success appears to be educating and repeatedly training as many people as possible.

Computer Systems↗

PubMed2002

[Coupling ventilation and defibrillation].

Fibrillation of the heart is one of the most common reasons for sudden death. In case of fibrillation, the brain gets damaged by hypoxia within minutes. Only a concept that bothly regards the cardial and pulmonal problem can be successful. A combination of AED (Automatic-External-Defibrillator) and breathing machine reduces the risks of hypoxia. It can furthermore benefit from the common use of sensors and a synchronised course.

Cardiopulmonary Resuscitation↗

PubMed2002

[Architecture of a software system for telemonitoring].

The TELTRA Televisite is a remote patient monitoring system, allowing the patient to remain at home and deliver monitoring data, images, speech and video recordings to the doctor. From this point, all the above mentioned sources of information will be referred to as data. As a medium for the information transfer, the Televisite uses ISDN or multi-channel HSCSD telephone. The system software architecture consists of the design of graphics patient interface, gathering and processing of data, transmittal of data and most importantly, providing highest security at all stages of the data, between patient and database server. The system also provides facility for emergency telephony between the patient and the physician. The technology employed in the Televiste is based on store and forward, where data is first collected and sent to the doctor at the end of a teleround session.

Computer Communication Networks↗

PubMed2001

[Artificial intelligence in sleep analysis (ARTISANA)--modelling visual processes in sleep classification].

We describe a novel approach to the problem of automated sleep stage recognition. The ARTISANA algorithm mimics the behaviour of a human expert visually scoring sleep stages (Rechtschaffen and Kales classification). It comprises a number of interacting components that imitate the stepwise approach of the human expert, and artificial intelligence components. On the basis of parameters extracted at 1-s intervals from the signal curves, artificial neural networks recognize the incidence of typical patterns, e.g. delta activity or K complexes. This is followed by a rule interpretation stage that identifies the sleep stage with the aid of a neuro-fuzzy system while taking account of the context. Validation studies based on the records of 8 patients with obstructive sleep apnoea have confirmed the potential of this approach. Further features of the system include the transparency of the decision-taking process, and the flexibility of the option for expanding the system to cover new patterns and criteria.

Adult↗

PubMed2001

[Conditions and success factors of telemedicine innovation].

Telemedicine and health telematics can play a significant role in improving the efficiency of health care systems. Currently, however, the potential of telemedical applications is far from being fully utilized. In the present study, an attempt has been made to identify factors that may aid the further dissemination and general acceptance of telemedical innovations. The results obtained suggest that apart from the factors under the sole control of legislation, and insurance providers, those that can be directly influenced by developers, manufacturers and providers of telemedical applications play an important role. Of particular importance for the successful and lasting use of such applications is the creation of promising business models, aspects of which are considered in the last part of the article.

Diffusion of Innovation↗

PubMed1998

Nuclear Magnetic Resonance Detection of Two Distinctly Different Chains in the Orthorhombic Crystalline Phase of Polyethylenes.

Several commercial and noncommercial, high- and low-density and ultraoriented polyethylene samples, as well as polyethylene samples with inorganic fillers, have been investigated by inversion-recovery cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (NMR). In all these samples two types of all-trans chains in orthorhombic crystalline domains are detected, which give two overlapping carbon-13 lines with different line widths and different relaxation times. From the NMR relaxation parameters we conclude that one type of the crystalline chains, which composes 60-90% of the crystalline fraction in all samples, can execute at room temperature 180 degrees flips with a frequency in the kilohertz domain. The other crystalline chains are more rigid and probably are found in more perfect structures in which such chain flips do not occur or occur on a much slower time scale. Adding kaoline filler particles to polyethylene enhances the contribution of the more mobile crystalline chains. The presence of the two distinctly different types of crystalline environments is found in all polyethylene samples investigated so far (more than 25 samples).

Journal Article↗

PubMed1998

A fractally coated, 1.3 mm2 high impedance pacing electrode.

Minimizing the geometric surface area of pacing electrodes increases impedance and reduces the current drain during stimulation, provided that voltage (pulse-width) thresholds remain unchanged. This may be feasible by coating the electrode surface to increase the capacity of the electrode tissue interface and to diminish polarization. Ten unipolar, tined leads with a surface area of 1.3 mm2 and a "fractal" coating of iridium (Biotronik SD-V137) were implanted in the ventricle, and electrogram amplitude (unfiltered), slew-rate, pacing threshold (0.5 ms), and impedance (2.5 V; 0.5 ms) were measured by the 5311 PSA (Medtronic). On days 0. 2. 5. 10, 28, 90, 180, 360 postimplant, sensing threshold (up to 7.0 mV, measuring range 1-14 mV on day 360 only) and the strength duration curve (0.5-4.0 V; 0.03-1.5 ms; steps: 0.5 V; 0.01 ms, respectively) were determined, the minimum charge delivered per pulse (charge threshold), and the impedance were taken from pacemaker telemetry (Intermedics 294-03). Data were compared with those of an earlier series of 20 unipolar, tined TIR-leads (Biotronik) with a surface area of 10 mm2 and a @actal" coating of titanium nitride. With the model SD-V137 versus TIR, intraoperative electrogram amplitudes were 15.1 +/- 6.1 versus 14.4 +/- 3.9 mV (NS), slew rates 3.45 +/- 1.57 versus 1.94 +/- 1.06 V/s (P < 0.05), pacing thresholds 0.16 +/- 0.05 versus 0.52 +/- 0.15 V (P < 0.01) and impedance measurements 1,136 +/- 175 versus 441 +/- 73 omega (P < 0.0001), respectively. During follow-up, sensing thresholds were the same with both leads. Differences in pulse width thresholds lost its significance on day 28 but resumed on day 360 (SD-V137; 0.08 +/- 0.04 ms; TIR: 0.16 +/- 0.06 ms at 2.5 V; P < 0.01). With an electrode surface of 1.3 mm2, charge per pulse and impedance consistently differed from control, being 0.15 +/- versus 0.66 +/- 0.20 microC (P < 0.001) and 1,344 +/- 376 versus 538 +/- 79 omega respectively, one year after implantation (P < 0.0001). In summary, "fractally" coated small surface electrodes do not compromise sensing; by more than doubling impedance against controls they offer pacing thresholds (mainly in terms of charge) that are significantly lower than with the reference electrode.

Aged↗

PubMed1998