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Biomedical subjects

H Maresch

Publications and source records attributed to H Maresch.

17 recordsLinked to original sources
PubMed1995

[Evaluating an interactive, multi-media learning system for the study of primary open angle glaucoma].

Using the interactive multimedia learning system for studying open-angle glaucoma [3] a prospective, randomized, case-controlled study was carried out to determine the value of this new form of learning in terms of acceptance and the imparting of knowledge. This article describes details of the study and presents their results. Results were established on the basis of targeted questions asked prior to and after the learning phase, followed by an analysis of frequencies and significance testing by the Chi squared method. It was shown that the imparting of knowledge is significantly improved when this learning system is employed. In addition, after its first use, acceptance of this new medium rose dramatically.

Case-Control Studies↗
PubMed1994

[A method for determining pulse wave transmission time].

Analysis of the transit time of a pulse wave is a possibility for the continuous observation of the changes in blood pressure activity. With invasive procedures, the interval between two notable events on pressure pulse waveforms, which is known as the pulse transit time, is often calculated. Using the second heart sound, the pre-ejection period and the left-ventricular ejection time (systolic time interval) are computed in order to be able to exclude the effect of haemodynamic parameters on aortic pressure increase. Since the use of noninvasive procedures excludes computation of the systolic time interval, and a phonocardiography is also often lacking, a method of relatively quickly determining the time interval between the R-wave of the ECG and the peripheral pulse was developed. The computed pulse transmission time is suitable for studying phasic events and their effects on the mean blood pressure.

Blood Pressure↗
PubMed1990

Electroencephalographic and evoked potential monitoring in the hyperbaric environment.

The purpose of this study was to investigate brain bioelectrical activity during hyperbaric oxygenation by continuous and simultaneous monitoring of electroencephalographic and bimodal (auditory, somatosensory) evoked potentials. Multivariable recordings (electroencephalogram, brainstem auditory evoked potentials, early somatosensory evoked potentials, heart rate, heart rate variability, and transcutaneous partial pressure of oxygen) were measured with a new technique in 12 healthy male volunteers 26 to 52 years old (mean +/- SD, 35.9 +/- 9.5 years). Recordings were obtained while the subjects breathed (1) air at normal atmospheric pressure, (2) 100% oxygen at normal atmospheric pressure, (3) air at 2 atm (10 meters sea water [msw]), and (4) 100% oxygen at 2 atm (10 msw). Spontaneous brain electrical activity, somatosensory evoked potentials, and heart rate variability were not significantly affected during hyperbaric oxygenation, whereas the heart rate showed a significant decrease (paired t test, P less than 0.05). Alterations in brainstem auditory evoked potentials were seen under hyperbaric conditions and did not reach statistical significance (increase of the I-V interpeak latency by paired t test; P less than 0.2). All subjects showed insignificant increases in dominant alpha frequency and decreases in delta frequency under hyperbaric situations.

Adult↗
PubMed1990

Computer-based sleep monitoring in SIDS-risk infants--preliminary results.

A computerized, PC-based system is introduced for sleep monitoring in infants. The system is capable of digitizing and storing 22 physiological variables over a whole-night sleep period. The preprocessed data can be displayed on a single page; further processing can be done on the digitally stored data.

Computer Systems↗
PubMed1987

Continuous and simultaneous monitoring of EEG spectra and brainstem auditory and somatosensory evoked potentials in the intensive care unit and the operating room.

Individual monitoring of EEG and evoked potentials is gradually becoming standard in neurosurgery: compressed power spectra during carotid endarterectomy, brainstem auditory evoked potentials (BAEP) during posterior fossa surgery, and somatosensory evoked potentials (SEP) mainly during spinal cord surgery. In this paper, a new technique is described in which EEG, BAEP, and SEP are recorded and evaluated simultaneously and continuously. This allows a better survey of different neuronal structures and systems in the brain and brainstem. First results from intraoperative and intensive care patient monitoring are reported.

Adult↗
PubMed1983

Simultaneous measurement of auditory brain stem potentials and EEG spectra.

Compressed EEG spectra and compressed brain stem auditory potentials (BAEP) can be measured at the same time, from the same derivation, if a wide band amplifier (1 Hz-2 kHz) is used and the complete brain stem signal is sampled between two EEG sampling points. For this approach sample rates of 64 Hz for the EEG and 12,800 Hz for the BAEP were used. The auditory stimulation was repeated every 6th EEG sampling point, corresponding to a repetition rate of 10.6 Hz. Processing and presentation of the results were performed on-line, permitting continuous monitoring of the patient.

Brain Stem↗
PubMed1979

Amplitude of evoked potentials and degree of event-related desynchronization (ERD) during photic stimulation.

The variations in amplitude of visual evoked potentials (VEPs) and parallel changes in amount of event-related desynchronization (ERD) of the rhythmic activity within the alpha band were studied in central derivations of scalp EEG, in 10 normal subjects. Two methods were used to estimate the amplitude of VEPs in small groups of 10 responses: (1) inverse and matched filtering techniques; (2) two-way rank analysis of variance by the Friedman test. The two methods gave similar results and two groups, statistically different, emerged. The first, with large VEP amplitude, having at the same time large ERD, and the second, with small VEP amplitude and small ERD.

Adult↗
PubMed1977

Inter- and intrahemispheric differences in the peak frequency of rhythmic activity within the alpha band.

EEG was recorded simultaneously from several scalp regions in 5 normal subjects and analysed, using a PDP 11/45 computer by means of an autoregressive model. Significant intra- and interhemispheric differences in the peak frequencies within the alpha band were observed, up to 0.8 c/sec. Local modality -dependent increases in the peak frequency were also observed, which were predominant in occipital areas during visual stimulation and in central regions during acoustic stimulation. In most cases an increase in the peak frequency occurred together with a marked decrease in power, which could be interpreted as a desynchronization of slow components within the alpha band. These peak frequency differences found in the scalp EEG lead to the assumption that there might also be different alpha rhythms at the level of the cortex.

Adult↗
PubMedDate not supplied

[Interactive, multimedia learning system for the study of primary open angle glaucoma--system description from the viewpoint of the computer scientist].

For use on an Apple Macintosh PC, a software packet was developed with the aid of which medical students can learn all about primary open-angle glaucoma; at the same time, it is also highly suitable for supplementing lectures. The subject is subdivided into the three sections anatomy, pathology and clinical picture. All the possibilities of computer technology, for example controllable animation, video sequences and special graphic effects are utilized. A special lexicon, a complex of questions and all the possible cross-references combine to make the learning system a very flexible and highly effective learning tool.

Computer-Assisted Instruction↗
PubMedDate not supplied

Realtime measurement of stroke volume--an adaptive monitoring system and its application.

A variety of monitoring systems is available for special fields of clinical application and scientific research. Whenever requirements change data acquisition and handling of signal analysis have to be adapted or even completely new structured, especially in real-time applications. This can be a time consuming procedure. In order to be able to focus on the development of algorithms without taking care how data are acquired a monitoring system has been developed which can be adjusted in terms of signal acquisition, analysis and user handling. New algorithms can be added and polygraphical presentation of results can be adjusted for special clinical requirements. As a specific application the online and real time calculation left ventricular ejection time (LVEJT), stroke volume (SV), cardiac output (CO), mean blood pressure and total peripheral resistance (TPRI) is presented.

Algorithms↗