Biomedical subjects

M Felsmann

Publications and source records attributed to M Felsmann.

3 recordsLinked to original sources

PubMed1990

[A computerized processing unit for ambulatory diagnosis of sleep apnea and nocturnal hypoxemia].

A new mobile device for the evaluation of the sleep-apnoea-syndrome in outpatients prior to conventional polysomnography, processes and stores the oronasal airflow detected by a thermistor, and the heart rate and oxygen saturation in a microprocessor unit. The major problem in on-line data processing of these variables is the interpretation of the thermistor signal for correct apnoea detection. This preliminary study investigates the reliability of the computer algorithm by control of the automatic airflow assessment. With a sensitivity of 97.3% the algorithm proved to be extreme reliable. Combined with the detection of heart rate and oxygen saturation it provides the capacity for comprehensive analysis of cardiorespiratory events and appears to be suitable for application in an outpatient setting.

Algorithms↗

PubMed1989

[A modified unit for detecting sleep apnea].

A comprehensive diagnostic work-up of patients with a suspected sleep apnea syndrome must include conventional polysomnographic monitoring during the night. On account of the considerable staff and technical requirement, however, this definitive diagnostic measure is not suitable for use as a screening programme. For this reason we undertook to develop a device for the computer-aided recording of sleep apnea. The heart of the unit is a 65816 microprocessor with an address capacity of 16 Mbytes. The oro-nasal airflow is recorded with the aid of thermistors, and, after digital filtering, the respiratory rate is continuously recorded on the basis of this signal. Continuous recording of the heart rate and oxygen saturation, is also effected, the recorded data being stored in the microprocessor. On conclusion of the data acquisition phase, evaluation and a compressed display is shown on any conventional personal computer. Our preliminary experience reveals that the algorithm employed is extremely reliable for the detection of respiration rate and apnea, even in the presence of unfavourable signal forms. Clinically relevant deviations from manual evaluation do not occur. As was to be expected, processing of the signals for heart rate and oxygen saturation presented no problems.

Humans↗

PubMed1988

Strontium as a tracer to study the transport of calcium in the epiphyseal growth plate (electronprobe microanalysis).

At the mineralization front of the epiphyseal growth plate large quantities of calcium (Ca) are necessary to form the mineral (a Ca-phosphate). It is an unsolved problem, whether Ca is transported through the cells of the growth plate cartilage or extracellularly. Electronprobe microanalysis (EPMA) allows the quantitative, morphologically correlated analysis of elements. EPMA can discriminate only different elements. To investigate the transport of Ca, Strontium (Sr) is a very good tracer, as it resembles Ca in many biological reactions. Our results demonstrate that the transport of Sr from the blood into the growth plate and through the growth plate needs only one or a few minutes. The measured intracellular Sr and Ca concentrations are much lower than the extracellular ones, while the intracellular Sr/Ca ratio is not or only a little bit lower than the extracellular one. It must be concluded, that significant amounts of Ca are neither transported through nor accumulated in the cells of the growth plate cartilage. The main transport is an extracellular diffusion. Using Sr as a tracer for Ca new results on the behaviour of Ca could be received.

Animals↗