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Biomedical subjects

U Boenick

Publications and source records attributed to U Boenick.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Biomechanical stress studies with a new Y-nail].

The current success of the treatment of trochanteric fractures of the femur still depends on the type of fracture involved. A number of surgical procedures have proved successful in the treatment of stable fractures (e.g. dynamic hip screw, gamma nail). However, the treatment of unstable fractures remains a problem. With this type of fracture the implant is exposed to very unfavourable biomechanical loading that often leads to failure of the osteosynthesis, and makes removal of the implant necessary. In extensive tests, the biomechanical loading capacity of a new Y-nail has been investigated as a function of the stability and location of the fracture. The results show that this form of intramedullary fixing is suitable for both stable and unstable fractures. Unstable, far distal subtrochanteric fractures of the femur remain borderline indications.

Biomechanical Phenomena↗
PubMed1997

[Evaluation of possible measuring errors from overlaying pressure components in invasive blood pressure recording with external transducers].

Invasive arterial blood pressure measurement using external transducers is a routine measure in intensive care medicine and anaesthesiology. Despite the frequency of its use, measuring errors may occur that can strongly affect the significance of the results. The error with the greatest influence on blood pressure measurement arises from an inadequate dynamic behaviour of the measuring chain, and has been investigated in numerous publications. Measuring errors due to hydrostatic and dynamic pressure have not been considered to date. The present investigation describes an analysis of such measuring errors and possible ways of avoiding them. A side-hole catheter permits pressure measurements to be made without the measuring error caused by dynamic pressure behaviour. However, both analytical and experimental studies revealed that, since the velocities involved are small, this error is negligible in blood pressure measurements, and the increased cost of such catheters is therefore not justified. Measuring error due to hydrostatic pressure can be eliminated by using a zero point compensator. Such a compensator that permits vertical changes in the position of the patient without the need for manual resetting of the zero point has now been developed. However, the clinical test showed that the advantages offered by the zero point compensator again do not justify the increased cost. Furthermore, lateral changes in the patient's position during its use can lead to erroneous measurements.

Artifacts↗
PubMed1996

[Development of a measuring set-up for determination of light distribution of scattered light applicators for interstitial laser treatment].

In the medical setting, scattering dome applicators are used in various therapeutic and diagnostic procedures, e.g. laser-induced interstitial thermotherapy. The present study reports on the development of an automatic measuring system for determining the light distribution along the active end of scattering dome applicators. Using a stepper motor, the applicator is gradually moved into an integrating sphere, in which the light intensity is measured with a photodetector. It was shown the light distribution is determined mainly by the conditions under which the laser beam is coupled to the transmission fiber. The results made it possible to optimize the production of applicators, and showed that the set-up was suitable for quality control use.

Equipment Design↗
PubMed1996

[Modeling vestibulo-ocular reflexes in everyday activities].

Fundamental data for the establishment of a new clinical testing procedure for patients suffering from equilibrium disorders were developed. A mathematical model that predicts vestibulo-ocular reflex responses (eye velocities) to three-dimensional head movements was investigated. An experimental set-up permitting the simultaneous recording of the head and eye movements was developed to investigate the vestibulo-ocular reflex (VOR) during everyday activities. The test results show that computer simulation of the VOR occurring during complex movements is indeed possible. The model was able to predict the trend of the experimentally determined eye velocities. It was ascertained that for the further development of the model, the influence of the cervico-ocular reflex (COR) on the resulting eye velocities also has to be taken into account. The proposed method for investigating patients with equilibrium disorders appears suitable enough to make further development to the clinical stage worthwhile. An adaptation of the feedback amplification parameters of the model to take account of the nature of the stimulus and the influence of COR is needed to improve the agreement between the amplitudes of measured and predicted eye velocities. To reliably quantify the feedback amplification parameters, tests need to be carried out in a large number of subjects.

Activities of Daily Living↗