Technology and Health Care

Healthy control subjects and Parkinsonian patients with and without l-DOPA medication were tested in a motor paradigm. The subjects were instructed to aim with the forearm as fast and as accurately as possible to the illuminated target. A quantitative dynamic model for planning and execution of voluntary aiming movements is developed. The proposed ‘motor model’ reproduces Parkinsonian symptoms and the therapeutic effects of the drug. The proposed model implies that the basal ganglia store movement and limb specific parameters which are necessary for the control of voluntary aiming movements. The model is contrasted against analytic concepts of motor control. Analytic concepts assume that movements are planned in space coordinates and then transformed to neural activities corresponding to the muscle force. In contrast, the neuronal activities simulated in the proposed ‘motor model’ can not be described by the terms ‘planned trajectory’, ‘muscle force’ or similar terms but suggest a more abstract dynamic concept.

Today, implant dentistry plays an important role in the maintenance of chewing function and oral health. For thirty years now oral implants and methods for implantation have been developed further to assure a lifetime stability of these devices and to optimize function and esthetics. Starting with the treatment of fully edentulous patients, oral implants are now used for the reconstruction of partially edentulous patients as well. Thereby, implants not only replace missing teeth but also help to preserve intact remaining teeth. They are usually incorporated to improve the patient’s subjective chewing comfort. The present paper gives an overview of the development and the current state of the art of oral implants, as well as their clinical indications.

In this study properties are concerned of ultrasonic Doppler spectra recorded distal to an irregularity localised in the internal carotid artery of a true-to-scale elastic model of a severely stenosed carotid bifurcation. Four models differing in irregularity were obtained by melting graded holes in the original wax cast, about 5–7 mm distal to the bifurcation. Velocity data were collected using an HP Sonos 2500 ultrasonograph working in pulsed Doppler mode.

The observed effect of the irregularity with respect to the smooth wall model consisted in: (1) presence of a reduced flow zone 15 mm distal to the severe irregularity situated at the outer wall of the model in the ICA branch; (2) presence of a recirculation zone 15 mm distal to the severe irregularity situated at the inner wall of this model; (3) negative values of the measure of symmetry of the Doppler spectrum and (4) decreased values of relative width of Doppler spectra obtained 25 mm distal to the bifurcation in models with severe irregularity. The alterations of flow distribution and Doppler spectra depend on the geometry of the model under investigation and this study provides an indication as to what phenomena can happen in a model of stenosed carotid bifurcation with irregular lesion surface and how these phenomena may affect the ultrasonic Doppler spectra. Such information could be used in the evaluation of the risk of cerebral embolism.

The mechanism of left ventricular outflow tract (LVOT) obstruction in the patient after mitral valve replacement or repair was examined with the aid of 2D echocardiography. For the interpretation of the spatial relationship between the aortic root and mitral annulus, however, the 2D display is sometimes inadequate since it may not simultaneously capture these structures in each center. We developed a method to clarify this relationship in 3D based on magnetic resonance images.

We defined the office of the left ventricular outflow tract (LVOT orifice), consisting of, in turn, a muscular region, i.e., edge of the interventricular septum, and an annular region, i.e., the annulus of the anterior mitral leaflet. In this paper we present image data obtained from one of eight normal subjects examined and compare this with data of one of two patients who preoperatively suffered degenerative mitral regurgitation and subsequently underwent chordal-preserving mitral valve replacement, in which anterior chordae were reattached to the anterior annulus.

In the normal subject, the mitral annulus exhibited a flexible change in shape during the systole, maintaining sufficient LVOT orifice size. In the patient, the prosthetic valve exhibited translational motion during systole, resulting in dynamic LVOT obstruction. This phenomenon was also observed in one other case. Furthermore, the lateral view of the LVOT orifice revealed a projection of the prosthetic valve into the LVOT, causing mechanical LVOT obstruction.

The finding that translational motion of the prosthetic valve with an inflexible mitral annulus results in dynamic LVOT obstruction may support the hypothesis that annular rigidity causes dynamic LVOT obstruction after mitral valve repair with a rigid prosthetic ring.

Due to more and more complex diagnosis and therapy measures, the critical care of patients requires an extensive work organisation which comprises patient, doctors, nurses and external services (e.g., central laboratory). In this organisation, the documentation plays a major role for the planning and coordination of work procedures and information flow within the medical staff. Various studies in intensive care units (ICU) reveal that the complex work organisation and the related information flow are faulty. Breakdowns are often caused by a lack of coordination between doctors and nurses and by poor transparency of work procedures. A typical example is the incorrect application of a doctor’s medication orders by a nurse because she might have overseen a plan modification. This intransparency increases the strain on the medical staff and might result in critical effects on the patient. One approach to design a computer support for medication planning as well as the coordination when executing medication plans is given by work flow models. This paper shows that work flow models could be used to improve deficiencies in medication planning and coordination. Furthermore, it is demonstrated how such a support can be mediated to the user through an appropriately designed user interface.

Bone mineral density (BMD) referral for dual energy X-ray absorptiometry (DXA) is generally based upon agreed clinical referral criteria (CRC). The aim of this study was to determine whether ultrasound measurements of Broadband Ultrasound Attenuation (BUA) and velocity (VOS) provide a superior selective pre-screen referral method for BMD assessment by DXA. 107 women aged 60–69 years (64.2 ± 2.8) had BMD measurements at lumbar spine and right femoral neck along with ultrasound BUA and VOS measurements of the left calcaneus. Each subject completed an extensive clinical and social questionnaire to ascertain those who would have met one or more of the five general clinical referral criteria adopted by our Centre. Each subject was classified by DXA using the WHO criteria as normal, osteopenic or osteoporotic at lumbar spine or femoral neck. The cost per osteoporotic subject correctly identified was calculated. As a reference, based upon DXA measurements alone on all 107 subjects, the cost per osteoporotic subject identified would be £ 185. If subjects had been referred using the clinical referral criteria the cost is £ 171. For assessment of referral by BUA or VOS, an additional charge for ultrasound measurement of all subjects was incorporated. At a BUA of 60 dB MHz⁻¹ the cost per osteoporotic subject is £ 107. Ultrasound velocity or a combination of BUA or VOS with clinical referral criteria did not provide a significantly reduced cost than the current clinical referral criteria alone. This study has demonstrated that BUA provides an improved referral procedure to that currently achieved with clinical referral criteria and supports the concept of BUA being used as a selective pre-screen for DXA in 7th decade subjects.

The effects of chronic toxic occupational factors and functional disorders of the central nervous system (CNS) in chemical industry were studied. These factors cause various stages of chronic chemical stress on the human CNS together with changes of the vigilance levels. On the basis of QEEG data analysis and psychometric tests we identified three stages of occupational chemical stress syndromes according to the CNS vigilance level (ordered from light to severe): hypersthenic syndrome, hyposthenic syndrome, and organic psychosyndrome. Each syndrome is characterized by specific changes in the QEEG data. A perceptron-based neural network was developed for the classification of the QEEG data to one of the above-mentioned syndrome classes. The data of 77 patients and 10 healthy subjects were selected to test the algorithm. Different combinations of the QEEG data as input features to the classifier were chosen. The most reliable classification was obtained when QEEG data measured during the visual stimulation of the CNS were used. However, sometimes the algorithm was unable to solve the classification problem, or it took a very long time to train the perceptron. In part, difficulties arose from using a perceptron-based algorithm, which can classify only linearly separable data.