Technology and Health Care - Volume 8, issue 1

Authors: Kessler, Volker | Ramirez, José | Braun, Günther | Mols, Georg | Guttmann, Josef

Article Type: Research Article

Abstract: For analysis of respiratory system mechanics the very complex structure of the respiratory system is strongly simplified to a simple resistance-compliance-model. While for most patients this simplification seems sufficient, in patients with pulmonary disease this model is inappropriate. Additionally, to regional inhomogeneity throughout the lung, large volume accelerations due to the strongly decreased respiratory system compliance together with a mass increase of the patients’ lungs, i.e. an increased respiratory system inertance I rs , result in a significant inertive pressure contribution. The aim of this study was to develop a physical inertance model, and its …description by conventional methods of respiratory monitoring. Its parameters are adjustable within the physiological range, with I rs between 0.06 and 0.2 mbar·s2 ·l−1 . The model proved well with static and dynamic analysis of respiratory system parameters. Using our physical model it is possible to evaluate new methods of respiratory monitoring and to investigate experimentally the interrelationship of respiratory system parameters. Show more

Keywords: ARDS, compliance, multiple linear regression, resistance, respiratory system mechanics

DOI: 10.3233/THC-2000-8101

Citation: Technology and Health Care, vol. 8, no. 1, pp. 1-14, 2000

Authors: Hutter, Roland | Schmitt, Kai-Uwe | Niederer, Peter

Article Type: Research Article

Abstract: For application in a Virtual Reality (VR) based laparoscopic surgery simulator, computationally efficient algorithms for the description of the mechanical behavior of soft tissue have been developed. The explicit Finite Element Method has turned out to be a robust method for this purpose provided that absolute strain formulations are applied. Furthermore, a VR model of a uterus and its adnexe has been generated and simulation results are presented.

Keywords: laparoscopy, virtual reality, finite element simulation, soft tissue modeling

DOI: 10.3233/THC-2000-8102

Citation: Technology and Health Care, vol. 8, no. 1, pp. 15-24, 2000

Authors: Walter, G.F. | Matthies, H.K. | Brandis, A. | von Jan, U.

Article Type: Research Article

Abstract: The chief relevance of telemedicine lies in its capability to link medical practitioners and remote hospitals to larger or specialized facilities in a very fast electronic manner. This may become even more important due to current increase in subspecialization and demand for more precise diagnosis and consultation in difficult cases. A network attaching small clinics or laboratories to larger and more specialized units, and to highly specialized referral centers may improve the professional standard of health care services and education. For a wider use, a technological standardization will be required, since the existence of several types of computer and numerous …image manipulation programs, have resulted in a proliferation of file formats. However, every potential user or client of telemedicine should keep in mind, that standardization also includes legal and ethical issues such as patient confidentiality and malpractice avoidance. The adoption of workable guidelines and protocols is required. Telepathology in general and teleneuropathology in particular is the practice of pathology at a distance, viewing digitized images of histological slides on a video monitor rather than directly through a light microscope. For the transmission of the digitized images from a telemicroscope to the remote diagnostic video monitor, different technologies such as ordinary telephone lines, broadband telecommunications channels, and the Internet can be used. The transmitted images may serve for primary neuropathological diagnosis, teleconsultation, quality assurance, proficiency testing, and distance learning. Static-imaging and dynamic-imaging are the two major competing technologies of telemicroscopy. Static-imaging systems appear to have levels of diagnostic accuracy which are not satisfactory for diagnostic neuropathology. On the contrary, high levels of diagnostic accuracy can be achieved using dynamic-imaging systems with the transmission of live video images in real time and by using a robotized telemicroscope with the possibility to examine the entire histological specimen under control of the remote teleneuropathologist. Show more

DOI: 10.3233/THC-2000-8103

Citation: Technology and Health Care, vol. 8, no. 1, pp. 25-34, 2000

Authors: D’Asseler, Y. | Koole, M. | Van Laere, K. | Vandenberghe, S. | Bouwens, L. | Van de Walle, R. | Van de Wiele, C. | Lemahieu, I. | Dierckx, R.A.

Article Type: Research Article

Abstract: A PACS (Picture Archiving and Communication System) is a system that is able to store, exchange, display and manipulate images and associated diagnoses from any modality within a hospital in a timely and cost-effective way. Several developments, such as the DICOM standard, fast and convenient networking, and new storage solutions for large amounts of data, make the setup of such a PACS system possible. As the information acquired with various imaging modalities is then available and often complementary, it is desirable for the clinician to have a point-by-point spatial co-registration of images from different modalities in order to enable a …synergistic use of the multimodality imaging of a patient for increased diagnostic accuracy. Various types of algorithms are available for the matching of medical images from the same or from different modalities. Co-registration algorithms based on voxel properties consist of a similarity or dissimilarity measure and an iterative or non-iterative method minimizing the dissimilarity or maximizing the similarity between the two images by a transformation of one image relative to the other. Show more

Keywords: image co-registration, brain imaging, evaluation

DOI: 10.3233/THC-2000-8104

Citation: Technology and Health Care, vol. 8, no. 1, pp. 35-52, 2000

Authors: Fescioğlu Ünver, Nilgün | Turgut Tümer, S. | Kemal Özgören, M.

Article Type: Research Article

Abstract: This paper presents a method for the mathematical modeling of both the single and double support phases of the human gait. The governing equations are obtained by considering the linkage model to be in a floating state and the foot-ground interaction is imposed in the form of geometric constraints. Two stages for the single support phase and one stage for the double support phase are considered, each described by a different foot-ground constraint. Feedback controller functioning according to the computed torque control method is used to achieve the normal gait described by the hip and ankle trajectories. Weighted least square …optimization is used to solve the redundancy of control torques during the double support phase. The geometric simulation indicates that the imposed trajectories can be realized by the proposed model with some deviations in joint motions. The control strategy is tested by artificially perturbing the trajectories. The corrective actions are able to resume the desired pattern within half cycle, but with control torque magnitudes considerably away from reasonable limits. This is attributed to the insufficiency of the planar kinematic model and the assumption that the joint torques are unbounded. Show more

DOI: 10.3233/THC-2000-8105

Citation: Technology and Health Care, vol. 8, no. 1, pp. 53-66, 2000

Authors: Schmölz, W. | Gordon, D.R. | Shields, A.J. | Kirkwood, D. | Grigoris, P.

Article Type: Research Article

Abstract: Cement-stem debonding is one of the most common reasons for failure in Total Hip Replacement (THR). Four similar THR prostheses design configurations were investigated with reference to the influence of mechanical stress occurring in a cement mantle of differing thicknesses and potentially affecting clinical performance. Non-linear finite element analysis was performed on constant cement mantle thicknesses of 1, 2, and 4 millimetres. The results obtained indicate stress levels within the cement mantle decrease with increasing cement mantle thickness. The prosthesis distal tip is shown to have particular significance. Truncation of the distal tip hemisphere to a flat profile for …the fixation of a centraliser increases the cement stresses. Show more

DOI: 10.3233/THC-2000-8106

Citation: Technology and Health Care, vol. 8, no. 1, pp. 67-73, 2000

Authors: Fette, A. | Schleef, J. | Haberlik, A. | Seebacher, U.

Article Type: Research Article

Abstract: In contrast to electrocautery, the ultrasound dissection scalpel allows tissue dissection and haemostasis to be performed without the danger of thermal tissue damage or burning caused by uncontrolled active current. In a clinical application study performed on 24 boys with an average age of six years, we examined whether the use of this instrument is also practical in a routine operation such as circumcision. It was possible to perform all operations with the ultrasound dissection scalpel (UltracisionR , manufactured by Ethicon) by the classic technique without the additional use of electrocautery for haemostasis. Although dissecting speed …is slower than with conventional instruments, the fact that simultaneous haemostasis is possible meant that operations could be carried out quickly and with minimal bleeding. There were no perioperative complications such as haemorrhaging or burning. All children were examined postoperatively over an average of 3 weeks (range 1–8 weeks). Wound healing was completely without complications for 22 patients (92%) patient (4%) week. One further patient (4%) from an extended chronic inflammation of the prepuce, developed pronounced swelling postoperatively. Heavy scarring occured subsequently in both cases. Our results show that the advantages of the ultrasound dissection scalpel, e. g. gentle tissue dissection with simultaneous haemostasis, can also be used to advantage for a technically simple operation such as circumcision without having to fear the risks of electrocautery. Show more

DOI: 10.3233/THC-2000-8107

Citation: Technology and Health Care, vol. 8, no. 1, pp. 75-80, 2000