Technology and Health Care - Volume 1, issue 3

Authors: Venet, Pierre

Article Type: Research Article

DOI: 10.3233/THC-1994-1301

Citation: Technology and Health Care, vol. 1, no. 3, pp. 191-196, 1994

Authors: Perktold, Karl | Tatzl, Helfried | Rappitsch, Gerhard

Article Type: Research Article

Abstract: Pulsatile non-Newtonian blood flow in three distal end-to-side anastomoses models of prosthetic grafts has been analysed applying computer simulation. The anastomotic angles of the three-dimensional geometric models vary over 30°, 45° and 60°. The pulsatile inflow conditions in the graft remain unchanged. Numerical results are presented for the axial and the secondary flow velocity and the wall shear stress distribution. Further, the paths of fluid particles and the particle residence times are demonstrated by means of numerical flow visualization. The quantitative study shows complex flow and wall shear stress patterns with flow separation and strong secondary motion in the host …vessel and a weakly migrating flow stagnation point on the arterial floor during the entire pulse cycle in the models under consideration. The flow dynamic effects, which seem to be important in the development of intimal hyperplasia, are dependent on the anastomotic angle and increase with increasing angle. Show more

Keywords: Bypass graft anastomosis, Intimal hyperplasia, Fluid dynamics, Computer simulation

DOI: 10.3233/THC-1994-1302

Citation: Technology and Health Care, vol. 1, no. 3, pp. 197-207, 1994

Authors: Hurley, P.K. | Smye, S.W.

Article Type: Research Article

Abstract: The performance of 14 jet nebulisers was assessed using 4 ml of 0.9% w/v saline and a flow-rate of 10 l/min. Nebulisation time (T), percentage mass of drug released as aerosol (P), rate of emission of aerosol (R) and mass median diameter of aerosol distribution (mmd) were recorded. The Side-Stream (Medic-Aid Ltd.), Sure-Mist (Unimed (UK) Ltd.) and Up-Draft (Hudson Inc.) had the lowest T (561 s, 618 s, 637 s respectively) and the Micro-Cirrus (Intersurgical Ltd.) and Up-Draft II (Hudson Inc.) had the highest T (2466 s, 1659 s respectively). The Micro-Neb III (Lifecare Ltd.), Side-Stream and Respirgard (Marquest Ltd.) …produced the highest P (68%, 67%, 66% respectively), the Sure-Mist and Up-draft had the lowest P (46.5%, 39% respectively). The Micro-Cirrus, Up-Draft II (Hudson Inc.) and Venticaire (S and W Vickers) had low R values (0.49, 0.801, 0.905 mg/min respectively), the Side-Stream had the highest R (4.08 mg/min). The Micro-Cirrus had a low mmd (1.04 m). The Pulmo-Neb (DeVilbiss Ltd.), Unineb (Unimed (UK) Ltd.) and Up-Draft had relatively high mmd (4.97 μm, 4.34 μm, 4.24 μm). Show more

Keywords: Nebulizer, Vaporizer, Respiratory therapy

DOI: 10.3233/THC-1994-1303

Citation: Technology and Health Care, vol. 1, no. 3, pp. 209-214, 1994

Authors: Urban, G. | Jobst, G. | Keplinger, F. | Aschauer, E. | Fasching, R. | Svasek, P.

Article Type: Research Article

Abstract: Miniaturized integrated thin-film biosensors were developed for use in clinical analyzers and for in vivo applications. A glucose and a lactate sensor were integrated with a pH-sensor on a flexible substrate. Both enzyme sensors are based on the electrochemical measurement of H2 O2 produced by the enzymes glucoseoxidase and lactateoxidase respectively. The solid state pH-sensor uses a neutral carrier membrane. The intended application of this device is the monitoring of metabolic parameters in the intensive care unit and the operation theater and the use as a sensor module in clinical analyzers. The glucose-, lactate- and pH-sensor was tested in …buffer solutions and undiluted serum showing excellent performance. Show more

Keywords: Glucose sensor, Lactate sensor, pH-sensor, Integrated biosensor, Thin-film technology

DOI: 10.3233/THC-1994-1304

Citation: Technology and Health Care, vol. 1, no. 3, pp. 215-218, 1994

Authors: Cecchetti, Walter | Biolo, Roberta | Jori, Giulio

Article Type: Research Article

Abstract: A diode laser with roughly 480 mW/cm2 emission at 776 nm was developed and engineered to obtain a uniform illumination of tumour cells deposited on Petri dishes having an external diameter of 5 cm. The efficacy of the apparatus in inducing photocytotoxic effects was successfully checked by irradiation of pigmented melanoma cells in the presence of a photosensitizer, Si(IV)-naphthalocyanine, having intense absorption bands at 776 nm. Our results open interesting prospects for extending photodynamic therapy to highly pigmented tumours.

Keywords: Laser diode, Optical fiber, Photodynamic therapy, Melanoma, pigmented

DOI: 10.3233/THC-1994-1305

Citation: Technology and Health Care, vol. 1, no. 3, pp. 219-222, 1994

Authors: Visser, H. | Mausberg, R. | Aschoff, T. | Jäger, A. | Hornecker, E. | Krüger, W.

Article Type: Research Article

Abstract: A device for quantitative morphometric analysis of tissue alterations caused by laser or electrosurgery was developed. The unit was designed for interactive evaluation of histological specimens obtained by experimental surgery. It consists of a microscope, a stepper-motor driven scanning stage, a digitizing tablet and a PC with software developed for this purpose. The depth of the incision, the width and the area of the coagulation zone can be measured independent of the microscopic magnification. Graphs and data can be exported in standard data-formats (ASCII, HPGL, DXF) for further processing. The application is demonstrated on experimental incisions with a CO2 -laser …in the oral mucosa of pigs; quantitative data are presented. Show more

Keywords: CO2-laser, Histomorphometry, Thermal necrosis, Computer, Oral mucosa

DOI: 10.3233/THC-1994-1306

Citation: Technology and Health Care, vol. 1, no. 3, pp. 223-226, 1994

Authors: Muller, L. | Granjon, Y. | Yvroud, E.

Article Type: Research Article

Abstract: For many applications in biomedical engineering, and especially for precise dosimetry in photodynamic therapy, it is essential to determine the absorption and scattering of light in biological tissue very precisely. At present it is not possible to measure the absorption and scattering coefficient separately by using an endoscopic sensor based upon the backscattering phenomenon. In this paper, we propose a solution to this problem. We present a new model derived from Kubelka and Munk's theory, which is known to be suitable for the description of optical phenomena in tissue. Then we apply an algorithm often used in signal processing, the …Auto Regressive with eXternal input or ARX model, which allows us to determine both optical coefficients separately. A first validation is done by numerical simulation, then measurements with phantoms were done. The results of both tests prove the model to be reliable and effective. Show more

Keywords: Photodynamic therapy, Light modelling, ARX model, Backscattering

DOI: 10.3233/THC-1994-1307

Citation: Technology and Health Care, vol. 1, no. 3, pp. 227-232, 1994

Authors: Shahsavar, N. | Gill, H. | Ludwigs, U. | Carstensen, A. | Larsson, H. | Wigertz, O. | Matell, G.

Article Type: Research Article

Abstract: This paper will demonstrate the clinical application of a knowledge-based decision-support system called VentEx for ventilator management. VentEx has been implemented using a knowledge-based development tool on a PC under the Microsoft Windows multitasking environment. It is integrated into a computer aided ventilator system including the Siemens Elema Servo Ventilator 900 C equipped with a Servo Computer Module 990 and the CO2 analyser 930. The system provides advanced ventilator monitoring with expert advice concerning ventilator strategy and settings based on data from on-line monitoring. The knowledge base has been primarily validated and the system has been clinically tested by …the intensive care unit staff. Different approaches such as knowledge acquisition, representation and system integration have been outlined and discussed. Show more

Keywords: Ventilator management, Knowledge-based system, Expert system, Decision-support system, Respirator system, Artificial ventilation

DOI: 10.3233/THC-1994-1308

Citation: Technology and Health Care, vol. 1, no. 3, pp. 233-243, 1994