Technology and Health Care - Volume 8, issue 6

Authors: Larsby, Birgitta | Hällgren, Mathias | Arlinger, Stig

Article Type: Research Article

Abstract: A system for recording of evoked potentials from auditory stimulation was developed. The system consists of a PC equipped with an audio bandwidth board with analog input and output channels. The sound stimulus signal is generated in the computer, D/A converted, and via audio amplifier fed to earphones on the test subject. Auditory evoked potentials in response to sound stimuli are recorded via electrodes, amplified and filtered in an EEG recording system and fed to an A/D converter. The signal is analysed in the PC. The modular design of the program makes it a flexible system where stimulus and recording …parameters can easily be modified and new applications can be added to standard clinical measurements. Three applications that are not possible with commercially available systems were developed and evaluated. a) A diagnostic procedure to verify hydrops in patients with Meniere's disease. b) Intraoperative recordings of auditory evoked potentials during neurootological surgery. c) Recording of mismatch negativity (MMN) potentials in evaluation of central auditory functions. Show more

Keywords: evoked potentials, auditory stimulation, electrophysiology, evoked response audiometry, electrocochleography, brainstem response audiometry, cortical response audiometry, travelling wave velocity, mismatch negativity

DOI: 10.3233/THC-2000-8601

Citation: Technology and Health Care, vol. 8, no. 6, pp. 315-326, 2000

Authors: Anayiotos, Andreas S. | Kortright, Eduardo | Doyle, Mark | Walsh, Edward G. | Fuisz, Anthon R. | M. Pohost, Gerald

Article Type: Research Article

Abstract: Hemodynamic imaging by phase contrast angiography was significantly accelerated by selective interpolation and segmentation in k-space using TURBO BRISK. The method was tested in vitro on three independent flowfields, representative of human blood rheology: a straight tube simulating the descending aorta, a curved tube simulating the aortic arch and a two-chamber orifice flow model simulating valvular regurgitation. The results were compared to data obtained by Laser Doppler Velocimetry (LDV) and showed good agreement. For the straight tube, the flow velocity obtained by five TURBO BRISK methods with increasing segmentation factors and corresponding time savings showed good agreement with LDV. For …the curved tube, the velocity showed good general agreement with some differences in the decelerating part of the cycle, and in the low-velocity secondary flow structures. The orifice flow evaluation, the most time consuming case, was performed by the control volume method. It showed good agreement with actual flows through the orifice. Data acquisitions for TURBO-4 BRISK could be performed in 20s for each velocity component. The method shows promise for breath-hold acquisitions in clinical applications, including calculation of blood flow volumes through diseased arteries, measurement of blood backflow volumes through dysfunctional heart valves to time valve replacement operations, and evaluation of arterial wall shear stress, an important factor in the genesis of atherosclerosis. Show more

DOI: 10.3233/THC-2000-8602

Citation: Technology and Health Care, vol. 8, no. 6, pp. 327-342, 2000

Authors: Mootanah, Rajshree | Ingle, Paul | Dowell, John | Cheah, Kevin | Shelton, Julia C.

Article Type: Research Article

Abstract: Long-term studies have shown that failure of the acetabular component in total hip replacement increases exponentially ten years following surgery and occurs mostly at the bone-cement interface. During the cemented fixation of the acetabular cup, straight anchorage holes, 3–15 mm diameter and 3–20 mm deep, are drilled in the acetabulum in order to increase torsional resistance at the bone-cement interface. The aim of this paper is to provide guidelines for improving the profile of anchorage holes. Results from our finite element models show that the efficiency of anchorage holes may be improved if they are drilled perpendicularly to the acetabulum …floor and if they have chamfered necks. A 10° inclination of the anchorage hole increases Von Mises stress in the cement mantle by 6% anchorage holes, instead of straight holes, decreases it by 14%. Increasing depth of anchorage holes does not improve efficiency. Show more

DOI: 10.3233/THC-2000-8603

Citation: Technology and Health Care, vol. 8, no. 6, pp. 343-355, 2000

Authors: Lavelle, S.M. | Mhic Iomhair, Maura

Article Type: Research Article

Abstract: Sarcoma arises extremely rarely on foreign bodies in man, but is aggressive and often lethal. A coating for implants which would further reduce the risk in man is desirable. The incidence in mice is much greater, and responds to chemical treatment of the implant surface. Coating with histones increases tumour yield. Accordingly, related substances, foreign DNA, DNase and a mixture of the two, were tested for anticancer activity by application to 25 mm nitrocellulose filters in groups of 30–45 BALB/c mice, in comparison with untreated filters. Other substances reported to influence neoplasia, paprika, β-carotene, rhodamine and tuftsin; and substances expected …to be neutral, oxyprenolol, liquid paraffin, iodine, and adenosine diphosphate were similarly tested against concurrent untreated controls for comparison. Bovine DNA (p=0.01) and DNA/DNase mixture (p=0.04) and DNase fomented tumour growth by 55, 45 and 59% The other substances were inert. None were candidates for an anti-sarcoma coating. Show more

DOI: 10.3233/THC-2000-8604

Citation: Technology and Health Care, vol. 8, no. 6, pp. 357-361, 2000

Authors: Al-Nashash, H.

Article Type: Research Article

Abstract: In this paper, ECG arrhythmia classification using principal component analysis is proposed. Hebbian neural networks are used for computing the principal components of an ECG signal. This provides an unsupervised feature extraction, dimension reduction and an improved computing efficiency. Results from 14 pathological records obtained from the MIT ECG database demonstrate the capability of this method in differentiating between five different types of arrhythmia despite the variations in signal morphology. An average value for classification sensitivity and positive predictivity were found to be Se% = 98.1% and +P% = 94.7% respectively.

Keywords: electrocardiograph, ECG, classification, Hebbian neural networks, principal components, data analysis

DOI: 10.3233/THC-2000-8605

Citation: Technology and Health Care, vol. 8, no. 6, pp. 363-372, 2000

Authors: Vanholder, R.

Article Type: Research Article

Abstract: The uremic syndrome is the prototype of a slowly progressive endogenous intoxication, when a detoxifying organ (in this case the kidney) fails. It is characterized by the gradual retention of a host of metabolites, which is in part corrected by dialysis, allowing survival with an acceptable quality of life. This paper reviews the main problems of hemodialysis today, and possible solutions. Adequacy of dialysis is estimated currently from the concentration of urea, which is used as a marker molecule. The problem is that urea is not really toxic by itself. Other markers with known toxicity, such as middle molecules (300–12,000 …D) and protein bound compounds should be considered. The question then arises whether the classical dialytic concept based on diffusion should be modified. Adsorptive systems may be strong binders of protein bound solutes. Other concepts that are now arising, and that may add to toxin removal, are slow and daily dialysis. Another question that could be raised is whether it would not be possible to support toxin removal, by administering peroral sorbants. Dialysis patients are prone to vascular disease and die early from cardio-vascular complications. One of the solutions for this problem could be to bring the blood of dialyzed patients into contact with antioxidants (e.g. vitamin C or E). The risk for perdialytic hemodynamic instability is increased in many dialysis patients. The ideal solution would be to develop an “intelligent” dialysis system, whereby blood volume and plasma osmolality are sensed continuously, and ultrafiltration and dialysate sodium concentration are adapted in function of this evolution. An adequate vascular access is indispensable to perform adequate dialysis, but thrombotic/stenotic complications are frequent. This could be prevented by molecular biological modification of vascular grafts, whereby genetic information is entered into the cells, blocking the natural chain of events that otherwise unavoidably leads to neointimal hyperplasia and atherosclerosis. Another old dream is to develop a wearable artificial kidney, whereby patients can move around, and be treated 24 hours per 24 hours, in stead of being treated intermittently at a specific location by the dialysis machine. According to some authors, part of the natural renal function could be replaced by cultured renal tubular cells, which are brought in contact with the blood of the patients. It is concluded that thrilling improvements lie ahead in the future, but the following questions arise: 1) What is the cost of all these improvements? 2) Will it remain possible to reimburse all this? 3) What is going to happen in transplantation, mainly regarding improvements in immunosuppression and the development of xenotransplantation? Show more

DOI: 10.3233/THC-2000-8606

Citation: Technology and Health Care, vol. 8, no. 6, pp. 373-379, 2000