Technology and Health Care - Volume 3, issue 1

Authors: Kadefors, Roland

Article Type: Editorial

DOI: 10.3233/THC-1995-3101

Citation: Technology and Health Care, vol. 3, no. 1, pp. 1-1, 1995

Authors: Lundberg, Ulf

Article Type: Research Article

Abstract: The major health problems in the industrialized countries have a multifactorial etiology, where stress and other psychosocial factors seem to play an important role. Mental stress is not only induced by high demands, but also by demands that are too low, which happens in many repetitive and monotonous work situations and, e.g., in response to unemployment. For a long time, musculoskeletal disorders were mainly considered to be caused by physical conditions. However, accumulating evidence from several sources now indicate that psychosocial factors are also significantly associated with, e.g., back pain and shoulder problems. Studies of assembly line workers with a …high incidence of back pain complaints indicate that the physical load on the spine at work is low, whereas psychophysiological stress levels are high and work satisfaction is low. Female assembly workers were found to have higher physiological arousal than men in traditional assembly line work, whereas their stress levels were lower in a more flexible and autonomous work organisation. In a recent laboratory experiment, both mental and physical stress was found to increase physiological stress levels and muscular tension. It was concluded, that data consistently support the assumption that mental stress is of importance for the development of musculoskeletal symptoms. Show more

Keywords: Musculoskeletal disorders, Mental stress, Physical load, Sex differences

DOI: 10.3233/THC-1995-3102

Citation: Technology and Health Care, vol. 3, no. 1, pp. 3-9, 1995

Authors: Hägg, Göran M.

Article Type: Research Article

Abstract: As a consequence of the large changes of industry work during the last decades, the measurement techniques used for load assessment have undergone a corresponding development to, if possible, reveal hazardous load situations associated with modern production technology. This development has implied methods focusing localized loads on muscles, tendons and joints. Posture is one externally observable load factor of great importance. Load distribution within the body can be assessed by computerized biomechanical models. Another important approach is the registration of the electromyographic (EMG) activity. The latter technique provides information on time patterns of loads which lately have gained increasing attention.

Keywords: Load exposure, Ergonomics, Electromyography, Posture

DOI: 10.3233/THC-1995-3103

Citation: Technology and Health Care, vol. 3, no. 1, pp. 11-14, 1995

Authors: Högstedt, P. | Kadefors, R. | Näslund, P.-E.

Article Type: Research Article

Abstract: Magnetopneumography (MPG) is a non-invasive technique to measure the amount of magnetizable dust retained in the lung. This study concerns the relation between MPG measurements of welding fume dust retention in the human lung on the one hand and chest radiography and crude counting of exposure time on the other. Precision and accuracy of the MPG instrument was found to be high. A weak but statistically significant correlation (r=0.45, P<0.05) was found between exposure time and retention of magnetizable material in a group of 112 full time manual metal arc welders. The variability was high. Retention rate was estimated on …a group level. Chest radiographs of 23 arc welders were reviewed separately in random order by two independent readers who were not aware of MPG findings, occupational anamnesis or the subject's identity and age. No statistically significant correlation was found between MPG and the observer's grading. A weak but statistically significant correlation was found between the readers. We conclude that MPG is highly sensitive to retention of magnetizable material retained in the lung and that the correlation between radiography and MPG reported by previous workers could not be verified in this study. The divergent results may well be due to methodological differences. Investigations using more specific roentgenological methods, such as high resolution computed tomography (HRCT), should be performed. Show more

Keywords: Lung, Chest radiography, Magnetopneumography, Welding, Dust retention

DOI: 10.3233/THC-1995-3104

Citation: Technology and Health Care, vol. 3, no. 1, pp. 15-21, 1995

Authors: Thijssen, J.M. | Cuypers, M.H.M.

Article Type: Research Article

Abstract: The considered causes of variability of visual evoked potentials (VEPs) are additive noise and time variability. The time variability can be modelled in three different ways: 1. time invariant VEP waveform and delay-time “jitter”; 2. time variant VEP waveform, due to 2a. jitter of individual components or 2b. constant VEP waveform and “wow”, i.e. expansion or compression of the time scale. The wow model has not been considered so far in the literature. Correction of jitter and/or wow is based on a frequency domain method: the “spectral phase difference” method (SPD). When jitter is present the SPD method is applied …in the frequency domain on the single responses, or on a subensemble of a small number of responses. For the wow a new method is proposed where the time scale is logarithmically compressed prior to the calculation of the spectrum. It is shown that the SPD method can also be applied then to estimate the compression factor yielding the wow. The single responses, or the averaged sub-ensembles, can subsequently be corrected by this factor and finally be averaged. Improvement of the precision and accuracy of estimates of both the peak latencies and the peak amplitudes, as well as a comparison between the results of the jitter and wow models, have been reported in a companion paper. Show more

Keywords: Evoked potential, Jitter, delay time, Wow, Time scale distortion, Spectral processing

DOI: 10.3233/THC-1995-3105

Citation: Technology and Health Care, vol. 3, no. 1, pp. 23-31, 1995

Authors: Cuypers, M.H.M. | Thijssen, J.M.

Article Type: Research Article

Abstract: Ensemble averaging is generally used for the estimation of Evoked Potentials. This paper deals with the assessment of correction procedures for the time variability of the ensemble components, this time variability reduces the improvement of the signal-to-noise ratio (SNR) by averaging. Evoked potentials were estimated by ensemble averaging, synchronized to a periodic stimulus. It is assumed that VEP-instability is partly caused by time-variability of the evoked potentials. Two time-variate models were used, from which procedures were derived to correct the single VEP-responses prior to ensemble averaging. The models are: (1) variation in response delay (jitter), (2) variable compression/expansion of …the time scale of the response (wow). The Spectral Phase Difference method was applied to estimate both the delay time jitter and the wow factor of single responses with respect to a template (conventional ensemble average). The effects of the devised correction on the average VEP waveform and on the SNR of the ensemble were investigated by using data from realistic simulations and from experiments (n = 23) with a number of healthy human volunteers (n = 17). Jitter- and wow-corrections were effective on simulations with time variability due to delay time jitter and time scale distortion (wow), respectively. Both wow- and jitter correction of the single responses improved the SNR of the VEP measurements significantly and to the same amount. A combined wow-jitter approach resulted in significantly better results than the exclusive application of jitter- or wow correction. Show more

Keywords: Evoked potential, Visual, Delay time jitter, Wow, Time scale distortion, Spectral processing, Averaging

DOI: 10.3233/THC-1995-3106

Citation: Technology and Health Care, vol. 3, no. 1, pp. 33-42, 1995

Authors: Svenningsen, N.W. | Wittström, Carina | Hellström-Westas, Lena

Article Type: Research Article

Abstract: In this pilot study a new device for respiratory stimulation with undulating oscillations and high frequency vibrations via an air mattress was tested as an additional therapy in 12 preterm infants with recurrent apnoeic episodes. The mean birthweight of the study population was 1760 g and gestational age 31.1 weeks. It was shown that an oscillating air mattress is an effective additional mode of treatment for apnoeic episodes in preterm infants. There was a clear reduction in rate of apnoeas in all 12 infants being transitory in 2 and more persistent in 10 infants. Besides restlessness in a few cases …no side effects were observed. Whether this mode of treatment could lessen the need for drug medication with xanthines will require a larger randomized investigation. Show more

Keywords: Preterm infant, Apnoea, Oscillation

DOI: 10.3233/THC-1995-3107

Citation: Technology and Health Care, vol. 3, no. 1, pp. 43-46, 1995

Authors: Bassios, P.Th. | Michail, A.A. | Koutsouris, D.

Article Type: Research Article

Abstract: Using a prototype system we determine the dynamic behaviour of the clogging effect of an erythrocyte suspension flow via micropore filters. The system functions as a simple electronic device and a characteristic curve of the change in height of the level of RBC suspension which flows through the filter versus time is plotted.

Keywords: Erythrocyte, Filter, Clogging

DOI: 10.3233/THC-1995-3108

Citation: Technology and Health Care, vol. 3, no. 1, pp. 47-52, 1995

Authors: Yova, D. | Kassis, K. | Agapitos, E. | Kavantzas, N. | Koutsouris, D. | Serafetinides, A.

Article Type: Research Article

Abstract: Laser angioplasty is a promising new technology, which sometimes offers the surgeon an alternative tool to conventional therapy. One of the main prerequisites of using powerful pulsed lasers in angioplasty is the optimum choice of the irradiation parameters (the wavelength, the pulse shape and duration, the energy parameters). Infrared lasers have numerous applications in surgery. Among them the pulsed CO2 laser emitting at 10.6 μm and the pulsed Nd:YAG laser emitting at 1.064 μm are the most widely used, since the delivery of laser energy in short pulses of high peak pulse power limits distant thermal effects. The CO2 …laser wavelength is greatly absorbed by tissue water, while the Nd:YAG laser wavelength is poorly absorbed by water or other tissue chromophores, affecting deeper the tissue. The CO2 laser incises effectively the tissue, but presents inadequate coagulation, while the Nd:YAG laser seems to present better coagulation properties. In this work, a comparative study of pulsed Nd:YAG and CO2 lasers in ablating cardiovascular tissue, is presented. The irradiation regime of the two lasers is determined, for the specific tissue and/or pathology. Also the depth of thermally induced coagulation is measured. The results are presented according to the efficacy of each laser for incision and/or coagulation. Show more

Keywords: Laser angioplasty, Nd:YAG laser, CO2 laser, Aortic valves decalcification

DOI: 10.3233/THC-1995-3109

Citation: Technology and Health Care, vol. 3, no. 1, pp. 53-59, 1995

Article Type: Calendar

DOI: 10.3233/THC-1995-3110

Citation: Technology and Health Care, vol. 3, no. 1, pp. 61-63, 1995