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Biomedical subjects

H Krueger

Publications and source records attributed to H Krueger.

At least 19 recordsLinked to original sources
PubMed1998

[Effects of presbyopia on clinical phoria].

BACKGROUND: Due to accommodation-vergence cross-link we can expect that presbyopia will affect vergence as well. From investigations of cross-link as function of age one may assess strain of visual system due to presbyopia. Furthermore, this observation will give hints on innervation of ciliary muscle. MATERIAL AND METHOD: Vergence is assessed as function of stimulus of accommodation in 27 subjects (24-65 years). RESULTS: Presbyops tend to be exophoric for near vision. Vergence is linked to accommodation by means of a quadratic polynome rather than by a linear function. CONCLUSIONS: We may expect, that missing vergence strains visual system of presbyops. Results support Hess-Gullstrand theory of presbyopia and indicate a loss of innervation of ciliary muscle with increasing age.

Accommodation, Ocular↗
PubMed1998

What makes an automated teller machine usable by blind users?

Fifteen blind and sighted subjects, who featured as a control group for acceptance, were asked for their requirements for automated teller machines (ATMs). Both groups also tested the usability of a partially operational ATM mock-up. This machine was based on an existing cash dispenser, providing natural speech output, different function menus and different key arrangements. Performance and subjective evaluation data of blind and sighted subjects were collected. All blind subjects were able to operate the ATM successfully. The implemented speech output was the main usability factor for them. The different interface designs did not significantly affect performance and subjective evaluation. Nevertheless, design recommendations can be derived from the requirement assessment. The sighted subjects were rather open for design modifications, especially the implementation of speech output. However, there was also a mismatch of the requirements of the two subject groups, mainly concerning the key arrangement.

Adult↗
PubMed1997

[Microfluctuations in accommodation].

BACKGROUND: So called microfluctuations of the power of crystalline lens are uncontested in scientific community. However, there are still open questions about possible artefacts which deserve discussion. PURPOSE: This contribution is intended to reopen discussion of matters concerning fundamentals about microfluctuations of the crystalline lens. METHOD AND RESULTS: Thoughts are outlined which render characteristics or even existence of microfluctuations questionable. CONCLUSION: There is still a need for a conclusive experiment to determine existence and role of microfluctuations.

Accommodation, Ocular↗
PubMed1996

A study of the quality of life and cost-utility of renal transplantation.

The objective of this study was to assess the cost-utility of renal transplantation compared with dialysis. To accomplish this, a prospective cohort of pre-transplant patients were followed for up to two years after renal transplantation at three University-based Canadian hospitals. A total of 168 patients were followed for an average of 19.5 months after transplantation. Health-related quality of life was assessed using a hemodialysis questionnaire, a transplant questionnaire, the Sickness Impact Profile, and the Time Trade-Off Technique. Fully allocated costs were determined by prospectively recording resource use in all patients. A societal perspective was taken. By six months after transplantation, the mean health-related quality of life scores of almost all measures had improved compared to pre-transplantation, and they stayed improved throughout the two years of follow up. The mean time trade-off score was 0.57 pre-transplant and 0.70 two years after transplantation. The proportion of individuals employed increased from 30% before transplantation to 45% two years after transplantation. Employment prior to transplantation [relative risk (RR) = 23], graft function (RR 10) and age (RR 1.6 for every decrease in age by one decade), independently predicted employment status after transplantation. The cost of pre-transplant care ($66,782 Can 1994) and the cost of the first year after transplantation ($66,290) were similar. Transplantation was considerably less expensive during the second year after transplantation ($27,875). Over the two years, transplantation was both more effective and less costly than dialysis. This was true for all subgroups of patients examined, including patients older than 60 and diabetics. We conclude that renal transplantation was more effective and less costly than dialysis in all subgroups of patients examined.

Adult↗
PubMed1996

[The suitability of various cephalometric planes for the determination of vertical alignment of the head].

Different cephalometric lines or planes may be used to determine vertical head tilt. 94 subjects were used to assess the difference in inclination between the Frankfurt horizontal and Reid's line by means of a photographic method. We found that the inclination of Reid's line differs about 13 degrees from the inclination of the Frankfurt horizontal and depends on the subject's sex but not on their age. Hand held inclinometer are used in most studies for determining the inclination of the head. In our study different experimenters assessed the above mentioned inclinations at our 94 subject's using a hand held inclinometer. It turned out that the results depend statistically significant on the experimenter. Data were compared to the ones assessed using the photographic method. By means of an analysis of variance in which the experimenter is considered, a significant correlation (p < 0.001) between data assessed with the two different methods was found. However, only 51% of the variance can be explained by our model. Variance might be due to inaccuracy in determining some of the points defining the Frankfurt horizontal and Reid's line, i.e. the lower orbit and the centre of the outer ear channel. The inclination of another reference line running from the tragion to the outer canthus was measured using the same subjects and the same experimental procedure as mentioned above. This line is easier to determine than the Frankfurt horizontal or Reid's line as its defining points can be assessed with greater accuracy. The inclination of this differs 10.5 degrees from the one of the Frankfurt horizontal.

Analysis of Variance↗
PubMed1994

Direction of gaze and comfort: discovering the relation for the ergonomic optimization of visual tasks.

Perceived exertion caused by the extraocular muscles was assessed as a function of the direction of gaze and recorded in 114 subjects using a psychometric method. The results confirm statements in the literature that maximum comfort is achieved when gaze is aimed downwards. We found no correlations between perceived exertion and age or viewing distance. The relationship is relevant to ergonomics, for example in lens fitting and workplace layout.

Adult↗
PubMed1993

The cost impact of cytomegalovirus disease in renal transplant recipients.

A retrospective case controlled study was performed to determine the cost impact of cytomegalovirus disease in the first year following renal transplantation as a basis for the analysis of cost effectiveness of prophylactic and therapeutic regimens directed at CMV infection. Eleven sequential cases of organ-specific CMV disease were matched with 22 controls for age, diabetic status, and donor/recipient CMV serologic status from 119 consecutive first cadaveric renal transplant recipients performed at a single university-affiliated, solid organ transplant unit between January 1, 1988 and March 31, 1990. The groups were comparable for sex, HLA match and mismatch, incidence of initial graft dysfunction, and immunosuppression. Hospitalization data, resource utilization, and costs for all 33 subjects were obtained for a one-year period after transplantation. The mean initial hospitalization time was comparable for both CMV cases and controls (14.5 vs. 15.0 days, P = NS), but patients developing CMV disease averaged 59 hospital days during the first year posttransplant versus 22 days in the control group (P = 0.001). A mean of 31 days hospitalization was directly related to CMV disease. Mean total institutional costs, calculated in 1988 Canadian dollars, were 2.5 times higher for patients with CMV disease than for controls ($42,611 vs. $17,309, P = 0.001), reflecting predominantly a difference in general ward ($19,988 vs. $7484, P = 0.001), hotel ($2508 vs. $927, P = 0.001), clinical laboratory ($5420 vs. $2558, P = 0.0001), radiology ($1581 vs. $640, P = 0.05), and pharmacy ($4916 vs. $1782, P = 0.01) costs and utilization. Operating room, special ward, ancillary, and mean per diem costs ($719 vs. $790, P = NS) were not significantly different between the two groups. Functional graft survival at 1 year was 72% in patients with CMV disease compared with 86% in controls, reducing the mean calculated cost-effectiveness of transplantation by 2.9-fold. These data show that CMV disease has significant economic impact on renal transplantation as a result of extended hospitalization. In order to develop a cost effective management approach to CMV infection, this impact must be considered when assessing therapeutic and prophylactic regimens and protocols of organ allocation.

Case-Control Studies↗
PubMed1993

Effects of a bronchoprovocation challenge test with cigarette sidestream smoke on sensitive and healthy adults.

In order to study the acute effects of environmental tobacco smoke on lung function, a cigarette sidestream smoke provocation test (analogous to a nonspecific bronchial provocation test) was performed. Ten persons with airways hyperreactive to methacholine and ten normoreactive persons were tested. A dose-response relationship was found for symptoms. The lung function of the normoreactive persons was not altered by short-time inhalation of sidestream smoke. The hyperreactive subjects, however, experienced significant decreases in FEV1, FVC, and MEF50. The decrease was most pronounced after the lowest dose of 2 ppm smoke-induced CO, leading to a mean fall of 6.3 percent in FEV1. Five of ten subjects with hyperreactive airways showed a decrease in FEV1 of more than 10 percent during the sidestream smoke provocation, one of them a decrease of over 20 percent after inhalation of 16 ppm CO sidestream smoke. We conclude that even short exposure to low concentrations of cigarette sidestream smoke causes significant impairment of lung function in sensitive persons.

Adult↗
PubMed1992

Coronary artery bypass grafting: how much does it cost?

OBJECTIVE: To calculate the cost of coronary artery bypass grafting (CABG) and to compare it with the costs determined in two previous Canadian studies. DESIGN: Retrospective cost-analysis study. SETTING: A tertiary care referral hospital. PATIENTS: Fifty patients who had undergone successful triple and quadruple CABG between Jan. 3 and 30, 1989. MAIN RESULTS: The cost of CABG per patient varied from $10,982 to $33,676 (mean $14,328) (in 1988 Canadian dollars). The cost tended to increase with age and number of vessels grafted. Compared with the patients in the two previous Canadian studies our patients were older, had more vessels grafted and cost more to treat, even after the total hospital costs were adjusted for inflation. CONCLUSIONS: The population undergoing CABG is changing: it is older and has more diseased vessels. These changes have had a significant impact on the cost of CABG. Further study is required to determine the outcome and benefit of CABG in this group of patients.

Age Factors↗
PubMed1992

Design of check-out systems including laser scanners for sitting work posture.

Forty-six laser scanner operators were compared with 106 cashiers operating conventional cash registers. The influence of job rotation on the two groups was evaluated, and several design features were examined. For this purpose the prevalence of musculoskeletal disorders was determined by means of a questionnaire and a physical examination. In addition, a three-dimensional movement analysis system was employed. Work postures were analyzed with the Ovako working analysis system. The results indicate that a beneficial effect on the musculoskeletal system is achieved by combining the operation of a laser scanner with job rotation. The study also points out the need for better equipment, including flat scanners and smaller keyboards, and a change in the angle between the scanner and the take-off belt running up to the cashier.

Adult↗
PubMed1991

[Eyeglass frame for detection of eye, head movements and pupillary diameter].

Up till now, the simultaneous recording of the movements of the eyes, the movements of the head and the diameter of the pupil required the combined use of several apparatus. In this paper we present a new apparatus developed for the simultaneous recording of the movements of the eyes and of the head, and the diameter of the pupil. The apparatus consists of a portable frame (weight 215 g) a 19" rack containing electronics, and a PC for storing and analyzing the recorded data. In comparison with other systems providing similar measuring possibilities the present apparatus has the advantage of smaller dimensions and lower weight.

Computer Terminals↗
PubMed1989

Work with magnifying glasses.

At workplaces with optical aids workers complain more often from visual and musculo-skeletal disorders compared to those working in offices. These complaints concern more often workers using magnifying glasses than those using stereomicroscopes. Bad working-postures at workplaces with loupes and the worse optical quality of todays loupes are two causes. In addition, the measured magnification was less than the theoretical value of standards. The strain of accommodation was high. The results of this study suggest use of eye-glasses for near-vision in addition to loupes. The use of stereo-microscopes instead of loupes must be recommended.

Adult↗
PubMed1989

[Concept: occupational medicine 2000].

The group of physicians practising occupational medicine in Switzerland is actually still small, and it will need a very important development to reach, on a nation-wide base and not only within a few large companies, a standard of occupational medicine which satisfies from a social security as well as from an economical point of view. The occupational medicine has, therefore, to elucidate to the social partners and to the public the benefit for health and public welfare of its preventive activity at the workplace. The following goals are thus to be pursued: Further development of a legal basis in Switzerland equal to the standard of the neighbouring countries of the European Community Provision of sound models assuring occupational medical care of all business, in particular of the small and middle-sized business Promotion of student's education, specialist formation and continuative schooling in occupational medicine Provision of an adequate university teaching and research capacity with firm links to the practice A more powerful and competent representation of occupational medical aspects in actual discussions of health legislation and social legislation.

Forecasting↗
PubMed1989

[Working at video display terminals].

With the introduction of VDU work the frequency of various health problems increased proportionally to an increase in work hours on VDU's. Today the frequency of health problems is still greater, than it is for traditional office work. The observed symptoms are mostly stress reactions of multifunctional cause. Only with a close collaboration of workphysiology oriented physicians and VDU users, using the principles of workphysiology and ergonomics, can a satisfactory solution be reached.

Abortion, Spontaneous↗
PubMed1986

[Special stresses at microscopy work places].

Many problems occur at workplaces with microscopes. These problems are related to vision, manipulation and sitting posture. A field study was carried out in order to establish guidelines for constructing ergonomic microscopes.

Back Pain↗
PubMed1986

[Number of complaints in cashiers at workplaces with conventional cash registers and those with barcode reader equipment].

115 cash register operators of supermarkets have been studied. Postural complaints are high, compared to office workers. The results obtained by questionnaire and by a rheumatological examination revealed that most cash register operators complain about pains in the back, in the left shoulder and in the left arm. The cashiers working on laser-scanner-systems have the same complaints, but they have significantly less pains in the right arm and the right hand because the cash register is only used infrequently. It seems to be better if cashiers have to do different tasks in a supermarket because the study shows that cashiers who work at different workplaces have significantly less pains then those who work only at the cash register.

Back Pain↗