Biomedical subjects

H Krueger

Publications and source records attributed to H Krueger.

At least 19 recordsLinked to original sources

PubMed2004

Information access at the point of care: what can we learn for designing a mobile CPR system?

OBJECTIVES: Hospitals have started to migrate their paper-based records to computerized patient records (CPR). The majority of today's CPR systems are stationary, which means that physicians use a clinical workstation to access CPR information. But health care professionals need to request and enter information at different locations, for example, on their daily ward round. This suggests the use of mobile computers, enabling an ubiquitous access to needed data. Different studies show that health care professionals are reluctant to use poorly designed mobile CPR systems, as the work at the point of care is very time-pressured and hectic. To design a system with high acceptance, it is essential to obtain empirical insight into the work practices and context in which the mobile CPR system will be used. METHOD: We investigated the physicians' work with the patient record during their daily round. With the help of a compact notation method, the physicians' interaction with the information system was recorded in real time. Fourteen physicians from three different departments (internal medicine, surgery, and geriatrics) of a middle-sized Swiss hospital participated in our study. RESULTS: Physicians have clear access preferences when they interact with the patient record during their daily round. There exists a clear profile of access frequencies and patterns, respectively. As an example, approximately 50% of all patient record accesses concern information about medications, vital signs and lab test results. DISCUSSION/CONCLUSION: A CPR system which is designed to reflect the access frequencies and patterns should improve the efficiency of data entry and retrieval and thus result in a system with high acceptance among physicians in the demanding environment during hospital rounds.

Access to Information↗

PubMed2003

The sun and heliosphere at solar maximum.

Recent Ulysses observations from the Sun's equator to the poles reveal fundamental properties of the three-dimensional heliosphere at the maximum in solar activity. The heliospheric magnetic field originates from a magnetic dipole oriented nearly perpendicular to, instead of nearly parallel to, the Sun's rotation axis. Magnetic fields, solar wind, and energetic charged particles from low-latitude sources reach all latitudes, including the polar caps. The very fast high-latitude wind and polar coronal holes disappear and reappear together. Solar wind speed continues to be inversely correlated with coronal temperature. The cosmic ray flux is reduced symmetrically at all latitudes.

Journal Article↗

PubMed2003

Continuous, intermitted and sporadic motor unit activity in the trapezius muscle during prolonged computer work.

The Cinderella hypothesis postulates the continuous activity of specific motor units (MUs) during low-level muscle contraction. The MUs may become metabolically overloaded, with the subject developing muscle pain and strain. The hypothesis requires MUs that are active for a time long enough to actually damage muscle fibers. The aim of this study was to determine if there are continuously active MUs in the right trapezius muscle during normal computer work using a computer mouse. Fourteen healthy subjects executed an interactive computer-learning program (ErgoLight) for 30 min. Six-channel intramuscular EMG and two-channel surface EMG signals were recorded from two positions of the trapezius muscle. Decomposition was achieved with automated, multi-channel, long-term decomposition software (EMG-LODEC). In two out of the 14 subjects, three MUs were continuously active throughout the 30 min. Although the majority of the MUs were active during only part of the experimental session, an ordered on-off behavior (e.g. substitution) pattern was not observed. As long-lasting activity was verified in some subjects, the results support the Cinderella hypothesis. However, it cannot be concluded here how long the MUs could stay active. If continuous activity overloads low threshold MUs, the potential exists for selective fibre injuries in low threshold MUs of the trapezius muscle in subjects exposed to long-term computer work.

Adult↗

PubMed2003

Course of low back pain among nurses: a longitudinal study across eight years.

AIMS: To describe the course of low back pain (LBP) among nurses across eight years. METHODS: A longitudinal study was performed with a follow up at 1 and 8 years among nurses employed by a large university hospital in Switzerland. A modified version of the Nordic Questionnaire was distributed to obtain information about demographic data, occupational activities, and various aspects of LBP. A clinical examination and several functional tests were used to overcome the problems associated with subjective pain reporting. Nurses having answered the questionnaire on all three occasions (n = 269) were classified into subgroups according to their pain intensity. For each subgroup the course of LBP was recorded. RESULTS: LBP was highly prevalent with an annual prevalence varying from 73% to 76%. A large percentage (38%) indicated the same intensity of LBP on all three occasions. The proportion of nurses reporting repeated increase of LBP (19%) was approximately as large as the proportion who complained about repeated decrease of LBP (17%). CONCLUSION: It became evident that LBP poses a persistent problem among nurses. Over an eight year period almost half of the nurses indicated the same intensity of LBP, thus supporting a recurrent rather than a progressive nature of LBP.

Adult↗

PubMed2002

[Participation--oriented analysis of the anesthesia workplace. A work system for anesthesia in a multidisciplinary operating room].

INTRODUCTION: The aim of this study was the detection and understanding of weak points in the ergonomic design of anaesthesia workplaces in a multidisciplinary operating room facility. METHODS: Analysis of workplaces and of working processes by means of observations, computer-supported task recording and video-photo documentation. During guided interviews the participants were provided with material for naming-by-pointing and drawing. Subsequently, the background of the problems encountered and possible improvements were visualised. RESULTS: Important deficits were devices not positioned within reach and view, difficulties in operating the lines connecting the patient and the devices, and inconsistent workplace layouts. These were caused by erroneous planning of the facility and disregarding ergonomic principles in equipment design. The initial improvements implemented were the development of a new concept for a flexible equipment positioning and the design of a tool for cable handling. DISCUSSION AND CONCLUSION: Although from the very beginning of the study the anaesthesia personnel quoted the handling of the lines connecting patients and devices as the main cause for working difficulties, the external ergonomist could contribute to a broader view of the problems. The method presented here initiated a mutual learning process between ergonomist and users and resulted in a common understanding of the problems and their causes. Compared to the traditional consulting process, more time and efforts were necessary but were offset by the users' acceptance of the improvements and the prevention of design errors.

Anesthesia↗

PubMed2001

Economic analysis of basiliximab in renal transplantation.

BACKGROUND: Basiliximab is a chimeric monoclonal directed against the alpha-chain of the interleukin-2 receptor. International studies have shown that it is highly effective in preventing acute rejection in patients receiving Neoral, and causes no measurable incremental toxicity, but its economic value remains unknown. METHODS: This study employed an economic model to examine the potential economic benefit of basiliximab. Parameter estimates were derived from a randomized, prospective, double-blind study conducted in 21 renal transplant centers in seven countries in which 380 adult primary allograft recipients were randomized within center to receive basiliximab (20 mg i.v.) on days 0 and 4 or placebo in addition to dual immunosuppression with Neoral and steroids. Key clinical events included primary hospitalization, immunosuppressive drug use, patient and graft survival, graft rejection, treatment of rejection, dialysis, and repeat hospitalization. Health resources were valued via a comprehensive electronic cost dictionary, based upon a detailed economic evaluation of renal transplantation in Canada. Medication costs were calculated from hospital pharmacy acquisition costs; basiliximab was assessed a zero cost. RESULTS: The average estimated cost per patient for the first year after transplant was $55,393 (Canadian dollars) for placebo and $50,839 for basiliximab, rising to $141,690 and $130,592, respectively, after 5 years. A principal component of the cost in both groups was accrued during the initial transplant hospitalization ($14,663 for standard therapy and $14,099 for basiliximab). An additional $15,852 and $14,130 was attributable to continued care, graft loss, and dialysis in the two groups, whereas follow-up hospitalization consumed an additional $15,538 for placebo and $13,916 for basiliximab. The mean incremental cost of dialysis was $5,397 for placebo compared with $3,821 for basiliximab, whereas incremental costs of graft loss were $2,548 compared with $2,295 in the two treatment groups. The principal costs associated with repeat admission to the transplant ward and the general ward were marginally higher for placebo ($7,395 vs. $6,300 and $5,986 vs. $4,625). Treatment of acute rejection and maintenance immunosuppressive drug use were associated with only limited savings as a result of basiliximab (savings <$200 each). Sensitivity analysis indicated that the most influential parameters affecting the savings as a result of using basiliximab were a reduction in the duration of initial and repeat hospitalization followed by the reduced risks of acute rejection and graft loss. CONCLUSIONS: Before accounting for the cost of the therapy itself, basiliximab produces an estimated economic saving of $4,554 during the first year after transplant, of which $3,344 is attributable to the reduced costs of graft dysfunction, including graft loss and dialysis ($1,722) and follow-up hospitalizations ($1,622). When marketed, basiliximab is expected to cost approximately $3,000 per course (two doses of 20 mg), resulting in a net first-year saving of $1,554. Under these circumstances, basiliximab can be considered a dominant therapy in renal transplantation.

Antibodies, Monoclonal↗

PubMed2001

[Virtual retinal display system with nodal point image of a laser beam: construction example and evaluation of subjective brightness perception].

We investigated the perception of brightness for red monochromatic laser light. For this purpose, a modified virtual retinal display (VRD) was constructed. The modification involved projecting the laser beam into the eye. In our VRD, the laser beam pivots in the nodal point of the eye (badal system). The displayed image therefore does not depend on the refractive state of the eye. Brightness perception was assessed by means of psychophysical experiments. The results of these experiments indicate that perception of brightness at 652 nm increases more rapidly with increasing physical stimulus than does the perception of white light (colour temperature 2'935 K). At a wavelength of 652 nm, an optical power of 79 nW is required to produce an image subtending 2 degrees of equal brightness, as is perceived with an image of about 2'900 cd/m2 subtending 2 degrees.

Adult↗

PubMed2001

Contraception. Myths, facts and methods.

OBJECTIVES: After reading this article, the reader should be able to: 1. Recognize the mechanism of action, side effects, contraindications, precautions and instructions for use of a variety of contraceptive methods. 2. Understand the advantages and disadvantages of the various contraceptive methods. 3. List the common myths and misconceptions about conception and contraception, and recognize how they can influence contraceptive decisions. Unintended pregnancy is a serious problem in the United States. Counseling a patient about conception and contraception involves more than simply imparting information and answering questions. Clinicians should actively detect and correct any myths and misapprehensions on the patient's part. These myths are quite common and can interfere with treatment if not attended to. This article summarizes common myths about pregnancy and contraception and reviews the key facts about both.

Contraception↗

PubMed2000

Hospital downsizing and trends in health care use among elderly people in British Columbia.

BACKGROUND: There has been considerable downsizing of acute care services in British Columbia over the past 2 decades. In this population-based study we examined changes in the proportion of elderly people who used acute care, long-term care and home care services between 1986-1988 and 1993-1995 to explore whether the downsizing has influenced use. Changes in death rates were also examined. METHODS: The British Columbia Linked Health Database was used to select all British Columbia residents aged 65 years, 75-76 years, 85-87 years or 90-93 years as of Jan. 1, 1986 (cohort 1), and Jan. 1, 1993 (cohort 2). Each person was assigned to 1 of 6 mutually exclusive categories of health care use reflecting different intensities of use (i.e., hospital, long-term or home care). The proportions of people within each category were compared between the 2 periods, as were the age-standardized death rates. RESULTS: There were 79,175 people in cohort 1 and 92,320 in cohort 2. Overall, the relative proportion of people in each use category was similar between the 2 study periods. The most substantial changes were an increase of 2 percentage points in the proportion of people who received no facility or home care services and a decrease of 2 to 3 percentage points in the proportion who received some acute care but no facility-based continuing care. The age-adjusted all-cause death rates for the earlier and later cohorts were virtually identical (15.7% and 15.8% respectively), although the rate increased from 63.6% to 70.1% among those in the "full-time facility with acute care" group. INTERPRETATION: Overall changes in health care use were small, which suggests that the repercussions of the decline in acute care services for elderly people have been minimal. The higher age-adjusted death rates in the later cohort in full-time care suggests that long-term stays are becoming reserved for a sicker group of elderly people than in the past.

Aged↗

PubMed2000

Lipopolysaccharide-induced nasal cytokine response: a dose-response evaluation.

Information on the dose-response relationship is a prerequisite to defining the non-response threshold of exposure. We investigated whether nasal lipopolysaccharide (LPS) challenges induce an inflammatory response in a dose-dependent way. In three settings nasal lavage was performed before, and 20 min, 1, 6, 23, and 29 h after instillation of 0 microg, 10 microg, and 40 microg LPS for 10 s, in seven healthy subjects. Lavage fluids were analysed for concentrations of interleukin-6 (IL-6), IL-8, tumour necrosis factor-alpha (TNF-alpha), histamine, and albumin. Symptoms were recorded by questionnaire and spirometric lung function was assessed after each lavage. The instillation of 40 microg LPS caused a small increase in nasal symptoms. TNF-alpha was below the detection limit (0.5 pg/ml) in most subjects and, like IL-8 and albumin, showed no relation to the LPS challenge. IL-6 increased over twofold with 10 microg LPS and over 13-fold with 40 microg LPS, with a peak at 6 h after LPS provocation, and the repeated design ANOVA was significant for dose and for time. Six hours after the 40 microg LPS challenge the histamine level significantly increased compared to the saline treatment. We conclude that short-lasting instillation of LPS causes a dose-dependent IL-6 release in the upper airways and minor nasal symptoms.

Administration, Inhalation↗

PubMed2000

Experimental exposure to methylformate and its neurobehavioral effects.

OBJECTIVES: The aim of the study was to investigate the acute effects of experimental methylformate exposure on the nervous system. METHODS: In an exposure chamber, 20 subjects were exposed to methylformate at 100 ppm [Swiss maximum allowable concentration (MAC)] for 8 h. The same number of subjects with the same ages (between 20 and 30 years), gender and education level (university) were examined by the same procedure as a control group. The subjects did not know if they were exposed or not. Three times (morning, noon, evening) during these 8 h, mood [Profile of Mood States (POMS)], neurobehavioral performance (reaction, Stroop, nonverbal learning, determination, tracking; Wiener Test System), vision (visual acuity, contrast sensitivity, color sensitivity) and postural sway were tested. During an undemanding test (POMS) and a demanding performance task (determination test), pulse, electromyography (EMG) of the forehead and of the neck were recorded. In the morning and evening spirometry [forced vital capacity (FVC), forced one-second expiration volume (FEV), medium expiration flow (MEF) and peak expiration flow (PEF)] and the odor perception threshold were measured. RESULTS: In the evening, in the exposed group, fatigue was significantly increased and the EMG of the forehead during a demanding task showed a different development during exposure. The other tests showed no significant solvent effect, but 16 of 43 test parameters showed a significant effect of time. CONCLUSIONS: The results of this study indicate a possible effect of methylformate exposure on the subjective feeling of fatigue after 8 h exposure at 100 ppm in young and healthy subjects, without measurable impairment of neurobehavioral performance. We assume that a similar effect in normal work, combined with a heavy workload and shift work, can lead to an impairment of productivity, and increase the risk of accidents.

Adult↗

PubMed2000

Isopropanol and methylformate exposure in a foundry: exposure data and neurobehavioural measurements.

OBJECTIVES: The aim of this study was to determine the dose-effect relationship between solvent exposure and acute neurobehavioural effects at the worksite. METHODS: In a balanced design, ten workers in a Swiss foundry were monitored for 15 days at ten different times during work. Urine samples were taken in the morning and at the time of examination, and personal exposure to isopropanol and methylformate was measured with active samplers. Neurobehavioural tests such as postural balance (bipedal, bipedal blind, monopedal), simple reaction time and digit span of the Neurobehavioural Evaluation System (NES2) and a combined memory and reaction-time test, the combi-test, were performed. A rating of well-being, and the last consumption of alcohol, caffeine, nicotine and medication were reported. RESULTS: Average environmental concentrations of isopropanol were at 44 ppm ( +/- 16 ppm), and at 36 ppm (+/-21 ppm) for methylformate. Maximum values of personal exposure to isopropanol reached barely the maximal allowable concentration (MAC) value (400 ppm); the methylformate personal exposure of three workers exceeded the MAC value (100 ppm). Urine concentrations of methanol were high (3.1 +/- 2.3 mg/l in the morning, 7.8 +/- 4.9 mg/l after exposure) compared with the results of other studies; concentrations of isopropanol were rather low (0.88 +/- 0.73 mg/l after exposure). CONCLUSIONS: Nevertheless, between personal exposure and biomonitoring, linear correlation was found. Methylformate exposure correlated with methanol and formic acid concentration in the urine, and isopropanol exposure with its concentration in the urine. With the neurobehavioural tests used, no solvent effect in relation to the dose could be determined.

2-Propanol↗

PubMed2000

Neurobehavioural effects of experimental isopropanol exposure.

OBJECTIVES: The study investigated the acute effects of isopropanol exposure at the maximum allowable concentration (MAC) level on the performance of neurobehavioural functions. METHODS: In an exposure chamber 20 healthy subjects aged between 21 and 30 years were exposed to isopropanol at a concentration of 400 ppm (Swiss MAC value) for 8 h. A control group of another 20 subjects of the same age range, gender and education as used in a previous study with methylformate were subjected to the same test procedures without exposure. Mood was measured with the profile of mood states (POMS) in the morning, at noon and in the evening. Neurobehavioural performance tests were administered using the Wiener Test System (Wiener reaction test, Stroop, nonverbal learning, Wiener determination test, "Konturtracking" test), and the digit span test of the Neurobehavioural evaluation system (NES2). A test for postural sway was also conducted. During the POMS and the Wiener determination test the electromyography of the forehead and the left neck muscle as well as the pulse were registered. In the morning and evening spirometry (FVC, FEV, MEF and PEF) and odour threshold were measured. RESULTS: Only postural sway in bipedal standing at noon showed stronger deterioration in the exposed than in the control group when compared with the morning values. The evening values of monopedal standing were also more impaired in the exposed than the control group. In the other tests, no solvent effect could be established. CONCLUSIONS: It can be assumed, that, similar to other alcohols, isopropanol affects postural balance. Our results point to such a disturbance, but because it is the only study so far using the MAC value, any conclusions about safety risks would be premature.

2-Propanol↗

PubMed2000

Motor-unit activity in the trapezius muscle during rest, while inputting data, and during fast finger tapping.

The Cinderella hypothesis postulates the continuous activity of specific motor units during low-level muscle contraction and contradicts the concept of motor-unit substitution. Constant trapezius muscle activity has been reported in typical visual-display-unit-related tasks. If it can be shown that constant muscle activity can be caused by the continuous firing of single motor units, this could explain the frequent complaints of muscular neck pain reported by computer users. The present study was undertaken to investigate motor-unit activity in the trapezius muscle during resting with closed eyes, while inputting three-digit numbers with auditory presentation at a rate of 0.5 Hz, and while tapping on a key with the right index finger at a rate of 5 Hz. Electrodes with four fine wires were inserted into the right upper trapezius muscle of six healthy subjects, and three-channel intramuscular electromyography was recorded. The decomposition programme MAPQuest, developed to analyse short-term one-channel signals, was complemented with MAPView, a programme that merges the short-term results of 10 s to a 3-min analysis. The results showed that activity in the trapezius muscle was induced in one subject while resting, in two subjects while inputting data, and in five subjects while finger tapping. Long-lasting single motor-unit firing was observed in two subjects while inputting data and in one subject while finger tapping. Whilst our findings may support the Cinderella hypothesis, the measurement periods are too short to confirm it fully, and for further discussion it is necessary to record and analyse for longer periods.

Adult↗

PubMed2000

Co-activity of the trapezius and upper arm muscles with finger tapping at different rates and trunk postures.

In the context of finding a model that describes the pathophysiological mechanisms leading to muscle pain at low-intensity repetitive work, in this study we investigated whether a simplified finger motor task that requires little mental demand can cause increased muscle activity in the upper arms and neck, and examined the impact of the variation of two parameters, finger tapping rate and body posture. Using the 5th and 95th percentiles from the surface electromyogram of six muscles of the fingers, upper arm and neck, we determined the static and dynamic components of the muscle activity. Correlation methods were used to find a component in the muscle activity that originated from the rhythm of the finger tapping. Further investigations included tapping steadiness and finger force. It was found that in many, but not all subjects, low or even high activity was constantly present in the upper arm and trapezius muscles, sometimes even during relaxation. Fast tapping and a forward-leaning body posture caused considerable increases, while a slightly reclined posture helped to reduce co-activity. However, motor control patterns varied strongly between individuals. Since certain subjects showed no co-activity at all we can assume that trapezius and upper-arm activation is not necessarily required for the completion of a task similar to ours. This may explain why some VDU users develop work-related musculoskeletal disorders while others remain healthy.

Adult↗

PubMed2000

Morphological study of Osteoplate 2000-extension implants after bending.

Unfavorable anatomical conditions of implant sites often require the insertion of implants in a direction that may interfere with the positioning of suprastructural elements in a functionally and esthetically satisfying manner. In some implant systems, bending of the implant neck is one of the possible methods for optimizing the insertion angle for the superimposed prosthesis. The aim of this study was to investigate whether bending procedures of the implant neck cause changes in the surface properties at the implant neck area. After bending of the implant neck up to 30 degrees, scanning electron microscopy revealed changes in the surface texture of the titanium. Superficial rips approximately 5 microns wide and 100 microns long had formed. These findings were confirmed by metallographic examinations. Values of Vickers hardness testing in the implant neck area after bending of 30 degrees showed significant differences between the compression or stretched zone and the neutral zone of the bending area. Bending of the implant neck between 0 and 20 degrees may influence the surface morphology, promoting superficial rips. Plaque accumulation and mechanically induced mucosal irritations due to changes of surface morphology and properties by bending should be further analyzed.

Acid Etching, Dental↗

PubMed1999

A tutorial on creating logfiles for event-driven applications.

This paper describes the practical steps necessary to write logfiles for recording user actions in event-driven applications. Data logging has long been used as a reliable method to record all user actions, whether assessing new software or running a behavioral experiment. With the widespread introduction of event-driven software, the logfile must enable accurate recording of all the user's actions, whether with the keyboard or another input device. Logging is only an effective tool when it can accurately and consistently record all actions in a format that aids the extraction of useful information from the mass of data collected. Logfiles are often presented as one of many methods that could be used, and here a technique is proposed for the construction of logfiles for the quantitative assessment of software from the user's point of view.

Computers↗

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↗