Biomedical subjects

M Loew

Publications and source records attributed to M Loew.

At least 37 records · Page 2Linked to original sources

PubMed2001

A virtual instrument for acquisition and analysis of the phonocardiogram and its internet-based application.

The objective of this study is to develop a phonocardiogram (PCG) acquisition and analysis instrument using virtual instrumentation technology and investigate its Internet-based application. The PCG instrument was developed using a Pentium 200 computer, a data acquisition board, and a two-channel custom designed bio-signal preamplifier. LabVIEW was used to create the instrument's front panels. Spectral and joint time-frequency analyses were implemented into the instrument. This instrument can be used to display the PCG and to analyze the individual heart sound and murmur for the detection of heart valve diseases. Using a test-bed, the PCG data acquisition and analysis were performed remotely over the Internet. Through the main PCG panel, an operator can control the acquisition and analysis of PCG signals. In the remote test, real-time transmission of the PCG signal over the Internet was possible. Remote operators were able to view smoothly scrolling PCG waveforms and could control all the acquisition parameters and perform spectral and time-frequency analyses on the acquired heart sound. This study demonstrated that a LabVIEW-based medical virtual instrument provides a low-cost and flexible solution for data acquisition and analysis of PCG. It also showed that the current Internet supports the transmission of real-time PCG signals. Compared with other telemedicine systems, this application transfers not only the medical data, but also the virtual instrument and its signal processing capability through the Internet.

Heart Valve Diseases↗

PubMed2001

Analytical solutions for time-resolved fluorescence lifetime imaging in a turbid medium such as tissue.

An analytical solution is developed to quantify a site-specific fluorophore lifetime perturbation that occurs, for example, when the local metabolic status is different from that of surrounding tissue. This solution may be used when fluorophores are distributed throughout a highly turbid media and the site of interest is embedded many mean scattering distances from the source and the detector. The perturbation in lifetime is differentiated from photon transit delays by random walk theory. This analytical solution requires a priori knowledge of the tissue-scattering and absorption properties at the excitation and emission wavelengths that may be obtained from concurrent time-resolved reflection measurements. Additionally, the solution has been compared with the exact, numerically solved solution. Thus the presented solution forms the basis for practical lifetime imaging in turbid media such as tissue.

Biological Phenomena↗

PubMed2000

[Recommendations for diagnosis and expert assessment of traumatic rotator cuff lesions].

Traumatic rotator cuff lesions are a very rare condition. However, this article represents a comprehensive survey according to current knowledge on anatomy, biomechanics, and pathogenesis of rotator cuff pathology. Because of the relatively high prevalence of degenerative changes with increasing age, including partial and complete rotator cuff tears, it may be difficult to demonstrate the causality of an acute traumatic rotator cuff tear. Therefore, a catalogue of potential adequate and inadequate trauma mechanisms is proposed. Emphasis is also placed on posttraumatic diagnostic steps following persistent rotator cuff deficient shoulder function (e.g., ultrasound, MRI). From a legal aspect (e.g., private accident insurance, workers compensation claim), different minor and major criteria are defined, which could help experts to judge the causality of posttraumatic rotator cuff deficiency. These criteria mainly refer to distinct details concerning patients' history, trauma mechanism, primary clinical appearance, and diagnostic findings.

Diagnosis, Differential↗

PubMed2000

A prospective study of pain control in the emergency department.

The most common complaint in the emergency department is pain. The management of acute pain, however, has not been well studied. This prospective study was designed to assess pain intensity and relief along with satisfaction in the emergency department. Adult patients with a primary complaint of acute pain were asked to complete a two-part questionnaire administered by a research assistant. The first part was completed on arrival and the second part on discharge from the emergency department. The respondents were not permitted to see the first part of the questionnaire while completing the second. The questionnaire used an unmarked, horizontal 10-cm visual analog scale along with short answer questions to measure pain, relief, and satisfaction. Choice of drug therapy was decided by the physician according to usual treatment methods. Fifty-seven people presented with the chief complaint of pain. Of those, 30 (53%) were treated with medications. The mean level of pain on admission for treated patients was 6.64 compared with a mean level of pain on discharge of 4.02 (P =.0001). Untreated patients had a mean admission visual analog scale score of 4.19. Compared with treated patients, this difference was statistically significant (P =.001). A mean visual analog scale score of 5.43, representing the mean amount of pain relief, was reported among treated patients. Treated patients also reported a visual analog scale score of 6.46 in overall satisfaction with pain management. The results of this study indicate that there is a significant and clinical difference in levels of pain and satisfaction between admission and discharge in these patients in the emergency department.

Adult↗

PubMed2000

[In Process Citation]

The traumatic etiology of rotator cuff lesions is a||| matter of controversial discussed in legal assessments. Because of the||| relatively high prevalence of degenerative changes with increasing age,||| including partial and complete rotator cuff tears, it may be difficult to||| demonstrate the cause of an acute traumatic rotator cuff tear. This article||| presents a review of the literature concerning current knowledge of the||| anatomy, biomechanics and pathogenesis of rotator cuff pathology. According to||| this, a catalogue of potentially adequate and inadequate trauma mechanisms is||| proposed. Another focus of this work is in the post-traumatic diagnostic steps||| following persistent rotator cuff-deficient shoulder function. X-ray,||| ultrasound, MRI and operative findings in rotator cuff tears underline the||| criteria for distinguishing between traumatic and degenerative lesions. From a||| legal point of view (e.g., private accident insurance, workers compensation||| claims), various minor and major arguments are defined, which could help the||| expert in judging the cause of post-traumatic rotator cuff||| deficiency.

Journal Article↗

PubMed2000

[Traumatic development of rotator cuff lesion. Scientific principles and consequences for expert assessment].

The traumatic etiology of rotator cuff lesions is a matter of controversial discussed in legal assessments. Because of the relatively high prevalence of degenerative changes with increasing age, including partial and complete rotator cuff tears, it may be difficult to demonstrate the cause of an acute traumatic rotator cuff tear. This article presents a review of the literature concerning current knowledge of the anatomy, biomechanics and pathogenesis of rotator cuff pathology. According to this, a catalogue of potentially adequate and inadequate trauma mechanisms is proposed. Another focus of this work is in the post-traumatic diagnostic steps following persistent rotator cuff-deficient shoulder function. X-ray, ultrasound, MRI and operative findings in rotator cuff tears underline the criteria for distinguishing between traumatic and degenerative lesions. From a legal point of view (e.g., private accident insurance, workers compensation claims), various minor and major arguments are defined, which could help the expert in judging the cause of post-traumatic rotator cuff deficiency.

Diagnosis, Differential↗

PubMed1999

Shock-wave therapy is effective for chronic calcifying tendinitis of the shoulder.

We report a prospective study of the effects of extracorporeal shock-wave therapy in 195 patients with chronic calcifying tendinitis. In part A 80 patients with chronic symptoms were randomly assigned to a control and three subgroups which had different treatment by low-energy and high-energy shock waves. In part B 115 patients had either one or two high-energy sessions. We recorded subjective, functional and radiological findings at six months after treatment. The results showed energy-dependent success, with relief of pain ranging from 5% in our control group up to 58% after two high-energy sessions. The Constant scores and the radiological disintegration of calcification were also dose-dependent. Shockwave therapy should be considered for chronic pain due to calcific tendinitis which is resistant to conservative treatment.

Adult↗

PubMed1998

[ECG changes after paroxetine. 3 case reports].

Selective serotonin reuptake inhibitors (SSRI) are known to exhibit far less cardiac side effects than tricyclic antidepressants. We report three cases in which the SSRI, paroxetine, induced clinically relevant ECG changes in patients with high risk profile. In two cases an increase in QTc time was observed, severe bradycardia was also observed twice.

Aged↗

PubMed1998

[Biometric planning of clinical-orthopedic studies. The optimal test].

A determinant for the evidence of a clinical trial is the magnitude of the sample size. The proper sample size can be easily computed with the knowledge of alpha, power and effect size. Standard values for alpha and power in clinical trials are 5% and 90%, respectively. As a consequence, effect size is crucial for the sample size. The effect size has to be determined by the clinician according to medical considerations. Possible consequences of sample sizes that are either too small or too large are discussed with regard to the meaning of alpha, Power and effect size. Trials with improper small sample sizes have a high risk of false negative results, and may subsequently prevent the application of a possibly effective therapy. Trials with improper large sample sizes may result in statistically significant differences without any clinical relevance.

Biometry↗

PubMed1998

Validated computation of physiologic flow in a realistic coronary artery branch.

The pulsatile flow field in an anatomically realistic model of the bifurcation of the left anterior descending coronary artery (LAD) and its first diagonal branch (D1) was simulated numerically and measured by laser Doppler anemometry. The inlet velocity profiles used in the computer simulation and in the physical experiments were physiologically realistic. The computational geometric model was developed on the basis of a digitized arterial cast. The curvature of the LAD over the cardiac surface leads to axial velocity profiles which are slightly skewed towards the epicardial wall. Downstream of the bifurcation, a strong skewing occurs towards the flow divider walls as a result of branching. Locally, the wall shear stress component caused by the complex secondary velocity can be as high as the axial component. The wall shear stress representation from a cell-based perspective exhibits low shear stress and large deviation from the time-averaged shear stress direction during systole. In diastole, the instantaneous wall shear stress direction nearly corresponds to the mean direction. The comparison of computed and measured axial velocity results shows generally good agreement. In contrast to computed flow patterns in simpler geometries constructed from cylindrical tubes, the flow field is found to be smoother, presumably reflecting the adaptation of the vascular contour to the contained flow.

Algorithms↗

PubMed1998

Distribution, tolerability and tissue compatibility of intrathecal tizanidine in the sheep.

BACKGROUND: Tizanidine (TZD) is an alpha-2-adrenergic drug with potential spinal analgesic action and could be a substitute or additive for intrathecal (i.t.) opiates in chronic pain treatment. However, long-term tolerability and tissue compatibility are not yet established. METHODS: Three sheep were infused intrathecally with TZD up to 4000 micrograms/d over a time period of up to 440 d using implantable drug administration devices; one control animal was infused with vehicle only; standard values were collected from untreated sheep. CSF samples and blood samples were analyzed to determine pharmacokinetics and systemic redistribution. Behavioral effects were studied. The spinal cord tissue was investigated using standard laboratory histology. RESULTS: Bolus kinetics after i.t. injection of TZD are best described by a two-phase model. Elimination half-lives of TZD in CSF were 15 min and 152 min, respectively. Clearance of TZD from lumbar CSF was 0.48 ml/min. Doses higher than 500 microgram i.t. caused dose-dependent motor inactivity and sleepiness. Continuous i.t. TZD up to 4 micrograms/d was well tolerated regarding behavioral, physical activity, heart rate, muscle counts and total protein were detected both in saline and TZD-treated animals, presumably due to local irritation by the catheter and repeated sampling procedures. Histological evaluation of the spinal cord and adjacent tissues showed no abnormalities. CONCLUSION: The long-term intrathecal infusion of TZD is well tolerated and non-toxic in the sheep. The data favor clinical trials in patients with chronic pain.

Adrenergic alpha-Agonists↗

PubMed1998

Training environment for inferior vena caval filter placement.

This paper describes a Virtual Environment system designed to aid in training interventional radiologists in inferior vena cava filter placement. It is being developed as part of a VE simulator for a number of surgical and interventional radiology procedures at the Laboratory for Advanced Computer Applications in Medicine at the George Washington University. In this procedure a filter is placed in the inferior vena cava to prevent blood clots from the lower portion of the body from reaching the lungs and causing a pulmonary embolus. The simulation is designed to provide both tutorial and testing modes for the filter placement procedure.

Algorithms↗

PubMed1995

[Results of treatment after traumatic shoulder dislocation. Thoracic abduction plaster case or Desault dressing].

In 80 patients with primary traumatic shoulder dislocation treated at the Heidelberg Orthopaedic University Hospital we had a follow-up examination. We wanted to know about age and sex of the patients, the number of redislocations in correlation to time and way of fixation. We had 70% male and 30% female patients with 97.5% of anterior dislocation. The minimum age was 16 and the maximum 87 years with an average of 44 years. 48 patients had a Desault bandage for 2 weeks and 32 had a shoulder-arm plaster cast for 3 weeks. There was no difference between both ways of fixation. We also could not see any better results after more than a 3 weeks' fixation. The most important fact for redislocation is the age and activity of the patients. A young man has a very high risk of redislocation within the first year.

Adolescent↗

PubMed1995

[Effect of extracorporeal shockwave therapy on tendinosis calcarea of the shoulder. A preliminary report].

UNLABELLED: The aim of a prospective study was to examine the effects of high energetic shock wave treatment on the course of calcareous tendinitis of the shoulder. 20 patients were entered into the study. Shock waves were applied to the calcifications with a Lithotripter MFL 5000 in two sessions of 2000 impulses each. The shock wave producing energy was 18 kV-22 kV. 6 and 12 weeks after treatment subjective and functional condition was checked by means of a 100-points functional score; all patients underwent x-ray control and MRI imaging. RESULTS: After 12 weeks 14 patients showed a marked improvement of symptoms, the average improvement on score measuring 25 points. The x-rays of 7 patients showed a complete resorption of the calcifications, in 5 cases partial disintegration of the calcium deposits was seen. The overall morbidity was low with 14 patients developing transient hematomas; MRI imaging showed no severe damages of bone and soft tissue.

Adult↗

PubMed1994

[Criteria for legal assessment of rotator cuff rupture].

The judgement of the correlation between an accident and a rotator cuff tear has an important role in legal and private accident insurance. Owing to the high morbidity of degenerative alterations and ruptures of the rotator cuff tendons, the causality of an acute traumatic rupture can be difficult to demonstrate, which means assessments are often controversial. In a retrospective study we evaluated 25 orthopaedic assessments and tried to find rules for an objective estimation. The judgement of correlation between trauma and rotator cuff tear should be based on four pillars: history, trauma mechanism, initial findings and course of the functional deficit. Possible mechanisms of traumatic rupture are discussed from various angles. Important clinical findings, e.g. a functional supraspinatus deficit, should be fully documented. X-Rays of both shoulders can lead to indirect demonstration of preexistent changes in the rotator cuff. Sonographic evaluation can show up the rotator cuff tear and demonstrate signs of acute injury. After persistent pain and functional deficit, in a few cases operative and microscopic findings will lead to a correct estimate of causality. Because of the diagnostic uncertainty a 20-point score is introduced for retrospective assessment of the history (2 points), trauma mechanism (3 points), initial clinical, radiological and sonographic findings (10 points) and course of functional deficit (5 points) to evaluate the role of trauma in rotator cuff tears. Using this score trauma can be classified as the main or partial cause or as irrelevant to the pathogenesis of rotator cuff tears.

Adult↗

PubMed1991

[New diagnostic criteria for surgical indications in carpal tunnel syndrome].

The difficulties encountered in objectively diagnosing carpal tunnel syndrome are described. A new method for quantitative analysis of skin sensitivity is presented and its value in determining whether surgery is indicated or not illustrated in 134 cases. Postoperative results were evaluated by electroneurography and quantitative analysis of skin sensitivity. It was shown that even in cases with severe thenar atrophy, measurable improvement of the function of the median nerve can be achieved.

Carpal Tunnel Syndrome↗

PubMed1990

[Management of unstable pertrochanteric femoral fracture by alloarthroplastic joint replacement].

The treatment of trochanteric fractures of the femur should aim at the reconstruction of the joint function and should allow early weight bearing. In the case of unstable fractures and advanced osteoarthritis of the hip joint the advantages and risks of a total hip replacement have to be compared with different methods of osteosynthesis. We report on 35 patients with trochanteric fractures primarily treated with a total hip replacement. Their perioperative mortality was 9%, the most common complication was a luxation of the replaced hip joint in 3 cases. 1 patient had to be reoperated because of a soft tissue infection. Comparing the literature the primary total hip replacement shows a lower morbidity and mortality rate than complicated methods of osteosynthesis.

Activities of Daily Living↗

PubMed1989

[Multiple sclerosis: atrophy of the corpus callosum and psychosyndrome].

Examination with magnetic resonance imaging of 176 patients with multiple sclerosis showed that corpus callosum (CC) atrophy is common. The thinning of the CC depends on the extension of the coalescent periventricular white matter changes. A highly significant association was found between CC-atrophy and, the severity of organic mental disorder.

Atrophy↗