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Biomedical subjects

R Klar

Publications and source records attributed to R Klar.

15 recordsLinked to original sources
PubMed1990

Medically inappropriate inpatient care in West Germany.

The extent of medically unnecessary hospital utilization in West German acute hospitals was measured by a representative study. A random sample of medical records was reviewed and assessed according to appropriateness by specially experienced physicians. This rating method was trained, standardized and evaluated. The study yields a mean length of stay of 13 days with 2.4 days (18.4%) of inappropriate use. Further analyses concern the influence of diagnoses, age, sex, hospital size etc. Prorated to all 461 300 West German acute hospital beds, 85,000 beds or 26.6 million patient days per year are affected by inappropriate use.

Adolescent↗
PubMed1990

Medical expert systems: design and applications in pulmonary medicine.

Expert systems are computer applications with a built-in knowledge of a special field to solve problems like a human expert on this subject. An expert system consists of an inference component for problem specification and solving, a knowledge base for storage of data, facts, rules and heuristics, an interface for knowledge acquisition, another for the interaction with the user, and a component for reasoning. Pulmonary expert systems are used for automatic interpretations of lung function data which are measured on-line and directly computed. There are also some expert systems for consultation in difficult pulmonary cases and for protection against overlooking rare diseases. Perhaps the most successful applications of pulmonary expert systems are for educational purposes and a large variety of teachware is available. Pulmonary expert systems are presently limited to small applications; often it is necessary to type in large amounts of data and to follow a deeply structured cumbersome dialog. Also, the problem of responsibility for computer decisions has to be mentioned. But pulmonary expert systems as integrated supplements of normal pulmonary measuring devices, as decision support, and as parts of pulmonary teachware will be helpful tools for the pneumological physician.

Artificial Intelligence↗
PubMed1990

Computer-assisted teaching and learning in medicine.

Induced mainly by the increased spreading of personal computers in the last few years computer-assisted instruction (CAI) systems for medicine have been developed on a large scale. Proven structure principles are above all the simulation of patient management in a problem-orientated approach, the mathematical simulation of (patho-) physiological functions independent of particular patients and the separation of educational mode and scoring mode. There exists already a large choice in programs dealing with topics of internal medicine--especially cardiology--while operative disciplines are less represented so far. Programs accredited in the US for continuing medical education (CME) are usually of high quality as to medical contents. Other important quality criteria to be mentioned concerning simulation programs are algorithms of medical decision making, completeness and refinement of the medical knowledge base, software design and user interface. CAI is a unique tool to enhance clinical problem solving skills although--of course--it can by no means replace bedside teaching.

Computer-Assisted Instruction↗
PubMed1990

[Discriminatory value of bronchoalveolar lavage parameters in differential diagnosis--exogenous allergic alveolitis, sarcoidosis and patients with healthy lungs].

For this study, the results of 487 BAL investigations involving 126 patients with sarcoidosis, 34 patients with exogenous-allergic alveolitis, 18 subjects with healthy lungs, and 309 patients with other pulmonary disorders, were analysed. The diagnoses had been established independently of the BAL results. After elimination of interdependent variables, the discriminatory usefulness of the BAL parameters: total number of cells, relative percentage of lymphocytes, natural killer cells, and T4/T8 ratio, was analysed with the aid of ROC curves and the Wilcoxon test. The ROC curves permit a rapid overview of the differential significance of the various BAL variables, and identify the relationship between sensitivity and specificity.

Alveolitis, Extrinsic Allergic↗
PubMed1989

[A representative study of the scope and structure of faulty admissions of acute hospital patients over 60 years of age].

The extent and the structure of inappropriate, i.e. medically unnecessary hospital utilisation by patients of 60 years of age and over, in German acute hospitals were assessed by reviewing a randomised sample of medical records judged by physicians. This rating method was tested, standardised and evaluated. The most important result of the study was that the mean length of story was 17.4 days of which 2.9 days (17%) were estimated to be inappropriately used. If this result is projected to all West German hospitals, 35,000 hospital beds are inappropriately occupied by patients over 60 years of age for a total of 10.5 million patient days per year.

Aged↗
PubMed1988

Synthesis of pyrenesulfonylamido-sphingomyelin and its use as substrate for determining sphingomyelinase activity and diagnosing Niemann-Pick disease.

A new fluorescent derivative of sphingomyelin (PSA12-sphingomyelin) containing a pyrene-sulfonylamide residue was synthesized by covalently linking 12-((1-pyrenesulfonyl)amido)-dodecanoic acid (PSA12) to sphingosylphosphorylcholine. It was used as substrate for acidic and neutral human and murine sphingomyelinases permitting development of sensitive assays for these enzymatic activities. The product of the sphingomyelinase assay, PSA12-ceramide, could be detected in picomole quantities due to a fluorescence intensity which was 10-35-fold greater than that of other fluorescent ceramides (such as pyrene or nitrobenzoxadiazole derivatives). PSA12-sphingomyelin could be used in pure form or admixed with natural sphingomyelin; in the latter case, the enzyme hydrolyzed the fluorescent and non-fluorescent species at equal rates. Use of PSA12-sphingomyelin permitted determination of sphingomyelinase activity in cell extracts (eg human blood lymphocytes, lymphoid cell lines or cultured skin fibroblasts) as well as in hair follicles and urine. This new fluorescent derivative of sphingomyelin also permitted the detection of acid sphingomyelinase deficiency in cells derived from patients with Niemann-Pick disease.

Animals↗
PubMed1988

[Principles for evaluating simple, diagnostic tests].

The fundamental terms in the evaluation of diagnostic tests are described and the differences to corresponding test parameters in clinical chemistry are emphasized. The derivation of a two-by two contingency table is explained in detail and basic characteristics of diagnostic tests, i.e. sensitivity and specificity as well as their independence of the prevalence (in the sense of a-priori-probability) is pointed out. The importance of the so-called predictive values is shown graphically, also the problem of selecting a cut-off-level (discrimination value) for the evaluation of quantitative data. The various attempts to find a single value for the description of a diagnostic test are discussed and it is stressed that there is no principal necessity to use other terms than those mentioned above. Nevertheless it is possible to give a prevalence-independent measure which has some additional advantages in rating and comparing simple diagnostic tests.

Diagnostic Tests, Routine↗
PubMed1988

[The PACS model plan at the Freiburg University Clinic. A first step toward a radiologic picture archiving and communication system].

In a study performed at several clinical departments of the University of Freiburg, West Germany, it was found that approximately 180,000 patient examinations based on computed tomography, magnetic resonance, nuclear medicine, ultrasound as well as digital and conventional radiography, produce over 1,000,000 pictures. It was assumed that modern technologies can greatly facilitate the handling of such a quantity of images. This applies to diagnosis and therapy planning as well as to communication and archiving of this large amount of data. The study also assumes that the technologies to be considered, e.g. fiber optical networks, optical archives and medical work stations, which represent the main components of PACS, should be introduced in a stepwise manner following a clear overall conception. As the first step the implementation of a local area network (LAN) in the departments of radiology and general surgery is planned. Important criteria for the selection of these particular departments are improvements in health care for a maximum number of patients and in the working profiles for the greatest possible number of physicians and assistant personnel. A cost reduction as compared to the present system through more efficient communication and archiving of the digital images is expected. New perspectives for medical research as well as for medico-technical developments are also expected. Examples are the 3-D representations of human anatomy and the manufacturing of custom-designed prothetic devices. Scheduling and budgetary plans for equipment and manpower are further study results for the Freiburg PACS-Project.

Germany, West↗
PubMed1986

[Diagnostic validity of CEA determination in metastasizing breast cancer].

The diagnostic validity of serial CEA determinations in metastatic breast cancer was investigated. First, the CEA values within 8 weeks after start of therapy were correlated with the response to therapy. Second, the CEA levels were used to predict progression after remission or stable disease. These investigations were performed in 150 patients with advanced breast cancer who had clinical follow-ups and serial CEA determinations every one to three months. CEA was not useful for monitoring response to therapy (sensitivity 63%, specifity 58%) or prediction of relapse (sensitivity 61%, specifity 82%) if CEA levels were correlated with clinical course in all patients. However, diagnostic validity of CEA was achieved if the patients were selected and appropriate definitions of significant changes in CEA used. Thus, 83% of the responders (sensitivity) could be identified by a significant decrease of CEA titers in patients with CEA levels of greater than or equal to 10 ng/ml. A decrease of more than 10% of pretreatment levels during the first 4-8 weeks after start of therapy proved to be the appropriate definition of a significant decrease of CEA titers. However, 32% of the nonresponders were misclassified as responders (unspecifity) using these criteria. The positive predictive value of a significant decrease of CEA for response to therapy was 72% (prevalence 45%), the negative predictive value 82% (prevalence 55%). Rising CEA titers specifically predicted progression of disease in patients with remission or stable disease. However, an appropriate sensitivity (86%) was achieved only in patients with baseline CEA levels of greater than or equal to 5 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

[The hospital service misuse problem in orthopedics].

In a representative study for all German acute hospitals the amount of inappropriate (medically not necessary) patient care was estimated. The data material, sampling design, weighting technic and the appropriateness expert rating (retrospective, consent judging) was controlled. An overall proportion of inappropriate days of care of 18.45% were found but for orthopedic diseases this rate was 31.9% and even 37.7% for the younger than 60 orthopedic patients. Similar high rates for orthopedic diseases were found in US hospital studies of inappropriateness and should lead to an analysis of their reasons.

Bed Occupancy↗