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Biomedical subjects

E Michel

Publications and source records attributed to E Michel.

At least 19 recordsLinked to original sources
PubMed2000

[Improving communication between ambulatory and inpatient care. A pilot project].

Medical care of our population has made dramatic progress during recent decades. However, problems arose from an increasing specialization and subspecialization on the one hand and from the complexity of care structures on the other hand. In light of scarce financial resources and of increasing demands regarding quality by both recipients and payers of medical care the analysis of diagnostic and treatment processes gained considerable attention. In this context, a lack of cooperation between ambulatory and in-patient care has been complained about for a long time. The aim of our pilot project introduced here was therefore to assess the cooperation between physicians in private practice and our psychiatric hospital by means of a random sample query. The results are communicated here.

Aged↗
PubMed2000

Brain tumor resection: intraoperative monitoring with high-field-strength MR imaging-initial results.

PURPOSE: To investigate the challenges and benefits of magnetic resonance (MR) imaging during brain tumor resection. MATERIALS AND METHODS: A short-bore 1.5-T MR system equipped with echo-planar-capable gradients was used in resection of brain tumors in 30 patients. MR sequences and need for contrast material enhancement were determined on the basis of the targeted lesion. MR images were acquired before, during, and after surgery. Tissue obtained at biopsy or excised as a result of intraoperative MR findings was examined histopathologically. RESULTS: MR images of enhancing lesions proved to be the most challenging to interpret intraoperatively, and relative enhancement at the resection cavity boundary was not specific for residual tumor. The ability to detect residual tumor intraoperatively resulted in a radiologically complete resection in 24 (80%) of 30 patients. The frequency of complications was low, and no untoward effects related to the MR environment were observed. CONCLUSION: Intraoperative MR imaging provided valuable information on the completeness of resection, and resection progress was well demonstrated during surgery.

Adolescent↗
PubMed2000

Posterior reversible encephalopathy syndrome: utility of fluid-attenuated inversion recovery MR imaging in the detection of cortical and subcortical lesions.

BACKGROUND AND PURPOSE: Posterior reversible encephalopathy syndrome (PRES) is typically characterized by headache, altered mental functioning, seizures, and visual loss associated with imaging findings of bilateral subcortical and cortical edema with a predominantly posterior distribution. Our goal was to determine whether fluid-attenuated inversion recovery (FLAIR) imaging improves the ability to detect subtle peripheral lesions of PRES, as compared with conventional MR techniques. METHODS: Sixteen patients with clinical and imaging findings consistent with PRES were studied. Thirteen patients had undergone transplantation and had cyclosporin A neurotoxicity. Fast-FLAIR images were compared with spin-echo proton density- and T2-weighted images. RESULTS: FLAIR imaging improved diagnostic confidence and conspicuity of the T2 hyperintense lesions of PRES, typically in the subcortical white matter of the parietooccipital regions bilaterally. On all 23 abnormal MR studies, FLAIR was judged superior to proton density- and T2-weighted images for the detection of PRES in the supratentorial brain. In a mean of 6.7 of 23 studies, FLAIR findings prompted a raise in the grade of disease severity. FLAIR also showed cortical involvement in 94% of patients with PRES and in a mean of 46% of the total lesion burden. In four cases, subtle lesions were virtually undetectable without FLAIR. Brain stem or cerebellar disease was encountered in 56% of patients. CONCLUSION: FLAIR improves the ability to diagnose and detect subcortical and cortical lesions in PRES as compared with proton density- and T2-weighted spin-echo images. We therefore believe that FLAIR should be performed in patients with suspected PRES to allow more confident recognition of the often subtle imaging abnormalities.

Adolescent↗
PubMed1999

Cystic hygroma of the skull base.

Cystic hygroma is a benign developmental tumor formed by lymph vessels that occurs in 1 of 12000 individuals and presents most frequently in the head and neck. It is often difficult to manage because the tumor frequently envelopes nearby vital structures. Lesions that extend significantly above the hyoid are especially difficult to excise because of the complexity of achieving a complete excision. This article describes a series of 3 cases of cystic hygroma that presented in the head and neck and, on further investigation, were found to also involve the skull base. This anatomic location is exceedingly rare, and these 3 cases represent new and difficult challenges not previously discussed in the literature, to our knowledge.

Child, Preschool↗
PubMed1999

Homonucleotide expansion and contraction mutations of PAX2 and inclusion of Chiari 1 malformation as part of renal-coloboma syndrome.

Renal-Coloboma syndrome, an autosomal dominant disorder characterized by colobomatous eye defects, vesicoureteral reflux, and abnormal kidneys, results from mutations in PAX2. The purpose of this study was to identify mutations in PAX2 and understand the associated patient phenotypes. We report a severely affected girl and a mildly affected mother and daughter, all of whom have PAX2 homoguanine tract (7 G) missense mutations. The mother and daughter have optic nerve colobomas and the daughter has vesicoureteral reflux. The severely affected girl developed renal failure and has bilateral colobomatous eye defects. Additionally, this girl developed hydrocephalus associated with platybasia and a Chiari 1 malformation. We examined genomic DNA from these individuals by SSCP and sequencing. The mother and daughter had a novel mutation: a contraction in a string of 7 G's to 6 G's in one allele of PAX2, leading to a premature stop codon two amino acids downstream. The severely affected girl had an expansion to 8 G's, leading to a premature stop codon 27 amino acids downstream. The 8 G expansion has been found in other patients without brain anomalies and has occurred spontaneously in a mouse model, PAX2(1Neu). We expand the known phenotype associated with mutations in PAX2 to include brain malformations. The homoguanine tract in PAX2 is a hot spot for spontaneous expansion or contraction mutations and demonstrates the importance of homonucleotide tract mutations in human malformation syndromes.

Abnormalities, Multiple↗
PubMed1999

Predicting length-of-stay in preterm neonates.

UNLABELLED: In neonatology, the early prediction of length-of-stay (LOS) may help in decision making. We retrospectively studied the accuracy of two LOS prediction models, namely a multiple linear regression model (MR) and an artificial neural network (ANN). Preterm neonates (n = 2144) were randomly assigned to a training-and-test (75%), or validation patient set (25%). A total of 40 first-day-of-life items (input data) and the date of discharge (output data) were routinely available. Training-and-test set data were used to identify input items with impact on LOS (input variables) using MR analysis to establish a MR prediction model and to train and test an ANN on those selected variables. Fed with validation set data, predicted LOS obtained from MR and ANN was compared individually with actual LOS. Predicted and actual LOS were highly correlated (for MR, r = 0.85 to 0.90; for ANN, r = 0.87 to 0.92). CONCLUSION: Even first-day-of-life data may contain substantial information with which to predict individual length-of-stay.

Humans↗
PubMed1999

[Management of dementia patients and their relatives: report from the routine practice of a family physician].

In the care of patients with dementia the family physician takes the role of a supportive coordinator. His main partner is the caring significant other. The family physician has to adapt the results of 'evidence based medicine' to the situation of the patient and transform it into 'individually balanced medicine'. His respective decisions have to be realized with the patient, the family and the professional carers. On the ground of clinical examples from day to day practice problems encountered at the beginning of the disease, regarding medication, in advanced stages and around death are discussed and solutions proposed.

Aged↗
PubMed1999

[Modular nursing system in pediatric ambulatory care according to nursing insurance legislation XI].

UNLABELLED: In the compulsory nursing insurance according to German legislation, the assessed degree of disablement in children is dependent on their daily quantitative need for nursing care with respect to 19 distinctive items belonging to the four sectors "personal hygiene", "mobility", "nutrition", and "household duties", that exceeds normal age-dependent requirements. In ambulatory nursing, exactly that care is given to the clients. OBJECTIVE: Are there typical combinations of items scoring positively, delivering the basis for a simplified billing schedule? DESIGN AND METHODS: 4500 records from the expert assessment of children < 18 years underwent a hierarchical cluster analysis (SPSS, Ward's method). RESULTS: The resulting dendrogram revealed distinct relationships between items. The items clustered into 4 main groups. Each cluster comprised items with a common thematic relationship (A = household duties, B = mobility, C = personal hygiene, D = nutrition/leaving one's home--scoring positively may indicate extra severe disablement). CONCLUSION: Remarkably enough, the resulting four clusters are very similar to the four sectors as defined by legislation (see above), although each single item is assessed independently. Our results are similar to that found in adults (Michel et al., 1998). Here we deliver the statistical basis for a modularised system of ambulatory paediatric nursing care, or its costing.

Activities of Daily Living↗
PubMed1999

Accidental iatrogenic intoxications by cytotoxic drugs: error analysis and practical preventive strategies.

OBJECTIVES: Drug errors are quite common. Many of them become harmful only if they remain undetected, ultimately resulting in injury to the patient. Errors with cytotoxic drugs are especially dangerous because of the highly toxic potential of the drugs involved. For medico-legal reasons, only 1 case of accidental iatrogenic intoxication by cytotoxic drugs tends to be investigated at a time, because the focus is placed on individual responsibility rather than on system errors. The aim of our study was to investigate whether accidental iatrogenic intoxications by cytotoxic drugs are faults of either the individual or the system. The statistical analysis of distribution and quality of such errors, and the in-depth analysis of contributing factors delivered a rational basis for the development of practical preventive strategies. METHODS: A total of 134 cases of accidental iatrogenic intoxication by a cytotoxic drug (from literature reports since 1966 identified by an electronic literature survey, as well as our own unpublished cases) underwent a systematic error analysis based on a 2-dimensional model of error generation. Incidents were classified by error characteristics and point in time of occurrence, and their distribution was statistically evaluated. The theories of error research, informatics, sensory physiology, cognitive psychology, occupational medicine and management have helped to classify and depict potential sources of error as well as reveal clues for error prevention. RESULTS: Monocausal errors were the exception. In the majority of cases, a confluence of unfavourable circumstances either brought about the error, or prevented its timely interception. Most cases with a fatal outcome involved erroneous drug administration. Object-inherent factors were the predominant causes. A lack of expert as well as general knowledge was a contributing element. In error detection and prevention of error sequelae, supervision and back-checking are essential. Improvement of both the individual training and work environment, enhanced object identification by manufacturers and hospitals, increased redundancy, proper usage of technical aids, and restructuring of systems are the hallmarks for error prevention. CONCLUSIONS: Errors follow general patterns even in oncology. Complex interdependencies of contributing factors are the rule. Thus, system changes of the working environment are most promising with regard to error prevention. Effective error control involves adapting a set of basic principles to the specific work environment. The work environment should allow for rectification of errors without penalty. Regular and ongoing intra-organisational error analysis needs to be an integral part of any error prevention strategy. However, it seems impossible to totally eliminate errors. Instead, if the environment guarantees timely error interception, most sequelae are avoided, and errors transform into a system-wide learning tool.

Antineoplastic Agents↗
PubMed1999

[Is there equality of nursing care insurance coverage for ambulatory and non-ambulatory clients according to German law?].

UNLABELLED: In nursing insurance according to German legislation, the act of classifying the client into degrees of severity of disablement (0 = none, 1 to 3 = considerable, severe, most severe disablement) by expert assessment is based on legally defined distinct criteria (need for help items). Over and above these criteria, information with regard to the activities of daily life (ADL) is also documented routinely. PURPOSE: Is there a fundamental difference between patients suitable for ambulatory or non-ambulatory nursing care, or are their positive pattern scores for needing help fundamentally different? METHODS: Based on 7,000 electronic records of the assessments for ambulatory, and another 7,000 records for non-ambulatory nursing care, we fed artificial neural networks with all, or subsets, of the available items. Thereafter, in a crossover design, we evaluated the nets' classification competencies on independent validation data, using the ambulatory net for non-ambulatory classification, and vice versa. Weighted kappa (kw) was calculated as an index of performance. RESULTS: The nets trained on ambulatory data uniformly performed slightly better on ambulatory than on non-ambulatory data (kw = 0.78 versus 0.65, all items; 0.68 versus 0.67, only ADL items), whereas the non-ambulatory nets showed no consistent difference in respect of the nature of the input data (kw = 0.76/0.77, and 0.71/0.66). Overall, the nets' classification competence was convincing. CONCLUSION: There are inter-group differences regarding the need for care. The more severely disabled clients are mainly in the non-ambulatory group. But the principles governing the need for care are very similar in both groups. Thus, a uniform assessment procedure with regard to individual patient disability is justified. From the viewpoint of quality control, the results are reassuring.

Ambulatory Care↗
PubMed1998

Characterization of a large motility gene cluster containing the cheR, motAB genes of Listeria monocytogenes and evidence that PrfA downregulates motility genes.

Through the analysis of a non-motile mutant of Listeria monocytogenes, we identified and characterized a locus containing the cheR, motA and motB genes. These three genes are homologous to the cheR, and motA/B genes of Bacillus subtilis which in this organism are 954 kb apart. The gene organization in Listeria is also not similar either to that of Escherichia coli in which cheR and motAB are 5.9 kb apart. CheR and motA/B, as previously reported for flaA, the flagellin gene, are thermoregulated with a higher expression at 25 degrees C and low expression at 37 degrees C. In a delta prfA strain, motA expression was derepressed at 37 degrees C, suggesting that PrfA, the transcriptional activator of virulence genes, downregulates motility genes in Listeria at 37 degrees C.

Amino Acid Sequence↗
PubMed1998

Gosling's Doppler pulsatility index revisited.

In Doppler sonography, the physiological meaning of Gosling's pulsatility index (PI) as a measure of downstream resistance is still under dispute. We deliver the theoretical derivation of its physiological significance. We present a mathematical model based on the linked theories of critical closing pressure (CCP) and cerebrovascular impedance, verified in preterm neonates. Mathematical transformation results in a series of equations interrelating several physiological parameters. Instead of indicating cerebrovascular resistance, PI is linked to the ratio of cerebrovascular impedances at the heart rate and at zero frequency. Next to arterial blood pressure, CCP is the principal determinant of PI. PI is identical to the ratio of the alternate and the direct component of the effective driving force. Thus, PI has no distinctive physiological meaning by itself. At present, our model is confined to physiological conditions where the lowest velocity is the end diastolic, and always more than zero.

Blood Flow Velocity↗
PubMed1998

Artificial neural network for predicting intracranial haemorrhage in preterm neonates.

Intraventricular haemorrhage (IVH) incidence is used to assess peri-/neonatal therapy, and to make intra- and inter-hospital quality assessments. Unbiased assessment is complicated by the amount of confounding factors. Is an artificial neural network (ANN) able to early and accurately forecast the occurrence of severe IVH in an individual patient? Is it superior to classic multiple logistic regression? We conducted an observational study on pre-existing routine data. Admission data were available from 890 preterm neonates (gestational age < 32 weeks, birthweight < 1500 g). Patients were randomly assigned to either a training, or a validation set (50%/50%). Using the training set data an ANN was trained. A second predictive model was developed by stepwise multiple logistic regression analysis. Using the validation set input data both models delivered estimates of the probability for severe IVH to occur in each individual patient. Receiver operating characteristic (ROC) curves were used to compare prognostic performance. The optimal ANN processed 13 input variables, whereas stepwise logistic regression analysis only identified five independent predictor variables. The area under the ROC curve was 0.935 for the ANN and 0.884 for the logistic regression model (p = 0.001). Adjusted for 95%, 90%, 85%, 80% and 75% specificity, the sensitivity of the ANN was significantly superior to that of the logistic regression model. Due to its ability to give an accurate prognosis based solely on admission data, a trained ANN qualifies as a tool for local quality control.

Cerebral Hemorrhage↗
PubMed1998

Artificial neural network for risk assessment in preterm neonates.

AIM: To predict the individual neonatal mortality risk of preterm infants using an artificial neural network "trained" on admission data. METHODS: A total of 890 preterm neonates (< 32 weeks gestational age and/or < 1500 g birthweight) were enrolled in our retrospective study. The neural network trained on infants born between 1990 and 1993. The predictive value was tested on infants born in the successive three years. RESULTS: The artificial neural network performed significantly better than a logistic regression model (area under the receiver operator curve 0.95 vs 0.92). Survival was associated with high morbidity if the predicted mortality risk was greater than 0.50. There were no preterm infants with a predicted mortality risk of greater than 0.80. The mortality risks of two non-survivors with birthweights > 2000 g and severe congenital disease had largely been underestimated. CONCLUSION: An artificial neural network trained on admission data can accurately predict the mortality risk for most preterm infants. However, the significant number of prediction failures renders it unsuitable for individual treatment decisions.

Area Under Curve↗
PubMed1998

High-field strength interventional magnetic resonance imaging for pediatric neurosurgery.

BACKGROUND: Interventional magnetic resonance (MR) imaging allows neurosurgeons to interactively perform surgery using MR guidance. High-field (1.5-Tesla) strength imaging provides exceptional visualization of intracranial and spinal pathology. The full capabilities of this technology for pediatric neurosurgery have not been defined or determined. MATERIALS AND METHODS: From January 1997 through June 1998, 10 of 85 cases performed in the interventional MR unit were in the pediatric population (mean age 8.3, median 8, range 2-15 years). Procedures included 2 brain biopsies, 5 craniotomies for tumor, 2 thoracic laminectomies for syringomyelia, and placement of a reservoir into a cystic brainstem tumor. The biopsies and reservoir placement were performed using MR-compatible equipment. Craniotomies and spinal surgery were performed with conventional instrumentation outside the 5-Gauss magnetic footprint. Interactive and intraoperative imaging was performed to assess the goals of surgery. RESULTS: Both brain biopsies were diagnostic for cerebral infarct and anaplastic astrocytoma and the reservoir was optimally placed within the tumor cyst. Of the 5 tumor resections, all were considered radiographically complete. One biopsy patient and 1 tumor resection patient experienced transient neurological deficits after surgery. The patient with the thoracic syrinx required reoperation when the syringosubarachnoid shunt migrated into the syrinx 3 months after initial placement. No patient sustained a postoperative hemorrhage. Tumor histologies found at craniotomy were craniopharyngioma, ganglioglioma, and 3 low-grade gliomas. No evidence of tumor progression has been seen in any of these patients at a mean follow-up of 5.3 (range 4-8) months. The goals of the procedure were achieved in all 10 cases. There were no untoward events experienced related to MR-compatible instrumentation or intraoperative patient monitoring, despite the present inability to monitor core body temperature. CONCLUSIONS: 1.5-Tesla interventional MR is a safe and effective technology for assisting neurosurgeons to achieve the goals of pediatric neurosurgery. Preliminary results suggest that surgical resection of histologically benign tumors is enhanced in the interventional MR unit. The incidence of surgically related morbidity is low.

Adolescent↗
PubMed1998

[Tina, a model for a supra-regional expert assessment information system].

A problem common to most medical assessment centres is how to avoid redoing work already done in a similar case? Or, more precisely, how to get knowledge about that similar case? The problem is aggravated by the companies' decentralization and the vast amount of yearly assessments. We present a model of an information system based on a public wide-area network which nevertheless complies with German law in respect of handling personal data. The system neither compiles a full-text data base, nor does it allow access to original documents. Instead, it automatically creates a thesaurus-based index file according to the users' specific queries. Each index points to the requested document giving its author and time of accomplishment. Upon written request the document will be mailed within the company. Internet technology is used, and hardware requirements are modest. As a hybrid system the Tina (thesaurus-based index file system with net access) model system guarantees data safety despite easy data base access. Its information is detailed, and the response time is adequate.

Abstracting and Indexing↗