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Results for “quality control”

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At least 1,171 records · Page 65Linked to original sources
PubMed2000

Reducing the risk of carotid surgery: a 7-year audit of the role of monitoring and quality control assessment.

BACKGROUND AND PURPOSE: The current risk of stroke after carotid endarterectomy may be worse than reported in the international trials. Because studies have suggested that most operative strokes follow surgeon error, the aim of the current study was to audit the impact of introducing a strategy of perioperative monitoring and quality control assessment on outcome. METHODS: A total of 500 patients underwent carotid endarterectomy with intraoperative transcranial Doppler scan monitoring, completion angioscopy, and 3 hours of postoperative transcranial Doppler scan monitoring. The last of these guided selective dextran therapy in patients with high rates of postoperative embolization, which in previous series has been shown to be highly predictive of progression to thromboembolic stroke. RESULTS: Intimal flaps were repaired in 3% of patients and luminal thrombus removed in 4% of patients. The rate of intraoperative stroke was 0.2%. A total of 313 patients had more than one embolus detected postoperatively (96% within 2 hours of flow restoration), but only 22 patients had sustained embolization requiring dextran. Embolization ceased in all but one patient receiving dextran, although the dose had to be increased in seven patients (36%). One patient was unable to receive adequate dextran therapy because of severe cardiac failure. Overall, the 30-day death/stroke rate was 2.2%, no patient had a perioperative stroke because of carotid thrombosis, and the rate of ipsilateral embolic stroke was 0.8%. Most complications resulted from cardiac pathology or intracranial hemorrhage. CONCLUSIONS: A program of monitoring and quality control assessment has been associated with a 60% decrease in the operative risk in comparison with that observed before implementation of the protocol.

Clinical Protocols↗
PubMed1981

Quality control of dose calibrators.

Radionuclide dose calibrators are instruments that require regular checks and proper usage to ensure that they are operating correctly. The responsibility for the accuracy of the activity and the resultant estimate of the dose delivered to the patient rests with the persons administering the radiopharmaceutical. Hence, it is essential that accurate measurements of radioactivity be provided by the dose calibrator in use in every nuclear medicine department. The routine testing of the calibrator would ensure the user that the overall characteristics of the instrument are within acceptable limits. The quality control of two dose calibrators was carried out elaborately and their performance was evaluated from various aspects of quality control such as geometry effect, instrument linearity, precision test, instrument accuracy etc. It was found that one of the calibrators was having non-linear response resulting in an error of 18% from the decay-predicted activity. It also showed a saturation effect beyond 310 mCi. Hence, it needed repair or recalibration. However, the other calibrator was working satisfactorily. This study also helped us in realizing certain operational pitfalls of the dose calibrators.

Dose-Response Relationship, Radiation↗
PubMed1985

Failure of quality control to detect errors in the preparation of technetium-99m disofenin (DISIDA).

Uptake of Tc-99m disofenin is so strongly hepatobiliary that striking appearance of radioactivity in the reticuloendothelial system (RES) is almost certainly caused by improper preparation of the disofenin kit. Four patients who received injections of Tc-99m disofenin demonstrated a pronounced RES biodistribution in addition to the expected hepatobiliary pattern. Since routine quality control testing had not forewarned us of this gross lack of radiochemical purity, Tc-99m disofenin kits were subjected to a variety of insults to elucidate the mechanisms of quality control failure. Assessment of radiochemical purity was conducted using instant thin-layer chromatography (ITLC) and two solvent systems. We concluded that both Tc-99m pertechnetate and Tc-99m sulfur colloid had been injected into the cold disofenin kit. Visual inspections were not reliable for verifying the final radiopharmaceutical product because of dilution of the sulfur colloid by pertechnetate. ITLC testing failed because the assay method being used at that time did not accurately assess the hydrolyzed fraction (colloidal component). Recommendations are made to preclude recurrence of the errors that occurred.

Adult↗
PubMed1999

ER protein quality control and proteasome-mediated protein degradation.

A variety of mutant polypeptides that are associated with human disease are targeted for degradation by an endoplasmic reticulum (ER) quality control system. In addition, physiological signals and viral gene products can target the degradation of several ER resident proteins and secreted proteins passing through the ER. Although the mechanism of protein quality control and the site of degradation were obscure, recent data indicate that degradation requires the cytosolic proteasome. Biochemical and genetic analyses have indicated that both lumenal and integral membrane proteins are selected for proteolysis and exported to the cytosol by a process that in several cases requires ER associated molecular chaperones.

Cysteine Endopeptidases↗
PubMed2005

[The importance of the autopsy in quality control of medicine (possibilities in the Hungarian conditions)].

The authors have examined the importance of the autopsy from several aspects of view as the primary cause of death, comparison between clinical and pathological diagnosis, recognition of clinically unknown diseases, as well as new anatomical constellations, epidemiological data, assessment of effectiveness of modern imaging technics, authenticity of statistic concerning the cause of death and the quality control in medicine general. Data of the literature and computer system of authors based on several thousands autopsies proves that the post mortem investigation is the most effective method in evaluation of reliability of imaging technics too. The autopsy even in the XXI. century seems to be of greatest value for quality control of medical activity, except in cases when clinical diagnosis can be made biochemically only. In order to fulfill these requirements mentioned above a high level technical control of the autopsy technic itself is also needed.

Autopsy↗
PubMed1998

Failure of quality control measures to prevent reporting of false resistance to imipenem, resulting in a pseudo-outbreak of imipenem-resistant Pseudomonas aeruginosa.

False results showing an outbreak of Pseudomonas aeruginosa with resistance to imipenem were traced to a defective lot of microdilution MIC testing panels. These panels contained two- to threefold lower concentrations of imipenem than expected and resulted in artifactual two- to fourfold increases in MICs of imipenem. The quality-control MIC results for Pseudomonas aeruginosa ATCC 27853 were 4 microg/ml, the highest value within the range recommended by the National Committee for Clinical Laboratory Standards. We recommend that this value be considered out of the quality-control range.

Case-Control Studies↗
PubMed1984

Interpretive standards and quality control guidelines for imipenem susceptibility tests with 10-micrograms disks.

Tests with 10-micrograms imipenem disks accurately categorized 98.5% of 551 bacterial isolates when interpretive breakpoints of less than or equal to 13 mm for resistant and greater than or equal to 16 mm for susceptible were used. Because a sufficient number of resistant or moderately susceptible strains were not available for testing, these interpretive standards must be considered tentative. Quality control limits for tests with Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 are 26 to 32 and 20 to 28 mm, respectively. Zones obtained with Staphylococcus aureus ATCC 25923 were too large and variable to be useful for quality control purposes.

Anti-Bacterial Agents↗
PubMed2005

Screening for mutants defective in secretory protein maturation and ER quality control.

A genetic strategy devised to understand the physiology of the unfolded protein response serendipitously generated mutants affecting a broad spectrum of functions needed for secretory protein biogenesis and quality control. These included N- and O-linked glycosylation, glycosylphosphatidylinositol anchor biosynthesis and transfer, protein folding, protein trafficking, lumenal ionic homeostasis, ER quality control, and ER associated protein degradation. As these pathways are incompletely understood, the screen provides a simple method for their genetic dissection. This article describes methods for isolating novel mutants of these pathways and strategies for identifying corresponding genes.

Base Sequence↗
PubMed2003

[Quality control of cytodiagnosis].

In the USA, an article of "Wall Street Journal" pointed out that there were many false negative cases in cytology of cervical smears in 1987. In the next year "Clinical Laboratory Improvement Amendments of 1988(CLIA'88)" was enforced. In CLIA'88 settled that 10% of negative cases must be reexamined and all slides were retained 5 years and so forth. In Japan, quality control of cytology is a problem to be established. Inaccurate diagnoses can be made due to simple mistakes like mistypes or misdiagnoses due to deficiency of ability. A manual to manage entire process of cytology is needed for quality control. It is impossible to prevent human error entirely; therefore, a system that prevents accidents due to human error is to be organized. The gold standard of cytological diagnoses is pathological diagnoses. Entire cytological and pathological records including slides and paraffin blocks must be maintained in hospitals for utilization for reference and consultation. While patients have a right to obtain certain information, the original medical record must be owned by the hospital or doctor.

Cytodiagnosis↗
PubMed2007

Preliminary investigations on the standardisation and quality control for the determination of gamma-glutamyltranspeptidase activity in seminal plasma.

The present study was designed to assess the effects of centrifugation velocity, standing time after dilution, freezing-thawing and chymotrypsin on the determination of gamma-glutamyltranspeptidase (gamma-GT) activities in seminal plasma, and to establish an instruction for the standardisation and quality control for the determination of gamma-GT within the same laboratory and among different laboratories. The gamma-GT level and sperm concentration of each of 72 samples of seminal plasma obtained by centrifugation at 1000 g for 10 min or 3000 g for 15 min were assayed. In addition, gamma-GT activities in diluted seminal plasma with different standing time and in samples with or without chymotrypsin were measured. The results showed that there was a significant difference of gamma-GT levels in seminal plasma obtained by centrifugation at different velocities (P < 0.001), and that gamma-GT activities in seminal plasma measured after standing for 30 min after dilution were notably lower than those measured immediately after dilution (P < 0.001). However, the data indicated that both chymotrypsin and freezing-thawing had no apparent effect on the determination of seminal gamma-GT. In conclusion, standing time after dilution and centrifugation velocity should be standardised, and frozen seminal plasma could serve as quality control products for the determination of gamma-GT activity among different laboratories.

Centrifugation↗
PubMed1991

Rapid preparation and quality control method for technetium-99m-2-methoxy isobutyl isonitrile (technetium-99m-sestamibi).

Technetium-99m-2-methoxy isobutyl isonitrile (99mTc-sestamibi) is a radiopharmaceutical that can be useful in the evaluation of patients with acute myocardial infarction. The current method for preparation requires a lengthy boiling water bath procedure and the recommended quality control procedure is cumbersome and time-consuming. Using a microwave oven, the heating time necessary to provide a labeling efficiency (averaging 97% for sestamibi-labeled with maximum allowable 99mTc activity and volume has been reduced to 10 sec. A new mini-paper chromatography (MPC) system has been developed to analyze the radiochemical purity of 99mTc-sestamibi involving a 1:1 chloroform/tetrahydrofuran developing solvent. The recommended thin-layer chromatography (TLC) system involving the use of an AI2O3-coated plate requires an average time for drying and development of 34.8 +/- 1.6 min (n = 58) to complete, whereas the new MPC system has an average developing time of 2.3 +/- 0.1 min (n = 26). For radiochemical purity values ranging from 71-99% (n = 31), the MPC and TLC methods correlated closely (r = 0.99) with a regression line of MPC% = 1.05 TLC%--5.75. The combined use of the microwave oven heating method and our quick quality control system will facilitate the rapid, emergency use of 99mTc-sestamibi and eliminate the need for advance preparation of multiple kits each day.

Chromatography, Paper↗
PubMed1994

[Quality control at the Istituto di Anatomia e Istologia patologica at the Università di Bologna].

The growing importance in medical practice of a standardized diagnosis in cyto- and histopathology and the recent recommendations for the adoption of standardized schemes for quality control in anatomic pathology by International Committees stimulated the medical staff of the Institute of Anatomic Pathology of the University of Bologna to adopt a pertinent method. The method used by the Department of Pathology of the Yale University (New Haven, Connecticut, USA) was chosen. A Committee for the quality control was appointed and two kinds of controls were set up: an External Quality Assessment (review of the difficult cases by external experts, slide seminars) and an Internal Quality Assessment performed by the members of the Committee on the diagnostic and laboratory routine of the Institute. Such a survey is periodically monitored during the monthly meetings of the Committee and described in the monthly reports. The present paper illustrates the method adopted and the preliminary results obtained in order to stimulate the discussion of such a critical theme in contemporary Anatomic Pathology at a national level.

Academies and Institutes↗
PubMed1992

Quality control of multichannel hematology analyzers. Bivariate on-line comparison of MCV and MCH values for the detection of random errors.

Volume and hemoglobin content of red blood cells are physiologically interdependent variables but are measured independently in multichannel hematologic analyzers. Therefore correlation of these results to each other can be used as an additional step in internal quality control. To facilitate precise correlation, data were collected from 44,873 consecutive routine determinations of red blood cell parameters. Gaussian distributions were fitted to the original distributions and bivariate elliptical acceptance limits were calculated for simultaneous evaluation of mean corpuscular volume and mean corpuscular hemoglobin results. With the proposed method, rare combinations of the three directly measured red blood cell parameters (hemoglobin, red blood cell count, and mean corpuscular volume) can be identified for the detection of random analytical or preanalytical errors. This mean corpuscular volume-mean corpuscular hemoglobin rule could be added to internal quality-control programs of hematologic analyzers to improve detection of unusual results and possible random errors.

Diagnosis, Computer-Assisted↗
PubMed2000

[Results of the first dermatomycoses quality control study in Germany].

For the first time in the history of German mycology, a multicenter study for identification of dermatophytes, yeasts and molds was conducted under the auspices of the German Speaking Mycological Society and the German Dermatological Society. A total of 1,008 dermatological offices and dermatology hospitals as well as 106 institutes of microbiology participated in this voluntary quality control trial. They were requested to identify four pathogens: Trichophyton tonsurans, Trichophyton mentagrophytes, Aspergillus niger, and Candida glabrata. T. tonsurans was correctly determined by 749 participants (67.2%), T. mentagrophytes by 974 (87.4%), A. niger by 922 (82.8%) and C. glabrata by 973 (87.3%). Four pathogens were identified at the species level by 591 investigators (53.1%). Three species were correctly identified by 310 investigators (27.8%), two by 143 (12.8%) and 0-1 by 70 (6.3%). The first dermatomycological quality control study in Germany may therefore be considered a success. Further trials will be carried out, initially at intervals of one year.

Aspergillus niger↗
PubMed1988

Computerized quality control of radioimmunoassay in Korea.

Automated data processing and quality control of radioimmunoassays offer not only increased speed but also a more thorough and statistically rigorous analysis of results. An external quality assessment scheme for serum thyroxine, triiodothyronine and thyroid stimulating hormone (TSH) assays was performed in five nuclear medicine laboratories in Korea to compare with the assay performances of the World Health Organization Radioimmunoassay Program. The required radioimmunoassay kits were supplied through the International Atomic Energy Agency (IAEA). We have determined the weighted root mean squared error, and variance ratio as the indices of standard curve and also the average batch coefficient of variation (ABCV) as the parameters of response error relationship curve and precision profile. There was a good fit for the triiodothyronine assay, but 3 of 5 laboratories showed possible bad fit in the T4 and TSH assay systems. The ABCV was less than 5 percent for the T3 and T4 assay system, however for the TSH system, only 1 laboratory showed the ABCV value of less than 5 percent. We have also calculated the within batch variation (drift) and between laboratory variations.

Electronic Data Processing↗
PubMed1993

Quality control of immunocytologic testing. Prolonged preservation of cell surface antigen reactivity with magnesium chloride-sucrose solution.

A sucrose-magnesium chloride-glycerol storage solution (sucrose-magnesium chloride) can preserve antigenicity of cytologic preparations for prolonged periods of time. This storage method was evaluated relative to our immunocytologic technology with the specific aim of exploring its use as a quality control measure. Neuroblastoma and leukemia cell lines, patient bone marrow, and blood specimens were serially tested during a 15-week period to evaluate preservation of immunoreactivity and cell morphological features. Slides that had been air dried and stored at 4 degrees C were compared with those that had been fixed with methanol and paraformaldehyde and stored in sucrose-magnesium chloride at -20 degrees C. The sucrose-magnesium chloride method proved to be superior, and antigen-antibody binding and cell morphology were preserved even after 15 weeks of storage. This method, now in use as a quality control measure in our laboratory, constitutes a practical assurance program for immunocytologic analysis.

Antigens, Surface↗
PubMed1995

[ROKO--computer-assisted roentgen quality control].

To guarantee the quality of 30 x-ray machines and 8 photographic processors 24,000 data are collected yearly. A computer system is introduced (ROKO-Röntgenkonstanzprüfung) which helps to collect the monthly data easily and to measure on-line dose and voltage. If given tolerance values are exceeded acoustic and graphic warnings appear, a trend analysis is made to assure the correctness of the collected data, a generator to design the layout of check form facilitates the controlling and an on-line documentation for each x-ray machine is available. All these features help save time and money.

Computer Graphics↗
PubMed1997

[Quality control of anesthesia equipment after maintenance procedure].

OBJECTIVE: To assess the value of quality control tests after routine maintenance procedures of anaesthesia machines. STUDY DESIGN: Prospective laboratory study. MATERIAL AND METHODS: Over a 4-year-period, anaesthesia machines were checked after regular maintenance procedures, in order to detect unrecognized dysfunctions before clinical use. RESULTS: Overall 106 tests were performed on 14 machines and five dysfunctions were identified. Three of them concerned gas proportioning devices, which delivered a hypoxic gas mixture (FO2 < 15%). This defect was recognized by gas analysis at their outlet, whereas mechanical controls were satisfactory. The last two concerned pressure relief valve linearity and gas leak at PEEP valve. CONCLUSIONS: This study underlines the necessity of both postmaintenance controls and gas analysis at the outlet of the gas proportioning device. These controls should be performed by hospital technicians, independent from those involved in regular maintenance procedures.

Anesthesiology↗