Quality assurance practices, general laboratory

Member States shall take all measures necessary to ensure that the laboratories referred to in Article 7 of Directive 89/397/EEC1 comply with the general criteria for the operation of testing laboratories laid down in European standard EN 450013 supplemented by Standard Operating Procedures and the random audit of their compliance by quality assurance personnel, in accordance with the OECD principles Nos. 2 and 7 of good laboratory practice as set out in Section II of Annex 2 of the Decision of the Council of the OECD of 12 Mar 1981 concerning the mutual acceptance of data in the assessment of chemicals.4... 

Part 3 practical implementation of the general guideline on quality assurance of culture media in the laboratory. 

The principles and concepts of TQM have been formalized into a quality management process, as illustrated in Figure 19-3. The traditional framework for managing quality in a healthcare laboratory has emphasized the establishment of quality laboratory processes (QLPs), QC, and quality assessment (QA). A QLP includes analytical processes and the general poHcies, practices, and procedures that define how all aspects of the work get done. QC emphasizes statistical control procedures but also includes nonstatistical check procedures, such as linearity checks, reagent and standard checks, and temperature monitors. QA, as currently applied, is primarily concerned with broader measures and monitors of laboratory performance, such as turnaround time, specimen identification, patient identification, and test utility. Quality assessment is the proper name for diese activities rather than quality assurance. Measuring performance does not by itself improve performance and often does not detect problems in time to prevent harmful effects. Quality... 

Quality Control Data. Data obtained from assays of blood gas and pH control materials may be handled in the same way as data from other clinical chemistry determinations (i.e., mean, SD, and coefficient of variation, and control and confidence limits for construction of Levey-Jennings plots). As stability of commercial aqueous control materials is generally several months, vendors often provide data reduction programs that standardize and simplify documentation. However, the resulting reports are temporally delayed and are most useful for meeting accreditation requirements as opposed to real-time corrective or preventive action. They are however useful to compare long-term performances with other laboratories. Equally important features of quality assurance to an active blood gas service are the sixth sense of practiced operators for detecting subtle manifestations of deterioration of instrument performance and the suspicion of trouble expressed by clinicians. 

As already mentioned above, at several stages of the analytical work and the control of its quality, reference materials (RMs) and certified reference materials (CRMs) are necessary and helpful tools. The present section will summarise all the steps in the work where and when they have to be used. Within the quality assurance scheme and at the three check levels RMs and CRMs are necessary. They are in fact essential for establishing the reliability of the analytical method, the operator and the laboratory as a whole. The practical use of CRMs for method validation will be discussed in Chapter 5 of this book. The general place of RMs and CRMs in QA/QC is shown in Figure 2.15. 

The realisation that every laboratory determination that is carried out is associated with both random and systematic errors has had a major impact on laboratory medicine in the last thirty years. It is also at the heart of quality control and quality assurance procedures which are primarily concerned with understanding the sources of such errors and their suppression or minimisation (Whitehead, 1977 Aitio, 1981 Taylor, 1987). However, it has been pointed out by Broughton (1983) that all laboratories may carry out some form of "quality control" but this is often designed to give retrospective reassurance rather than provide prospective action. The dual concepts of bias and precision in laboratory medicine are well known, but not always appreciated even by users of reference materials (Taylor. 1985 Taylor, 1987). By definition an unbiased result should be the "true" result, but in practice this is hardly ever achieved. The nearest approach to a true value is generally obtained by using a certified reference material and a definitive method, but these ideals are unobtainable in the case of most trace metal analyses. 

In general, the results of these proficiency testing programs indicate a considerable improvement in the performance of PbB determination in most laboratories (for review see Parsons, 1992). According to the practice in clinical chemistry, quality assurance including internal and external quality control should, therefore, be an integrated part of PbB measurements. 

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