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临床实验室质量控制措施
Quality control measures within a clinical laboratory
Quality Control 质量控制
The main responsibilities of the clinical laboratory are:临床实验室的主要职责是：
疾病过程的实现
为了治疗、诊断或预防疾病而在组织或体液中测量物质
为了实现这些目标，所产生的信息是值得信赖的，以保持高质量的控制。这些变化源的分析定义的质量控制，这是用于识别和减少它们的过程，和实验室的责任。
可靠的分析过程被认为是质量控制。特定过程的可靠性取决于其精度、灵敏度、准确度和特异性.。在监督分析过程性能的准确性和精密度的同时，质量控制的重要性正在被确定.。
特异性是一种分析方法来估计待测物的容量.。
Realizing of disease process
Measuring of substances in tissues or body fluids for the sake of treatment, diagnosis, or prevention of disease
To accomplish these targets, the generated information has to be trustworthy to maintain high quality control. Analysis of those sources of variation defines the quality of control which are the processes utilized to identify and reduce them, and laboratory responsibilities.
Reliable analytical process is considered in quality control. Reliability of particular process depends on its precision, sensitivity, accuracy, and specificity. On supervising the accuracy and precision of the analytical process performance, importance of quality control is being laid.
Specificity is the capacity of an analytical procedure to estimate the analyte alone which is to be measured.
Sensitivity is the analytial method's ability to trace out the minute quantities of the measured analyte
Precision is the extent of repeated determination on independent sample alters using a specific method and depends on strictness of methodology.
Accuracy is the Proximity of amount of sufficient substance on a sample to the actual quantity of determinations present and depends on utilized methodology.
The method of comparing the value pointed on measuring device scale to the amount needed to be measured is known as calibration and required in analytical processes. Quantity of substance contained in a solution where its concentration is articulated in terms of weights per unit volume or mole is known as standard solution.
Standard solution used:
To regulate auto analyzers, standard solution of entire glucose, protein, creatinine, albumin, and urea etc, obtained from commercial sources are utilized.
To draw a standard solution graph, for e.g. to evaluate amount of glucose in CSF, urine, and blood, glucose standard solution is utilized.
To evaluate the unknown concentration through comparison of absorbance of standard and test solutions is measured by using calorimeter concentration of unknown substance.
Where T, B, and S are the absorbance of test, blank, and standard solutions respectively.
To prepare buffer solutions, for e.g. base and its conjugate acid which are standard buffer elements are prepared as standard solution. To obtain standard buffer solution with required pH value, they are mixed in different ratios.
Two major types of errors may occur in a laboratory:
Systematic errors: arise because of poor control on analytical variables. E.g. unstable calibrators, polluted calibration material, changeable reagent blanks are occurring due to calibration error.
Random errors: occur because of poor control on pre-analytical variables, sample labeling, measuring devices, handling and transport, sample collection, and patient identity etc.
To notice and to correct any variation in precision or accuracy, the performance of regularly utilized process should be supervised incessantly through QC procedures.
Two types of QC:
Internal QC: only one laboratory is utilized for process building for quality control.
Program points:
The patient is supposed to be suffered from disease, clinical correlation of test for that.
Within assay variant: lot of variation signifying one or more errors. At the time of assay alike sample is examined two times and the result is recorded. No error exists when the result is identical.
Intra laboratory reproduction: for two days repeated samples can be analyzed and four values duplicability is tested.
Compare the outcomes of present and previous tests conducted on patient. The values are predicted to enhance by disease development and vice versa. Error indicated by any difference from this method.
External QC: several laboratories are utilized to analyze the identical samples.
Program of external QC:
By considering situation of lab, a troubled laboratory is offered by ampoules of control devoid of reference standards for analysis. For conformation the obtained outcomes will be sent to the reference laboratory. External QC program is suitable for accuracy to evaluate the proximity of a outcome to the real value. Internal QC program is suitable for precision to find out the duplicability of outcome.
The process must be interchanged by other process instantly if the outcome of currently utilized procedure highly diverges from the number of other methods which have same opinion with each other. In a case of any type of worsening revaluation of pipettes, measuring devices, calibration standards, and reagents should be measured.
To guarantee that the apparatus is every time gives accurate outcomes, QC is executed regularly. Every lab must have their individual QC program, following with certification procedures. Advantages of implementing comprehensive QC method in a laboratory:
Conforming the apparatus functionality
Troubleshooting abnormalities
Ensuring the report of exact sample outcomes.
Fundamentals of QC program
Functionality: is the only method to notice the instrument non-functionality.
Must identify all features of the:
Shutdown
Every day tests or startup
Noise of instrument and common sights
Standards of working
QC Techniques for the Laboratory
All information about really effectual quality guarantee can’t be provided by any individual QC process. High quality control plan includes: good record maintaining, instrument and control checks, protection, and technologist analysis. Patient controls, XB, calibration, XM, participation in IQAP, commercial controls, proficiency testing, and extended QC are all procedures assists for quality assurance in hematology laboratory. QC with XB and controls or combined process provides helpful information.
Instrument Checks
It is essential to confirm the total system is functioning correctly before going to check the instrument precision and accuracy. This regular instrument tests are mentioned in startup part of instrument manual. If instrument troubles are distrusted,
Troubleshoot as per laboratory procedure
Confirm instrument precision and carryover
QC Procedures
Utilization of Multiple QC methods are accepted in Beckman Coulter hematology systems. This system suggests that QC checks be executed using patient or commercial controls at intervals recognized by lab. Using of commercial control refer to the introduce package to know which process is used for sample introduction.
Setting up Controls
For supervising the functionality of an analytical method or instrument, control is a substance utilized in regular task. Refer to arrangement: QC in individual instrument IFU for information on automatic form and for information on setting up controls, auto stop, host transmission, printing and extra features.
Commercial Controls
Through the total range of Beckman Coulter instrument and reagent methods Beckman Coulter controls are created particularly for use. To examine a range of clinical standards, they are obtained in different rages. IFU can be utilized as troubleshooting aid and be confident to read the control instructions. It illustrates:
How to inform if the product has dropped
How the product should be utilized
How to take steps while investigating a difficulty
Monitoring Adjustments
The Clinical and Laboratory Standards Institute (CLSI) identifies the necessities for supervising QC outcomes, and sometimes suggests adjustment of QC statistics and recalculating. All valid information assembled since the material was used is significant to take an account. Exclude data points induced by known operator or instrument error while revaluating QC ranges. The data which lies outside a 2 SD range is not omitted. These faraway points eliminated from data set will not consider for accurate inconstancy and may be the element of regular allocation.#p#分页标题#e#
Introducing a New QC Lot
The data be gathered beside the present QC lot is suggested while estimating a new lot of the same QC material. Assume that the means was not changed considerably. A better symbol of deviation is expected from new QC lot observed in present QC lots SDs, which have been enhanced over a long period.
Establishing QC Ranges
For all types of analyzers, every laboratory must set up a test specific for suitable range of QC values. Examine whether there is a trouble with control material when QC outcomes are not in range.
Laboratories are required to verify control mean and expected ranges when using commercial controls. Follow guidelines for quality control ranges as established by:
CLSI (Clinical and Laboratory Standards Institute), CAP (College of American Pathologists) and ISO (International Organization for Standardization) Medical laboratories.
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