Automation in Clinical Chemistry

Janzene Jen MartinDennie Leo LoganMaria Elena AronRina AnanayoMary Joy Santiago

CLINICAL CHEMISTRY AUTOMATIONLaboratory automation proposes to improve the quality and efficiency of laboratory operations, and may provide a solution to the quality demands and staff shortages faced by todays clinical laboratories. The Clinical laboratory has had available a wide variety of analytical instruments and techniques that were largely manually operated until the generation of automation. Automation has had a major impact on pathology, particularly in clinical biochemistry. The availability of automated systems has improved the overall analytical performance of many assays and has radically altered the turnaround time for results. This Permits the operator to focus on tasks that cannot be readily automated and increasing both efficiency and capacity. The different types of auto analysers have used various approaches for measurements that included photometry and potentiometry. The analytical systems are versatile and have enabled improvement in sensitivity and specificity in test delivery.The analytic process can be divided into three major phases preanalytic, analytic, and postanalyticcorresponding to sample processing, chemical analysis, and data management, respectively. Substantial improvements have occurred in all three areas during the past decade. The analytic phase is the most automated, and more research and development efforts are focusing on increasing automation of the preanalytic and postanalytic processes.HISTORY OF AUTOMATION IN LABORATORY PRACTICEThe first autoanalyser was introduced by Technicon in 1957. This analyser used a special flow technique and was named a continuous flow or segmented flow analysis. The single channel analyser was capable of providing a single test result on approximately 40 samples per hour. The next generation of analysers by Technicon instruments was the Sequential Multiple Analyser, and the Sequential Multiple Analyser with Computer working synchronously to produce 60 to 180 test results per hour. Advances in computer technology and improvement in clinical chemistry instrumentation have led to the proliferation of different types of autoanalysers that employ continuous flow for batch, discrete and random access analysis of samples. Major developments that revolutionized clinical chemistry instrumentation were patient identification, infrequent calibration and interruption for urgent sample analysis (STAT).New generation of automated equipments have adopted more successful features and technologies to remain competitive in the marketplace.BASIS FOR AUTOMATIONWith the evolution of clinical chemistry a wide range of tests has been developed to assist in the diagnosis of diseases and disorders and to monitor therapy. With the growing demand for investigations, it is becoming inevitable to replace manual operations by mechanical devices for fast results on a large number of specimens. Automation provides a means by which an increased workload can be processed rapidly and with reproducible results. The quality of results is controlled by running the samples of known values (standards) with every batch of tests. Through mechanization of analysis there is increased reproducibility of results and thereby minimizing the variations in test results from one laboratory person to another. Automation enables the elimination of manual related errors such as pipetting steps, results calculation and transmission as well as data storage and retrieval. Automated analysis allow the use of small volumes of samples and reagents thereby allowing less blood to be drawn and reducing cost of consumables in the performance of tests.WHY AUTOMATIONIncrease the number of tests by one person in a given period of timeMinimize the variations in results from one person to anotherMinimize errors found in manual analyses equipment variations pipettesUse less sample and reagent for each testTYPES OF ANALYSERS BY TECHNIQUE USEDContinuous Flow AnalysersTubing flow of reagents and patients samplesThis first AutoAnalyzer (AA) was a continuous-flow, single-channel, sequential batch analyser capable of providing a single test result on approximately 40 samples per hour. The major drawbacks that contributed to the eventual demise of traditional continuous-flow Analysers in the marketplace were significant carry-over problems and wasteful use of continuously flowing reagents.Continuous flow is also used in some spectrophotometric instruments in which the chemical reaction occurs in one reaction channel and then is rinsed out and reused for the next sample, which may be an entirely different chemical reaction.

Two types:Single channel continuous flow systemThis can perform a single estimation on a large number of specimens simultaneously. In this system the specimens to be analysed pass sequentially through a single hydraulic line in which all the reactions and incubations take place in a continuous stream of fluid. All the samples and reagents flow continuously and the specimens are introduced at intervals. An essential principle of the system is the introduction of air bubbles. The air bubbles segment each sample into discrete packets and act as a barrier between packets to prevent cross contamination as they travel down the length of the tubing. The air bubbles also assist mixing by creating turbulent flow (bolus flow), and provide operators with a quick and easy check of the flow characteristics of the liquid. The relative proportions of samples and reagents are determined by manipulating their flow rates by varying the diameters of the tubes. Mixing takes place when the specimen and reagents join to form a common pathway. The reactions take place as the fluid mixture passes through the tubing. Various separations steps such as dialysis, the use of density gradient for removal of interfering substances such as proteins or extractions by solvents, occur during the passage through the tubing. The reagents, sample and reagent volumes, flow rates, and other aspects of the instrument analysis depend on which analyte is being measured. The extent of reaction is finally read using colorimeter, spectrophotometer, fluorometer or nephelometer. The results may be displayed on a screen or are printed out.Multi-channel continuous flow analyserMulti-channel continuous flow analysers are large scale equipments which analyses two or more parameters at the same time. The principles used for the analysers are generally the same as those for the single channel analysers. Measurements are initiated by transferring measured amounts of sample and reagent into a cuvette. The cuvette contents are mixed, incubated, and then optically analyzed at the times and wavelengths specified in the programmed parameters for that test. A computer is used for the continuous monitoring of the chemical reactions. It also calibrates the machine with reference sera at fixed intervals. The report is produced by the printer. Analysers with multiple channels (for different tests), working synchronously to produce 6 or 12 test results simultaneously at the rate of 360 or 720 tests per hour.Centrifugal AnalysersCentrifuge force to mix sample and reagentsDiscrete aliquots of specimens and reagents are pipetted into discrete chambers in a rotorThe specimens are subsequently analyzed in parallel by spinning the rotor and using the resultant centrifugal force to simultaneously transfer and mix aliquots of specimens and reagents into radially located cuvets.The rotary motion is then used to move the cuvets through the optical path of an optical systemDiscrete AnalysersSeparate testing cuvettes for each test and sampleDiscrete analysis is the separation of each sample and accompanying reagents in a separate container and quantitatively processed as single units. These analysers have the ability of performing a test at a time from multiple samples.They are the most popular and versatile analysers and have almost completely replaced continuous-flow and centrifugal analysers.Sample reactions are kept discrete through the use of separate reaction cuvettes, cells, slides, or wells that are disposed of following chemical analysis. This keeps sample and reaction carryover to a minimum but increases the cost per test due to disposable products.Thin-film or dry chemical autoanalysersThe thin-film analysers are discrete analysers. They use dry reagents spread in extremely thin layers on a plastic slide to which serum specimen is added. The reaction is read with the help of a reflectrometer instead of a photometer. The system consists of plastic chip which contains several thin layers of dry reagents. The serum specimen provides the solvent necessary for the reaction. The coloured end products are confined to a fixed area on the slide.TYPES OF ANALYSERS BY TESTS PERFORMEDRoutine Biochemistry AnalysersThese are machines that process a large portion of the samples going into a hospital or private medical laboratory. Automation of the testing process has reduced testing time for many analytes from days to minutes. The types of tests include enzyme levels (such as many of the liver function tests), ion levels (e.g. sodium and potassium, and other tell-tale chemicals (such as glucose, serum albumin, or creatinine). Simple ions are often measured with ion selective electrodes, which let one type of ion through, and measure voltage differences. Enzymes may be measured by the rate they change one coloured substance to another; in these tests, the results for enzymes are given as an activity, not as a concentration of the enzyme. Other tests use colorimetric changes to determine the concentration of the chemical in question. Turbidity may also be measured.Immuno-based AnalysersAntibodies are used by some analysers to detect many substances by immunoassay and other reactions that employ the use of antibody-antigen reactions.When concentration of these compounds is too low to cause a measurable increase in turbidity when bound to antibody, more specialised methods must be used.Recent developments include automation for the immunohematology lab, also known as transfusion medicine.Hematology AnalysersThese are used to perform complete blood counts, erythrocyte sedimentation rates (ESRs), or coagulation tests.Cell CountersAutomated cell counters sample the blood, and quantify, classify, and describe cell populations using both electrical and optical techniques. Electrical analysis involves passing a dilute solution of the blood through an aperture across which an electrical current is flowing. The passage of cells through the current changes the impedance between the terminals (the Coulter principle). A lytic reagent is added to the blood solution to selectively lyse the RBCs, leaving only WBCs and platelets intact. Then the solution is passed through a second detector. This allows the counts of RBCs, WBCs, and platelets to be obtained. The platelet count is easily separated from the WBC count by the smaller impedance spikes they produce in the detector due to their lower cell volumes.CoagulometersAutomated coagulation machines or Coagulometers measure the ability of blood to clot by performing any of several types of tests including Partial thromboplastin times, Prothrombin times (and the calculated INRs commonly used for therapeutic evaluation), Lupus anticoagulant screens, D dimer assays, and factor assays.Coagulometers require blood samples that have been drawn in tubes containing sodium citrate as an anticoagulant.Other Hematology ApparatusMiscellaneous AnalysersAnalysers that fall into this category include instruments that perform:DNA labeling and detectionOsmolarity and osmolality measurementMeasurement of glycosylated hemoglobin (hemoglobin A1C), andAliquotting and routing of samples throughout the laboratorySUMMARY OF CHEMISTRY ANALYZERS AND OPERATIONS

WITH AUTOMATION, THERE ARE STILL SOME VERY BASIC STEPSSpecimen preparation and IdentificationLabeling still critical Programming of instrumentLaboratory personnel must perform and observe:Quality AssuranceQuality ControlDISPENSERS AND DILUTERSAutomatic measuring devices such as dispensers, diluters and automatic pipettes are used in many clinical laboratories. These devices permit repetitive and accurate delivery of predefined volumes of any fluid.The delivery of multiple volumes of the same regent as diluents is performed by dispensers that use a syringe as the measuring device on bottle top device. The range of dispensers falls into three categories. Hand-operated mechanical pipette have extensively been used in laboratory analysis.The common features include a disposable plastic tip at the end of thumb operated push button device that displaces air from spring loaded syringe. The plastic tip is dipped into the liquid after the air has been displaced by depressing the push button. The liquid which enter the tip is delivered to a suitable container by repressing the button. The instrument is available either as fixed or variable volumes that measure from 10 to 1000l. Typical settings for variable types include 1-10l 10-100l, 10-200l, 100-1000l. Performance is affected when pipettes are not used as recommended by manufacturers. Automatic dispenser syringe are pipette syringes mounted tightly on top of reagent bottles. The calibrated syringes are adjusted to volumes required for analytical work. The syringe is filled by upward pull of the plunger through a Teflon tube dipping in the reagent and subsequently dispensed when the syringe plunger is depressed. The use of automated diluters has also greatly enhanced laboratory analysis. These are dual syringe diluters have two syringe drives and a valve positioned for single or serial dilutions. The Hamilton dual syringe diluter has two programmable syringes. One syringe is filled with the solvent (diluent) connected to a reservoir, whiles the second syringe is connected to a tip and programmed to aspirate from samples for dilution. When dispensed, a complete dilution is achieved. TOTAL LABORATORY AUTOMATION

SELECTION PROCESSAutomated systems are selected to fit into the modes of analysis that is optimal for a particular set up. Standardised approach to the selection and evaluation of instrumentation for automated, semi automated, and manual modes are based on useful checklists, workshop manuals and published data. Selection of type of analyser is determined by the systematic analysis of the role of an automated system in the workflow and identification of equipment mode. Cost-effectiveness and acceptability to operators alongside the analytical performance of instruments are logic candidates that predetermine acquisition. The success of many automated systems depends heavily on the interface between the equipment and the human operator. Once a system has been delivered, performance evaluation must ensure that the sensitivity, specificity, accuracy and precision claimed by the manufacturer are achieved. The National Committee for Clinical Laboratory Standards (NCCLS) user-evaluator protocol EP17-A provides a standardized approach for the determination of limits of detection and performance in laboratories. Microprocessor technology has reduced the dependency on manufacturers service engineers by incorporating diagnostic routines on software. Most automated systems contain software that schedules the order in which the instrument performs pending tasks. Tests to be performed are entered on a keyboard as requested for either routine tests or emergency (STAT) tests that is always scheduled ahead of a routine test. The software monitors the status of the system during testing and alerts the operator to conditions that may affect system performance including required reagents, calibrators, sample monitoring and controls.