Automation in the clinical laboratory

Recent advances

• Point-of-care benchtop analyzers: small, portable, easy to operate; used in physician’s offices, surgical, and critical care units
• Immunochemistry analyzers: assaying drugs, specific proteins, tumor markers, hormones - for very small concentrations
• Immunoassay-based instruments use a variety of techniques, including fluorescence-polarization immunoassays, nephelometry, and chemiluminescent immunoassays

Modular analyzers

Modular analyzers: utilize a combination of laboratory methods; absorbance, ISEs, immunoassays, etc. (found in large core laboratories)

Siemens Dimension Vista 500

Roche Cobas modular analyzers

- perform a lot of QC and maintenance

Driving forces toward more automation:

• Higher volume of testing
• Fewer, more centralized core laboratories
• Relieve staffing shortages
• Decline in use of lab panels or profiles
• Regulatory standards requiring greater accuracy and precision
• Intense competition among instrument manufacturers
• Decreased operating budgets for labs

Advantages to automation:

• Increase the # of tests performed in the laboratory
• Decreases labor and cost per test
• Minimizes variation in results among laboratorians - standardization
• Eliminates potential errors of manual analyses
• Instruments use very small amount of specimens and reagents; this decreases the cost of “consumables”, which are the components of a test that used and discarded (cuvettes, pipette, tips, reagents, etc.)

Summary of chemistry analyzer operations

ADD TABLE!! MEMORIZE STEPS IN ORDER

Basic approaches to automation

• Continuous flow: liquids are pumped through a system of continuous tubing; specimens are introduced in a sequential manner
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• Centrifugal analysis: force of centrifugation transfers and contains liquids; capable of batch analysis
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• Discrete analysis: separation of each specimen and reagent in a separate container; most popular types can run multiple tests on one specimen at a time or multiple specimens one test at a time

Specimen preparation and identification

• Typically a manual process
• Can be automated by robotics
• Can be skipped, if whole blood is used for analysis
• Plasma separator tube can be used and primary tube sampling performed with plasma
• Specimen ID: manual label on sample cup; bar code label affixed to primary collection tube (has been the best innovation in preventing errors in identification)

https://www.mc.vanderbilt.edu/documents/vmcpathology/files/PAL%20Specimen%20Labeling.pdf

Specimen measurement and delivery

• Circular carousels or rectangular racks hold specimen containers
• Primary collection tubes or microsample tubes are placed in carousels and racks
• An aliquot is measured through aspiration of the sample into a probe
• Probe and tubing are cleaned after each dispensing to minimize carryover (contamination), unless disposable probes or tips are used

Limitations of current systems

Samples are uncapped, and exposure of the sample to air can lead to sample evaporation, produce errors in analysis, and expose you to biohazards during the uncapping step

Evaporation of the sample may be significant, and may cause concentration of the constituents being analyzed to rise 50% in 4 hours

Analyzers performing electrolyte measurements can lose CO2 to the atmosphere, resulting in decreased CO2 values

Some manufacturers have developed lid covers for trays and individual caps that can be pierced, which includes closed tube sampling from primary collection tubes

exam: what happens if you pull cap off - blood gases

Reagent systems and delivery

• Liquid: available in bulk volume containers or unit doses
• Dry: bottled as a lyophilized powder (dehydrated reagent), requiring reconstitution; also, multilayered dry chemistry slide (Vitros)
• Preservation: refrigeration, reconstitution of a dry tablet, or combination of two stable components
• Dispensed via tubing from bulk containers, syringes that pipet reagents into reaction containers, piston-driven pumps connected by tubing, or pressurized reagent bottles

Chemical reaction phase

• Mixing: reagents and sample
• coiled tubing (continuous flow analyzers)
• rapid start-stop of reaction tray (RA1000)
• rapid start-stop of rotation or bubbling of air (centrifugal)
• Separation: separating undesirable substances from sample
• Incubation: heating bath (water or air) to maintain required temperature of reaction mixture
• Reaction time: depends on rate of transport through system, and timed reagent additions

Measurement phase

After the reaction is complete, the products must be quantified

Methods for quantification:

• Ultraviolet, fluorescence, and flame photometry
• Ion-specific electrodes - electrolytes
• Gamma counters
• Luminometers
• UV-Visible spectrophotometry
• Fluorescence polarization, chemiluminescence, bioluminescence

Signal processing and data handling

Accurate calibration is essential to obtain accurate information

Multiple instruments that measure the same constituent in a lab should be calibrated so that results are compatible

Automated instruments, once calibrated, provide long-term stability of standard curves; some instruments are self-calibrating

Advanced automated instruments have a method of reporting printed results

Computerized monitoring is available for many parameters

PRINCIPLE:

The cortisol assay is a competitive binding immunoenzymatic assay. A sample is added to a reaction vessel with rabbit antibody to cortisol, cortisol-alkaline phosphatase conjugate, and paramagnetic particles coated with goat anti-rabbit capture antibody. Cortisol in the sample competes with the cortisol-alkaline phosphatase conjugate for binding sites on a limited amount of specific anti-cortisol antibody. Resulting antigen: antibody complexes bind to the capture antibody on the solid phase. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field while unbound materials are washed away. Then, the chemiluminescent substrate Lumi-Phos 530 (adamantyl dioxetane phosphate ester) is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is inversely proportional to the concentration of cortisol in the sample. The amount of analyte in the sample is determined from a stored, multi-point calibration curve.

Schematic of total laboratory automation

Preanalytic phase

Analytic phase (chemical analysis)

• Ever-smaller microsampling
• Expanded onboard and total test menus
• Accelerated reaction times
• Higher-resolution optics
• Improved flow-through electrodes
• Enhanced user-friendly interactive software for QC, maintenance, and diagnostics
• Ergonomic and physical design improvements

Postanalytic phase

• Bidirectional communication between analyzers and host computer
• Integration of work station managers into communication system
• Automated management of quality control data 
• User-defined parameters for many values
• The use of autoverification capabilities found with many postanalytic laboratory information systems (LIS) has contributed to a significant reduction in result turnaround time

Future trends in automation

• More system and workflow integration will occur with robotics and data management for more inclusive TLA
• The incorporation of artificial intelligence and machine learning into analytic systems will likely evolve and expand within the clinical laboratory
• Collectively these will advance the technologies of robotics, digital processing of data, computer-assisted diagnosis, and data integration with electronic patient records