Medical Instrumentation Clinical Rotation MLT406 PDF

# Medical Instrumentation Clinical Rotation ## Unit 1. Equipment Management and Maintenance ### Recommended Resources for Equipment Management * Manuals in a fluent language * Scheduled Maintenance * Repair Services * Contract Management * Consumables supply * Spares Supply ### Effective Mainte...

# Medical Instrumentation Clinical Rotation ## Unit 1. Equipment Management and Maintenance ### Recommended Resources for Equipment Management * Manuals in a fluent language * Scheduled Maintenance * Repair Services * Contract Management * Consumables supply * Spares Supply ### Effective Maintenance Strategy * User as well as service manuals * Receipt and incoming inspection * Inventory and documentation * Installation and final acceptance * Equipment history record * Maintenance * Condemnation of old and obsolete equipment ### Types and Approaches to Maintenance of Medical Equipment There are two types of maintenance: * **Corrective Maintenance (or Repair)** This is done to take corrective action in the event of a breakdown of the equipment. The equipment is returned repaired and calibrated. * **Planned (or Scheduled) Preventive Maintenance** This work is done in a planned way before repair is required and the scheduled time for the work circulated well in advance. It involves cleaning, regular function/safety tests and makes sure that any problems are picked up while they are still small. ### Levels of Maintenance There are three levels of maintenance commonly identified: * **Level 1. User (or first-line)** The user or technician will clean the filters, check fuses, check power supplies etc. without opening the unit and without moving it away from the point of use. * **Level 2. Technician** It is recommended to call the local technician when first-line maintenance cannot rectify a fault or when a six monthly check is due. * **Level 3. Specialized** Equipment such as chemistry analyzer, hematology automated instruments etc. will need specialized engineers and technicians trained in this specific equipment. They are normally employed by vendor companies. ### Setting Up a Complete System When many items of equipment are under the care of a single biomedical department, it is better to keep the planned preventive maintenance computerized with a programmed schedule. This will require: * An equipment inventory * Definition of maintenance tasks * Establishing intervals of maintenance * Personnel * Reminder system * Special test equipment * Technical library * A full technical library should be available. ## Troubleshooting - Electronic Diagnostic Equipment | Fault | Possible Cause | Solution | |---|---|---| | 1. Equipment is not running | No power from mains socket | Check power switch is on. Replace fuse with correct voltage and current rating if blown. Check mains power is present at socket using equipment known to be working. Contact electrician for rewiring if power not present. | | | Electrical cable fault | Try cable on another piece of equipment. Contact electrician for repair if required. | | 2. Fuse keeps blowing | Power supply or cable fault | Refer to electrician | | 3. Equipment not fully operational | Part malfunction | Check controls for correct positioning and operation (refer to user manual). Check all bulbs, heaters and connectors for function. Repair or replace if necessary. | | 4. Electrical shocks | Wiring fault | Refer to electrician | ## User Maintenance Checklist - Electronic Diagnostic Equipment ### Daily | Task | Action | |---|---| | Cleaning | Wipe dust off exterior and cover equipment after checks. Remove any tape, paper or foreign body from equipment. | | | | | Visual checks | Check all fittings and accessories are mounted correctly. Check there are no cracks in covers or liquid spillages. | | | | | Function checks | If in use that day, run a brief function check before clinic | ### Weekly | Task | Action | |---|---| | Cleaning | Unplug, clean outside with a damp cloth and dry off. Clean any filters or covers as directed by the user manual. | | | | | Visual checks | Tighten any loose screws and check parts are fitted tightly. Check mains plug screws are tight. Check mains cable has no bare wire and is not damaged. | | | | | Function checks | Check any paper, oil, batteries etc. required are sufficient. Check all switches operate correctly. | ### Every Six Months Biomedical Technician check required ## Unit 2. Light Microscope ### Learning Objectives At the end of this module, you will be able to: * Store the microscope properly * Clean the microscope including the eye pieces and objective lenses * Replace the microscope bulb * Troubleshoot the common problems associated with the use of the microscope ### Microscope Storage * Proper storage of the microscope will prevent or reduce problems. * Optics and mechanisms of the microscope must be protected from: * Dust and dirt * Fungus * Store the microscope: * Under a protective cover * In a low humidity environment ### Cleaning Solutions and Solvents * Soap solution for cleaning of body and stage * Ethyl ether-alcohol, alcohol, or lens cleaner solution for cleaning of lenses * Refer to manufacturer's guide for appropriate organic solvent ### Cleaning Solutions | Cleaning Solutions | Frequent Use | Infrequent Use | |---|---|---| | Manufacturer's recommendation | Yes | Yes | | Ethyl ether/alcohol (80/20) | Yes | Yes | | Alcohol | No | Yes | | Benzene/petrol | No | Yes | | Xylol | No | No | ### Cleaning Materials * Lint-free cotton gauze pads * Lint-free cotton swabs * Lens paper * Alternatives include: * Fine quality tissue paper * Muslin cloth * Silk ### Microscope Cleaning Process * **Eyepiece:** * Blow to remove dust before wiping lens * Clean the eyepieces with a cotton swab moistened with lens cleaning solution * Clean in a circular motion inside out * Wipe the eyepieces dry with lens paper * Repeat cleaning and drying if required * **Objectives:** * Objectives are cleaned while attached to the microscope * Moisten the lens paper with the cleaning solution * Wipe gently the objective in circular motion from inside out * Wipe with dry tissue or lens cleaning paper. * Objectives should never be removed from the nosepiece. * **Microscope** * Unplug the microscope from the power source * Moisten the cotton pad with a mild cleaning agent * Wipe the microscope body to remove dust. dirt, and oil * **Stage** * Unplug the microscope from the power source * Clean the condenser lens and auxiliary lens using lint-free cotton swabs moistened with lens cleaning solution * Wipe with dry swabs * **Body** * Unplug the microscope from the power source * Clean the condenser lens and auxiliary lens using lint-free cotton swabs moistened with lens cleaning solution * Wipe with dry swabs * **Condenser** * Unplug the microscope from the power source * Clean the condenser lens and auxiliary lens using lint-free cotton swabs moistened with lens cleaning solution * Wipe with dry swabs ### Microscope Repair * Never disassemble the microscope * Optics: * Eyepieces and objectives * Mechanics: * Stage and focus adjustments * Repair of these items requires a service engineer ## Troubleshooting Problems of Microscope * Many common microscope problems can be prevented or repaired by routine cleaning, adjustment, and maintenance. * Seek professional service for problems that cannot be fixed. **Problem: Eye Strain and Headaches** * Adjust interpupillary distance * Adjust eyepiece diopter setting * Use matched eyepieces **Problem: Poor Image Quality** * Clean objective and lens * Clean scope throughly * Check oil, replace if any contamination or haze is visible * Ensure the slide is thoroughly dry before applying oil **Problem: Uneven Illumination** * Ensure nosepiece is rotated to position where it clicks into place * Center condenser * Adjust Kohler illumination * Check to see bulb is correct model **Problem: Constant Refocusing** * Be sure slide is flat on stage * Clean stage and underside of slide * Be sure microscope is on a flat and leveled surface ## Maintenance of Microscope * Professional Service * Minimum of once a year if possible * Problem that cannot be fixed by laboratory staff * Daily Maintenance * Optimum illumination * Cleanliness * Light bulb * Immersion oil * Check cord * Keep it covered ## Unit 3. Clinical Chemistry Analyzer ### Chemistry Analyzer Description * Chemistry analyzers can be benchtop devices or placed on a cart; other systems require floor space. They are used to determine the concentration of certain metabolites, electrolytes, proteins, and/or drugs in samples of serum, plasma, urine, cerebrospinal fluid, and/or other body fluids. ### Principles of Operation * Samples are inserted in a slot or loaded onto a tray, and tests are programmed vie a keypad or bar-code scanner. Reagents may be stored within the analyzer, and it may require a water supply to wash internal parts. Results are displayed on the screen, and typically there are ports to connect to a printer and/or computer. * After the tray is loaded with samples, a pipette aspirates a precisely measured aliquot of sample and discharges it into the reaction vessel; a measured volume of diluent rinses the pipette. * Reagents are dispensed into the reaction vessel. * After the solution is mixed (and incubated, if necessary), it is either passed through a colorimeter, which measures its absorbance while it is still in its reaction vessel. or aspirated into a flow cell, where its absorbance is measured by a flow-through colorimeter. * The analyzer then calculates the analyte's chemical concentrations. ### Operating Steps * The operator loads sample tubes into the analyzer: reagents may need to be loaded or may already be stored in the instrument. * A bar-code scanner will read the test orders off the label on each test tube, or the operator may have to program the desired tests. * After the required test(s) are run, the results can be displayed on-screen, printed out, stored in the analyzer's internal memory, and/or transferred to a computer. ### Use and Maintenance * User(s): Laboratory technician * Maintenance: Laboratory technician, biomedical or clinical engineer * Training: Initial training by manufacturers and manuals ### Environment of Use * Settings of use: Clinical laboratory * Requirements: Adequate benchtop or floor space, water supply, line power, biohazard disposal ### Types and Variations * Some chemistry analyzers can be interfaced to an automated immunoassay analyzer to decrease operator intervention and possibly improve work flow. ## Unit 3. Hematology Analyzers ### Introduction * A complete blood count (CBC) is usually the first test requested by a physician to evaluate a patient's general health status. CBC is used to measure the oxygen-carrying red blood cells (RBC), the platelets (PLT) that help clot the blood, and the white blood cells (WBC) of the immune system. * As part of the CBC, a WBC differential is conducted. Traditionally, a laboratory technician uses a microscope to manually count 100 WBC and differentiate them into neutrophils (NEU). lymphocytes (LYM), monocytes (MONO), eosinophils(EOS), and basophils (BASO). * Each cell type is reported as a percentage of total WBC, and a shift in the percentage indicates a condition. ### Automated Analyzer Versus Manual Analysis * In today's general screenings, CBC tests are performed using automated hematology analyzers. In addition to reporting RBC, PLT, and WCB counts, an analyze also measures the oxygen-containing hemoglobin (HGB) and determines a range of other parameters such as the mean cell volume (MCV), PLT width distribution, and hematocrit (HCT), that is, the red blood cell-to-plasma ratio. * Hence, an automated analyzer can provide much more information than a manual count. ### Principle of Automated Hematology Analyzers * A 3-part instrument commonly uses impedance to differentiate WBC into granulocytes (mainly neutrophils, but also eosinophils and basophils), lymphocytes, and MID cells (mainly monocytes, but also eosinophils) based on cell size. * Each cell passing through the aperture causes a drop in the electrical current (a pulse). The number of generated pulses correlates with the number of cells, whereas the size of the pulse is related to the cell size. ### Five Parts Automated Hematology Analyzers * In addition to impedance, a 5-part instrument employs the principle of flow cytometry to differentiate WBC into their five major sub-populations—neutrophils, lymphocytes, monocytes, eosinophils, and basophils—based on cell size and complexity (granularity). * In flow cytometry, cells are forced to flow in a single file through the aperture by a sheath fluid, created by a fast-moving diluent that surrounds the slow moving sample. * A laser beam is passed through the sample, and when a cell passes through the sensing zone. the light is scattered and measured by a photoconductor that converts the light into an electrical impulse. * The number of generated impulses correlates with the number of cells, whereas the light scatter is used to determine cell granularity, shape, and size. ### 3-Part Versus 5-Part Analyzers * Although each WCB type provides information that helps diagnose blood-related conditions, a 3-part instrument will provide sufficient information for the typical physician office laboratory (POL). * With a simple CBC, the neutrophil and lymphocyte counts will answer the question of a viral infection or a bacterial infection that can be treated with antibiotics. For specialty laboratories, however, a 5-part instrument can provide a more detailed and targeted assessment of the blood status. * To distinguish eosinophils and basophils from neutrophils, for example, a 5-part differentiation is mandatory. * However, the cost for a typical 5-part instrument can be two to three times higher (20,000 to 50,000 USD) than for a 3-part instrument (less than 10,000 USD). In addition, a 5-part differential often requires more reagents than a 3-part differential, also increasing the cost per test from below 1 USD/test for a 3-part differential to 1.5 to 3 USD/test for a 5-part differential. ## Unit 3. Specimen Collection Automation ### Specimen Collection Automation * Specimen collection is the process of obtaining tissue or fluids for laboratory analysis or near-patient testing. It is often a first step in determining diagnosis and treatment. * The potential for misdiagnosis, misidentification, and other errors increases with the incorporation of human or manual processes, and that has been the spur for efforts to automate specimen collection. * Economic factors are also pushing lab leaders to consider automated approaches. What inroads is automation making? Will some processes always require human involvement? ### Why Has It Been More of a Challenge to Automate Specimen Collection? * Automated specimen collection must be differentiated from automated specimen processing. The latter has long benefitted from extensive automation. * Part of the reason is the variety of sample types that must be collected—for example, blood, urine, throat swabs, bone marrow, nasopharyngeal and aspirate, and mucosal secretions. It is difficult to imagine a single technology that would be adaptable to all. * Despite the challenge of fully automating sample collection, some progress has been made. One vendor is developing a fully automated venipuncture solution. * This "robot phlebotomist” incorporates infrared light, image analysis, and ultrasound to locate the right vein, confirm blood flow, and insert the needle. * The patient slides and arm inside a padded archway: the device tightens a cuff around the arm and deploys an infrared camera together with software analysis—matching skin patterns with models—in search of a vein. It then uses ultrasound to ensure sufficient blood flow before aligning the needle and drawing blood with a vacutainer system. * The vacutainer's low pressure vacuum design allows for some level of automation in the volume of blood that is drawn. However, a nurse or phlebotomist is still needed to interact with the patient, and shepherd the process along. * According to its developer, the device is successful 83 percent of the time, a rate which is on par with experienced phlebotomists and superior to newly trained staff, who typically draw blood successfully on the first attempt one-third of the time. * When the procedure involves children. the elderly. or a dysmorphic patient, the failure rate, even for experienced phlebotomists, is 55 percent. The vendor plans to improve the device's accuracy to 90 percent or above before starting clinical trials. * Another similar device, also in development, claims to have achieved close to 100 percent success. Relying on much the same technology, this robot automatically identifies, matches, locates, and exploits a vein without a human needing to come in contact with needles, or the specimen. * Its makers tout its efficacy in hazardous environments, such as Ebola-challenged areas, where necessary medical rigor is combined with the dangers of exposure. ### Should This Product Ever Come to Market, Do Its Results Justify Consideration? ## Unit 5. Medical Laboratory Equipments ### Common Laboratory Equipment * Types of equipment and instruments commonly found in the laboratory include centrifuges, autoclaves, laboratory balances, pH meters, and various temperature-controlled chambers, such as refrigerators, freezers, and water baths or heat blocks. Procedures for the correct use and quality control checks required for each of these will be specified in the SOP manual. These procedures must be followed for safe and accurate use of the instrument(s). ### Laboratory Centrifuges * Centrifuges are instruments that spin samples at high speeds, forcing the heavier particles to the bottom of the container (usually a tube). * The part of the centrifuge that holds the tubes and rotates during operation is the rotor. * Centrifuges are frequently used to separate the cellular components of blood from serum or plasma and to centrifuge urine to obtain urine sediment. * Clinical centrifuges can be large floor models or small enough to fit on a bench top. These usually have a speed capacity of 0 to 3000 rpm (revolutions per minute), and hold tubes ranging in size from 5 to 50 mL, depending on the rotor or tube carriers. * A serological centrifuge is a centrifuge used in blood banking to spin small tubes (approximately 2 to 3 mL capacity). * Microcentrifuges, or microfuges, are widely used in the clinical laboratory to spin special microtubes (0.5 to 1.5 mL capacity) at high speeds, up to 14,000rpm. * Other types of centrifuges include high-speed refrigerated centrifuges that have speed capabilities up to 20,000 rpm, and ultracentrifuges that are capable of speeds over 50,000 rpm. These centrifuges are specially equipped to keep samples cool during centrifugation. Ultracentrifuges are often used in research laboratories but not usually required for clinical laboratory samples. ### Quality Assessment * The rotation speeds and accuracy of centrifuge timers must be verified and documented at specific intervals. usually monthly or quarterly. ### Centrifuge Safety * Centrifuges present several safety hazards. Because they are used to process biological specimens, Standard Precautions must be observed and appropriate PPE must be worn when operating a centrifuge. All centrifuge surfaces (interior and exterior) must be cleaned using surface disinfectant any time spills or splashes occur. ### Laboratory Balances * Several types of balances or scales are used in the laboratory. They differ in the maximum amount they can accurately weigh, their sensitivities, and basic design. Measurements that require sensitivity to 0.10 g can be made using inexpensive double- or triple-beam balances. Measurements of as little as 0.0001 g (10–4 g) or even 0.00001 g (10–5 g) can be made using an analytical balance with sufficient sensitivity. Most critical weighing is done using electronic top-loading balances or analytical balances. **Laboratory Balance Safety** * Because balances are used to weigh chemicals, appropriate chemical safety precautions must be used to prevent exposure to the chemical or chemical dust. Technicians should observe basic safety rules, know the hazards of the chemicals they are working with, and wear appropriate PPE. Care should be taken that chemical dusts are not created during transfer of chemicals. Work practice controls should include: * Wear eye protection to avoid getting chemicals in the eyes. * Wear a mask to avoid breathing in chemical dusts that can be respiratory irritants. * Wear gloves and a laboratory coat to avoid chemical contact with skin and clothing. * Clean up spills around the balance to keep the work are safe. **Quality Assessment** * Chemicals must be weighed accurately to prepare reagents correctly. The manufacturer's instruction manual must be followed for the particular balance being used. Purchased sets of calibration weights can be used to calibrate balances. These weights must be kept protected from dust and only handled with forceps, never touched with the bare hands. Some general rules to follow to protect the balance and ensure quality's results are: * Keep balances clean and wipe up any spills immediately. * Protect the balance from jarring, sudden shocks, and temperature extremes. * Keep the balance in the same location: do not move it from place to place. * Level the balance by adjusting the balance legs. * Position the balance in a location free of drafts and vibrations. Special stabilizing tables are available if vibrations are a problem. * Check zero adjustment: scale should read zero (0) when the weigh pan is empty. ### pH Meter * pH is the universal accepted scale for the concentration of hydrogen ion in aqueous solution, which gives a measurement of the acidity or alkalinity of a given solution. pH is defined as the negative logarithm of the molecular concentration of the active The pH of any solution will be in the range of 0 to 14.0. If pH of a solution is less than 7.0, it is known as acidic, whereas, pH value greater than 7.0 is considered as basic. A mixture with pH value of 7.0 is a neutral solution. pH value may be change inversly with the change of temperature. For optimum readings it is better to use a temperature of 25C. * pH meter is an instrument used to measure the pH or hydrogen ion concentration of a given solution by the potential difference between two electrodes. Major components of pH meter are: * Glass bulb electrode; * Reference (calomel) electrode and: * Potentiometer (sensitive meter) which measures the electric volt. * pH can be estimated using special papers treated with indicator solutions. These papers are dipped into the solution to be tested, and the color that develops is compared to a color chart to determine the pH. This method is suitable for measuring urine pH, but is not sensitive enough for preparing most laboratory reagents. **pH Meter Safety** * Care should be used when performing pH measurements. Caustic or acid solutions must be handled carefully. Chemical spills must be wiped up immediately. The pH meter should be disconnected from the electrical source before attempting any repair. **Quality Assessment** * Special care must be taken in handling, maintaining, and storing the pH electrode so it will not dry out or be broken. The electrodes must always be rinsed with distilled or reagent water between samples, but never stored in water. Manuals that come with the meters give detailed instructions for use and storage of electrodes. * Electrodes must be calibrated using solutions of known pH values, usually 4.0, 7.0, and 10.0, which should be stored at room temperature. The electrodes are immersed in the known solutions. and the meter is calibrated. Reagents should be at room temperature before attempting to measure pH. ### Temperature-Controlled Units * Most test procedures, specimens. and reagents require testing or storage at specific temperatures. Many reagents must be stored refrigerated or frozen: patient specimens are refrigerated or frozen: and microbiological cultures and some chemistry tests require special incubation conditions. To accomplish these tasks. several types of temperature-controlled chambers are used in the clinical laboratory. These include: * Ovens for drying labware * Microbiology incubators * Water baths and heating blocks * Refrigerators * Freezers * Microwaves | Equipment | Temperature (°C) | Permissible Range (°C) | |---|---|---| | Refrigerator | 6 ± 2 | 4 to 8 | | Freezer | -20 ± 5 | -15 to -25 | | Ultracold freezer | -70 ± 5 | -65 to -75 | | Microbiology incubator | 36 ± 1 | 35 to 37 | | Water bath | 36 ± 1 | 35 to 37 | **Temperature-Controlled Chamber Safety** * Temperature-controlled units such as refrigerators, freezers, and water baths, must be used only for laboratory purposes, not for storing or heating food. Because biological specimens are stored or used in these chambers, Standard Precautions must be followed when using and cleaning the units. Stable racks and trays should be used to secure specimens and prevent tipping, spilling, or breakage. Cooling units should be cleaned regularly inside and out with a surface disinfectant. Units such as water baths must be emptied and cleaned frequently using surface disinfectant, followed by wiping with 70% alcohol or dilute (3% to 6%) hydrogen peroxide to prevent growth of microorganisms. Bacteriostatic chemicals or copper wire can be placed in the water of water baths to inhibit bacterial and fungal growth. **Quality Assessment** * Laboratory air flow, room air exchange, and laboratory temperature maintenance influence the operation of temperature-controlled units. Increased air flow over waterbaths will contribute to more rapid water evaporation. Fluctuating room temperatures and increased air flow can also make it more difficult for temperature-controlled units to maintain their set temperatures. All temperature-controlled units must be monitored regularly to be sure they are operating at the correct temperature. Temperatures must be recorded daily and checked before each use of a unit. ### Autoclaves * Autoclaves use steam under pressure to sterilize items such as dental and surgical instruments, solutions, and materials to be used in microbiology. Autoclaves are also used to decontaminate materials such as blood specimens, bacterial cultures, or filled biohazard containers before disposal. * Autoclaves can range in size from large (refrigerator size) to tabletop size. Large autoclaves obtain steam from either an internal steam generator or a connection to the facility’s steam plant. Smaller ones create their own steam by heating water. * The temperature, lenght of cycle, and pounds of steam pressure are set. Typical autoclave conditions are 121°C for 15 to 20 minutes at 15 pounds per square inch (psi). **Autoclave Safety** * Because of the pressurized steam generated by an autoclave, great care must be used during autoclave operation. The autoclave door must never be opened unless the chamber pressure is zero (0) psi. Regularly scheduled safety inspections by a qualified autoclave service technician are required. To prevent burns, tongs and/or heat-proof gloves must be used to remove items from the autoclave. When liquids are sterilized, they must be in loosely capped, heat-resistant containers that are no more than half full. These containers must be placed in an autoclavable tray or pan to catch overflow. Chamber pressure must be reduced slowly at the end of a “liquid run” to prevent the liquids from boiling over because of rapid decreases in pressure. **Quality Assessment** * It is important that autoclaves work properly, since nonsterile items could endanger both worker and patient or could cause problems in a test procedure requiring sterile solutions or components. Indicator strips containing spores from the bacterium Bacillus stearothermophilus can be used to check the effectiveness of the steam sterilization process. The strips are autoclaved with a normal load, removed, and incubated in a tube of bacterial growth medium. Lack of bacterial growth confirms the efficiency of sterilization: growth of bacteria indicates the sterilization method was inadequate and the items in that run are not sterile. Temperature, pressure, and time controls must then be checked to determine the cause of failure. * Daily records must be kept of sterilization times. temperatures. chamber pressures, and indicator strip results. The temperature chart recorder must be changed at specified intervals and the charts maintained in the equipment logbook.