automated sample analysis Flashcards
types of automated analysers?
(6 marks)
- biochemistry analysers
- haematology analysers
- electrolyte blood gas analysers
- coag analysers
- snap test analysers
- urinalysis analysers
use of biochemistry analysers?
(1 mark)
measure various biochemical substances within blood
use of haematology analysers?
(1 mark)
automatically determine total RBC + WBC counts, differential WBC counts, packed cell vol + platelet counts
use of electolyte / blood gas analysers?
(3 marks)
measures plasma electrolyte levers, resp blood gases + ionised calcium
tells us if any electrolyte disturbance that may impact aci base balance
requires use of arterial blood
use of coag analysers?
(2 marks)
measure activated partial thromboplastin time + prothrombin time.
identify clotting disorders
use of snap test analysers?
(1 mark)
automatically activates, times + interprets SNAP test results
use of urinalysis analysers?
(2 marks)
read + interpret urine dipstick for standard biochemical urine parameters.
identification of cells, bacteria, casts + crystals
advantages of analysers?
(9 marks)
- accurate + easy to use
- fast, reliable methods of blood examination
- minimise technician error + time required to perform test
- expedited results for diagnosis of emergancy cases
- test kits + reagents easily obtained
- tests can often be run on whole blood / serum
- improve customer satisfaction - minimal waiting time
- multiple tests performed at one time
- machines link to practice managament system + patient record, allowing easy access to results
disadvantages of analysers?
(9 marks)
- training required ensure staff use equipment efficiently + effectively
- machines costly to purchase + maintain
- operator error / machine malfunction can delay results + diagnosis
- errors common with haematology due to fragility of BCs - support with manual testing
- machine maintainance can be complicated
- chemical reagens costly + short dates can result in wastage
- machine cumbersome + require large work space
- staff member required to run bloods which removes them from rotated tasks
- reference intervals unavailable for all species
what can be analysed?
(4 marks)
- blood - whole blood, serum / plasma
- urine
- faeces
blood in lithium heparin tube seperates into?
(1 mark)
plasma, WBCs + platelets, RBCs
blood in plain tibe seperates into?
(1 mark)
serum, blood clot
types of interferons?
(3 marks)
- haemolysis
- icterus
- lipaemia
what do interferons do?
(1 mark)
impact quality of results machine provides
types of biochemistry machines?
(4 marks)
- IDDEX - catalyst one, procyte Dx
- zoetics - vetscan VS2
- samsung - biochemistry analyser
- seamaty - blood chemistry analyser
biochemistry info?
(6 marks)
- run time approx. 8 mins (15m with TT4)
- 29+ biochem parameters: including FRU, PHEN, ELEC, TT4, UPC
- fully automatic
- on-board centrifudge
- sample size: 100-700ul whole blood, 300ul serum / plasma
- some can run multiple tests simultaneously
use of biochemisty?
(! mark)
give indication of chemical content of blood sample
how do dry chemistry analysers work?
(3 marks)
- reagents provided on impregnated slides / pads
- machine determines the assay to be performed by reading a bar code / QR on the slide
- during machine process the sample is placed on the pad + inserted into the machine
how do the layers of dry chemistry analysers work?
(10 marks)
- spreading layer - sample is distributed evenly
- filtering layer - filters out substances that interfere with results
- reagent layer - reagent reacts with sample
- indicator layer - reacted sample collects for spectral analysis
- support layer - optical interface
what is dry chemistry?
(1 mark)
refers to the slides which are impreganted with dry reagent
what the colour change (of dry chemistry) means?
(2 marks)
colour change commonly occurs
degree of colour change is proportionate to the chemical concentration
how are the results (of dry chemistry generated)?
(1 mark)
chemistry concentration is measured + generated as digital reading / result
what is wet chemistry?
(2 marks)
uses small wells of fluid instead of dry slides
generates specific wavelengths
how does wet chemistry work?
(2 marks)
light is passed through a liquid sample
intensity of emergant light is measured, converted into electrical energy + displayed digitally
advantage of wet chemistry?
(4 marks)
- mutliple samples analysed at one time
- multiple chemical tests performed
- improved accuracy of results
- because more sensitive than dry chemistry
disadvantages of wet chemistry?
(9 marks)
- smaller machines used in praactice labs can be imprecise
- cumbersome
- require sufficent storage space
- large amounts chemicals + consumables needed
- can be complicated to operate + maintain
- requires daily calibration + maintainance
- operator error more common than dry chem
- slower to generate results than dry chem
- expensive to purchase + maintain
types of haematology machines?
(2 marks)
- IDDEX - lasercyte Dx, procyte one
- zoetis - vetscan HMS
info of haematology machines?
(9 marks)
- complete blood count - up to 26 parameters
- can support synovial abdo + thoracic fluid -
- inflammatory cells
- include 3-5 part differential depending on species -
- identification of WBCs
- 30-90ul sample size
- 2-10 min run time
- some machines can run sample for -
- dogs, cats, horses, ferrets, pigs, rabbit, bovine, gerbil, guinea pig
use of haematology analysers?
(! mark)
provide quantitive analysis of blood cells
what techniques can haematology analysers use?
(4 marks)
- laser flow cytology
- laminar flow inpendence cytology
- optical fluorescence cytology
- combination of above
how does laser flow cytology work?
(5 marks)
- beam of laser light projected through the blood
- cells within give otu signals when struck which are
- picked up by detectors
- detects reflectance, transmission, scattering of light by cells allowing them to be identified
- each cell analysed giving numerical respresentation of likely overall distribution of cell populations
how does laminar impedence flow cytometry work?
(5 marks)
- suspension of cells in fluid, pumped through highly sensitive microchip
- allows cytometer to extract impedance (electrical resistance) signature from every cell as they pass through small apeture
- each time a cell impedes a pulse is produced,
- size of pulse determines size of cells
- cell counts are determined by number of pulses measured in a given volume of blood over set period of time
how does optical fluorescence cytometry work?
(2 mark)
- optical elements of flow cytometer direct photons emitted by fluorophores (bound to the cells) to the detection system
- detectors convert signal photons from scattered light / florescence to an electrical current allowing cells to be identified
how is cell identification determined?
(2 marks)
- size + ability to fluoresce
- floresce = indicated agrandular, granular + nucleic content
use of dot plots?
(2 marks)
- allow visual appreciation of ratio of different cells within a sample
- visualise results seen in figures
how is quality control achieved?
(5 marks)
- manual + detailed differntial white cell counts carried out to monitor quality control + highlight cell abnormalities
- clean analyser to avoid debris build up + particle interference
- preventaitve maintainance - manufacter provided - ensure result accuract
- replenish chem reagents as required
- update technology with data manufacter provide
types of electrolyte machines?
(2 marks)
- IDDEX - vetlyte, catalyst one, catalyst Dx, vetstat
- zoetis - vetscan 2
info of electrolyte machines?
(3 marks)
- generally measured by flame photometry
- at least 100ul of sample
- take whole blood, serum / heprinised plasma (only anticoagulant to be used)
how does flame photometry work?
(2 marks)
- measures intensity of light emitted when element is exposed to a flame (light source)
- flame emited depends on metal ion component within sample
how do electrolyte analysers work?
(3 marks)
- small analyser = use ion-sensitive electrons
- electrical current passed through specific ion-sensitive electrode bathed in chemical
- measurement of charged particle taken = identifies ion
what are the most common electrolytes used in practice?
(3 marks)
- sodium, magnesium
- potassium, chloride
- calcium run alone as one of the analyser within a CBC panel
types of snap analyser machines?
(2 marks)
- IDDEX - snap shot analyser + snap pro analyser
- zoetis - vetscan vue
info of snap analyser machines?
(5 marks)
- sample quantities depend on machine used
- use whole blood, plasma / serum
- accurate results generated in up to 15 mins
- used for screening / diagnostic tests
- some machines take multiple samples at once
feline snap tests?
(what they test for)
(6 marks)
- combo (FeLV, FIV)
- giardia
- FPL
- pro BNP
- total T4
- bile acids
canine snap tests?
(what they test for)
(10 marks)
- CPL
- 4DX (anaplasma, heartworm, lyme, e.canis)
- leishmania
- parvo
- giardia
- total T4
- cortisol
- bile acids
- leptospirosis
- angio
consumable storage?
(4 marks)
- consumables written in black stored at room temp /
- green in fridge /
- blue in freezer
- expiration date 3 months if room temp
advantages of snap tests?
(6 marks)
- result in 10 mins
- most accurate pet slide tests available
- SNAP pro / reader allows integration with PIMS
- no other equipment necessary
- used as screening test
- ease of use
disadvantages of snap tests?
(3 marks)
- labour intensive
- sensitivity / specificity variable (may need follow-up at lab)
- vaccination may interfere
equipment care?
(7 marks)
- instruments sensitive - careful mainaintance
- avoid spills that may damage elctrical equipment
- switch off + cover equipment when not in use
- manufacter operate instruction followed carefully
- staff trained before access to equipment
- set personal responsible for equipment maintainance - updates + calibrations run regularly
- internal + extrernal quality control tests regular to ensure accurate + valid results
examples of pre-analytical errors?
(3 marks)
- sample collection, preservation + storage
- identification errors - give incorrect reference ranges
- incorrect sample times - incorrect results
examples of analytical errors?
(6 marks)
- operator error
- improper instrument calibration
- errors in pipetting e.g. air bubbles
- use of outdated, contaminated / improperly stored reagents
- inadequate time for reagents / slides to reach room temp after removal from fridge / freezer prior to use
- drug interference - should be obtained prior to meds
