diagnostic equipment (done) Flashcards
diagnostic lab equipment?
(12 marks)
- compound light microscope
- centrifudge / stat spin
- micro-haemocrit spin
- biochemistry analyser
- haematology analyser
- blood gas +/ electolyte machine
- snappro analyser
- point of care test kits
- refractometer
- hawksley reader / PCV reader
- incubator
- fridge
what is a compound light microscope?
(2 marks)
essential piece of lab equipment that commonly used for disease diagnosis
uses lenses and light to magnify the image to allow visualisation and identification.
info of compound microscopes?
(2 marks)
- can have one (monocular) or two (binocular) eye pieces
- commonly 3-4 objective lenses allowing varying degrees of image magnification
types and use of objective lenses?
(12 marks)
- x4 - main scanning lens. allows detailed visualisation of macroscopic objects + overall scanning of the slide
- x10 - low power objective. used for locating area of interest
- x40 - high power. dry lens used for more detailed focusing
- x100 - oil immersion. powerful lens which uses refracted through an oil layer rather than through air
slide examination techniques?
(2 marks)
- battlement technique
- vernier scale
how is battlement technique carried out?
(slide examination technique)
(2 marks)
- slide examined systematically to ensure all of the slide is covered + to prevent double counting of cells.
- two fields up, two fields along and two fields down
how is vernier scale technique carried out?
(slide examination technique)
(2 marks)
- plate is divided into 10 divisions
- record co-ordinates of object using both X and Y readings
use of a centrifuge?
(2 marks)
- spins a substance at high speed using centrifugal force to seperate fluid portion (supernatant) from soild portion (sediment)
- electric motor rotates at high speed around a fixed axis applying perpendicular force to axis
what are the 2 types of centrifuge?
(2 marks)
- swining arm
- angled head
how does swinging arm centrifuge work?
(3 marks)
- movable specimen cups that are suspended vertically from arms
- as rotor increases cups swing out into horizontal position
- results in supernatant that is uniformly distributed therefore easy to remove
limitation of arm swinging centrifuge?
(1 mark)
heat build up at high speeds - damage sample
what is the optimum temperature control for fluid seperation?
(1 mark)
4 degrees C
info of angled head centrifuge?
(tube position, + and -)
(3 marks)
- tubes positioned 25-40 degree angle
- supernatant collects at an angle so more difficult collection
- higher speeds can be achieved
info of microhaematocrit centrifuge?
(5 marks)
- flat horizontal surface with slots for capillary tubes
- rubber cushions are positioned at the outer edge of plate to prevent breakage
- safety plate screwed down on top of tubes to firmly hold in place
- plate can often be removed and replaced with standard horizontal buckets for multi-use
- specifically used for separating blood cells from plasma e.g. PCV
centrifuge health and safety?
(7 marks)
- placed on flat, sturdy surface
- balance centrifuge - place substance opposite with similar density
- never lift lid when in use
- ensure safety lid secure before spinning
- clean away spillages and breaks immediately, using correct protocols
- service regularly to ensure quality control
- clean and disinfect at end of each day use
use of incubators?
(1 mark)
incubation of sample for bacterial culture
info of incubator?
(7 marks)
- double walled metal container with insulation material (e.g. fibreglass) between
- double insulated doors: inner glass and outer metal allow contents of incubator to be veiwed without heat loss from cabinet
- electrical heating element inside cabinet (25-100 degree C, usually maintained at 37)
- wire shelves allow air circulation
- thermostat, and internal thermometer
- plates placed lid side down on wire shelves to reduce condensation on agar surface
- require annual servicing and daily cleaning
use of bunsen burner?
(3 marks)
- during prep of agar plate for bacterial culture (loop sterilisation)
- fixing bacteria on microscope slide prior to staining
- heating liquid in glass beaker
bunsen burner health and safety?
(7 marks)
- long hair tied up
- wear goggles at all times
- ensure ventilation hole closed prior to lighting
- always turn flame to orange safety when not in use by closing air hole
- blue flames only used for direct heating
- location of emergancy switch noted to turn gas supply off if needed
- servied annually
define refraction
(1 mark)
= change of velocity and resulting bending of light as it passes from one medium to another with different optical density (e.g. air into urine).
what is a refractometer?
(1 mark)
cylindrical instrument with prism and calibration scale
use of a refractometer?
(2 marks)
- measures SG of urine and other fluids
- measures protein conc of plasma and other fluids
info of refractometer?
(how to use, info and advantages)
(4 marks)
- MUST be calibrated before every use using distilled water
- reading gtaken on granulated SG scale at blue/white line interface
- units are temperature compensated therefore temp fluctuations unlikly to affect results
- precise, accurate, durable, easy to use, cheap to buy and only small volume of sample required to achive result
advantages of glucometer?
(4 marks)
- fasts, reliable and accurate method of blood glucose level exam
- small drop sample required
- minimal trauma for patient
- allows regular + accurate blood glucose measurements
how to calibrate glucometer?
(2 marks)
- use control solution
- check ranges of calibration on vial match result machine reads.
how to use glucometer?
(4 marks)
- read test strip bottle as shows code that links monitor and reference ranges
- place test strip in monitor and check code match
- place monitor to small blep of blood until beep is heard
- number shown is glucose reading
what are commercial test kits?
(1 mark)
in house serology test kits
use of commercial test kits?
(1 mark)
test for infectious disease agent and antibodies, hormones and immunoglobulin levels
advantages of commercial test kits?
(2 marks)
reliable and easy to use
give immediate results
most common type of commerical test kits?
(2 marks)
- ELISA test which are microwell / membrane based
- immunomigration and agglutination tests also available
kits most commonly used in practice?
(11 marks)
- enzyme linked immunmosorbent assay test (ELISA)
SNAP tests: - 4Dx plus test
- heartworm RT test
- cPL test (canine pancreatitis lipase)
- giardia
- parvo
- lepto
- feline triple test
- FIV/FeLV combo test
- fPL
- feline pro BNP
what does ELISA stand for?
(1 mark)
Enzyme Linked Immunosorbent Assay
how do ELISA test kits work?
(4 marks)
- impregnated with appropriate antibodies for specific antigen, depending on disease being tested for
- antibodies within the test well bind to viral antigen present in sample
- dye is activated resulting in colour change within test well (indicate ++ result) - attaching fluorescent compound to its target antibody / antigen and observe reaction under UV light
use of cite, combi and snap tests?
(4 marks)
- detect presence of viral antibody / antigen
- high specificity + sensitivity associated with these tests reducing risk of inaccurate results
- direct ELISA employs antibodies to detect presence of particular antigen in sample
- indirect ELISA determine presence of particular antibody in specimen
why may false positives occur?
(2 marks)
- animals recently vaccinated with live virus - carry viral antibodies without carrying virus
- false FIV positives can occur in kittens as can have antibodies passed from infected mother
why may false negative occur?
(1 mark)
only recently exposed - incubation period can be few months in some cases
positive test results for FeLV should be supported with what?
(1 mark)
immunofluorescent antibody assay
what do other commercial test kits test for?
(4 marks)
- hormone levels
- allergic conditions
- blood clotting disorders
- urinalysis
what is urine dipstick?
(and what is it used for?)
(2 marks)
urinalysis reagent strips that test urine biochemistry
urine dipstick errors?
(5 marks)
- inaccurate results if test strips pass expiry date / patient recieved drug therapy
- designed to measure human urine parameters
- sample not fresh - sample contamination and breakdown of chemistry within
- exposure to sunlight will oxidize bilirubin and urobilinogen - false low readings
- erroneous reading for blood and gluocse if disinfectants present in sample container
