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Flashcards in Electronic blood analysers Deck (13)
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Describe biochemistry analysers

Measure various biochemical substances within the blood e.g. glucose, total protein, blood urea nitrogen, creatinine etc.


Describe haematology analysers

Automatically determine total red and white blood cell counts, differential white blood counts, packed cell volume and platelets counts etc


Describe electrolyte analysers

Measure plasma electrolyte levels e.g. sodium, chloride, potassium, bicarbonate etc


Describe hormone analysers

Measure blood hormone levels. Commonly carried out at commercial laboratories but thyroxine and cortisol test kits are now available for diagnosis of hyperthyroidism, Cushing disease etc within vet lab


What are the advantages of automated blood analysers?

Accurate and easy to use

Rapid results for diagnosis of emergency cases

Test kits and reagents are easily obtained

Rapid results and minimal skill required to operate

Minimal degree of calibration and quality control required to ensure data is accurate.

Reliable and comprehensive technical and educational support available from equipment provider

Fast, reliable method of blood examination

Minimise technician error and time require to perform test


What are the disadvantages of automated blood analysers?

Numerous machines available each with a very different technique. Manufactures recommendations should be adhered to for each machine

Errors are common with haematology analysers due to the fragility of blood cells etc therefore supporting results with manual testing is often performed


What are the three types of automated haematology machines?

Quantitative Buffy Coat (QBC)

Impedance counter machines – More accurate

Laser Cell counters – More accurate


Describe Quantitative Buffy Coat Analyser's (QBC)


Total and differential white blood cell counts

Total red blood cell counts

Whole blood pipetted into microhaematocrit tube and float added

Sample spun in centrifuge to separate sample

Float separates buffy coat into constituent cell layers which are measured accordingly

Provides a granulocytes count and a combined mono and lymphocyte count in addition to red blood cell count


Describe impedance counter machines

Measures electrical resistance (impedance) as cells pass through a small aperture.

Each time a cell impedes a current a pulse is produced

Cell counts are determined by the number of pulses measured in a given volume of blood over a set period of time.

Size of pulse is proportional to size of cell

Produces large numbers of parameters and accompanying graphs. Some machines also give white cell differentials.


Describe laser cell counters

Laser detection systems is used to detect the reflectance, transmission and scattering of light by cells

Each cell is analysed by sophisticated software giving a numerical representation of the likely overall distribution of cell populations.

Provides larger numbers of parameters to illustrate cell distribution for red cells, white cells and platelets.

Produces white cell differentials using peroxidase staining, measurement of cell size and nuclear density.


Describe dry chemistry analysers

Reagents are provided on impregnated slides or pads

Serum sample is placed on to the pad and inserted into the machine

The machine determines the assay to be performed by reading a bar code on the slide

A colour change on the pad commonly occurs, the degree of colour change is proportionate to the solution concentration

The solution concentration is measured and generated as a digital reading or result

Most commonly used

Idexx Vet Test chemistry analyser

Catalyst Dx chemistry analyser


Describe wet chemistry analysers

Uses small wells of fluid instead of dry slides

Generates specific wavelengths

light is passed through a liquid sample

The intensity of the emergent light is measured, converted into electrical energy and displayed digitally

Multiple samples can be analysed at one time

Multiple chemical tests can be performed at one time

Improved accuracy of results

Specific maintenance requirements

Chemical reagents

Daily calibration

Cleaning etc


Describe automated electrolyte analysers

Electrolytes are generally measured by flame photometry in the large commercial laboratories (NaCl (orange) KCl (purple)

Smaller versions used in practice use ion-sensitive electrodes.

An electrical current is passed through a specific ion-sensitive electrode bathed in a chemical and the measurement of the charged particles is taken.

The commonest electrodes used in practice are sodium, potassium and chloride.

Sample quality, particularly haemolysis can strongly affect the results and should be taken into consideration