Automation Flashcards
What are the four (4) principles of automation in hematology?
- Electrical impedance principle
- Radiofrequency conductivity
- Flow cytometry
- Analysis of instrumental data output
What is the electrical impedance principle also called?
Coulter principle
State the principle behind electrical impedance.
It is the changes in electrical impedance (resistance)
produced by a particle as it passes through a
small aperture.
What is electrical impedance is also referred to as?
resistance
Increases or Decreases?
As a diluted suspension of cells is drawn through
the aperture, the passage of each individual cell
momentarily \_\_\_\_\_\_\_ the impedance (resistance) of the electrical path between two submerged electrodes that are located on each side of the aperture
increases
what is the relationship between the # of pulses generated during a specific period to the # of particles?
proportional
True or False
1 resistance = 1 pulse
True
True or False
1 resistance = 1 pulse = 1 cell
True
In electrical impedance, what indicates the cell’s volume?
a. resistance
b. interruption of current
c. amplitude or magnitude of electrical pulse
d. angle
c. amplitude or magnitude of electrical pulse
What device displays the pulses that are generated by the cells as they interrupt the current?
Oscilloscope
True or False
When using an oscilloscope, the height of each pulse corresponds the volume of the cell.
True
It depicts the volume distribution of the cellscounted.
Volume Distribution Histogram
True or False
In a histogram, the size of the voltage pulse is equal to the size/volume of the cells.
True
What is the range of the volume threshold for RBC?
24-36 fL
What is the range of the volume threshold for WBC?
30-35 fL
What is the range of the volume threshold for platelets
2-20 fL
Factors that affect volume measurement
- Aperture diameter
- Protein buildup
- Coincident passage loss
- Orientation of the cell in the center of their aperture
- Deformability of the RBC
- Recirculation of cells back into the sensing zone
Mechanism of hydrodynamic focusing
The sample stream is surrounded by a sheath fluid
as it passes through the central axis of the aperture
In hydrodynamic focusing, what is the purpose of the sheath fluid?
It ensures that the cells flow in a single line
In hydrodynamic focusing, explain the purpose of laminar flow to the central sample stream.
It allows the central sample stream to narrow sufficiently to separate and align the cells into a single file for it to pass through the sensing zone
Formula for hematocrit determination
HCT = (RBC x MCV) / 10
Principle of hematocrit determination
Cumulative RBC pulse height detection
Identify if the interference/s causes spurious increase or decrease
unlysed red cells and platelet clumping
WBC
spurious increase
Identify if the interference/s causes spurious increase or decrease
monoclonal proteins
WBC
spurious increase
Identify if the interference/s causes spurious increase or decrease
cryoglobulin, cryofibrinogen, and heparin
WBC
spurious increase
Identify if the interference/s causes spurious increase or decrease
Nucleated red cells
WBC
spurious increase
Identify if the interference/s causes spurious increase or decrease
clotting
WBC
spurious decrease
Identify if the interference/s causes spurious increase or decrease
smudge cells
WBC
spurious decrease
Identify if the interference/s causes spurious increase or decrease
uremia plus immunosuppressants
WBC
spurious decrease
Causes of spurious increase in RBC count
Interference / potential causes of erroneous results in with ACC
ACC= automated cell counters
- cryoglobulin
- cryofibrinogen
- giant platelets
- High WBC (>50 000/mL)
Causes of spurious decrease in RBC count
Interference / potential causes of erroneous results in with ACC
ACC= automated cell counters
- autoagglutination
- clotting
- hemolysis (in vitro)
- microcytic red cells
Causes of spurious increase in platelet count
Interference / potential causes of erroneous results in with ACC
ACC= automated cell counters
- cryoglobulin
- cryofibrinogen
- hemolysis (in vitro and in vivo)
- microcytic red cells
- red cell inclusions
- white cell fragments
Causes of spurious decrease in platelet count
Interference / potential causes of erroneous results in with ACC
ACC= automated cell counters
- clotting
- giant platelets
- heparin
- platelet clumping
- platelet satellitosis
This principle of automation is determined using a high-frequency electromagnetic probe that provides information on the cells’ internal constituents.
Radiofrequency conductivity
It is the resistance to a high voltage electromagnetic current flowing between both electrodes simultaneously
Radiofrequency (RF) resistance
True or False
In radiofrequency conductivity, the total volume of the cell is proportional to the change in direct current (DC), the cell interior density is proportional to pulse height or change in the RF signal.
True
What principle of automation?
simultaneous measurement of multiple physical characteristics of a single cell as the cell flows in a suspension through a measuring device.
Flow cytometry
True or false
In flow cytometry, as the cells pass through the sensing zone and interrupt the beam, light is scattered in all directions.
True
Describe the relationship
In flow cytometry, the # of pulses generated is ________ to the # of cells passing through the sensing zone in a specific period.
directly proportional
what medium makes the results obtained from flow cytometry superior to impedance because it is more accurate and specific?
Immunoflourescence dye
What is the corresponding mechanism of ‘threshold’ (impedance) in flow cytometry?
Gating
what is being identified with the given angles of light scatter
0° forward angle
cell size
what is being identified with the given angles of light scatter
10° light scatter
Cell structure & complexity
what is being identified with the given angles of light scatter
90° light scatter
Lobularity (granulocyte)
what is being identified with the given angles of light scatter
Depolarized 90°
Resolves Eosinophils
because of their crystalline
granularity
It is a numerical or graphical boundary that
can be used to define the characteristics of
particles to include for further analysis
Gate
Explain the gating process
It is the process of selecting an area in a scattergram during the flow experiment to be able to decide what will you analyze.
In quadrants, we can separate your cells unto four principal populations (Q1, Q2, Q3, Q4), describe the expression of the cells in each quadrant.
Q1- cells that are strongly expressing positive color (single positive; either red or blue)
Q2 - double positive; it has blue & red
Q3- double negative (neither blue & neither red)
Q4- single positive same as Q1
What does VCS stand for?
Volume, conductivity, and scatter
Identify which factor in VCS technology is described
using direct current impedance, the
volume of each cell is measured
volume
Identify which factor in VCS technology is described
radiofrequency penetrates the cell which generates the data points of cell size and cell internal structure.
Conductivity
Identify which factor in VCS technology is described
mid-angle scatter detected by a beam of laser light which generates data about cellular granularity and cell surface structure.
scatter
It is a single channel that analyzes approximately 8,000 cells in a near-native condition.
VCS technology
In VCS technology, approximately how many cells are analyzed in a near-native condition
approximately 8,000 cells
In flow cytometry, what is used to interpret results instead of a histogram?
A scattergram
what is the shape and distribution of a histogram
Symmetrical bell-shaped or Gaussian
distribution
In a histogram, how would you interpret a flattened curve?
Increase in standard deviation
In an erythrocyte histogram, what is the interpretation if there is another population in the right bottom threshold?
The presence of macrocytic RBCs
In an erythrocyte histogram, what is the interpretation if there is another population in the left bottom threshold?
The presence of microcytic RBCs
What does MPV stand for?
Mean platelet volume
An incease in MPV can denote the presence of __________
giant platelets
Disorders associated with a decreased MPV
- Aplastic anemia
- Megaloblastic anemia
- Wiskott-Aldrich sydrome
Decreased or increased MPV
After chemotherapy
decreased mpv
Disorders associated with an increased MPV
- Idiopathic thrombocytopenic purpura
- sickle cell anemia
Decreased or increased MPV
After splenectomy
increased mpv
Abnormal Curve in front of lower discriminator
a. AG Flag
b. WU Flag
c. UD Flag
a. AG Flag
Deviation on upper discriminator curve
a. AG Flag
b. WU Flag
c. PU Flag
b. WU Flag
This refers to the level at which the machine can
measure the particular analyte
Linearity
This flag appears when UD exceeds the preset height by > 40%
a. AG Flag
b. WU Flag
c. UD Flag
UD Flag (PU Flag)
What causes platelet clumps (2)
- Clotted sample
- EDTA-incompatibility
What are the possible causes of an abnormal height at the upper discriminator (UD/PU Flag) in a platelet histogram? (3)
- Platelet clumps
- Giant platelets
- Micro RBCs
What are included in an electrical impedance report? (4)
- CBC results
- Scattergram
- Histogram
- Flagging
Intrumental error (negative or positive)
excessive lysing of RBC
negative
Intrumental error (negative or positive)
bubbles
positive
Intrumental error (negative or positive)
extraneous electrical pulses
positive
Intrumental error (negative or positive)
aperture plugs
positive
what is the most common intrumental error that causes positive results
a.excessive lysing of RBC
b. bubbles
c. aperture plugs
d. extraneous electrical pulses
c. aperture plugs
what casues aperture plugs
sucking of clotted samples
what causes extraneous electrical pulses?
improper grounding
