Week 7 Flashcards
List 2 types of point of care whole blood COAGULATION assays
Thromboelastography (TEG) Rotational Thromboelastometry (ROTEM)
List 2 whole blood PLATELET FUNCTION assays
Multiplate
TEG6s
List the advantages of point of care coagulation tests
Fast turn-around
Whole blood (no need to centrifuge)
Real time visual display
Reduction in non-evidence-based transfusion
List the disadvantages of point of care coagulation tests
Artificial conditions
Training and competency of non haematological staff
Rigorous quality assurance standards
More expensive
Describe the principle of the ROTEM
There is a rotating axis, a formation of a clot leads to a change in the torque, computer develops a curve and numerical parameters.
EXTEM = the combination of what
MCF (max clot firmness) = sum of fibrinogen + platelets + F XIII activity
What is the principle of the TEG
Sample is vibrated with a multi tone frequency, movement of the meniscus is monitored
What does ESR stand for?
Erythrocyte Sedimentation Rate
ESR measures the rate of what?
Measures rate of fall of Red Blood Cells
ESR is Influenced by _______charged plasma protein levels and ________ charged Erythrocytes
positive, negative - they repel eachother
A High retic count =
high rate of release of RBC from marrow
Reticulocyte is the last immature stage in
erythropoiesis
Do babies have a higher retic count?
yes especially at birth
What are reticulocytes? What are you seeing in on a blood film?
Remnants of cell production in cytoplasm
• RNA, organelles (mitochondria, ribosomes)
Describe the principle behind Electrical impedance For WBCC, RBCC & Platelet counts.
Particles are drawn through a small aperture with a DC current, each particle = a count, displacement of volume = size
Degree of light scatter is proportional to particle ______
size
With the beckman coulter instrument what is measured directly and what is calculated/derived?
Directly: RBC, WBC, & Hb
Calc/Deriv: Hct, MCH, MCHC, RDW
MCV = average volume from size distribution data
What are the advantages in automation in FBC
- Speed / throughput
- Reproducibility (precision)
- On-line to laboratory information system
List some factors to consider when selecting
a haematology analyser
- Range of tests
- Time per analysis
- Automation
- Reagent supply
- Sample size and microsampling
- Accuracy, precision, and linearity
- Maintenance, calibration, and QC
- Results analysis and storage
- Footprint
List 3 Pre-Analytical limitations and interferences that can occur
Collection - errors and artifacts
Age - deterioration
Transport - too hot, too cold
List some Analytical limitations and interferences that can occur
- Very high cell counts (linearity)
- Lipaemia
- Nucleated red blood cells
- QC out of range
- Operator error (manual or automated)
Reference range = interval within what percentage of population falls
95%
List 2 Advantages of point of care testing units
- Rapid results
* Portability – ambulance, helicopter, operating theatre
List some shortcomings of point of care testing units (4)
- Range of tests (usually limited)
- Operator variability
- Connectivity, capture of results
- Cost
What are some factors that influence ESR results.
positively charged plasma proteins
negatively charged RBCs
Rouleaux would cause a raised ESR
