Point of Care Flashcards
What tube type is used for blood gas analysers
Calcium balanced dried heparin monovette tube
What is the principle used by the blood gas analyser to measure pCO2, pH and electrolytes
Potentiometric
What is potentiometry?
A pair of electrodes are placed in the sample solution
The potential between two electrodes is measured using a high-impedance voltmeter
Uses ion selective electrodes
Measure of the voltage
What is amperometry
A form of measurement used on the blood gas analyser
Measures current generated by enzymatic or bioaffinity reaction at the electrode surface, at a constant working potential with respect to the reference electrode
E.g. measuring glucose
It measures the current - direction + speed
Difference between potentiometry and amperometry
Amperometry measures the amperes/current between the two electrodes in ISE
Potentiometry measures the voltage (power) between the two electrodes in ISE
What are the advantages of POCT
Enables a result to be obtained rapidly and the patients trestment regime adjusted in a timely manner
What factors might affect blood gas samples
Exposure to air
Temperature of specimen
What is the principle of the hemocue
Consists of disposable microcuvettes containing the reagents and a photometer
RBCs are haemolysed to release Hb
What does the ROTEM Sigma do
Detects clot formation, firmness and ultimately lysis/disolution of the clot
How does the ROTEM SIGMA work
Based on a fixed cylindrical cup and a permanently oscillating vertical axis
If no clotting takes place the movement is not obstructed
When a clot is formed and attaches itself between the pin and cup surfaces, the movement is obstructed
The firmer the clot the more the rotational axis is reduced
Reaction curve called a temogram is produced
