PATIENT TESTING - 6
VerifyNow System User Manual Page 55 14340.J
Percent Inhibition (%) is the percent change from baseline aggregation and is
calculated from the PRU result and the Base result. The Base result is an
independent measurement based on the rate and extent of platelet aggregation from
thrombin receptors, specifically the PAR-1 and PAR-4 receptors. The Base result
serves as an estimate of a patient’s baseline platelet function independent of P2Y12
receptor inhibition. The Base result is normalized to report units that are equivalent to
baseline PRU. Percent inhibition is calculated using the following formula:
% Inhibition = (Base – PRU) X 100
Base
This feature can be used without first obtaining a baseline sample prior to P2Y12
drug administration. In the example shown here, if the baseline result was 328 PRU
and the post-drug result was 164 PRU, this would calculate to 50% inhibition.
The result may be printed by pressing the Print key, if your instrument has an
attached printer. Press the Next key to return to the Main Menu. Press the
Retrieve key to retrieve past assay results. Refer to Chapter 7, Retrieving Test
Results for more information on stored results.
6.5.3 IIb/IIIa Assay Results
The IIb/IIIa assay reports patient results in Platelet Aggregation Units (PAU) with an
option to calculate Percent Inhibition (Figure 6-17). Platelet Aggregation Units (PAU)
are calculated as a function of the rate and extent of aggregation.
Figure 6-17 IIb/IIIa Assay Results
When a blood sample is drawn prior to administering the GP IIb/IIIa inhibitor, it can
serve as a baseline reading for determining percent inhibition in samples drawn
shortly after injecting the GP IIb/IIIa inhibitor (10 minutes). Percent inhibition is
calculated using the following formula:
% Inhibition = (pre-drug PAU – post-drug PAU) X 100
pre-drug PAU
Use the following procedure to calculate percent inhibition.
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