ITC ProTime Microcoagulation System - Manual (Page 5)

5
PRINCIPLES OF OPERATION
The ProTime Microcoagulation System measures the PT using fibrin clot formation and detection. The
ProTime cuvette is a self-contained, micro volume reaction cell constructed of precision-molded plastic.
There are two user options within the ProTime Microcoagulation System: the standard ProTime cuvette and
the ProTime3 cuvette. These cuvettes differ from each other in the amount of blood that needs to be
collected and tested.
The standard ProTime cuvette has five micro-channels, which contain the dried reagents required to
perform triplicate testing of the PT assay and two levels of controls. The ProTime3 cuvette has three
functional micro-channels. Two micro-channels perform the controls, and one micro-channel performs the
PT test. The standard ProTime uses the Tenderlett Plus device for performing the fingerstick, and it is
designed to hold 65 µL of blood (approximately 3 drops) needed to fill all five micro-channels. The
ProTime3 uses the Tenderlett Plus LV (low volume) device for performing the fingerstick, and it collects 27
µL of blood (approximately 1 large drop) needed to fill the three micro-channels of the ProTime3 cuvette.
The instrument draws the precise volume of blood into the micro-channels of each cuvette, which contain
thromboplastin and other reagents. An array of LEDs detects the motion of sample/reagent mixtures as they
move through a precision restriction in each channel. The blood is pumped back and forth until a clot
forms, obstructing the channel and slowing the flow of blood. The instrument detects the clot when the
blood movement decreases below a predetermined rate.
SAFETY FEATURES AND QUALITY CONTROL
Each ProTime and ProTime3 cuvette has two channels for performing the two levels of control which work
simultaneous with the channel(s) used for testing the PT assay. The built-in safety features of the
instrument and integral reagent controls work together to ensure that the instrument and reagent systems
are working properly and that the test procedure was performed correctly. Two levels of quality control are
performed with each and every test.
Calibration
The ProTime instrument and cuvettes are pre-calibrated. No additional calibration is required.
Reagents
ProTime cuvettes are pre-loaded with dried thromboplastin, stabilizers and buffers. The thromboplastin
has a high sensitivity, measured as an ISI near 1.0. Each cuvette performs the prothrombin time test and,
in addition, has one channel for a Level I control and one channel for a Level II control. The controls
consist of purified plasma-extracted coagulation factors and anticoagulants.