ITC Hemochron Signature+ Whole Blood Microcoagulation System - Manual (Page 3)

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The HEMOCHRON Jr. PT test measures the extrinsic coagulation pathway and is sensitive to coagulation
factors VII, X, V, II, and fibrinogen. PT results may be abnormal in patients with liver disease or Vitamin K
deficiency. The test is widely used to monitor oral anticoagulant therapy. The PT test is a unitized test
system utilizing a highly sensitive thromboplastin for improved specificity and sensitivity.
The HEMOCHRON Jr. PT Citrate test performs the same measurement as the PT test, using a citrated whole
blood sample.
PRINCIPLES OF OPERATION
The HEMOCHRON Jr. Signature+ Whole Blood Microcoagulation System provides many features for ease of
use and reliability, including a patented clot detection system, a data storage module, interfaces for a
laboratory computer and/or printer, and a streamlined user-interface panel.
The system measures whole blood clotting times using HEMOCHRON Jr. disposable single-use cuvettes.
Each cuvette contains all of the reagents necessary for a specified test.
The operator inserts a cuvette for the test into the instrument and then enters information about the
sample (if desired). After the cuvette has warmed to 37 °C ±1.0 °C, the instrument beeps, signaling the
operator that a blood sample can be added to the cuvette and the test started.
The operator then places a drop of blood in the sample well of the cuvette and presses the START key. The
instrument measures the required volume of blood and automatically moves it into the cuvette test
channel, where it is mixed with reagents. The remainder of the blood sample, not needed for testing, is
automatically drawn out of the sample well and into an enclosed waste channel on the cuvette.
After mixing with the reagent, the sample is moved back and forth at a predetermined rate within the test
channel and monitored for clot formation. The test channel is maintained at 37 °C ±1.0 °C during the test.
The rate of movement of the sample is monitored by a series of LED optical detectors that are aligned with
the test channel. When the blood clots, the flow of the blood sample within the test channel is impeded,
reducing its rate of flow between the optical detectors.
This reduction in flow below a predetermined value signals to the instrument that a clot has formed. The
instrument also emits an audible beep when clot formation occurs, indicating the end of the test. An
internal timer measures the elapsed time between the start of the test and the clot formation. During the
test, the whole blood clotting time (in seconds) is displayed.
APTT and APTT Citrate results are displayed as plasma equivalent (PE) values, and PT and PT Citrate results
are displayed as the International Normalized Ratios (INR) and PE values. ACT+ and ACT-LR results are
displayed as Celite ACT equivalent time.
The results will remain on the display while the cuvette remains in the instrument.
The result can be automatically printed along with the time and date the test was run, the Patient ID,
Operator ID, and other information, if entered. The result is also saved in an internal database. Up to 400
patient test results and 400 quality control test results can be stored on the instrument for later printing or
downloading.
Individual HEMOCHRON Jr. Signature+ instruments can be customized so that designated quality control
tests must be performed whenever a specified period of time has elapsed. The instruments can also be
configured so that only authorized operators can operate the system and/or operators cannot perform
certain functions such as deleting test results from the instrument database. These and other configuration
options are entered using HEMOCHRON Configuration Manager Software on a personal computer.