ITC Hemochron Response Whole Blood Coagulation System - Manual (Page 2)

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INTENDED USE
The HEMOCHRON ® RxDx ® Analysis Module is a supplementary module for the HEMOCHRON Response
Whole Blood Coagulation System that provides automated calculations for use during cardiopulmonary
bypass surgery and cardiac catheterization procedures.
These calculations are used to determine the doses of heparin to be administered before and during these
procedures, the dose of protamine needed to reverse the effects of heparin after the procedure is
completed, and the patient's clotting time and residual heparin level after protamine has been
administered.
The results that are obtained are saved to an internal database and can be printed or downloaded to a
personal computer.
Note: Refer to the HEMOCHRON Response Whole Blood Coagulation System Operator's Manual for the
intended use and instructions for the use of the HEMOCHRON Response Whole Blood Coagulation
System.
SUMMARY AND EXPLANATION
Heparin is used to maintain hemostasis during cardiac surgery and percutaneous coronary interventional
(PCI) procedures. However, its administration can pose significant risk to the patient. Since individual
patients can vary as much as twelve-fold in heparin sensitivity, overdosing heparin can result in dangerous
bleeding and underdosing heparin can lead to thrombosis. Therefore, monitoring heparin therapy is vital in
guarding against these undesirable side effects.
The doses of heparin to be administered before and during the procedure, the dose of protamine to
administer after the procedure, and the patient's clotting time and residual heparin level are determined by
running a series of clotting time tests. This series of tests for a patient is referred to as an RxDx case.
Note: In this manual, a case is the patient information and the series of test results that are
associated with a specific patient ID.
Prior to administration of heparin, an Activated Clotting Time (ACT) and Heparin Response Time (HRT) test
are run on the HEMOCHRON Response Whole Blood Coagulation System. These tests measure the patient's
baseline clotting time and determine how the patient will respond to heparin. The patient blood volume can
then be directly entered (if available) or calculated by the system based upon the patient's height, weight
and gender. The initial heparin dose (referred to as the bolus heparin dose) is then calculated by the
system. During this process, the case is in the heparin mode.
Once the patient has received heparin, additional ACT or High Dose Thrombin Time (HiTT) tests are run to
measure the coagulation status, determine the efficacy of heparin, and calculate additional heparin doses
that may be needed to maintain the target clotting time in the patient. The case is now in the additional
heparin mode.
After the cardiac surgery or cardiac angioplasty procedure is completed, the effects of administered heparin
can be reversed by administration of protamine. Like heparin, protamine must be administered in the
correct dose to prevent dangerous bleeding or thrombosis. For this reason, a Protamine Response Time
(PRT) test is performed, and the results of this test and the most recent ACT test are used to determine the
dose of protamine that is required. The case is now in the protamine mode.
Once the protamine has been administered, the patient's clotting time and residual heparin level are
measured, using an ACT and a Protamine Dose Assay - Orange (PDA-O) test to determine the post-
protamine clotting time and residual heparin level in the patient's blood. Dual Thrombin Time and Heparin
Neutralized Thrombin Time (TT/HNTT) tests can also be run after protamine administration to identify the
presence of heparin rebound or abnormal fibrinogen function.
Since Celite
®
(diatomaceous earth) is sensitive to the presence of serine protease inhibitors such as
aprotinin, it is recommended that kaolin test tubes are used instead of Celite test tubes when aprotinin is on
board.