Abbott i-STAT 1 System Manual - Modes For The I-Stat
Abbott Point of Care Inc. • Abbott Park, IL 60064 • USA
Art: 715617-00D
Rev. Date: 06/11/08
Technical BulleTin
i-STAT
®
ACT Test Result Calibration Options:
PREWARMED vs. NON-PREWARMED Result Calibration
Modes for the i-STAT
®
1 Analyzer
BACKGROUND
The Activated Clotting Time (ACT) test has been in existence for over 30 years. It is the most popular test
for measuring the effect of heparin administered during an interventional procedure. By placing an activator
in the test chamber, the blood sample is “activated” to promote clotting. When heparin is present in the
sample, the clotting is delayed in proportion to the amount of “anticlotting” effect of the heparin.
Since its inception, numerous changes have taken place to ACT tests, including increased automation
and decreased sample volume. Today, there are many new, fully automated, low blood volume ACT tests
on the market, in addition to the older, macro blood volume, semi-automated tube-based systems (i.e.,
Hemochron
®
, Actalyke™). The micro sample ACT systems typically employ test cartridges or cards (instead
of tubes), and all have incorporated an automatic test cycle prewarming step that brings the ACT testing
chamber to 37°C prior to initiating the clotting reaction. As blood clotting is an enzymatic process, the
temperature at which the clotting cycle takes place has a marked impact on the rate at which the blood clot
forms. The ACT tests that incorporate a prewarming step allow the entire clotting reaction to take place
at 37°C. ACT tests that do not use a prewarming step are subject to a delay before the blood specimen
reaches (and stabilizes at) 37° degrees; the actual time needed to reach 37°C is dependant on the starting
temperature of the sample test tube. For example, a 30°C blood sample placed into a (non-prewarmed)
25°C ACT tube will take a few minutes before the test environment (blood, reagent, tube) stabilizes at 37°C.
The result of this thermal delay is an increase in the reported ACT clot time that will depend on sample tube
temperature.
ACT Instruments WITH an automatic
prewarming step
ACT Instruments WITHOUT an
automatic prewarming step
Medtronic
®
ACTII (plus)
Hemochron 801/401/8000/Response
Medtronic HMS (plus)
Actalyke
Bayer/TAS HMT
Roche ACT
Hemochron
®
Jr. (Signature/PCL)
i-STAT