20-8 Art: 714382-00D Rev. Date: 02/20/06
measurement process which are the most likely to impact quality, including the
characteristics of the individual sensors and the operator’s actions.
i-STAT’s quality control regimen has four aspects, resting on the foundation
of a system design which reduces the opportunity for the type of error which
traditional quality control regimens are designed to detect:
1) A series of automated, on-line quality measurements that monitor the
sensors, fluidics and instrumentation each time a test is performed.
2) A series of automated, on-line procedural checks monitors the user
each time a test is performed.
3) Liquid materials are used to verify the performance of a batch of
cartridges when they are first received or when storage conditions are
in question.
4) Traditional quality control measurements verify the instrumentation
using an independent device, which simulates the characteristics of
the electrochemical sensors in a way which stresses the performance
characteristics of the instrumentation.
Similarities
to Traditional
Laboratory Quality
Control Regimen
Although the more significant aspects of i-STAT’s quality control regimen are
the quality checks automatically performed with each unit-use cartridge, many
principles of the quality control regimen are similar to traditional regimens.
Laboratory quality control methods are statistical. They assess the quality of
the measurement process by intermittently inserting pseudosamples (controls)
into the stream of samples being tested.
The approach implicitly assumes that the elements of the measuring
system persist from run to run so that the repeatability and accuracy of the
measurement of patient samples can be predicted by the repeatability and
accuracy of pseudosamples.
The i-STAT regimen uses an analogous approach to monitor the part of the
testing process which persists from run to run – the handheld analyzer or Blood
Analysis Module.
An Electronic Simulator, which mimics the electrical characteristics of the
signals produced by the sensors, is inserted into the handheld analyzer or Blood
Analysis Module on a daily basis. The Simulator produces signals consistent
with both very low and very high concentrations of each of the analytes. The
analyzer or module causes the Simulator to change the signals via a control
signal fed through the interconnect.
The software in the analyzer and module measures these signals as it would
measure signals from a cartridge. The software checks the measurements
against predetermined thresholds and indicates their acceptability to the user
via a PASS/FAIL message.
All analyzers that pass the Electronic Simulator test are equivalent. Therefore,
any representative number of analyzers that pass the simulator test may be used
for compliance with regulatory and accreditation quality assurance procedures.
These procedures include initial performance verification studies, calibration
verification, proficiency testing, and method comparison studies.
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