Bead count rate (BCR) monitoring successfully identifies pipetting error during
single platform enumeration. Enumeration beads are a stable constant in each
patient’s sample and if these can be multitasked to monitor overall flow cytometer
operation in a model of continuous quality control (CQC), they could reveal
further details of flow cytometer operation and fulfill more quality assurance
functions than identify pipetting error alone.
Methods
The CQC model used manufacturer recommended quality control procedures
daily. In addition, methods were developed to monitor flow cytometer fluidics and
electronics as well as sample preparation to standardise and extended quality
monitoring. Sample-to-sample CQC included monitoring BCR, selected time,
optical and fluorescence histograms as well as FPCV and MCN. This model also
incorporated diligent monitoring of BCR patterns to detect instrument
malfunctions. Post standardisation and implementation of the CQC model, an
extended EQA exercise assessed bias between standardised CD4 counting
methods and determined a ‘near true’ CD4 count to use as a calibrator.
Conclusion
The proposed CQC model standardised overall flow cytometer and automated
sample preparation systems and, established imprecision reference intervals for
each aspect of testing (fluidics <3%, sample preparation 2-4% and protocol and
electronics <2%). Further BCR pattern recognition was used to identify
instrument malfunctions in real-time and, longitudinally for pro-actively identifying
imminent breakdowns. CD4 counts were calibrated to consensus mean ‘near
true’ counts on two flow cytometers in the Reference Laboratory.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/13858 |
| Date | 18 February 2014 |
| Creators | Lawrie, Denise |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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