POINT-OF-CARE DIAGNOSTICS
Fig 2. qLabs FIB, a novel POC system for monitoring functional fibrinogen.
“But for patient
safety, it is important that any POC device can demonstrate that it correlates well to laboratory standards; and we have the evidence to show that qLabs FIB provides robust, consistent results comparable to laboratory-based Clauss fibrinogen assays. Further, it reports results in laboratory equivalent units of g/L, which removes any chance of clinical confusion and enables easy integration of qLabs FIB results within bleeding management protocols.”
Strong correlation to laboratory testing A poster presented at the International Society on Thrombosis and Haemostasis 2022 congress has demonstrated strong results correlation of qLabs FIB with Stago’s STA-Liquid Fib Clauss fibrinogen assay (r 2
[CV] for precision ≤7%).6
>0.92; coefficient of variation The system’s
algorithm calculates the fibrinogen concentration value in g/L, taking into account the simultaneously estimated haematocrit by the single electrode pair. Automatic haematocrit adjustment is within a 20–60% range.
The system detects the insertion of a qLabs FIB test strip and heats the strip to a preset operating temperature. When a drop of blood is added to the sample well, the blood flows through the test channels to the two reaction zones. Here the blood reacts with pre-coated reagent (thrombin) and begins to coagulate. Each reading zone contains a pair of electrodes to which a constant voltage is applied by the qLabs ElectroMeter. This detects the change of the current voltage in the test zone and determines the fibrinogen result based on the migration time. The coating on the dry reagent strips includes polybrene to inhibit heparin and abciximab to inhibit platelet aggregation. The strips are therefore insensitive to a platelet count (up to 800,000/µL) as well as heparin therapy (up to 2 IU/mL). The strips can be stored at room temperature for immediate use and have a shelf life of up to 24 months. The qLabs FIB system also includes lyophilised bi-
level quality control (QC) material; a touchscreen handheld rapid testing platform with the option of an eStation II docking system; and an inbuilt barcode scanner plus a communications port for printers and computer networks. It is extremely easy for non-laboratory staff to learn how to operate the system – and the hands-on time for running a test is only 40 seconds. This point is stressed in professional
guidance supplied to its members by the Institute of Biomedical Science, which makes it clear that the success of POCT, “depends crucially
on the effectiveness of any training for non-laboratory staff” likely to be asked to use the device.
Quality control and governance Point-of-care testing systems such as Stago’s qLabs FIB undoubtedly save clinical time, providing the rapid test results that enable effective patient blood management and treatment. In addition, they also facilitate service cost- effectiveness.
When aligned with current governance
standards, use of POCTs can lead to a safe, quality, and compliant-led service, a point highlighted recently in Pathology in Practice.7
An NHS trust is currently trialling
Stago’s qLabs FIB and integrating the POC test results into the hospital’s clinical information technology (IT) systems for safe patient test result transmission. This is being carried out in step with UK Accreditation Service (UKAS) ISO 15189: 2022 governance standards. The trial is facilitated because
qLabs FIB is supplied with its own data management solution (DMS) that can be interfaced to a laboratory information management system (LIMS), and enables remote management of the patient, QC data and audit trail.
The use of qLabs FIB ensures transfusion of the ‘right product at the right time’, which is particularly important in cases of PPH because i) haemostatic impairment, and in particular low plasma fibrinogen, has been shown to increase the risk of progression to severe PPH;8 ii) transfusion of inappropriate blood products during PPH has the potential to exacerbate bleeding;9
and iii) time delays
in transfusion of fibrinogen products has been shown to result in further increased blood loss.9
UK NEQAS confirms precision with laboratory tests A preliminary evaluation of Stago qLabs FIB has been carried out by UK NEQAS Blood Coagulation (UK NEQAS BC) to establish the feasibility of provision of EQA for this POCT device. Lyophilised samples (citrated plasma) were tested in duplicate on the qLabs FIB system and compared to the median value obtained from testing by over 88 laboratories using a range of reagents. See Tables 1 and 2 for the full results.
Results of six samples showed the average of the duplicate results versus the median result from the value when the sample was distributed in a UK NEQAS BC exercise. The mean values obtained were 2.67 g/L and 2.64 g/L for UK NEQAS BC and qLabs FIB, respectively, with a difference from the median of –0.2 g/L. Further testing was performed 10 times on two of the six samples to establish precision. Results showed good precision, with both samples showing coefficients of variance <5%. Overall, qLabs FIB gave good acceptance within its testing range of 1.0–4.0 g/L when compared with the Clauss fibrinogen assays used by testing
Drop of blood (15 µL)
Sample reaches the first pair of
thrombin-coated electrodes
Sample migrates
through both channels
Sample has
reached both electrodes
Result
processing Software
determines the haematocrit corrected fibrinogen result in g/L
Fig 3. The testing process using qLabs FIB.
WWW.PATHOLOGYINPRACTICE.COM JUNE 2023 36
Result displayed (1 - 10 min max)
The lower the fibrinogen level, the faster the time to result
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