HAEMATOLOGY
platelet function, the presence of heparin or reduced enzymatic clotting factors. Figure 3 shows the excellent correlation between the Quantra’s PCS parameter and the laboratory’s platelet count, while Figure 4 shows a good correlation of the Quantra CT with the APTT, particularly post-surgery. The weak correlation observed in the baseline samples can be explained by the narrow spread of clot time values within the normal range.
Guidance from NICE
These findings are in line with new guidance from the National Institute for Health and Care Excellence (NICE),3
which makes a
number of recommendations to help reduce variation in practice, increase patient safety, and prevent wasteful and unnecessary use of resources.
Clinicians have to make very fast decisions about how to treat significant bleeding in patients at a time of acute perioperative situations – and if the source of bleeding cannot be determined, they will order more blood products and transfuse their patients. In cardiac surgery, post-surgical bleeding occurs in up to 20% of cases. Despite their relative safety, blood transfusions carry potential risks. In 2014, 3668 reports of adverse events were submitted to the Serious Hazards of Transfusion (SHOT) scheme. Of these, almost 80% related to errors. These ranged from the choice of blood component not always being based on clinical findings and laboratory test values, patients not being monitored for adverse effects, some patients being transfused unnecessarily, while others received the wrong blood components.
Quantra technology
Many of these concerns can be addressed by the Quantra POC system and technology,
Parameters
CTH vs. APTT CT vs. APTT
Samples (n) All (30)
which can be introduced easily into a hospital’s existing clinical workflow for use across numerous departments. It delivers the same standardised, automated results. Already available in Europe, Quantra and its first QPlus cartridge have now received de novo approval by the US Food and Drug Administration (FDA) for use in the clinical laboratory.
Quantra measures the change in viscoelastic properties of a patient’s blood during coagulation and delivers actionable results within 15 minutes – from a closed POC cartridge. Point-of-care viscoelastic testing4–6
l Time between diagnostics and haemostatic intervention.
has already been demonstrated to improve patient outcomes by reducing: l Unnecessary blood product usage l Length of stay in hospital l Costs associated with blood product usage l Complications associated with bleeding or transfusions
Pearson r-value 0.51
Pre and Post (20) 0.65 Pre (10) Post (10)
0.36 0.87
APTT >50 sec CT >170 sec PRE
160 140 120 100 80 60 40 20 0
0 5
y=2.3113x + 80.976 r2
=0.1273
200 180 160 140 120 100 80 60 40 20 0
10 15 APTT (sec) Figure 4. Clot times: correlation with APTT. NOVEMBER 2019
WWW.CLINICALSERVICESJOURNAL.COM I 89 20 25 30 0 10 20 30 APTT (sec)
200 180 160 140 120 100 80 60 40 20 0
0 10 20 30 APTT (sec) POST
What is different about Quantra’s approach to testing is that it is able to measure evolving clot stiffness without touching or disrupting the clot. It does this by means of a unique, proprietary ultrasound technology, Sonic Estimation of Elasticity via Resonance (SEER), or sonorheometry. The use of sonorheometry makes it possible to eliminate potential interferences that might occur in the pressured environment of, for example, the operating theatre. An ultrasound pulse goes into the blood sample to generate a shear wave which makes the sample resonate. As the clot vibrates, ultrasound ‘tracking’ pulses come into play to estimate sample motion. It then calculates the shear modulus of the sample at a specific point by analysing sample motion patterns (Fig 5).
PRE and POST
y=1.3811x + 97.543 r2
=0.4287
40
50
60
y=1.8262x + 77.942 r2
=0.76 40 50 60
CT (sec)
©xixinxing -
stock.adobe.com
CT (sec) CT (sec)
t
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