HAEMATOLOGY


Ultrasound transducer


Shear modulus


Blood sample


10 minutes after activation


Ultrasound pulse


6 minutes after activation 3 minutes after activation


Time Figure 5. The elements that comprise Sonic Estimation of Elasticity via Resonance (SEER), also known as sonorheometry. Shear modulus, expressed in hectoPascals


(hPa), is a measure of clot strength and more accurately reflects the force with which blood resists oscillation. It is therefore a more accurate indicator of the platelet contribution to the developing clot (PCS).


Amplitude is a measure of the strength or intensity of the shear wave. With some systems using viscoelastic testing, transformation of clot amplitude into clot elasticity is sometimes necessary; for instance, when calculating the platelet component of a clot. As sonorheometry is able to measure the clot’s shear modulus directly, there is no need for any post-processing transformation of clot amplitude.


As far back as 2014, a study published


in the BMJ flagged up evidence from randomised, controlled trials and meta-analyses that increasingly supported a far more restrictive use of blood transfusion, but noted the slow progress in changing protocols.7


Health economics study flags up transfusion costs


Further endorsement of the need to save unnecessary transfusion costs comes from a seven-year cost analysis study by the Home Economic Research Centre (HERC; Nuffield Department of Population Health), part-funded by NHS Blood and Transplant.8


Costing results were combined with costs of blood product wastage to calculate the cost per unit transfused, separately for different blood products. Applying estimates to the


blood components supplied to UK hospitals in 2015, it found that blood administration alone, excluding the cost of actual blood products, exceeded £120 million. From 2011 to 2017, a detailed micro- costing study was carried out to look at the cost relating to two key frequently occurring inputs into transfusion: laboratory inputs for grouping and issuing blood, and nursing inputs associated with blood samples for group and screens and administering blood. A total of 438 data collection forms were completed by 74 staff.


The cost of administering blood was £49 per unit for red blood cells (RBCs), £58 for platelets, £38 for fresh-frozen plasma (FFP) and £49 for cryoprecipitate (at 2014/15 prices). The costs of blood administration add substantially to the costs of the blood products themselves. For RBCs, costs are 40% higher when the costs of administration are added; the cost of administering FFP exceeds the cost of the blood product itself.


Cardiac care diagnostic decisions


The comparative study instigated at the Royal Wolverhampton NHS Trust, in collaboration with Stago UK, puts the clinical laboratory at the heart of NHS diagnostic decisions in the cardiac care setting. It also shows how well POC systems can fit into the existing workflow – supporting clinicians in deciding on the appropriate use of blood products.


The HERC study shows the financial implications of unnecessary blood transfusions. With the use of a pioneering


Stago technical presentation


Key findings were featured in Stago’s technical presentation on the Quantra point-of-care technology ‘for guided blood transfusion in cardiac surgery’ at this year’s IBMS Congress (Monday 23 September at 1.30 pm). The Quantra is able to measure kinetic changes as the sample clots. The presentation outlined its potential to differentiate between multiple causes of coagulopathy and surgical bleeding – and so reduce unnecessary transfusions.


POC system like Quantra, complications would be reduced, while patient outcomes are improved, ensuring they receive faster and more appropriate treatment plans. CSJ


References


1 Ogawa S, Szlam F, Bolliger D, Nishimura T, Chen EP, Tanaka KA. The impact of hematocrit on fibrin clot formation assessed by rotational thromboelastometry. Anesth Analg 2012; 115 (1): 16–21.


2 Solomon C, Rahe-Meyer N, Schöchl H, Ranucci M, Görlinger K. Effect of haematocrit on fibrin-based clot firmness in the FIBTEM test. Blood Transfus 2013; 11 (3): 412–8.


3 Weber CF, Görlinger K, Meininger D et al. Point-of- care testing: a prospective, randomized clinical trial of efficacy in coagulopathic cardiac surgery patients. Anesthesiology 2012; 117 (3): 531–47.


4 National Institute for Health and Care Excellence. Blood Transfusion. NICE guideline NG24. London: NICE, 2015.


5 Pearse BL, Smith I, Faulke D et al. Protocol guided bleeding management improves cardiac surgery patient outcomes. Vox Sang 2015; 109 (3): 267–79.


6 Haas T, Spielmann N, Mauch J, Speer O, Schmugge M, Weiss M. Reproducibility of thrombelastometry: point-of-care versus hospital laboratory performance. Scand J Clin Lab Invest 2012; 72 (4): 313–7.


7 Goodnough LT, Murphy MF. Do liberal blood transfusions cause more harm than good? BMJ 2014; 349: g6897 (www.bmj.com/content/349/bmj.g6897).


8 Stokes EA, Wordsworth S, Staves J et al. Accurate costs of blood transfusion: a microcosting of administering blood products in the United Kingdom National Health Service. Transfusion 2018; 58 (4): 846–53 (www.herc.ox.ac.uk/ publications/813460).


90 I WWW.CLINICALSERVICESJOURNAL.COM NOVEMBER 2019


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