Testing blood thickness could be key to combatting Covid-19

Chloe Kent 5 August 2020 (Last Updated August 5th, 2020 16:37)

A clinical blood viscosity diagnostic device, manufactured by a small company in Wales, is becoming an important tool for understanding how Covid-19 affects the body. Verdict Medial Devices investigates.

Testing blood thickness could be key to combatting Covid-19
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Benson Viscometers, based in Haverfordwest, Wales is the market leader in the UK and Ireland for clinical viscometers, instruments which can be used to measure the viscosity, or thickness, of blood. They work by drawing a small sample of plasma through a narrow capillary using a constant pressure and measuring the time taken for the sample to move a known distance.

At Addenbrookes Hospital in the UK, the company’s equipment is now being used to explore how best to understand and treat Covid-19. Clinicians have been carrying out viscometry tests on all Covid-19 patients to establish a link between blood viscosity and the viral disease, and explore how it may relate to disease severity and recovery. Health Services Laboratories in London is also on the case, using blood viscosity tests to monitor inflammatory status in certain groups of Covid-19 patients, exploring the possibility that high inflammatory markers might indicate the need for alternative strategies for stroke prevention in these patients.

Anecdotal reports about the thick blood of Covid-19 patients have poured in from clinicians around the world, and a study recently published in The Lancet has now found that critically ill Covid-19 patients in Emory Healthcare’s intensive care unit (ICU) had plasma viscosity levels above the normal range. The sickest Emory patients had the highest plasma viscosity levels, more than double what is normal in some cases, and were more likely to have blood clots.

Raised levels of fibrinogen

“Plasma is a clear, pale yellow liquid portion of the blood, that remains after the red cells, white cells and other cellular components are removed. It is the single largest component of human blood and makes up about 55% of its volume. Its contents are water, salt, enzymes, antibodies and other proteins, notably fibrinogen,” says Benson Viscometers founder and managing director Bernie Benson.

The Emory patients all had extremely high levels of fibrinogen, a big sticky protein, which increases with inflammation and is one of the key building blocks of a blood clot. Because of this, blood thinning medications did little for the patients, as they work to slow the mechanisms by which coagulation occurs rather than reduce the viscosity of the blood itself. Once the level of fibrinogens increases, it’s hard to turn back.

Benson says: “The plasma viscosity is raised due to the acute phase response, part of the body’s early defence and part of the innate immune system. The immune system is automatically hardwired to respond to conditions within the body, and these conditions are triggered by different stimuli, including infection, tissue injury, trauma and surgery. A raised plasma viscometry looks to be an excellent way to monitor Covid-19.”

Continuous patient monitoring

If plasma viscosity of Covid-19 patients is regularly tested, doctors will be able to see when levels are rising ahead of time and administer anti-clotting medication earlier in a patient’s treatment, potentially preventing further deterioration.

Using a viscometer is one of the best ways of assessing this metric. Plasma viscometry tests yield exceptionally reliable results when assessing the thickness of the blood. Viscometry is also cost-effective compared to other biochemical methods of assessing blood viscosity, can be performed with the same EDTA tubes used to take a full blood count and is quick and easy to perform.

Benson says: “We are foreseeing a greater demand for our equipment because it serves the purpose of monitoring the progress of the Covid-19 condition in a quick, efficient manner. This way clinicians can monitor the progress of the condition in the patient and give the very best treatment in advance or at the most appropriate time, rather than waiting for the patient to get into a worse condition.”

Demand for viscosity testing has risen so much as a result of the Covid-19 pandemic that Benson Viscometers is now looking into taking on additional development premises in Haverfordwest. The company’s equipment has also started to be used in US hospitals.

“We are very excited because the market opportunity in America is immense, and where American doctors, physicians and scientists go, we’re sure the rest of the world will follow. We have great excitement for the future,” says Benson.