High plasma viscosity seen in critically ill COVID-19 patients

Until you find causation I'm going to be demanding my doctor give me tPA immediately. Would an autopsy be able to determine viscosity because the autopsy results from the lungs mentioned thrombi all over the place?

High plasma viscosity seen in critically ill COVID-19 patients

Abnormally high plasma viscosity could be contributing to the thrombotic complications seen in many COVID-19 patients, a new report suggests.

Dr. Cheryl L. Maier of Emory University School of Medicine in Atlanta describe 15 COVID-19 patients with thickened blood who were admitted to their intensive-care unit in a letter in The Lancet.

"We found that the sickest patients had the highest plasma viscosity levels, more than twice normal levels," Dr. Maier told Reuters Health by email. "These levels were similar to those seen in a type of blood disorder called Waldenstrom macroglobulinemia, where the high viscosity leads to dangerous sludging of the blood in the brain and other organs."

She added, "Plasma exchange is the key treatment of hyperviscosity in diseases like Waldenstrom macroglobulinemia, but we need further studies to understand its impact on patients with COVID-19 hyperviscosity."

Fourteen of the 15 patients in the report had acute respiratory distress syndrome and were on ventilators, 14 had encephalopathy, 12 required vasopressor treatment for shock and 11 needed continuous renal replacement therapy due to failing kidneys.

Five patients with D-dimer concentrations of 3 ug/mL or above and confirmed or suspected thrombosis were given therapeutic anticoagulation. Four patients with lower D-dimer concentrations received low-dose treatment with low-molecular-weight heparin (LMWH) or subcutaneous heparin. Six who had high D-dimer concentrations but no known clotting received subtherapeutic doses of LMWH or IV heparin.

Plasma viscosity was above 95% of normal in all patients, and ranged from 1.9 to 4.2 centipoise (cP). The normal range is 1.4-1.8 cP.

Thrombotic complications occurred in all four patients who had plasma viscosity exceeding 3.5 cP, including one patient with pulmonary embolism (PE), one with limb ischemia and suspected PE, and two with clotting related to continuous renal replacement therapy.

Plasma viscosity was strongly associated with illness severity based on Plasma Viscosity and Sequential Organ Failure Assessment Scores (Pearson's r=0.84, R2=0.71, P<0.001).

"We found a strong correlation between plasma viscosity and illness severity," Dr. Maier said. "But correlation does not equal causation, and we need more studies to understand whether viscosity is simply a marker of disease or actually contributing to it. As part of this work, we're investigating what components of plasma cause the hyperviscosity."

She added, "We use plasma exchange to treat hyperviscosity in other diseases, and we're beginning to use it in some patients with COVID-19. We need larger studies to evaluate the impact of plasma exchange in COVID-19 and we're currently developing a clinical trial here at Emory."

"There's still a lot we don't know about COVID-19, and there's more going on with these atypical blood clots than we first realized," Dr. Maier said. "Hyperviscosity may be an important piece of the puzzle in linking severe inflammation to poor outcomes in COVID-19."

--Anne Harding

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