Patients suffering from COVID-19 pneumonia often develop very low levels of oxygen, called hypoxia, in the arterial blood supplying the body. Researchers from the University of Oxford hypothesise that the underlying problem is that the virus disrupts a normal process in the lungs called hypoxic pulmonary vasoconstriction, which diverts blood away from the diseased, non-functional parts of the lung and towards the parts of the lung that are still working properly. If the lungs are prevented from diverting blood to better-oxygenated lung segments, then this can cause the profound hypoxia from which patients with COVID-19 may die. The supportive therapy in hospitals aims to prevent this by using supplementary oxygen and ventilators to support breathing.
Almitrine bismesylate, a drug first developed in France, has been successful in treating acute respiratory distress syndrome by constricting the blood vessels in regions of the lung where the oxygen is low. Researchers say Almitrine could have the same effect in COVID-19 patients, with the potential to help restore the natural protective process in the lungs and increase oxygen levels in the arterial blood. The trial team hopes that administering this drug to COVID-19 patients will consequently reduce the amount of other respiratory support the patient needs.