Altered pulmonary blood volume distribution as a biomarker for predicting outcomes in COVID-19 disease

BackgroundEvidence suggests that vascular inflammation and thrombosis may be important drivers of poor clinical outcomes in patients with COVID-19. We hypothesized that a significant decrease in the percentage of blood vessels with a cross-sectional area between 1.25–5 mm2 (BV5%) on chest computed tomography (CT) in COVID-19 patients is predictive of adverse clinical outcomes.MethodsRetrospective analysis of chest CT scans from 10 hospitals across two state in 313 COVID-19 positive and 195 COVID-19 negative patients seeking acute medical care.ResultsBV5% was predictive of outcomes in COVID-19 patients in a multivariate model, with a BV5% threshold below 25% associated with an odds ratio (OR) 5.58 for death, OR 3.20 for intubation, and OR 2.54 for the composite of death or intubation. A model using age and BV5% had an area under the receiver operating characteristic curve 0.85 to predict the composite of intubation or death in COVID-19 patients. BV5% was not predictive of clinical outcomes in patients without COVID-19.ConclusionThis data suggests BV5% as a novel biomarker for predicting adverse outcomes in patients with COVID-19 seeking acute medical care.

Sympathetic α-adrenergic regulation of blood flow and volume in hamsters arousing from hibernation

Mammals arousing from hibernation display pronounced regional heterothermy, where the thoracic and head regions warm faster than the abdominal and hindlimb regions. We used laser-Doppler flowmetry to measure peripheral hind foot blood flow during hibernation and arousal and gamma imaging of technetium-labeled albumin to measure whole blood volume distribution in hamsters arousing from hibernation. It was discovered that the hibernating hamster responds to physical but not to sound or hypercapnic stimulation with rapid, 73% reduction of hind foot blood flow. Hind foot blood flow vasoconstriction was maintained from the onset of arousal until late in arousal when rectal temperature was rapidly increased. α-Adrenergic blockade early in arousal increased hind foot blood flow by 700%, suggesting that vasoconstriction was mediated by activation of sympathetic tone. Gamma imaging revealed that, by the early phase of arousal from hibernation, the blood volume of the body below the liver is greatly reduced, whereas blood volumes of the thorax and head are much greater than corresponding volumes in anesthetized hamsters. As arousal progresses and cardiac activity increases and regional heterothermy develops, this regional blood volume distribution is largely maintained; however, blood volume slowly decreases in the thoracic region and slowly increases in the shoulder and head regions. The rapid increase in rectal temperature, characteristic of mid- to late- arousal phases, is probably mediated, in part, by reduction of adrenergic tone on abdominal and hindlimb vasculature. Warm blood then moves into the hind body, produces an increase in temperature, blood flow, and blood volume in the hind body and compensatory reductions of blood volume in the neck, head, and thoracic regions.