Skin microcirculation reactivity to local thermal hyperaemia in patients with COVID-19 - A pilot observational study

Assessment of Blood Microcirculation Changes after COVID-19 Using Wearable Laser Doppler Flowmetry

The present work is focused on the study of changes in microcirculation parameters in patients who have undergone COVID-19 by means of wearable laser Doppler flowmetry (LDF) devices. The microcirculatory system is known to play a key role in the pathogenesis of COVID-19, and its disorders manifest themselves long after the patient has recovered. In the present work, microcirculatory changes were studied in dynamics on one patient for 10 days before his disease and 26 days after his recovery, and data from the group of patients undergoing rehabilitation after COVID-19 were compared with the data from a control group. A system consisting of several wearable laser Doppler flowmetry analysers was used for the studies. The patients were found to have reduced cutaneous perfusion and changes in the amplitude-frequency pattern of the LDF signal. The obtained data confirm that microcirculatory bed dysfunction is present in patients for a long period after the recovery from COVID-19.

Long-term assessment of systemic microcirculatory function and plasma cytokines after coronavirus disease 2019 (COVID-19)

Systemic microvascular dysfunction has been shown to be present in COVID-19, and serum cytokines are known to be involved in the regulation of vascular function. We sought to evaluate systemic microvascular endothelial function, with laser doppler perfusion monitoring (LDPM), and plasma levels of cytokines after acute COVID-19. Individuals admitted to a Cardiology hospital with acute COVID-19 and followed for 12-15 months after recovery underwent noninvasive evaluation of systemic endothelium-dependent microvascular reactivity by cutaneous LDPM with local thermal hyperemia (LTH). A multiplex biometric immunoassay panel was used to assess 48 serum cytokines and chemokines. Twenty patients and 14 control volunteers were enrolled. The areas under the curves of vasodilation induced by LTH were significantly increased after recovery (P=0.009) and were not different from values obtained in healthy volunteers (P = 0.85). The peak microvascular flow during LTH did also significantly increase (P = 0.02), and was not different form values obtained in healthy volunteers (P = 0.55). Several cytokines displayed significantly reduced serum concentrations after recovery from COVID-19. In conclusion, endothelium-dependent systemic microvascular reactivity improved after recovery from COVID-19 in patients with cardiovascular diseases, in parallel with a reduction in the levels of several serum cytokines and chemokines involved in the regulation of vascular function and inflammation.