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Currently, there is enough data to suggest a significant role of microcirculation abnormalities in the pathophysiology of COVID-19. However, no clinical studies on noninvasive assessment of blood microcirculation in patients with the new coronavirus infection have been performed. We measured skin microcirculation by laser Doppler flowmetry in the thermal and inspiratory gasp tests in 3 patients with various courses of COVID-19. A decrease in the skin microcirculation reactivity was found in a patient with a more severe course of coronavirus infection. We believe that assessment of skin microcirculation could become a promising tool for the development of new diagnostic approaches and in future of new treatments for patients with coronavirus infection, as well as for identification of patient categories with a high risk of its severe course. Further studies are required to evaluate the clinical applicability of laser Doppler flowmetry for assessment of skin microcirculation in patients with COVID-19.

Rationale: An increase in vascular tone is believed to be a major factor leading to arterial hypertension (AH). There are no means for a direct measurement of the vascular tone in clinical practice. Perfusion assessment by laser Doppler flowmetry (LDF) allows for an indirect evaluation of the vascular tone of the microcirculation system. Perfusion is assessed by the change in blood flow per unit of time in the given area. Therefore, this parameter should be inversely correlated with vascular tone. Aim: To compare the forearm skin perfusion measured by LDF in patients with AH and healthy volunteers with normal blood pressure, and to review the feasibility of this parameter for the assessment of the microvasculature tone.Materials and methods: The study was carried out in two groups: group one, patients with AH (n = 43; age 62 [57; 71] years), and group 2, healthy volunteers without AH (n = 62; age 28 [24; 37] years). The perfusion in the forearm skin was measured by LDF for 2 minutes without any functional tests. "Baseline perfusion” for each subject was calculated as the average perfusion rate in a representative portion of the microcirculatory curve.Results: Median of basic perfusion in the forearm skin in the patients with AH is significantly higher than that in the normotensive individuals: 4.88 [2.87; 8.98] PU and 3.41 [2.47; 4.99] PU, respectively (p = 0.013). The interquartile range of the baseline perfusion in the control group was chosen as provisional threshold values for the "normal” perfusion level. In 39.5% of patients with AH, their basic perfusion was within the "normal level”; 46.5% of the patients had the baseline perfusion above the "normal level”, which might be due to reduced tone of the peripheral vessels. Only 14.0% of the patients had a decreased level of the basic perfusion.Conclusion: An increase in the skin perfusion in some patients with AH may indicate a decrease in their peripheral vascular tone, which could be a potential compensatory reaction in response to the rise in blood pressure. The results obtained could have been influenced by the age-related changes in the cardiovascular system, drug therapy, etc. Further studies into the specifics of peripheral vasculature seem reasonable. They can contribute to the understanding of the pathophysiology of AH in a given patient and, in future, could be used to guide a personalized choice of therapy.

The article is devoted to current views on the ECG diagnosis in pediatrics. The group of authors considered some of the most characteristic changes in ECG in children.