Evaluation of microcirculation disorders in patients with severe COVID-19 by nail bed capillaroscopy

Microcirculation disorders caused by thrombosis are the most important factor determining the pathogenesis of organ damage in severe COVID-19 including the absence of obvious macrohemodynamic instability. However, there are very few publications demonstrating the results of intravital visualization of changes in the microcirculation system in this disease.

The objective: to assess the state of microcirculation in patients with viral pneumonia associated with COVID-19 using nail bed microscopy.

Subjects and methods. Eleven patients with COVID-19 were examined; they were admitted to the intensive care unit due to progressing acute respiratory failure. Vital microscopy of the microcirculatory bloodstream in the fingers’ nail bed was performed by admission and over time. When assessing microcirculation, the presence of aggregates in the lumen of capillaries and avascular zones, and the linear velocity of blood flow were taken into account. The results were summarized taking with the outcome consideration (6 people recovered, 5 died).

Results. Microcirculation disorders were objectively confirmed in all patients. In 100% of cases, microaggregates were detected in the capillary lumen. The values of the mean linear velocity of capillary blood flow turned out to be extremely variable. However, the values of the maximum linear velocities of capillary blood flow in the patients who subsequently died were significantly lower versus survivors (190 μm/sec (135.5; 237) and 387 μm/sec (329.3; 407.5), p = 0.018). The irregularity of blood flow in the visualized field was revealed: when the value of the maximum linear velocity in some capillaries was less than 180 µm/sec, in others, disturbances in the form of pendulum-like movement were already noted. Further slowing down of the blood flow velocity led to the development of stasis and the formation of avascular zones.

Conclusion. Impaired microcirculation (decreased blood flow rate in the capillaries, the presence of microaggregates and a lower number of perfused capillaries in the form of avascular zones) develops in all patients with severe COVID-19.

1. Kozlov V.А., Savchenko А.А., Kudryavtsev I.V., Kozlov I.G., Kudlay D.А., Prodeus А.P., Borisov А.G. Klinicheskaya immunologiya. [Clinical immunology]. Krasnoyarsk, Polikom Publ., 2020, 386 p. doi: 10.17513/np.438.

2. Starshinova А.А., Kushnareva E.А., Malkova А.M., Dovgalyuk I.F., Kudlay D.А. New coronavirus infection: specific parameters of the clinical course, diagnosis opportunities, treatment and prevention of the infection in adults and children. Voprosy Sovremennoy Pediatrii, 2020, vol. 19, no. 2, pp. 123-131. (In Russ.) https://doi.org/10.15690/vsp.v19i2.2105.

3. Fabrikantov O.L., Pronichkina M.M. Capillaroscopy parameters of the nailfold microcirculation (review). Sibirsky Nauchny Meditsinsky Journal, 2018, vol. 38, no. 2, pp. 62-67. (In Russ.) doi: 10.15372/SSMJ20180210.

4. Ackermann M., Verleden S.E., Kuehnel M. et al. Pulmonary vascular endothelialitis, thrombosis, and angiogenesis in COVID-19. N. Engl. J. Med., 2020, vol. 383, pp. 120-128. doi:10.1056/NEJMoa2015432.

5. Aird W.C. The role of the endothelium in severe sepsis and multiple organ dysfunction syndrome. Blood, 2003, vol. 101, pp. 3765-3777. doi: 10.1182/blood-2002-06-1887.

6. Bermejo-Martin J.F., Martin-Fernandez M., Lopez-Mestanza C. et al. Shared features of endothelial dysfunction between sepsis and its preceding risk factors (aging and chronic disease). J. Clin. Med., 2018, vol. 7, pp. 1-15. DOI:10.3390/jcm7110400.

7. Bradley D.T., Johnston R., Chaudhry I. et al. Histopathalogy and ultrastructural findings of fatal COVID-19 infections in Washington State: a case series. doi: https://DOI.org/10.1101/2020.04.17.20058545.

8. Bray M.A., Sartain S.A., Gollamudi J. et al. Microvascular thrombosis: experimental and clinical implications. Transl. Res., 2020, vol. 225, pp. 105-130. doi: 10.1016/j. trsl. 2020.05.006.

9. Carsana L., Sonzogni A., Nasr A. et al. Pulmonary post-mortem findings in a series of COVID-19 cases from northern Italy: a two-centre descriptive study. Lancet, Infect. Dis., 2020, doi:10.1016/S1473-3099(20)30434-5.

10. Ciceri F., Beretta L., Scandroglio A. M. et al. Microvascular COVID-19 lung vessels obstructive thromboinflammatory syndrome (MicroCLOTS): an atypical acute respiratory distress syndrome working hypothesis. Crit. Care Resusc., Journal of the Australasian Academy of Critical Care Medicine, 2020, vol. 22, no. 2, pp. 95-97. PMID: 32294809.

11. Colantuoni A., Martini R., Caprari P. et al. СOVID-19 sepsis and microcirculation disfunction. Front Physiol., 2020, vol. 11, pp. 747. doi: 10.3389/fphys. 2020.00747.