Figure 3.

Upper panels: Recordings of skin microvascular flow using laser doppler perfusion monitoring, with local thermal hyperemia (LTH) stimulus. (A) Patient with COVID-19, first test (worst day during clinical evolution). (B) Same patient, second test, after clinical and laboratory improvement. There is higher baseline flow, as well as post-LTH flow on the second test. Lower panels: Bar graphs showing the effect of LTH on mean (C) and peak (D) cutaneous microvascular flow of the patient, in the first test (blue bars) and on the second test (red bars), compared to a sex- and age-matched healthy control (green bars). APU, arbitrary perfusion units; LTH, start of local thermal hyperemia; TEMP, skin temperature.