 In order to study microcirculatory changes, sublingual microcirculatory videos will be obtained using a side-stream dark field-imaging device SDF; Microscan, MicroVissionMedical, Amsterdam, the Nederlands derived from the orthogonal polarized spectral imaging technology. Images acquisition and analysis will be performed according international recommendations 3 with dedicated software analysis Automated Vascular Analysis AVA v. 1.0; Academic Medical Center, University of Amsterdam, Amsterdam, the Nederlands. These recommendations are summarised below: 