 2. Sublingual microcirculation using Sidestream Dark Field imaging SDF After removal of secretions with a gauze, the device will be applied below the tongue and three sequences of about 20 seconds from adjacent areas will be recorded and stored. The investigators will measure the perfused vessel density PVD, the proportion of perfused vessels PPV and the microvascular flow index MFI for small vessels. Each image will be divided into four quadrants, and the predominant type of flow 0 absent, 1 intermittent, 2 sluggish, 3 normal, 4 high will be evaluated in each quadrant. The mean of the four quadrants will be used for analysis. 