Figure 2

Sidestream dark-field (SDF) imaging. This imaging technique is an improved method of observing the human microcirculation at the bedside. (a) SDF imaging consists of a light guide surrounded by green light-emitting diodes (LEDs; wavelength 530 nm) whose light penetrates the tissue and illuminates the microcirculation. The light is absorbed by hemoglobin of the red blood cells and scattered by leukocytes. A magnifying lens projects the image onto a video camera. Placed on organ surfaces, SDF imaging provides crisp images of the red blood cells and leukocytes flowing through the microcirculation (for real-time films, see http://www.sdfimaging.net). (b) As an example of the improved image quality provided by SDF imaging, the sublingual microcirculation of a volunteer is shown, with a magnified inset showing several leukocytes.