[Near infrared spectroscopy. Limits and problems in the intensive care unit]

Near infrared spectroscopy is a non-invasive method of calculating changes in cerebral oxygenation. We have now evaluated a new near infrared spectroscope, the NIRO-500 (Hamamatsu Photonics, Japan), in an intensive care unit setting. The influence of extracerebral and intracerebral physical-technical, physiological and pathophysiological parameters was investigated. The results showed that the method is very sensitive to changes in oxygenation and perfusion in the cerebral vasculature. However, the influence of other factors can be considerable and not always easy to detect and interpret.