Near-infrared spectroscopy (NIRS) technology, such as that used in pulse oximetry, has been used in medicine for decades. Several characteristics contribute to its widespread use, including its noninvasive nature, reliability and safety. The Somanetics' INVOS® System harnesses this power to safely and reliably "see inside" the brain and body. NIRS devices measure the venous weighted oxy-hemoglobin saturation (color of blue blood) in a field of tissue, rather than in arteries, and thus the rSO2 parameter provides a window into regional oxygen supply-demand relationships. Monitoring rSO2 at two distinct sites (cerebral and somatic) has become common practice at our institution for all infants and children in the intensive care unit and provides valuable feedback about potentially deleterious trends in regional tissue oxygenation that cannot easily be obtained by other modalities in such patients.