NIRS: So Near Yet So Far (From the Brain)

Cerebral oximetry is touted as a magic wand to detect cerebral hypoperfusion. Inability to completely exclude extracranial oxygen however is a limitation. Variation in scalp vascularity can magnify the limitations of relatively short emitter–detector distances. The combination of brain ischemia and cutaneous hyperemia, as is the situation during anaphylaxis and anaphylactoid reactions, can be associated with a paradoxical increase in cerebral oximetry values. This could compromise the quality and accuracy of care delivered. We report the association of red man syndrome with exaggerated cerebral oximetry values.