cerebral oximetry
Also written as: NIRS — near-infrared spectroscopy
Non-invasive monitoring technique measuring regional brain tissue oxygen saturation using near-infrared spectroscopy.
Full Definition
A monitoring modality that uses near-infrared spectroscopy (NIRS) to measure regional cerebral oxygen saturation (rSO2) through sensors placed on the forehead. The technology penetrates approximately 2-3 cm into brain tissue, reflecting a weighted average of arterial, capillary, and venous oxygen saturations. Normal values range from 55-75%. In cardiac surgery, cerebral oximetry helps detect cerebral hypoperfusion during CPB, aortic cross-clamping, or circulatory arrest. Decreases greater than 20% from baseline or absolute values below 40-50% may indicate cerebral ischemia requiring intervention.
Usage
Usage note: Often documented as rSO2 values; specify bilateral monitoring when both hemispheres are assessed.
In Context
- "Cerebral oximetry showed bilateral decreases to 35% during circulatory arrest, prompting immediate intervention." — Anesthesia record
- "The anesthesiologist monitored cerebral oximetry throughout the arch repair to ensure adequate cerebral perfusion." — Operative note