Near-infrared spectroscopy (NIRS)

Near-infrared spectroscopy (NIRS) is a non-invasive method used to assess cerebral oxygenation. Although it does not measure ICP directly, NIRS can provide valuable information about cerebral perfusion and oxygen delivery, which are closely related to ICP dynamics. NIRS uses near-infrared light to measure the oxygen saturation of hemoglobin in the cerebral cortex, offering a continuous, non-invasive assessment of brain oxygenation. For anesthesia providers, NIRS is especially valuable during surgeries where cerebral perfusion is at risk, such as cardiac surgery, major vascular procedures, and neurosurgery. In situations where ICP is elevated, cerebral perfusion may be compromised, leading to decreased cerebral oxygenation. NIRS can serve as a surrogate marker for cerebral hypoperfusion and guide interventions to optimize oxygen delivery to the brain. One of the main advantages of NIRS is that it provides continuous, real-time monitoring of cerebral oxygenation, which can be integrated into routine anesthetic monitoring. NIRS devices are easy to use, non-invasive, and do not require significant operator training. However, the limitation of NIRS lies in its regional specificity—it only measures oxygenation in the area of the brain directly beneath the sensors, typically the frontal lobes. Thus, it may not detect global changes in ICP or perfusion that occur in other brain regions.