Recent research has underscored the potential benefits of utilizing cerebral monitoring techniques like bispectral index (BIS) monitoring or auditory-evoked potential monitoring to titrate general anesthesia. Evidence suggests that adjusting anesthesia depth using these methods can reduce cognitive dysfunction three months after surgery. For instance, the Cognitive Dysfunction after Anesthesia trial demonstrated that BIS-guided anesthesia, which involves adjusting anesthetic doses to maintain a BIS between 40 and 60, prevented postoperative cognitive dysfunction (POCD) in 23 out of every 1,000 patients at the three-month mark. However, the long-term impacts of this approach on POCD at one week and one year postoperatively remain unclear.
On the other hand, a meta-analysis examining four studies found no significant correlation between the depth of anesthesia, as measured by these monitoring techniques, and the incidence of POCD. This inconsistency in findings suggests that while cerebral monitoring during anesthesia might offer some benefits, these do not strictly correlate with the monitored values themselves.
Given the variations in methodological rigor and the types of cognitive assessments used across studies, it is prudent to approach the endorsement of BIS-guided anesthesia with caution. By aiming to avoid both excessive depth of anesthesia and patient awareness, this approach could potentially mitigate the risk of POCD, yet definitive conclusions require more consistent research.
