Depth of Anesthesia: Difference between revisions

Processed EEG monitor, translating EEG waves into a numeric scale ranging from 0 (complete EEG suppression) to 100 (fully awake). It is said that adequate anesthesia may be present with a BIS value of 40-60. Studies have shown that intraoperative BIS, compared to clinical signs, may have a reduction of intraoperative awareness (OR) 0.36, 95% CI 0.21 to 0.60; I2 = 61%; 27 studies; 9765 participants<ref name=":0">https://pubmed.ncbi.nlm.nih.gov/31557307/</ref>, time to eye opening, time to orientation, and time to discharge patient from PACU<ref name=":0" />. However, BIS guided anesthesia did not show a clinical difference to anesthesia guided by end tidal anesthetic gas concentration (ETAC). Furthermore, studies show that neuromuscular blockade alone, without other anesthetics, decrease the value of BIS.<ref>Schuller PJ, Newell S, Strickland PA, Barry JJ. Response of bispectral index to neuromuscular block in awake volunteers. Br J Anaesth. 2015 Jul;115 Suppl 1:i95-i103.</ref> Therefore, the accuracy and reliability of BIS are questionable.

Processed EEG monitor. The PSI (Patient State Index) translates the effect of anesthetic drugs in humans into a numeric scale ranging from 0 (complete EEG suppression) to 100 (fully awake). The target value for general anesthesia is between 25-50. A study showed that this monitor better captured changes in brain state from dexmedetomidine sedation, compared to RASS score and SEF95<ref>EEG response of dexmedetomidine during drug induced sleep endoscopy https://pubmed.ncbi.nlm.nih.gov/37521700/</ref>. Another study suggests that PSI may be adequate to monitor anesthesia with sevoflurane in the pediatric population, when compared to the BIS monitor<ref>Usefulness of bispectral index and patient state index during sevoflurane anesthesia in children: A prospective observational study