Optimal bispectral index exists in healthy patients undergoing general anesthesia: A validation study

Area of Science:

• Neuroscience
• Anesthesiology
• Critical Care Medicine

Background:

• Continuous cerebrovascular reactivity monitoring is crucial for predicting outcomes in neurocritical and operative care.
• An optimal sedation level, termed BISopt, has been identified in neural injury populations, linking cerebrovascular reactivity to the bispectral index (BIS).

Purpose of the Study:

• To investigate the presence and characteristics of BISopt in healthy individuals undergoing general anesthesia and in awake controls.
• To determine if BISopt exists outside of neural injury populations and its relationship with systemic blood pressure.

Main Methods:

• Examined the relationship between BIS and continuous cerebrovascular reactivity in two cohorts: patients under general anesthesia for spinal surgery and awake healthy volunteers.
• Analyzed BIS values in relation to cerebrovascular reactivity to identify the BISopt phenomenon.

Main Results:

• BISopt was present in 96% of patients under general anesthesia but absent in awake controls, validating its existence beyond neural injury.
• BIS was found to be independent of systemic blood pressure, indicating distinct pathophysiological influences on cerebrovascular reactivity.

Conclusions:

• The findings suggest that the individualized BISopt concept can be adapted for non-neural injury populations in critical care and operative settings.
• Further exploratory research is necessary to fully understand and implement BISopt in broader clinical applications.