Authors: Douville N et al.
Anesthesiology 144(4):1026–1027, April 2026
Summary:
This reply reinforces and expands on the argument that traditional hemodynamic parameters are inadequate for assessing anesthetic depth, agreeing with prior commentary that blood pressure and heart rate reflect secondary physiologic responses rather than direct brain effects.
The authors emphasize that anesthetic depth should be grounded in neurobiology, with electroencephalography (EEG) representing a more direct and physiologically appropriate tool for monitoring the central nervous system. They highlight that their prior work identified genetic factors influencing anesthetic response—particularly those affecting hemodynamic reactions—further supporting the disconnect between cardiovascular signs and true anesthetic effect.
However, the authors also introduce an important nuance: while EEG is promising, its role is not fully established. Although EEG-guided anesthesia has been shown to reduce anesthetic dosing and time spent in deep suppression, evidence remains mixed regarding whether this translates into improved clinical outcomes such as reduced delirium, faster emergence, or better cognitive recovery.
A major limitation identified is the absence of a simple, reliable biomarker for brain function or injury—something analogous to creatinine for kidney injury or troponin for cardiac injury. This gap makes it difficult to standardize care or definitively link monitoring strategies to outcomes.
Ultimately, the authors call for continued research into both EEG-based monitoring and the development of objective biomarkers to better guide anesthetic dosing and improve neurologic outcomes.
Key Points:
- Hemodynamics are inadequate for assessing anesthetic depth
- EEG is a more direct measure but lacks definitive outcome-based validation
- Genetic factors influence anesthetic and hemodynamic responses
- EEG may reduce anesthetic exposure but outcome benefits remain uncertain
- Lack of a reliable brain injury biomarker limits progress in the field
What You Should Know:
They agree with the criticism—but add reality. EEG is better than guessing, but it’s not the final answer yet. Until we have a true brain biomarker, we’re still improving—but not perfect. This is where the field is headed, but we’re not fully there.
We would like to thank Anesthesiology for allowing us to summarize and share this article.