Aperiodic exponent ceases to track changes in propofol dose at deep surgery-level hypnotic depths
Discuss this preprint
Start a discussion What are Sciety discussions?Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Background
Accurately tracking hypnotic depth during surgery is key to deliver personalized and precise anaesthesia. The aperiodic exponent of electroencephalographic (EEG) data has shown great promise as a marker of the balance between excitatory and inhibitory cortical activity and of hypnotic depth. In humans, this relation has been mostly evidenced by pairwise comparisons between awake and superficial anaesthesia states. However, it is unclear if this relation is also present across deeper hypnotic depths. Here we examined the relation between aperiodic exponent and hypnotic depth across different surgery-level propofol doses.
Methods
The present was an exploratory prospective observational analytical study where we recorded high-density EEG data from patients before surgery and during continuous target-controlled propofol infusions with different intraoperative target concentrations. We evaluated the relation between steady-state propofol dose and several EEG features including aperiodic exponent and spectral band powers.
Results
All EEG measures were different when comparing awake versus anaesthesia conditions. At surgery-level hypnotic depths, some spectral band powers continued to track propofol dose displaying either with positive (delta R 2 = 0.23, p = 0.001) or negative correlations (alpha R 2 = 0.36, p < 0.001; beta R 2 = 0.045, p < 0.001). Importantly, the aperiodic exponent was not associated with propofol dose’s absolute value (R 2 = 0.011, p = 0.43) or with its relative change (R 2 = 0.011, p = 0.51).
Conclusions
Our results suggest that the relation between aperiodic exponent and excitatory/inhibitory balance is circumscribed to more superficial hypnotic depths than those typically employed for surgery.
