Monitoring TIVA EEG

BIS Interpretation For TIVA
Understanding BIS Values
BIS values range from 0-100. Target 40-60 for general anesthesia, 60-70 for sedation, and 70-85 for light sedation.
Correlation With TIVA Dosing
Adjust propofol TCI to maintain target BIS. Generally, 3-5 μg/ml effect-site concentration correlates with BIS 40-60.
Interpreting Sudden Changes
Rapid BIS increases may indicate awareness risk. Decreases below 30 suggest excessive anesthetic depth requiring dose reduction.
Optimizing Infusion Rates
Use BIS trending to guide titration. Stable values within target range confirm appropriate TIVA delivery and depth of anesthesia.
Basics of EEG Monitoring in Anesthesia
What Is EEG?
Electroencephalography (EEG) is a tool to record electrical brain activity. It is a non-invasive method. In the OR, EEG monitoring assesses anesthesia depth. It tracks brain activity in real time.
Why EEG Matters in TIVA
Objective Assessment: EEG provides an objective measure of brain activity. It is better than subjective clinical signs.
Titration of Anesthetics: EEG patterns correlate with sedation levels. This guides dose adjustments.
Reducing Awareness: Accurate EEG helps decrease awareness risks. It promotes a rapid emergence.
Fundamental EEG Waveforms
Delta Waves (0.5–4 Hz)
High amplitude, slow waves that dominate during deep sleep and deep anesthesia stages. Delta waves indicate cortical deactivation and are prominent at BIS values below 40.
Theta Waves (4–8 Hz)
Slower, lower amplitude waves appearing in light sleep and moderate sedation. Theta activity becomes prominent at BIS values between 40-60, correlating with surgical anesthesia.
Alpha Waves (8–13 Hz)
Moderate amplitude waves typical of relaxed wakefulness and light sedation. Alpha rhythms predominate at BIS values of 60-80.
Beta Waves (13–30 Hz)
Low amplitude, fast waves associated with active thinking, focus, and high-level cognitive function. Beta activity increases with anxiety, stressed concentration, and problem-solving.
EEG Changes During Anesthesia
The brain's electrical activity transforms predictably as patients transition through TIVA stages:
1
Awake State
Alpha and beta waves predominate. Fast, low-amplitude patterns reflect active cognition and alertness.
2
Induction Phase
Beta activity decreases as propofol takes effect. Theta waves emerge as consciousness fades.
Surgical Anesthesia
Theta activity increases. Regular, rhythmic patterns indicate stable hypnotic effect and adequate TIVA dosing.
Deep Anesthesia
Slow delta waves dominate. Burst suppression patterns may appear, indicating excessive anesthetic depth.
BIS Interpretation For TIVA
Baseline Assessment
Record awake EEG patterns before induction. This establishes the patient's normal electrical activity.
Induction Monitoring
Observe transition from beta to theta/delta waves. Target appropriate BIS levels based on procedure type.
Maintenance Phase
Maintain BIS 60-80 for moderate sedation. For general anesthesia, target BIS 40-60.
Emergence Observation
Monitor return of alpha and beta activity. Use these changes to time extubation.
During TIVA, watch for continuous slow waves (stable anesthesia), burst suppression (excessive depth), and transient beta activity (potential arousal).
TIVA Agent Effects on EEG and BIS Monitoring
Different TIVA agents produce characteristic EEG patterns that impact BIS interpretation. Understanding these signatures improves depth-of-anesthesia management.