Using EEG to Teach Delivery of TIVA Donald M Mathews, MD Professor of Anesthesiology Director of Research Department of Anesthesiology Robert Larner MD College of Medicine, University of Vermont

Masimo Inc.: Scientific Advisory Board

MY BIAS I strongly believe that Propofol-TIVA is a superior anesthetic to Inhalational-Volatile Agent anesthesia in most instances. My Bias

My Interpretation of the Scientific Literature TIVA is associated with: Less nausea Better mood scores Lower pain scores Higher quality of recovery scores TIVA is associated with: Less nausea Better mood scores Lower pain scores Higher quality of recovery scores

Confession Doing TIVA well is more difficult that giving volatile anesthesia!

Reason #1: Population Variation MAC Cp50 2 SD = 0.3 MAC 2 SD = ~ 8 mcg ml-1

Reason #3: Synergy Differences 10 8 6 4 2 12 14 20 MAC 1.0 0.5 1.5 Propofol Cp50 mcg ml-1 95% 95% 5% 5% 1 2 3 4 5 6 7 8 9 10 Fentanyl or Remifentanil ng ml-1 1 2 3 4 5 6 7 8 9 10 Fentanyl or Remifentanil ng ml-1

We care for patients, not populations Wouldn’t it be nice if there was a way to determine an individual patient’s requirement… That was more useful than interpreting changes in the sympathetic nervous system?

Propofol and Frontal EEG Increasing Propofol

Brown and Purdon: Challenging Dogma Can Anesthesiologists learn to interpret EEG to make clinical decisions? Can additional tools help with this? Can we correlate EEG changes with neurobiologic circuitry?

One Educational Goal of the UVM TIVA Rotation Learn to titrate propofol to EEG and DSA parameters, not to a processed EEG index value.

EEG Guidance a al Goldilocks JUST RIGHT TOO DEEP TOO LIGHT

TOO LIGHT JUST RIGHT TOO DEEP

JUST RIGHT

Just Right

TOO LIGHT JUST RIGHT

Too Light

TOO DEEP

Too Deep

TOO LIGHT JUST RIGHT TOO DEEP

TOO LIGHT JUST RIGHT TOO DEEP

Becoming Too Deep

Too Deep Progression Finally, just before burst supression, the remaining alpha power is overwhelmed by the delta power and the spectral edge is quite low. Note: when “just right, the Spectral edge is 2-3 Hz greater than the alpha prominence As things begin to be “too deep”, the spectral edge collapses into the alpha prominence

Just Right > Too Deep > Just Right

Putting it Together Goal: “Sweet Spot” of Synergy 1 2 3 4 5 6 7 8 9 10 Remifentanil or Sufentanil x 10 ng ml-1 Propofol Cp50 mcg ml-1 10 8 6 4 2 12 14 20 95% Propofol 2 mg kg-1, then 125- 150 mcg kg-1 min Remifentanil 1 mcg kg-1, then 0.085-0.1 mcg kg-1 min OR Sufentanil 0.3 mcg kg-1 ,then 0.2-0.3 mcg kg-1 hr-1 Titrate propofol infusion to EEG parameters with Goldiloxian logic. Titrate opioids to the usual parameters. Enjoy an excellent anesthetic! 5%

Illustrative Case: Patient 1:1000 (1:10,000 ?) 62 year old man, 175 cm, 81 kg Scheduled for multilevel lumbar decompression with hardware placement Rx: metoprolol for HTN No issues with prior GA No Ethanol, drug use/abuse.

Illustrative Case Propofol 2 mg kg-1, then 125 mcg kg-1 min-1 1 2 3 4 5 6 7 8 9 10 Remifentanil or Sufentanil x 10 ng ml-1 10 8 6 4 2 12 14 20 95% Propofol 2 mg kg-1, then 125 mcg kg-1 min-1 Sufentanil 0.3 mcg kg-1 ,then 0.3 mcg kg-1 hr-1 Required several 100 mg propofol boluses and increases in infusion rate for inadequate EEG “level” 250 mcg kg-1 min-1 Required several 10 mcg sufentanil boluses and infusion rate increases for hemodynamic reasons. 0.6 mcg kg-1 hr-1 5%

100 mg propofol, increased to 250 mcg kg-1 min-1 from 225 10 min from end: Sufentanil discontinued. Propofol 125 mcg kg-1 min-1 End of case: Patient flipped over Propofol discontinued Opened eyes 3 minutes later No coughing, bucking Alert, oriented, comfortable

Conclusions Propofol TIVA can be difficult to delivery accurately. Propofol causes predictable changes in frontal EEG Practitioners can learn to titrate anesthetics to the EEG and DSA. Ideally, the next generation of anesthesiologists will not need processed- EEG indices.