Depth of Anesthesia Monitoring

Question 1

What are the goals of DoA monitors?

Answer 1

1. detect depth & risk of awareness
2. determine if patient is “too deep”
3. should work similarly across all patient populations
4. work the same regardless of meds/anesthesia technique

Question 2

What is EEG activity?

Answer 2

• synaptic activity within cerebral cortex results in voltage change
• detected by electrodes placed on forehead/scalp

Question 3

What are the EEG waveforms?

Answer 3

• vary in frequency
• correspond to specific neurophysiological processes
• delta < theta < alpha < beta

Question 4

EEG processing: Time domain vs. Frequency domain

Answer 4

time: voltage changes against time, burst suppression, does not analyze complex signals
frequency: fast calculations, freq present in EEG compared to degree in which these freq are present

Question 5

BIS Index range

Answer 5

0 (isoelectric)- 100 (awake)

Question 6

Advantages of BIS

Answer 6

• beneficial for TIVA

- designed for use with propofol, versed, ISO

Question 7

Disadvantages of BIS

Answer 7

• does not accurately reflect effects of ALL drugs
• N2O- no change
• ketamine- increase BIS
• artifact

Question 8

BIS range to reduce recall/awareness

Answer 8

40-60

Question 9

“triple low” and greater post-op mortality

Answer 9

• low BIS index
• low MAP
• low EtVA concentration (MAC)