Case report The application of BIS bispectral index

Case report: The application of BIS (bispectral index monitor) during the operation Present by: Ri 陳賢典 Ri 詹宗諭 Supervisor: CR 郭書麟

Brief history n n n Gender: male Age: 25 y/o OP & anesthetic history: 92/01 in NTUH, Left lung pneumothorax s/p chest tube insertion. Present illness: Left lung pneumothorax, came for VATS and pleurodesis this time.

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Morning Meeting BISPECTRAL INDEX MONITOR (BIS) 日期： 2003. 09. 19 報告者：Ri陳賢典 Ri詹宗諭 指導者：CR郭書麟

Deep (or Adequate) of anesthesia

Bispectral index n n n Index for hypnotic status manufactured by Aspect Medical Systems (Newton, USA) a continuous processed EEG parameter that provides a measure of the state of the brain computed real-time using a combination of three analysis steps BIS value lags 5 to 10 seconds behind the clinical change in the patient. a score number between 0 and 100 → awake ; 0 → Isoelectric EEG

BIS

BIS: Electrode and location

BIS development

BIS Range Guideline

BIS vs EEG feature

idealized pattern of changes in the EEG

Bispectral Index in Response to Drugs and Stimulation n Oscillations in BIS can potentially provide a direct measure of the brain's response to stimulation and an alternative measure of responsiveness / reactiveness similar to other vital sign endpoints.

Physiological factors may also alter the hypnotic state n n Ischemia or severe hypoxia, resulting in a decrease in the BIS if severe enough to cause global EEG slowing or outright suppression Hypothermia (<33℃) will generally result in a corresponding decrease in BIS levels as brain processes slow Artifacts (EMG… ) BIS monitoring usually will not detect episodes of focal ischemia caused by embolic events.

The Benefit of BIS use (1)

The Benefit of BIS use (2) n n n More Precise Titration of Anesthetic Agents More appropriate use of Adjuvant Drugs Faster, More Consistent Emergence and Extubation Better OR Utilization (i. e. less time spent waiting for extubation / transport to PACU) Shorter PACU Stays Reduces the Risk of Intraoperative Awareness

Awareness during general anesthesia

Awareness during general anesthesia n n n Incidence of awareness during elective general anesthesia ★ elective and emergency surgery: 0. 2~0. 4% ★ BIS use: 0. 003% most awareness with BIS : BIS number>65 So BIS reduce the risk of awareness? 1. It is difficult to prove that BIS can reduce this risk 2. for high risk group use, such as cardiac surgery, C/S

BIS and Immobility n n n Initially, the BIS was evaluated “as a measure of adequate anesthesia defined by patient movement in response to skin incision. ” However, when sevoflurane was administered alone, the BIS did not predict movement after skin incision better than chance alone. BIS has not been derived to predict movement

BIS For Pediatric Use n n n The influence of neuronal and physiologic maturation of the brain on BIS, as well as its correlation to drug effects and anesthetic outcome, is unknown in pediatric patients an approximately linear relation between BIS and end-tidal sevoflurane concentration in infants and children BIS values obtained before anesthesia, during maintenance, and at emergence will be similar to those reported for adults

Current Limitation of BIS monitor n n n Drug exception: nitrous oxide , Ketamine insufficient data to evaluate the use of BIS in patients with neurologic disease Data are currently lacking regarding opioid dose–responses and interaction of opioids with hypnotics on BIS Could not detect cerebral ischemia EMG contamination (artifacts)

Monitored Anesthesia Care and Intensive Care n n BIS values of 65– 80 define an acceptable loss in conscious information processing and recall during sedation–hypnosis preliminary data from the ICU suggest that oversedation is common The influence of multi-system failure on hypnotic pharmacokinetic–pharmacodynamic response is unpredictable in these patients It would probably benefit patients and speed recovery from long-term sedation to accurately monitor and titrate hypnosis in the ICU

Intra-OP response , BIS and management

Combination of three analysis steps n 3 steps: n n n First step – an EEG pre-processor, which breaks the EEG signal down second by second and marks those segments containing artifact Second step - the calculation of the hypnosis /sedation index by combining selected EEG features using the algorithm Third step – The index is modified to better reflect the level of suppression in the EEG. The suppression ratio (SR) is computed as the percentage of suppressed EEG in the non-artifact data

Hypnotic state/sedation level scoring criteria

The Bispectral Index development process