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Define anesthesia awareness?
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•Conscious recall (explicit memory) of intraoperative events
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Define anesthesia awareness?
•Conscious recall (explicit memory) of intraoperative events
what is •Explicit Memory
•Conscious
•Awareness of anesthesia classified as....
•Recollection of experiences
•Remembering
what is •Implicit Memory
•Unconscious
•Lack conscious recall of intraoperative awareness
•Pts may respond to commands
•Brain function monitors should be considered for use and or available when?
in clinical situations that place a patient at increased risk for AWARENESS!
•Combining brain function monitoring with 2 things
• Traditional monitoring
• Assessment of clinical signs
what are •Concerns regarding the consequences of both inadequate and excessive anesthetic effect have increased in the last few years
•Cardiovascular depression
•Cardiac arrest
•High doses of VAA at risk for acute transient epileptiformchanges in the EEG.
•Adverse long term outcomes
•Avoidance of excessive anesthetic effect reduces the occurrence of prolonged recovery and delayed orientation
5 out of the 10 things you should know about awareness
1.Even though intraoperative awareness is rare, when it does occur, it can be very disturbing and traumatic for some patients.
2.Awareness can range from brief, hazy recollections to some specific awareness of your surroundings during surgery. Most patients experiencing awareness usually do not feel any pain. Some patients may experience a feeling of pressure.
3.Patients who dream during surgery, or who have some perception of their surroundings before or after surgery, may think they have experienced intraoperative awareness. But such a sensation or memory does not necessarily represent actual awareness with recall during the surgical procedure.
4.Some procedures are performed under local or regional anesthesia with modest levels of sedation. In these circumstances, deep unconsciousness is not intended, and patients will predictably have varying levels of recall of events and surroundings without experiencing surgical pain. Your anesthesia provider will clearly explain exactly what you should expect to experience.
5.Experts in the field of anesthesia are actively studying awareness under general anesthesia, and they are seeking the most effective ways to minimize it. Practice advisories and position statements have been established for anesthesia professionals to help minimize the risk.
5 more out of the 10 things you should know about awareness
6.Intraoperative awareness can occur in high-risk surgeries such as trauma and cardiac surgery in which the patient's condition may not allow for the usual dose of anesthetic drugs to be given. In those instances, the anesthesia professional will weigh the potential for awareness against the need to guard the patient's life or safety. The same is true during a delivery by cesarean section, particularly if it is an emergency delivery. The usual doses of anesthetic drugs may not be the safest for the mother or child.
7.It has been shown that early counseling after an episode of awareness is vital to lessen feelings of confusion, stress, or trauma associated with the experience.
8.Over the last 20 years, researchers in anesthesia have spearheaded developments that have dramatically improved patient safety and comfort during surgery.
9.A highly trained anesthesia professional should be involved in your surgery. No technology can replace this expertise.
Patients should talk with their anesthesia professional before surgery to discussall oftheir concerns, including the remote possibility of awareness. These professionals work to ensure the best possible care of patients in the operating
6.Intraoperative awareness can occur in high-risk surgeries such as ________ & _________________ in which the patient's condition may not allow for the usual dose of anesthetic drugs to be given. In those instances, the anesthesia professional will weigh the potential for awareness against the need to guard the patient's life or safety. The same is true during a delivery by cesarean section, particularly if it is an emergency delivery. The usual doses of anesthetic drugs may not be the safest for the mother or child.
as trauma and cardiac surgery
how to prevent awareness?
•Premed with benzodiazepine
•Adequate doses of induction drugs
•Avoid muscle paralysis if possible
•Give volatile anesthetic at dose of 0.7 or greater end tidal level to ensure adequacy
•Avoid underdosing anesthesia
what are 3 major causes of awareness
•Light anesthesia- most common cause
•Increased patient anesthetic requirements
•Anesthetic delivery problems
how to assess for incidence of awareness? it is a an accepted tool for detecting awareness post operatively
Brice questionnaire
Brice Questionnaire questions (5)
what was the last thing you remember before going to sleep?
what is the first thing you remember after waking up?
do you remember anything between going to sleep & waking up?
did you dream during your procedure?
what was the worst thing about your operation?
how is •Depth of anesthesia is monitored ?
by EEG activity
what is the most commonly used and researched device that is used for brain monitoring in anesthesia
BIS
what are 3 BIS monitoring technologies
•Bispectral analysis
•Power spectral analysis
•Time domain analysis
list High risk of intraoperative awareness populations
•Cardiac surgery
•Impaired cardiovascular status
•Trauma surgery
•Cesarean section
•Chronic opioid or benzodiazepine use
•Heavy alcohol intake
•Prior history of awareness
what are some pre-op recommendations to prevent awareness
identify potential risk factors for awareness
interview the patient
obtain informed consent for patients at increased risk for awareness
what are some things you can do during the pre induction phase of anesthesia?
use a check list for machine/equipment check
verify function of IV access and infusion equipment
consider prep benzo
what are some intra-op monitoring to prevent awareness during GA?
- use multiple modalities to monitor the depth of anesthesia
- clinical (ex purposed or reflex monitoring)
- convention monitors (end tidal anesthetic analyzer, HR, BP)
- brain function monitoring on a case by case basis.
- during total IV anesthesia, maintaining BIS of 40-60 reduces awareness compared to routine care
- studies show that if a VA is primary anesthetic, use ET anesthetic concentration of more than 0.7 age adjusted MAC in high risk patients reduces the incidence of awareness
what are some recs to prevent awareness during intra op and post op management?
- consider bento if pt becomes conscious
- speak w pt post op
- consider structured interview or brice questionaire to determine patients experience
- report occurence for continuous quality improvement
- offer pt psychological counseling
what is a BIS monitor? (bispectral index)
•is a proprietary algorithm to convert a single channel of frontal EEG activities into an index of hypnotic level, ranging from 100 (awake) to 0 (isoelectric electroencephalogram).
how are BIS measurements effective?
effective in determining the level of anesthesia produced with inhalation agents, but remains less predictable with pediatric patients & during regional & intravenous anesthesia
list EEG monitoring systems
•BIS monitoring (Aspect Medical Systems)
•S/5 Entropy Module (GE Healthcare)
•Cerebral State Monitor (Danmeter)
•SNAP II monitor (Stryker)
•AEP Monitor/2 (Danmeter)
•SEDLine Patient State Analyzer (Hospira)
BIS value
1) 100?
2) 0?
3) 40-60?
4). below 40?
5) 0-20
6) •It is suggested that BIS less than ________ for more than _______ min is associated with increased post op mortality
1. 100 awake/ conscious
2. 0 absence of brain activity/ flat EEG
3. 40-60 adequate general anesthesia (low probability of recall and unresponsive to stimuli)
4. Below 40 deep hypnotic state
5. 0-20- burst suppression
6. It is suggested that BIS less than 40 for more than 5 min is associated with increased post op mortality
what level of BIS can a pt respond to verbals stimuli?
80-100
what level of BIS can a pt respond to loud verbal/ physcial stimuli?
60-80
what level of BIS can a pt have burst suppression?
0-20
BIS display screen. BIS index (0-100) is shown in upper _______. BIS is trended versus time in the lower window.
left
in BIS, what represents the cumulative percent of cortical silence over the last 65 seconds.
Suppression ratio (SR)
on BIS, how might •Data reliability may be assessed ?
by evaluating the bar graphs for signal quality index (SQI; global parameter incorporating electrode impedance and artifact •detection) and electromyographic activity (EMG) of the frontalis muscle in the 70-110 Hz band (dB).
what is the EEG frequency that will show on a BIS as the anesthetic increases?
beta --> alpha --> theta --> delta
what does an awake BIS EEG look like?
beta
what does moderate sedation BIS EEG look like?
alpha
what does general anesthesia BIS EEG look like?
theta
what does deep anesthesia BIS EEG look like?
delta
4 steps to apply a BIS monitor
-
application of BIS sensor is based off
how many channels of the EEG?
should It be placed on the right or left hemisphere?
1. based on 1 channel EEG
2. either left or right hemisphere
using BIS during induction
•Titrate dose for induction
•Know time frame/ strategies for placement of airway device
•Difficult airways- pt getting light?
using BIS during maintenance
•stain adequate anesthetic depth
•Avoid adverse events
•Prepare for emergence
•Abrupt changes in BIS warrant clinical assessment and correlation
using BIS during emergence
•~70 responsive, eye opening
•May remain 40-60 until stimulate pt (suction, moving) & then increase quickly
•Increased BIS value & pt not responding- ? NMB effect, EMG artifact
