OR Awareness Flashcards
The biggest fears intraoperatively:
Awareness
Explicit Memory =
Conscious
Implicit Memory =
Unconscious
Conscious recollection of previous is what type of memory
explicit
Memory equivalent to remembering is
Experience(s)
Awareness during anesthesia describes
conscious recall (explicit memory ) of Intraop events
Patients can respond to commands and lack conscious recall in what form of memory?
Implicit
Questions to evaluate awareness:
Brice Questionnaire
- )What was the last thing you remember bf going to sleep?
2) What is the first thing you remember after your operation?
3) Can you remember anything in b/w?
4) Can you remember if you had any DREAMS during the procedure?
5) What was the worst thing about your procedure?
Incidence of awareness US & Sweden:
12,000 patients (sweden)
0.18% (18/10,000) had awareness under GA w/NMBD
.10% (10/10,000) had no NMB
0.13% (13/10,000) overall incidence
Awareness most likely in:
-Co-exisiting morbidities
-OB
Cardiac procedures (EMERGENT/light sedation)
-Patients with INCREASED anesthesia requirements
-anesthetic delivery problems (machine, meds, circuit)
-When volatile anesthetics aren’t used
Why would you have light anesthesia?
hemodynamic intolerance
OB or Cardiac surgeries
Reduced anesthetic doses for safety of hypovolemic or limited cardiac reserves
Patients Requiring increased Anesthesia:
ASA 3-5 (in major surgery)
Abuse of ETOH or Drugs
Genetics (redheads)
MAC Dose known to prevent conscious recall is:
MAC >= 0.7
What might mask Awareness?
NMBD
Most Patients often recall:
Lights, sounds, feelings of helplessness, fear, anxiety
-pain is less common; may occur w/NMBD use
Psychological Sequelae is:
- flashbacks, ANXIETY, nervousness, loneliness, nightmares, fear and panic attacks.
- 1/3 patients who experience awareness manifest this
- an acute emotional reaction to the experience significantly predicted the development of late psychological sequela.
Interventions for Psychological Sequelae
early psychotherapy may reduce acute and long term
-explain or validate the awareness effect presence and duration of psychological consequences.
can patients report awareness?
yes - registry exists
Preop Evaluation to reduce awareness complications (box 47.1)
*Identify Risk Factors:
*Interview Patient:
-listen to pt fears. answer questions.
Obtain informed consent:
-talk to pt about the anesthesia procedure
-let them know what to expect –> MAC case vs
Regional w/sedation, vs. GA
-let them know they’ll get pain & antiemetics; more if
they need when awake.
Use of BIS (bispectral index system)?
Used to aid anesthesia administration and reduce awareness
- Not Gold Standard
- clinical trials: if one more pt had reported awareness, they would not be statistically significant. (Hawthorne effect)
Hawthorne Effect
the alteration of behavior by the subjects of a study due to their awareness of being observed.
Prevention of Awareness:
- Premed w/Benzo (VERSED)
- Adequate doses of induction drugs
- avoidance paralysis if possible
- MAC at least 0.7
Out of how many injuries from negligent care result in malpractice claims (and fewer when standard of care was delivered)?
1 out of 25
Approx how many claims per year are made for awareness?
10 per year
Factors that influence Awareness Lawsuits:
- poor communication
- unmet expectations
- financial pressures on the pt
- poor relationship with their physician/provider
Brain Function monitoring
- Assess depth of anesthesia (EEG activity) - BIS
- frontal eeg activities into an index of hypnotic level
- 100 (awake) to 0.
BIS Range recommended to reduce consciousness during GA?
40-60
Compared to routine care, BIS is shown to reduce awareness in use of:
TIVA (total IV anesthesia)
Does BIS or End Tidal gas monitoring decrease awareness?
end tidal anesthetic gas monitoring
Preinduction Phase of Anesthesia:
to prevent awareness complications (box 47.1)
- Use checklist for machine/equip check
- verify function of IV and infusion equip
- Consider preop benzo
Intraop Monitoring:
[ to prevent awareness complications (box 47.1)]
- multiple modalities to monitor depth of anesthesia
- clinical (purposeful or reflex movement)
- conventional monitoring (bp, hr, end tidal analyzer)
- brain function monitoring
Intraop and postop managment:
to prevent awareness complications (box 47.1)
- benzo may be needed if pt unexpectedly becomes conscious
- speak w/pt postop
- interview pt to determine pt experience (Brice questionnaire)
- offer pt psychological counseling
The anesthetic depth required to block implicit memory is GREATER THAN, OR LESS THAN that required to block explicit memory?
Greater than
awareness is considered what form of memory?
explicit
What types of patients tend to have awareness more frequently?
patients w/ co existing morbidities tend to have more frequent incidence of awareness
tell me the three major causes of awareness
light anesthesia
increased patient anesthesia requirements
anesthetic delivery problems
examples of when light anesthesia may be necessary:
due to hemodynamic intolerance of anesthetic drugs
OB or caridac surgeries
reduced anesthetic doses may be necessary for optimal physiology and safety in hypovolemic patients or those w/limited cardiac reserve.
Name examples of when patients may have greater anesthesia requirements:
- ASA 3-5 undergoing major surgery
- abuse of ETOH, opioids, amphetamines and cocaine
- Genetics
Who else is also more likely to experience awareness?
Children (p. 813)
Intraoperative awareness is more likely to happen during…
induction of anesthesia with N20 and IV administered anesthetics.
Awareness is less likely to occur ….
when volatile anesthetics are used.
MAC 0.7 or greater
what prevents us from seeing early signs of inadequate anesthesia?
NMB
-miss patient movement
A MAC of 0.7 or more prevents ______ _____.
Conscious recall
A MAC of 0.7 or more prevents conscious recall in anesthetized patients similar to that achieved by:
a brain function monitor of anesthetic depth.
What early sign of awareness is unavailable when NMB ‘s are used?
patient movement
what is important in the pathogenesis of awareness during anesthesia?
anesthetic technique
intraoperative awareness can occur in the absence of
tachycardia or htn
