Awareness and Anesthesia Flashcards
Components of awareness under anesthesia
- Hearing
- Weakness or paralysis
- Feelings of helplessness, anxiety, panic, and impending death
- Dreaming (incidence report 7%)
Definition of anesthesia awarenuss from AANA position statement
Postoperative recall of events experienced under general anesthesia
Unintended- not part of the anesthesia care plan
What is not included in awareness?
The phenomenon of dreaming
Surgeries where awareness has higher incidence
- Cardiac
- Obstetric (0.4%)
- Major trauma (11-43%)
General incidence of awareness in non obstetric, non cardiac cases?
Pediatric incidence of awareness?
0.1-0.2%
20,000-30,000 per year
Pediatric 0.6-2.7%
Why is awareness more common in obstetric surgery?
Increased CO causes rapid redistribution
Also less agents used to prevent neonatal depression
Why is incidence of awareness greater in major trauma surgery?
HD instability require reduction of anesthetic
What type of memory involves information consciously remembered by patient?
Is pain involved?
Explicit memory
With or without pain
Examples of explicit memory
Vivid OR conversations or vague unpleasant sensation or dreams
(but i thought dreams dont count?)
Which type of memory is more sensitive to anesthesia?
Explicit memory
Which type of memory involves memory stored but not recalled but leads to changes in behavior or performance?
Implicity memory
How can you test implicit memory?
Hypnosis or behavioral suggestion
Recall may occur during dreaming
What medical problems may awareness lead to?
- Traumatic neurosis (10%)
- PTSD (71%)
- Fear of dying, nightmares, hallucinations, inability to sleep
Are there legal consequences to awareness?
Duh
Costs of lawsuits from %1,000 to $1.7 million with average cost $195,327
What percent of malpractice claims are associated with awareness?
2%
Where is the “storage sight” for memory?
Temporal lobes of the cerebral cortex
How is short term memory made?
Reverberating circuits, or post-tetanic potentiation causes increased excitability of the synapse or decreased resting membrane potential after prolonged period of excitation
What does long-term memory require?
- Physical or chemical change of the size and conductiveness of the dendrites
- Changes reuire about 1 hour to maximally consolidate
Which S/S of light anesthesia occur first: hemodynamic or motor?
Motor
What may block motor signs of light anesthesia?
NMB
Motor signs of light anesthesia (6)
- Eyelid or eye movement
- Swallowing
- Coughing
- Grimacing
- Movement of extremities or head
- Increased respiratory effort- intercostal and abdominal muscles
Are hemodynamic S/S of light anesthesia reliable?
Nope
Why causes hemodynamic S/S of light anesthesia?
What may modify these S/S?
Caused by sympathetic stimulation
Modified by anesthetic agents
Hemodynamic S/S of light anesthesia
- Hypertension
- Tachycardia
- Mydriasis
- Tearing
- Sweating
- Salivation
What is the last sense suppressed by anesthesia?
Why?
Hearing (auditory pathways)
Becuase it is most metabolically actice part of brain
What drugs may make hearing more acute?
NMB
How can conversation in the OR affect the patient post-op?
May have implicit memories of hearing convo
What may proivde a glimpse into anesthetic depth based off hearing?
Auditory evoked potentials
What is the best monitor for anesthetic depth?
No single monitor
Use multiple
How do you assess analgesia, areflexia, and hypnosis?
- Analgesia- vital signs
- Areflexia- patient movement or nerve stimulation
- Hypnosis- processed EEG (BIS) monitor tires to give quantitative measurement
How does BIS monitor meausure anesthetic depth?
It doesn’t necessarily
Based upon the cortical EEG, they measure the relative hypontic effect of the anesthetic
Recommended BIS level to achieve appropriate anesthetic depth
50-60
Is BIS valuable in predicting awareness?
Questionable….
Beach chair position effect on BIS
Lowers
Trendelberg position effect on BIS
Raises
Ketamine and nitrous oxide effect on BIS
Increases
What drugs/substances are associated with higher incidence of awareness?
Heavy alcohol intake
Chronic benzos, opioids, requiring treatment or both
What patient conditions/ features are associated with higher incidence of awareness?
- Impaired CV status
- Severe end-stage lung disease
- ASA Physical Status 3,4 and 5
- Anticipated difficult intubation
- History of awareness
What procedure/ times in procedure are more associated with awareness?
Acute trauma with hypovolemia
Cardiac surgery, including off-pump
C-section under GA
Bronchoscopy, laryngoscopy, or both
Expected intra-op hypotension requiring treatment
Preventable causes of awareness under anesthesia
- Light anesthesia
- Equipment malfunction
- Increased anesthetic requirements
- Herbal
What may cause awak paralysis?
Syringe swap
Mislabeled succinylcholine drips
😱
Why are difficult intubations high risk for awareness?
Redistribution of induction agent
Requires redosing
What equipment malfunctions may result in awareness?
these cards are stupidddddd sry
Vaporizers not turned or not filled
Pump malfunction
Empty nitrous tank
Disconnected delivery tubing/circuit
What factors cause increased anesthetic requirements?
- Multiple general anesthetics (cause long term tolerance)
- Chronic alcoholism
- Hypernatremia
- Hyperthemia
- Drugs that increase CNS catecholamines (MAOIs, TCAs, cocaine, amphetamines)
What herbal supplement places pt at risk for awareness?
St. John’s wort
What drugs are associated with increased risk of awareness?
I feel like there are 18 cards that say this but it says it 18 times in our notes slightly different ways
- Muscle relaxants
- Nitrous with opioids
- Opioid based (in cardiac anesthetic)
why is TIVA associated with increased risk of awareness?
Due to variability of dosage requirements and variation in elimination
TC says idk why you would do this but….
If using inhalational agents alone, what MAC would you use to prevent awareness?
At least 0.8-1 MAC
What MAC of inhalational agents do you use to prevent awareness in combo with nitrous and opioids?
End Tidal 0.6 MAC (potent agent)
Name some drugs that lower the concentration needed to prevent recall
- Benzodiazepines
- Scopoloamine
- IV anesthetics
- Ketamine
What should you use on patients at high risk for recall?
Amnestics
What important step in you anesthesia setup can help prevent awareness?
Machine check
- Check vaporizers
- Check delivery system
Steps to take if you know your anesthetic is going to have to be on the light side
- Inform patient of possibility for awareness
- Use “auditory masking”
- Do not use disparaging remarks (duh)
S/S of PTSD
- Flashbacks or nightmares
- Avoidance behaviors
- Emotional numbing
- Preoccupation with death
- Hyperarrousal
Do patients usually spontaneously complain of recall?
No
After direct questioning, may complain of fear, anger, sadness, or “just not right”
What things may patient describe recalling?
- Conversations
- Pain
- Weakness or paralysis
- Intubation
What is PTSD usually associated with?
Recall of pain
Things to ask patient experiencing recall
- Obtain details to determine validity
- Assess timing to confirm they are not confused about post-op pain
Techniques and assurances to use when patient experiences recall
- Question with empathy and compassion
- Honest and sincere explanation of what happened and the possible reasons
- Reassure patient that future anesthetic should not result in the same
What should you document about patient’s recall experience?
Who do you notify?
What referrals need to be made?
Document interview
Notify risk managment
Refer promptly to psychologist or psychiatirst trained in PTSD treatment
