Accidental Awareness during General Anesthesia (AAGA)
1. 🎯 Definition
- AAGA
= intraoperative consciousness + explicit recall
- spectrum:
- auditory
perception → full
awareness + paralysis + pain
- พบมากในช่วง induction / emergence มากกว่า
maintenance
2. 📊 Incidence
- ~ 1–2
/ 1000 (ถ้า actively ask)
- ~ 1
: 14,000–19,000 (self-report)
- สูงขึ้นใน:
- obstetric
(~1:600)
- use NMBA
- TIVA
มากกว่า volatile anesthesia
3. ⚠️ Major Risk Factors
🔴 3.1 Neuromuscular
Blocking Agent (NMBA) = สำคัญที่สุด
- incidence:
- 1:8,000
(with NMBA)
- vs 1:136,000
(no NMBA)
- ปัญหา:
- ไม่มี movement →
detect awareness ยาก
- ↑ psychological trauma
(feeling of paralysis)
🟠 3.2 Technique-related
- TIVA
- ไม่มี real-time drug level monitoring
- risk:
underdosing / IV line failure
- medication
error / pump error
- vaporizer
off (rare but critical)
🟡 3.3 Surgery-related
- trauma
/ emergency
- cardiac
surgery (CPB)
- cesarean
section
- RSII
🟢 3.4 Patient-related
- difficult
airway / prolonged intubation
- obesity
- prior
AAGA (↑ risk ~5x)
- substance
use:
- alcohol
(chronic ↑
requirement)
- opioid
tolerance
- benzodiazepine
use
- CYP
inducer drugs (rifampicin, phenytoin, etc.)
4. 🔍 Pathophysiology / Key
Concept
- anesthesia
depth ≠ binary →
continuum
- paralysis
masks awareness
- TIVA → no ETAC (end-tidal anesthetic
concentration) monitoring → higher risk
- “neural
inertia” → partial
recall during transition states
5. 🛡️ Prevention
5.1 Monitoring (Core strategy)
3 หลัก
- ETAC
(volatile anesthesia)
- NMBA
monitoring
- EEG
(BIS) → especially
in TIVA
👉 Physiologic signs (HR,
BP) unreliable
5.2 Anesthetic technique
- หลีกเลี่ยง deep paralysis ถ้าไม่จำเป็น
- ensure
continuous drug delivery
- TIVA → consider:
- BIS
(bispectral index) monitoring
- TCI
(target controlled infusion) (if available)
5.3 Human factors
- avoid
syringe swap
- check
vaporizer / IV line
- use
protocol / checklist
5.4 Patient communication
- อธิบาย:
- GA
vs sedation
- possibility
of recall (rare)
- manage
expectation (e.g. mask, tube, awakening)
6. 🚨 Recognition (Intraop)
- movement
(if no NMBA)
- autonomic
response (limited reliability)
- EEG
change
👉 ถ้าสงสัย:
- deepen
anesthesia immediately
- give:
- benzodiazepine
(amnestic)
- opioid
(analgesia)
7. 🧠 Postoperative
Complications
- 33–69%
→ psychological
symptoms:
- PTSD-like:
- nightmares
- flashbacks
- anxiety
- hypervigilance
- worst
experience:
- awake
+ paralysis
8. 🏥 Postoperative
Management
🔹 Early detection
- actively
ask:
- “จำอะไรระหว่างผ่าตัดได้ไหม”
🔹 3-step support pathway
1.
Meeting
o listen
+ validate + express regret
2.
Analysis
o review
case / determine likelihood
3.
Support
o monitor
psychological symptoms
o follow-up
(≈2
weeks)
o refer
psych if needed
🔑 Key Clinical Pearls
- NMBA
= risk factor #1
- TIVA
→ ต้อง vigilance
สูง
- HR/BP
ใช้ assess depth ไม่ได้
- BIS ช่วยได้ โดยเฉพาะ TIVA
- complication
สำคัญสุด = psychological trauma
- ต้อง actively screen postop
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