Awareness Under General Anesthesia

On this page

Definition & Incidence - Unwanted Wakefulness

  • Definition: Unintended consciousness during general anesthesia (GA) with explicit (conscious) recall of intraoperative events.
    • Perceptions: Auditory (most common), tactile sensations, sense of movement, or pain.
  • Incidence:
    • General surgery: 0.1-0.2%.
    • High-risk settings: ↑ up to 1-2% (e.g., cardiac surgery, major trauma, obstetric GA).
    • Awareness with pain: Less common, reported in approx. 1/3 of awareness episodes.

⭐ Modified Brice questionnaire is used for postoperative screening of awareness.

Risk Factors - Danger Zones

  • Patient Factors:
    • History of previous AUGA; ASA status III-V
    • Chronic use of opioids, benzodiazepines, or illicit substances
    • Anticipated difficult intubation or mask ventilation; obesity (BMI > 30)
    • Reduced cardiovascular reserve (e.g., shock, trauma); younger age (children)
  • Surgical Factors:
    • Cardiac surgery (especially on cardiopulmonary bypass)
    • Emergency surgery (e.g., C-section); major trauma surgery
    • Major orthopedic, neurosurgical, or ENT procedures
  • Anesthetic Factors:
    • Use of neuromuscular blocking agents (NMBAs)
    • Inadequate anesthetic delivery: ↓volatile agent concentration, TIVA errors, equipment failure
    • Rapid Sequence Induction (RSI); planned light anesthesia

⭐ NMBAs are a major risk, masking movement, a key awareness sign. Consider BIS/entropy monitoring in high-risk scenarios.

Clinical Features & Diagnosis - Silent Screams

  • Intraoperative Signs (often subtle/masked):
    • Autonomic: ↑HR, ↑BP, sweating, tearing (non-specific)
    • Movement (if neuromuscular blockade incomplete)
  • Postoperative Recall (Definitive): 📌 Mnemonic: SCREAM
    • Sounds (conversations, noises) - most common
    • Can't move (paralysis, helplessness)
    • Recall of events, tactile sensations (pain, ETT)
    • Emotions (fear, panic, distress)
    • Awake but unable to signal
    • May lead to PTSD, anxiety, nightmares
  • Diagnosis:
    • Structured postoperative interview: Modified Brice Questionnaire.

    ⭐ The most common patient recollection is auditory (e.g., hearing conversations).

Management & Sequelae - Healing the Harm

  • Immediate: Listen empathetically. If ongoing: deepen anesthesia; consider Midazolam (1-2 mg IV).
  • Post-op Protocol:
    • Interview: Modified Brice Questionnaire.
    • Communicate: Apologize, explain.
    • Support: Refer for psychological counseling (CBT).
  • Flowchart: Key Management Steps
  • Common Sequelae: PTSD, anxiety, nightmares, fear of future anesthesia.

⭐ Post-traumatic stress disorder (PTSD) can occur in up to 70% of patients experiencing definite AUGA.

High‑Yield Points - ⚡ Biggest Takeaways

Error: Failed to generate content for this concept group.

Practice Questions: Awareness Under General Anesthesia

Test your understanding with these related questions

Premedication is prescribed to – a) Allay anxiety b) Make the patient asleep before coming for operation c) Reduce the dose of induction agents d) Produce amnesia

1 of 5

Flashcards: Awareness Under General Anesthesia

1/10

A sudden fall in EtCO2 with hypotension along with normal airway pressure during surgery is suggestive of _____.

TAP TO REVEAL ANSWER

A sudden fall in EtCO2 with hypotension along with normal airway pressure during surgery is suggestive of _____.

CO2 embolism

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial