Emergence from Anesthesia

Delayed Emergence

Definition: Unresponsiveness > 30–60 min post-anesthesia.
Top Etiologies:
- Drug excess/residual (most common): NMBAs, opioids, benzos, volatiles.
- Metabolic: Hypoglycemia, hypothermia (< 35°C), CO₂ narcosis/hypercapnia.
- Neurologic: Perioperative stroke, ICH, nonconvulsive seizures.
- Enzyme deficiency: Pseudocholinesterase deficiency (prolonged succinylcholine apnea; ventilate until spontaneous recovery).
Stepwise Action:
1. ABCs + 100% FiO₂.
2. POC Fingerstick Glucose (rule out hypoglycemia immediately → D50 IV).
3. ABG (check PaCO₂ and pH).
4. TOF monitoring (assess residual paralysis).
5. Reversal trials:
  - Opioids → Naloxone (titrate to avoid flash pulmonary edema/pain crisis).
  - Benzos → Flumazenil (rarely used; risk of seizures).
6. Non-contrast Head CT if metabolic/drug causes excluded.

Adequate Extubation Criteria: TOF ratio > 0.9, sustained head lift > 5s, strong hand grip.
Sugammadex:
- Direct binder of steroidal NMBAs (Rocuronium > Vecuronium).
- Can reverse deep blockade rapidly.
- High-Yield Pearl: Inactivates oral contraceptives → barrier contraception x 7 days.
Neostigmine:
- AChE inhibitor; only works for shallow/partial block (TOF ≥ 2–4).
- Must co-administer Glycopyrrolate or Atropine to prevent lethal bradycardia and bronchospasm.

Classic Population: Pediatric (Sevoflurane), young athletic males, PTSD.
Priority Algorithm:
1. Rule out hypoxia (pulse ox) and hypercapnia (EtCO₂/ABG).
2. Rule out hypoglycemia (POC glucose).
3. Rule out physical triggers: Full bladder / urinary retention (perform bladder scan/place Foley) and acute surgical pain (IV opioids).
4. If refractory: Low-dose Dexmedetomidine or small boluses of Propofol.

Presentation: Inspiratory stridor, paradoxical chest/abdominal motion during light anesthesia (Stage 2).
Management Hierarchy:
1. Remove airway irritants (suction blood/secretions).
2. 100% FiO₂ + tight-seal CPAP.
3. Larson maneuver (vigorous jaw-thrust at laryngospasm notch behind ear).
4. Refractory: Low-dose Succinylcholine (0.1–0.5 mg/kg IV) ± re-intubation.

Pathophysiology: Massive negative intrathoracic pressure created by forced inspiration against a closed glottis (young, muscular males biting ETT or post-laryngospasm).
Presentation: Rapid hypoxemia and pink, frothy sputum immediately post-obstruction relief.
Management: Supportive (CPAP/PEEP, 100% O₂). Self-resolving in 12–24h. Avoid aggressive diuretics (PCWP is normal).

Presentation: Wheezing, high peak inspiratory pressures, “shark-fin” capnography.
Management: Inhaled Albuterol, deepen anesthesia with propofol/volatiles, IV Epinephrine if severe/anaphylaxis.

Post-Op Shivering:
- Increases O₂ consumption by up to 400% (myocardial ischemia risk).
- First-line: Active rewarming (Bair Hugger).
- Drug of Choice: Low-dose IV Meperidine.
Malignant Hyperthermia (MH):
- Triggers: Volatile anesthetics, Succinylcholine.
- Earliest sign: Unexplained rising EtCO₂ + tachycardia + masseter spasm.
- Late signs: Hyperthermia, rhabdomyolysis, hyperkalemia.
- Tx: Stop triggers, hyperventilate with 100% O₂, IV Dantrolene, cool patient.
Severe HTN/Tachycardia:
- First: Treat pain or bladder distension.
- Second: Short-acting IV beta-blockers (Esmolol, Labetalol).

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