Endotracheal Intubation

Indications & Contraindications - The Why & Why Not

• Indications (Why Intubate? 📌 Mnemonic: ABCD)
  • Airway: Compromise (obstruction), inability to protect (e.g., aspiration risk).
  • Breathing: Failure (apnea, hypoxemia, hypercarbia), increased work of breathing.
  • Course: General anesthesia requiring airway control, muscle relaxation.
  • Disability: Decreased consciousness.

  ⭐ GCS ≤ 8 is a key indication for intubation to protect the airway.

• Contraindications (When Not To?):
  • Absolute: Complete upper airway obstruction (surgical airway needed), laryngeal transection.
  • Relative: Anticipated difficult intubation (prepare alternatives!), severe facial/neck trauma, patient refusal.

Airway Assessment - Predicting Difficulty

📌 LEMON Method:

• Look Externally: Facial trauma, large tongue/incisors, beard.
• Evaluate 3-3-2 Rule:
  • Inter-incisor gap (IIG): > 3 fingers.
  • Hyoid-mental distance (HMD): > 3 fingers.
  • Thyroid-to-floor of mouth (TFM): > 2 fingers.
• Mallampati Score:

  ⭐ A Mallampati Class III or IV view significantly increases the likelihood of difficult laryngoscopy.

• Obstruction: Tumors, hematoma, angioedema.
• Neck Mobility: Reduced.

Other predictors:

• Thyromental Distance (TMD): < 6 cm.
• Sternomental Distance (SMD): < 12.5 cm.
• Upper Lip Bite Test (ULBT): Class III.

Equipment & Drugs - Tools & Potions

• Laryngoscopes:
  • Macintosh (curved): Vallecula. Miller (straight): Lifts epiglottis.
  • Sizes: Adult (Mac #3-4, Miller #2-3).
• Endotracheal Tubes (ETT):
  • Cuffed / Uncuffed.
  • Size (ID):
    • Children (uncuffed): $(Age/4) + 4$ mm.
    • Children (cuffed): $(Age/4) + 3.5$ mm.
    • Adults: ♀ 7.0-7.5 mm, ♂ 8.0-8.5 mm.

⭐ The Murphy eye on an ETT provides an alternative passage for gas flow if the bevel is occluded.

• Key Drugs:
  • Induction: Propofol 1.5-2.5 mg/kg.
  • Muscle Relaxant: Succinylcholine 1-1.5 mg/kg; Rocuronium 0.6-1.2 mg/kg.
  • Opioid: Fentanyl 1-2 mcg/kg.

Procedure Steps - The Intubation Dance

⭐ The 'sniffing' position (atlanto-occipital extension with neck flexion) aligns airway axes for optimal view during laryngoscopy.

• 1. Preparation:
  • Position: "Sniffing" position.
  • Pre-oxygenate: 100% O2 for 3-5 mins or 4-8 vital capacity breaths.
  • Equipment check. 📌 RSI: SOAPME (Suction, Oxygen, Airway equipment, Pharmacy, Monitoring, Emergency equipment).
• 2. Laryngoscopy & Intubation:
  • Induce anesthesia & muscle relaxant.
  • RSI: Apply cricoid pressure (Sellick’s maneuver) before loss of consciousness until ETT cuff inflation.
  • Laryngoscopy: Visualize cords (Cormack-Lehane grade).
  • Insert ETT, inflate cuff, remove stylet.
• 3. Confirmation:
  • Clinical: Auscultate (bilateral air entry, no gastric sounds), chest rise.
  • Gold Standard: End-tidal CO2 (EtCO2) waveform.

Confirmation & Complications - Check & Troubleshoot

• Confirmation Methods:
  • Clinical: Symmetrical chest rise, bilateral air entry (5 zones), no epigastric sounds.
  • ETCO₂: Continuous waveform capnography (most reliable).

  ⭐ Continuous waveform capnography is the most reliable method to confirm endotracheal tube placement.

  • Other: Tube condensation, esophageal detector device.
• Complications:
  • Immediate: Esophageal/Endobronchial intubation, airway trauma (teeth, lips, cords), laryngospasm, bronchospasm, aspiration, hemodynamic instability (↑BP, ↑HR).
  • Delayed: Sore throat, hoarseness, laryngeal/subglottic edema, VAP, tracheal stenosis.
• Troubleshooting (Sudden Deterioration):
  • 📌 DOPE Mnemonic:
    • Dislodgement (tube movement)
    • Obstruction (kink, secretions, cuff)
    • Pneumothorax
    • Equipment failure (ventilator, circuit)

High‑Yield Points - ⚡ Biggest Takeaways

• Capnography (EtCO2) is gold standard for confirming ETT placement.
• Cormack-Lehane grading (I-IV) assesses laryngeal view; Grade III/IV indicate difficulty.
• Sellick's maneuver (cricoid pressure) during RSI prevents aspiration.
• LEMON score predicts difficult airway (Look, Evaluate, Mallampati, Obstruction, Neck).
• Optimal ETT cuff pressure: 20-30 cm H2O for seal and perfusion.
• Critical ETT misplacement: esophageal intubation; confirm with bilateral air entry, capnography.
• Extubate when awake, following commands, with intact airway reflexes.