Endotracheal Intubation

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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. Mallampati Classification Classes I-IV

  • 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). Macintosh blade laryngoscopy technique
  • 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.

Airway axes for intubation

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.

Practice Questions: Endotracheal Intubation

Test your understanding with these related questions

During preanaesthetic evaluation, an anaesthetist wrote a Mallampati grade 3. What does this signify?

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Flashcards: Endotracheal Intubation

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_____ administration may lead to salivation and lacrimation which can be prevented by premedication with glycopyrrolate

Hint: IV anesthetic

TAP TO REVEAL ANSWER

_____ administration may lead to salivation and lacrimation which can be prevented by premedication with glycopyrrolate

Ketamine

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