Direct Laryngoscopy

Direct Laryngoscopy: Basics - Gateway to Glottis

• Definition: Visual examination of the larynx and glottic opening using a rigid laryngoscope.
• Primary Goals:
  • Direct visualization for endotracheal intubation.
  • Diagnosis of laryngeal pathology.
  • Foreign body removal.
• Key Indications:
  • Endotracheal intubation (e.g., general anesthesia, respiratory failure).
  • Diagnostic evaluation of larynx/pharynx.
  • Management of foreign body aspiration.
• Contraindications:
  • Absolute: Epiglottitis (risk of complete airway obstruction, unless managed by an expert).
  • Relative: Unstable cervical spine injury, severe trismus, significant facial trauma.

⭐ Direct laryngoscopy provides an unmediated, direct line of sight to the larynx, crucial for intubation.

Laryngoscope Equipment - Choosing Your Weapon

• Handles: Standard/stubby. Check battery.
• Blades:

  Feature	Macintosh (Mac)	Miller
  Shape	Curved	Straight
  Tip Placement	Vallecula (indirectly lifts epiglottis)	Directly lifts epiglottis
  Adult Sizes	3-4	2-3
  Advantages	More tongue space	Better view in anterior/floppy epiglottis
  Common Use	Adults	Infants, difficult anterior airway
  📌 Mnemonic	Mac in Vallecula	Miller Lifts (epiglottis)

• Adjuncts:
  • Stylets: Shape ETT for insertion.
  • Magill forceps: Guide ETT, remove foreign bodies.
  • Suction: Clear airway, maintain view.

⭐ The Macintosh blade is generally preferred in adults, while the Miller blade is often used in infants and patients with a long, floppy epiglottis or an anterior larynx.

Patient Prep for DL - Setting Up Success

• Airway Assessment (📌 LEMON):
  • Look: external (trauma, large incisors, beard).
  • Evaluate 3-3-2: IIG >3F, HMD >3F, Thyroid-to-mouth >2F. (F=fingers)
  • Mallampati (I-IV).
  • Obstruction (tumor, edema) / Obesity.
  • Neck mobility (reduced = difficult).
  • Difficulty: TMD <6 cm, IIG <3 cm.
• Patient Positioning:
  • Sniffing position: head elevated (e.g., on a pad), neck extended.

  ⭐ The sniffing position aligns the oral, pharyngeal, and laryngeal axes.

• Preoxygenation (Denitrogenation):
  • 100% O2 for 3-5 mins OR 4-8 vital capacity breaths.
• Equipment Check:
  • Laryngoscope (light), Endotracheal Tube (cuff), Suction ready.

DL Technique & Views - Visualizing Victory

• Technique Algorithm:

• Laryngeal View: Cormack-Lehane (Grade I-IV) assesses glottic structures.

  • 

  ⭐ A Cormack-Lehane Grade I view: entire glottis visible, including commissures.

• View Improvement:

  • ELM / BURP: External Laryngeal Manipulation (Backward, Upward, Rightward Pressure on thyroid) (📌 BURP).

• Sellick's Maneuver (Cricoid Pressure):

  • Technique: Firm pressure (30N) on cricoid during RSI.
  • Indications: Prevent aspiration.
  • Contraindications: Active vomiting, cricotracheal/C-spine injury, foreign body.

DL Complications - Scope Snafus

• Common:
  • Dental trauma (teeth, crowns, bridges)
  • Lip, tongue, or mucosal injury
  • Sore throat, hoarseness
• Serious:
  • Hypoxia, hypercarbia (prolonged attempts)
  • Esophageal intubation, unrecognized aspiration
  • Bronchospasm, laryngospasm (airway reactivity)
  • Cardiovascular: Hypertension (↑BP), tachycardia (↑HR), arrhythmias
  • Failed intubation, airway trauma
• Difficult/Failed Laryngoscopy Management:
  • Immediately call for experienced help
  • Utilize alternative airway devices (e.g., LMA, video laryngoscope)

⭐ Dental trauma is the most common complication of direct laryngoscopy.

High‑Yield Points - ⚡ Biggest Takeaways

• Direct Laryngoscopy (DL) is crucial for endotracheal intubation.
• Macintosh blade (curved) fits into the vallecula; Miller blade (straight) directly lifts the epiglottis.
• Optimal patient positioning is the "sniffing position" for axis alignment.
• Cormack-Lehane classification (Grades I-IV) grades the laryngeal view obtained.
• Common complications include dental trauma, sore throat, and laryngospasm.
• BURP maneuver (Backward, Upward, Rightward Pressure) can improve laryngeal view.
• Sellick's maneuver (cricoid pressure) aims to prevent aspiration during RSI (Rapid Sequence Intubation).