Airway Assessment & Management
The cornerstone of resuscitation — "A" before B and C. Every critically ill patient encounter begins here.
Clinical Airway Anatomy
Upper Airway
- • Nose & Nasopharynx — warms, humidifies, filters air. NPA placed here.
- • Oropharynx — tongue is the #1 cause of obstruction in unconscious patients.
- • Epiglottis — landmark for direct & video laryngoscopy. Vallecula above, arytenoids below.
- • Hypopharynx — piriform fossae on either side. Foreign body lodgement site.
Lower Airway
- • Larynx — vocal cords (true & false), subglottic space. Narrowest in children < 8y.
- • Trachea — 10–12 cm long, C-shaped cartilage rings. Cricothyroid membrane at C5-6.
- • Carina — at T4-5 (sternal angle). Right main bronchus shorter, wider, more vertical.
- • Bronchial Tree — right mainstem intubation is the most common ETT malposition.
Difficult Airway Predictors — LEMON
- L — Look externally: facial trauma, large tongue, short neck, obesity, beard
- E — Evaluate 3-3-2: ≥3 fingers mouth opening, ≥3 fingers hyomental, ≥2 fingers thyro-hyoid
- M — Mallampati: Class III/IV predict difficulty. Assess sitting, tongue out, no phonation
- O — Obstruction: epiglottitis, peritonsillar abscess, angioedema, Ludwig's angina, tumor
- N — Neck mobility: C-spine injury, ankylosing spondylitis, RA with C1-2 instability
⚡ Clinical Pearl
In my experience, the single most reliable predictor of a difficult airway is restricted mouth opening (< 3 cm). Mallampati alone has poor sensitivity (~50%). Always do a composite assessment. The airway that kills you is the one you didn't anticipate.
Basic Airway Maneuvers & Adjuncts
Head Tilt – Chin Lift
Gold standard for non-trauma. Extends atlanto-occipital joint, lifts tongue off posterior pharyngeal wall.
⚠ Contraindicated in suspected C-spine injury.
Jaw Thrust
Trauma-safe maneuver. Bilateral mandibular angles pushed anteriorly. Maintains neutral C-spine alignment.
✓ Use with in-line C-spine stabilization.
OPA (Guedel Airway)
Size: corner of mouth to angle of mandible. Insert inverted, rotate 180°. Only in unconscious patients — triggers gag.
✗ Never in conscious/semi-conscious → vomiting + aspiration.
NPA (Nasopharyngeal)
Size: tip of nose to tragus. Lubricate well. Insert perpendicular to face (not upward). Tolerated in semi-conscious.
✗ Relative CI: basal skull fracture (Battle's sign, raccoon eyes, CSF rhinorrhoea).
BVM (Bag-Valve-Mask)
C-E grip technique. Two-person preferred. Ensure seal before squeezing. Deliver over 1 second. Watch for chest rise.
⚡ Stomach inflation = poor seal or excessive pressure. Reposition.
Supraglottic Devices
LMA / i-gel — rescue device, intubation conduit. i-gel preferred (no cuff inflation). Size by weight.
✓ First-line rescue when intubation fails. Can ventilate while planning next step.
Preoxygenation — The Safety Net
Preoxygenation replaces nitrogen in the FRC with O₂, buying 6–8 min of apnea time in a healthy adult (as little as 90 seconds in obese/pregnant patients).
Techniques
- 1NRB mask at 15 L/min × 3 min (8 vital-capacity breaths if emergent)
- 2HFNC at 60–70 L/min — provides apneic oxygenation during laryngoscopy
- 3NIV (CPAP/BiPAP) — best for obese patients, recruits atelectatic lung
- 4BVM with PEEP valve (5–10 cmH₂O) — prevents derecruitment
⚡ From the ICU
Head-up 20–30° during preoxygenation improves FRC and safe apnea time. In obese patients, use ramped position (ear-to-sternal-notch alignment).
Apneic oxygenation: Keep nasal cannula at 15 L/min or HFNC running during intubation attempt. This alone extends safe apnea time by 2–3 minutes. I do this for every RSI.