Difficult Airway Algorithm

Per ASA: "A clinical situation in which a conventionally trained anesthesiologist experiences difficulty with facemask ventilation of the upper airway, difficulty with tracheal intubation, or both."

Patients do not die from failed intubation — they die from lack of oxygenation. If the pulse ox is dropping, fall back to whatever lets you oxygenate.

1. Assess likelihood and impact of:
2. - Difficulty with patient cooperation/consent
3. - Difficult mask ventilation
4. - Difficult supraglottic airway placement
5. - Difficult laryngoscopy / intubation
6. - Difficult surgical airway access
7. Actively oxygenate throughout the process.
8. Consider awake vs asleep, non-invasive vs invasive, video-laryngoscopy first, preserve vs ablate spontaneous ventilation.
9. Develop primary and alternative strategies.
10. Call for help early.
11. After failed intubation: SGA → fiberoptic through SGA → wake / surgical airway.

MaMaBOATS (any 3 = high risk): - Mallampati III or IV - Mandibular protrusion decreased - Beard - Obesity (BMI > 30) - Age > 57 - Teeth (lack of) - Snoring (OSA)

Predictors of IMPOSSIBLE mask ventilation (MaMaBORa): Mallampati III–IV, Males, Beard, OSA / upper airway surgery, Radiation changes to neck.

Successful direct laryngoscopy requires aligning oral, pharyngeal, and laryngeal axes.

• Mallampati III or IV
• Short, thick neck
• Thyromental distance < 3 finger breadths
• Inter-incisor distance < 3 cm (small mouth opening)
• Prominent overbite
• Decreased TMJ mobility; inability to prognath
• Limited cervical range of motion
• High-arched / narrow palate
• Poor submandibular compliance (mass, infection, radiation)
• Underlying pathology (laryngeal stenosis, epiglottitis, tumor)

History of prior airway difficulty is the single most important predictor — always check old records.

Requires flexion at C7 and extension at C5-C6. - Ramp obese patients until the line between the tragus and sternal notch is parallel to the floor. - For neonates and infants, place a roll under the shoulders (large occiput causes neck flexion). - Poor positioning can turn a Cormack-Lehane grade 1 view into a grade 4 view.

Proper positioning is worth your effort, even at the start of an emergent case.

• Mask ventilate in sniffing position
• Oral airway (Guedel) or nasal trumpet (caution with skull-base fracture, coagulopathy)
• Supraglottic airway (LMA)
• Nasal cannula apneic oxygenation (high-flow nasal: Optiflow, THRIVE 30–70 L/min) — extends safe apnea time
• During fiberoptic: endoscopic mask (Patil-Syracuse) for PPV, or swivel adapter on ETT
• Rigid bronchoscope side port
• Jet ventilation (specialized airways, beware barotrauma)

Indications: known/predicted difficult airway, unstable c-spine, severe airway pathology (tumor, abscess, edema).

Key is topicalization: - Antisialagogue: glycopyrrolate 0.2 mg IV/IM ~30 min ahead - Sedation: dexmedetomidine, low-dose midazolam, ketamine — preserve spontaneous ventilation - Local anesthetic options: - 4% lidocaine nebulized (5–10 min) - 4% lidocaine atomized or via mucosal atomizer - Cetacaine spray (benzocaine — methemoglobinemia risk) - Transtracheal injection (2% lido through cricothyroid membrane) - Superior laryngeal nerve block (above hyoid bone) - Glossopharyngeal nerve block (lateral oropharynx)

Techniques: flexible bronchoscopy (FOB), video laryngoscopy (awake AWS, GlideScope), retrograde wire, lighted stylet.

From an ENT chief resident: "Even in an emergency, always invest 20 seconds to:" - Identify someone to assist - Position the patient (extend the neck, palpate the cricothyroid membrane) - Have a 6.0 ETT and scalpel ready

Cricothyrotomy (preferred over tracheostomy emergently): 1. Scalpel — vertical skin incision over cricothyroid membrane 2. Horizontal stab through the membrane 3. Bougie introduced caudally 4. Railroad 6.0 ETT over bougie

Confirm: EtCO₂, bilateral breath sounds, no subcutaneous emphysema with positive-pressure ventilation.