What is the approach and medication protocol for difficult airway intubation?

Difficult Airway Intubation: Approach and Medication Protocol

For difficult airway intubation, follow the 2022 ASA algorithm: perform awake intubation when difficulty is anticipated with both intubation AND ventilation, use video laryngoscopy as first-line for emergency intubation, administer rocuronium 0.6-1.2 mg/kg for neuromuscular blockade (avoiding in awake intubation), and have propofol 1-2 mg/kg plus succinylcholine 1 mg/kg immediately available for laryngospasm rescue. 1, 2, 3

Pre-Intubation Assessment and Planning

Rapidly assess four critical factors even in urgent situations 1:

• Difficult laryngoscopy/intubation risk: Evaluate Mallampati score, thyromental distance, sternomental distance, interincisor distance, mouth opening, ability to prognath, head/neck mobility, prominent upper incisors, and upper lip bite test 1
• Difficult mask ventilation risk: Assess facial features including presence of beard, neck circumference, and ratio of neck circumference to thyromental distance 1
• Aspiration risk: Determine if significantly increased 1
• Rapid desaturation risk: Identify patients at increased risk 1, 2

If ANY ONE factor indicates difficulty, consider awake intubation rather than proceeding after induction of general anesthesia 1

Team Preparation and Equipment

Ensure immediate availability 1, 2:

• Most experienced operator performs the intubation 2
• Skilled assistant for airway management 1
• Portable difficult airway cart with specialized equipment in the room 1
• Video laryngoscopy equipment 1, 2
• Flexible bronchoscope 1
• Supraglottic airways (consider size, design, and first vs. second generation) 1
• Cricothyrotomy kit for emergency surgical airway 1, 2
• Vasopressors drawn up (epinephrine, norepinephrine) 2

Conduct pre-intubation team briefing with clear role assignments and explicit discussion of Plans A (primary intubation), B/C (rescue ventilation), and D (emergency surgical airway) 1, 2

Patient Positioning and Preoxygenation

Position the patient 1, 2:

• Head-up 25-30° when tolerated to improve upper airway patency 2
• "Sniffing position": flex lower cervical spine, extend upper cervical spine with face horizontal 2
• Ramping technique for obese patients: external auditory meatus level with sternal notch 2

Preoxygenate thoroughly 1, 2:

• Tight-fitting facemask with 10-15 L/min 100% oxygen for 3 minutes (traditional method) 1
• Two-handed technique to minimize leak, confirmed by capnograph trace 2
• Target end-tidal oxygen concentration >85% 2
• Alternative: four maximal breaths in 30 seconds (fast-track method, less effective than traditional) 1

Awake Intubation Protocol

Choose awake intubation when 1:

• Predicted difficulty with BOTH intubation AND ventilation
• Significantly increased aspiration risk
• Patient cooperation is possible
• Benefits outweigh risks of proceeding after induction

Awake intubation technique 1:

• Maintain continuous monitoring: ECG, non-invasive blood pressure, pulse oximetry, and end-tidal CO₂ throughout 1
• Position patient sitting up when feasible for physiological advantages 1
• Techniques include flexible bronchoscopy, videolaryngoscopy, direct laryngoscopy, combined techniques, or retrograde wire-aided intubation 1
• Videolaryngoscopy has comparable 98.3% success rate to flexible bronchoscopy 1
• Consider combined approach using both VL and FB 1

Topicalization and sedation 1:

• Administer topical anesthesia to airway
• Provide appropriate sedation while maintaining patient cooperation
• Monitor closely for over-sedation causing airway obstruction and hypoventilation 1

Post-Induction Intubation Protocol

Proceed after induction ONLY when 1:

• Benefits judged to outweigh risks
• Success predicted in maximum of three attempts 4
• Adequate mask or supraglottic ventilation predicted as fallback 4

Neuromuscular blockade medications 2, 3:

• Rocuronium 0.6 mg/kg IV: Standard intubating dose, provides excellent-to-good intubating conditions within 2 minutes, clinical relaxation for median 33 minutes 3
• Rocuronium 0.9-1.2 mg/kg IV: For rapid sequence intubation, provides 58-67 minutes of clinical relaxation 3
• Dose obese patients based on actual body weight, not ideal body weight 3
• NOT recommended for rapid sequence in Cesarean section due to inadequate intubating conditions in some patients 3

Intubation technique 1, 2:

• Use videolaryngoscopy as first-line to increase first-pass success and prevent esophageal intubation 2
• Noninvasive devices include: rigid laryngoscopic blades of alternative designs, introducers, bougies, stylets, alternative tracheal tubes, flexible intubation scopes, supraglottic airways, lighted/optical stylets 1
• Limit attempts and be aware of passage of time and oxygen saturation 1
• Provide and test mask ventilation after each attempt when feasible 1
• Limit total attempts to avoid injury and complications 1, 4

If difficulty encountered with individual techniques, use combination techniques 1:

• Direct or video laryngoscopy combined with optical/video stylet, flexible scope, airway exchange catheter, retrograde-placed guide wire, or supraglottic airway placement 1

Emergency "Cannot Intubate, Cannot Ventilate" Protocol

When invasive airway necessary 1:

• Call for help immediately 1
• Attempt supraglottic airway if mask ventilation inadequate 1
• Perform emergency invasive airway as rapidly as possible by individual trained in invasive techniques 1
• Techniques include: surgical cricothyrotomy, needle cricothyrotomy with pressure-regulated device, large-bore cannula cricothyrotomy, or surgical tracheostomy 1
• Consider rigid bronchoscopy and ECMO 1
• If selected approach fails or not feasible, identify alternative invasive intervention 1

Laryngospasm Management

Immediate treatment sequence 1, 5:

1. Call for help 1, 5
2. Apply continuous positive airway pressure with 100% oxygen using reservoir bag and facemask while ensuring upper airway patent 1, 5
3. Larson's manoeuvre: Place middle finger in 'laryngospasm notch' between posterior mandible and mastoid process while jaw thrusting 1
4. Propofol 1-2 mg/kg IV if laryngospasm persists and/or oxygen saturation falling 1, 5
5. Succinylcholine 1 mg/kg IV for worsening hypoxia with severe laryngospasm or total cord closure unresponsive to propofol 1, 5
6. Alternative routes without IV access: intramuscular (2-4 mg/kg), intralingual (2-4 mg/kg), or intraosseous (1 mg/kg) 1, 5
7. Atropine may be required for bradycardia 1
8. In extremis, consider surgical airway 1

Avoid unnecessary airway stimulation during treatment as this worsens laryngospasm 1, 5

Confirmation of Tube Placement

Confirm tracheal intubation using 1, 2:

• Waveform capnography or end-tidal CO₂ monitoring (100% sensitivity and specificity, most reliable method) 1, 2
• Continuous waveform capnography in addition to clinical assessment 2
• Colorimetric CO₂ detectors as initial confirmation when waveform capnography unavailable 2

When uncertain about tube location, determine whether to remove and attempt ventilation or use additional confirmation techniques 1

Critical Pitfalls to Avoid

Do not make these errors 1, 5, 4:

• Multiple repeated intubation attempts causing laryngeal edema or hemorrhage 4, 6
• Failure to recognize and escalate treatment promptly in laryngospasm 5
• Proceeding after induction when both difficult intubation AND difficult ventilation predicted 1, 4
• Dosing obese patients based on ideal rather than actual body weight 3
• Using rocuronium for rapid sequence in Cesarean section 3
• Delaying call for help in "cannot intubate, cannot ventilate" situation 1

Special Considerations for Infectious Patients

For COVID-19 or high-risk infectious patients 2:

• Perform intubation in airborne isolation room 2
• Use appropriate PPE: fit-tested N95 mask, protective whole-body garment, two layers of gloves, goggles/face shield, waterproof gown 2
• Install high-efficiency breathing circuit filters between mask and circuit 2
• Minimize number of personnel present 2
• Use videolaryngoscopy to increase distance between patient's airway and operator 2