Difficult Airway Algorithms

OVERVIEW

• Difficult airway algorithms are useful for considering all the contingencies that may occur during intubation
• All team members must be aware of all of the contingency plans
• All intubation attempts should be considered potential difficult airways
• Algorithms involve a step-wise approach using different techniques for difficult intubation and difficult ventilation

TECHNIQUES

Techniques for difficult intubation

• Alternative laryngoscope blades
• Awake intubation (either video laryngoscope or fiberoptic scope)
• Blind intubation (oral or nasal)
• Fiberoptic intubation
• Intubating stylet or tube changer (e.g. Cook catheter or bougie)
• Laryngeal mask airway as an intubating conduit
• Light wand
• Retrograde intubation
• Invasive airway access

Techniques for Difficult Ventilation

• Esophageal tracheal Combitube
• Intratracheal jet stylet
• Laryngeal mask airway
• Oral and nasopharyngeal airways
• Rigid ventilating bronchoscope
• Invasive airway access
• Transtracheal jet ventilation
• Two-person mask ventilation

LEVITAN AIRWAY ALGORITHM

Patient safety using RSI hinges on a redundancy of safety.

• Can you intubate? If intubation fails, can you ventilate? Algorithm (above) focuses on the route of intubation and RSI decision.

The colored arrows are contraindications to RSI.

• In cardiac arrest (blue box – patient apneic) muscle relaxants are not needed. When there is obvious oral pathology, or intrinsic laryngo-tracheal pathology (green boxes – patient breathing spontaneously), the redundancy of safety does not exist – avoid RSI.
• When the mouth is blocked (step 2), intubate through the nose or through the neck (cricothyroidotomy). RSI is specifically done to optimize laryngoscopy conditions and permit oral intubation. If it is apparent that the oral route has obvious anatomic problems (not merely potential difficulty), RSI should never be considered.
• When the oral route is impossible, intubation will need to take place through the nose or neck, and this should be done with the patient awake.
• Examples include massive angioedema, advanced Lundwig’s angina, wired jaw, or readily apparent combinations of airway distortion, disproportion, and dysmobility (cervical spine and mandible), that preclude oral intubation. With intrinsic laryngeal pathology (step 3), safest approach is with the patient breathing spontaneously, using fiberoptic intubation, or a surgical airway (tracheotomy) below the level of the lesion.

At step 4, the decision to use RSI is a matter of judgment, not a strict contraindication.

• The four Ds (distortion, disproportion, dysmobility, dentition) may make direct laryngoscopy with standard equipment impossible.
• Is an “awake” approach feasible? Will you be able to rescue ventilate? How fast are intubation and patient control needed? What are the risks of delay vs. the potential risks of RSI?

After crossing the RSI line, patient safety often depends on first pass success at laryngoscopy, since many patients requiring emergent intubation have very short safe apneic periods.

• Pre-oxygenation is only marginally effective in critically ill patients.

STRAYER AIRWAY ALGORITHM

• RSI vs. Awake – latter preferred if:
  • Less urgent intubation
  • More difficult airway features
  • Low risk of vomiting
• Prepare for failure of intubation and failure of ventilation
  • Discuss plan A, B, C, D with team
  • Equipment for plan A, B, C, D at bedside
• Airway attempt successful -> post-intubation management
• Airway attempt unsuccessful, able to ventilate -> Plan B/C/D
  • change patient position
  • change blade
  • change modality (e.g. direct vs video laryngoscopy)
  • change proceduralist
• Airway attempt unsuccessful, unable to ventilate -> supraglottic airway -> surgical airway if unsuccessful -> post-intubation management

WALLS AIRWAY ALGORITHMS

Ron Wall’s algorithms from his Airway Course and Manual of Emergency Airway Management:

AUSTIN HOSPITAL AIRWAY ALGORITHMS

Algorithms from the Austin Hospital ED, Melbourne, courtesy of George Douros. Here’s the RSI pre-intubation checklist

Here’s the difficult airway action plan

THE VORTEX APPROACH

Nicholas Chrimes and Peter Fritz have developed an algorithmic approach to airway management based on a cognitive aid called ‘The Vortex’

DIFFICULT AIRWAY SOCIETY ALGORITHM

The Difficult Airway Society in the UK has comprehensive guidelines for airway management, including multiple algorithms.

• The integrated algorithm can be downloaded here (pdf).
• the Austin Hospital’s algoirthm by George Douros above, is a modified version of the DAS integrated algorithm – note that the option of waking the patient up has been removed for ‘out-of-theatre’ use!

References and Links

Journal articles

• Apfelbaum JL, et al; American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology. 2013 Feb;118(2):251-70. PMID: 23364566. [Free Full Text]
• Henderson JJ, Popat MT, Latto IP, Pearce AC; Difficult Airway Society. Difficult Airway Society guidelines for management of the unanticipated difficult intubation. Anaesthesia. 2004 Jul;59(7):675-94. PMID: 15200543.

FOAM and web resources

• Airwaycam.com — Algorithms for Emergency Airway Management
• DIFFICULT AIRWAY SOCIETY (United Kingdom) GUIDELINES
• DAS — Update on new DAS Guidelines 2015
• EMCrit Podcast 47 – Failure to Plan for Failure: A Discussion of Airway Disasters
• EMCrit 92 — EMCrit Intubation Checklist
• Emergency Medicine Updates — Emergency Department Intubation Checklist v13 (2012)
• Emergency Medicine Updates — ED Procedural Sedation and Analgesia Checklist
• Own the Airway! (LITFL collection of online airway videos)
• Project Check — Checklist for Checklist Development
• Resus.ME — Anaesthesia’s dirty laundry – let’s all learn from it
• Resus.ME — Inutbation checklist
• The Vortex Approach