Question 3

College Answer

Initial management should ensure assessment and management of airway, breathing and circulation, as well as level of consciousness.   Must be prepared for difficult intubation (essential equipment should be listed, checked and ready; adequate skilled assistance should be present; backup plans are essential).   Specific plan should be elucidated with relation to reason for difficult intubation (eg. limited mouth opening, versus high anterior larynx etc.).  Main difficulty is that bag-valve-mask ventilation  or laryngeal  mask ventilation  may be impossible.   The use of facemask  CPAP may provide some time if not contraindicated by deteriorating neurologic state.  Bronchoscopic or blind nasal intubation may be reasonable if operator adequately skilled in techniques.   Paralysis may otherwise be essential.  Early resort to surgical airway may be appropriate if problems develop.

Discussion

This question is another one of those "how do you manage a difficult airway" questions.

The answer would need to be systematic.

History

• Why is the patient a difficult intubation?
  Look through previous anaesthetic records, if time permits.
• Why does the patient need intubation?
  This step helps assess the likely complications (eg. in Question 1c from the first paper of 2004 the patient is having emergency gastroscopy for an upper GI bleed, and the likely complications inevitably include aspiration).

Examination

• Assess for difficulty of intubation, to determine which specific features were problematic.
• Assess for difficulty of bag-mask ventilation.
  This is all discussed in the chapter on recognising the difficult airway.
• Look at the most recently available ABG or venous biochemistry: specifically, the PaCO₂ helps determine the dose of anaesthetic induction agent, and the serum K⁺ level helps select the muscle relaxant.

Planning

• Decide beforehand what the algorithm is going to be, depending on what is available locally.
• Have a plan for intubation
• Have a plan for oxygenation
• Have a backup plan (or two) for each
• Have a clear idea of what the locally available cricothyroidotomy kit looks like and roughly how long it takes to set up (given that pretty much all of the algorithms lead to cutting the throat).

Preparation of the staff

• Choose a competent assistant to assist with the airway: somebody who knows what BURP is and how to correctly do cricoid pressure
• Choose a competent assistant to give drugs
• Assign a staff member to act as “access”, i.e. somebody to run around and get equipment
• Inform standby staff to be ready (eg. inform ENT surgeon, senior anaesthetist)
• Discuss the plan with the team to ensure everyone is aware of what is going to happen (eg.  “OK people, Plan A is videolaryngoscopy with bougie, Plan B is Fastrach”).

Preparation of the equipment

• Plan A equipment should be ready for use
• Plan B equipment should be available within 60 seconds (which means, in the room, within arm’s reach, and wherever possible unwrapped and lubricated).
• Drugs should be drawn up, including a couple of adrenaline ampoules in case CPR becomes a part of the rapid sequence induction.
• An end-tidal CO2 monitor should be within reach
• The equipment should be checked, and its operability ensured (i.e. those CMAC batteries better be charged).

Specific equipment (the contents of the difficult intubaton trolley)

• A selection of oropharyngeal airways
• A selection of nasopharyngeal airways
• Macintosh laryngoscope blades size 3 and 4.
• Alternative laryngoscope blades (eg. a Kessel blade)
• A short laryngoscope handle (for fat or big-breasted people)
• An endotracheal tube introducer
• A malleable blunt atraumatic stylet.
• Normal LMAs of different sizes
• Intubating LMA kids, eg. Fastrach
• A selection of specialised ETTs, eg. long flexometallic, nasal, etc.
• A long airway exchange catheter.
• A surgical cricothyroidotomy kit
• A kink resistant cricothyroidotomy cannula and jet ventilation kit
• A capnograph, capnometer or colorimetric end-tidal CO₂ detector.

Preparation of the patient

• Explain to the patient what the plan is (if they are conscious and capable of processing this information, it would be helpful to have them on your side).
• Commence high flow oxygen
• Preoxygenate for a minimum of 3 minutes. The utility of this is debated.
• During this time, either position the patient for intubation, or (if they cannot tolerate that position) prepare equipment and assistants to put them into that position as soon as the induction is commenced.

ANZCA have a statement on the equipment which should be available to manage a difficult airway.

Nørskov, Anders Kehlet, et al. "Diagnostic accuracy of anaesthesiologists’ prediction of difficult airway management in daily clinical practice: a cohort study of 188 064 patients registered in the Danish Anaesthesia Database." Anaesthesia 70.3 (2015): 272-281.

Apfelbaum, Jeffrey L., et al. "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." The Journal of the American Society of Anesthesiologists 118.2 (2013): 251-270.

Frerk, C., et al. "Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults." British journal of anaesthesia 115.6 (2015): 827-848.

Heidegger, T. "The 2015 Difficult Airway Society guidelines: what about the anticipated difficult airway." Anaesthesia 71 (2016): 592-3.

Law, J. Adam, et al. "The difficult airway with recommendations for management–part 2–the anticipated difficult airway." Canadian Journal of Anesthesia/Journal canadien d'anesthésie 60.11 (2013): 1119-1138.

Walls, Ron M., and Michael Francis Murphy, eds. Manual of emergency airway management. Lippincott Williams & Wilkins, 2008.

Lim, M. S., and J. J. Hunt-Smith. "Difficult airway management in the intensive care unit: Practical guidelines." (2003): 43.

Caldiroli, D., and P. Cortellazzi. "A new difficult airway management algorithm based upon the El Ganzouri Risk Index and GlideScope® videolaryngoscope: a new look for intubation." Minerva Anestesiol 77.10 (2011): 1011-1017.

El-Ganzouri, Abdel Raouf, et al. "Preoperative airway assessment: predictive value of a multivariate risk index." Anesthesia & Analgesia 82.6 (1996): 1197-1204.

Zaouter, C., J. Calderon, and T. M. Hemmerling. "Videolaryngoscopy as a new standard of care." British journal of anaesthesia 114.2 (2015): 181-183.