# Difficult Airway Management

## Overview

This module describes how to manage a patient who is difficult to intubate or ventilate. Most of these cases may be recognised early by a pre-operative assessment, or during emergency assessment. The unanticipated difficult airway is rare, but may rapidly become urgent.

## Indications

1. Any patient who has failed initial attempts at intubation

## Contraindications

1. None

## Patient information & consent

Patients with an anticipated difficult airway should be informed of the additional risks they face and consent for potential additional procedures obtained. In patients with an unanticipated difficult airway, the procedure is emergent and consent is inferred, unless “Do Not Resuscitate” (DNR) orders, “Not For Max” orders, or living wills that specify that no resuscitation may be performed are present.

## Preparation

During the pre-operative assessment, evaluate risk factors generally, and using airway assessment tests.

### General Risk Factors

Suspect difficulty ventilating if:

1. Bearded
2. Obese
3. No teeth
4. Elderly
5. Snorer
6. Facial anatomical abnormalities

Suspect difficulty intubating if:

1. History of difficult intubation
2. Protruding upper incisors
3. Large tongue
4. Small mandible
5. Short neck
6. Obesity
7. Restricted neck motility
8. TMJ limitation
9. Stridor
10. Facial trauma or burns
11. Previous radiotherapy to head and neck

### Airway Assessment Tests

1. Mallampati Scale

The visibility of the patient’s uvula and palate is assessed while they are sitting with their head in neutral and the mouth open.

- Class I: the soft palate, uvula, and pillars are visible
- Class II: the soft palate and the uvula are visible
- Class III: only the soft palate and base of the uvula are visible
- Class IV: only the hard palate is visible

2. Mouth Opening

Ask the patient to insert three fingers vertically into the mouth to assess mouth opening. An inability to do so is a risk factor for a difficult airway.

3. Lower Jaw Motility

Ask the patient to protrude/shift forward their lower jaw. An inability to protrude the lower jaw beyond the upper jaw is a risk factor for a difficult airway.

4. Neck Motility

Ask the patient to flex and extend their neck. Reduced motility is a risk factor for a difficult airway.

5. Thyromental Distance

Measure the distance between the thyroid prominence (Adam’s apple) and the tip of the chin with the neck extended. A distance < 7 cm is a risk factor for a difficult airway.

If a difficult airway is suspected, an experienced practitioner should perform the intubation, video laryngoscopy should be made available, and preparations made for alternative measures, e.g. awake intubation should be considered. The patient should be evaluated for ease of emergency invasive airway access.

#### Equipment

A difficult airway trolley containing a variety of

supraglottic airway devices

supraglottic airway devices

1st Generation SAD: simple breathing tube, usually with some form of mask or opening at the larynx. Examples: the Classic LMA is most common.

2nd Generation SAD: includes provision for gastric drainage and improved protection against aspiration. Examples: Proseal LMA, LMA-Supreme, and i-gel are most common in South Africa.

(SAD)

## Site & Positioning

The patient should be in the “sniffing” position, with the ear aligned to the sternal notch. This may require building a ramp with pillows and blankets to raise the patient’s head.

## Procedure

Use medical asepsis with non-sterile gloves. Follow the DAS guidelines: call for help and proceed, starting with step 1.

1. Attempt facemask ventilation and tracheal intubation

   1. Optimise head and neck position
   2. Preoxygenate
   3. Administer neuromuscular blockade
   4. Attempt direct/video laryngoscopy (maximum 3+1 attempts)
   5. Attempt external laryngeal manipulation
   6. Use a bougie
   7. Remove cricoid pressure if used
   8. Maintain oxygenation and anaesthesia

   If successful: confirm tracheal intubation with capnography.

   If unsuccessful: declare failed intubation and proceed to step 2.

2. Insert supraglottic airway device (SAD)

   - Use a 2nd generation device
   - Consider changing the device or size (maximum 3 attempts)
   - Oxygenate and ventilate

   If successful: Options (consider risks and benefits):

   1. Wake the patient up
   2. Intubate trachea via the SAD
   3. Proceed without intubating the trachea
   4. Tracheostomy or cricothyroidotomy

   If unsuccessful: Declare failed SAD ventilation and proceed to step 3.

3. Attempt facemask ventilation

   1. If facemask ventilation fails, administer paralytic
   2. Attempt facemask ventilation once more (final attempt), using two-person technique and adjuncts

   If successful: wake patient up

   If unsuccessful: Declare Can’t Intubate, Can’t Oxygenate (CICO) and proceed to step 4.

4. Obtain emergency front-of-neck access:

   - Continue to give oxygen via upper airway
   - Ensure neuromuscular blockade
   - Position patient to extend neck
   - Assemble equipment:
     - Scalpel (no. 10)
     - Bougie
     - Lubricated tube (cuffed size 6)
   - Identify cricothyroid membrane

   If cricothyroid membrane is palpable:

   - Make a transverse stab incision through the cricothyroid membrane.
   - Turn blade 90° (sharp edge caudally).
   - Slide the bent coude tip of bougie along blade into trachea.
   - Railroad lubricated tube into trachea.
   - Ventilate, inflate cuff and confirm position with capnography.
   - Secure tube.

   If cricothyroid membrane is impalpable:

   - Make an 8-10cm vertical skin incision, caudad to cephalad.
   - Use blunt dissection with fingers of both hands to separate tissues.
   - Identify and stabilise the larynx.
   - Proceed with technique for palpable cricothyroid membrane as above

## Troubleshooting

I am unsure about alternative methods of endotracheal intubation.

Alternative methods include video laryngoscopy, using different laryngoscope blades, intubating through a supraglottic airway, fibre optic intubation, using a stylet, and blind intubation.

## Risks

1. Hypoxic brain injury
2. Cardiac arrest ± death due to hypoxia
3. Damage to dentition
4. Airway injuries
5. Aspiration & resultant pneumonia

## References

1. American Society of Anesthesiologists. Practice guidelines for management of the difficult airway: An updated report. Anesthesiology. 2013; 118(2).
2. Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth. 2015;115(6):827-848. doi:10.1093/bja/aev371. Available at https://das.uk.com/guidelines/das_intubation_guidelines