Plan A

This skill station covers:

Tracheal intubation (TI) is a core skill in critical care. CICM and ACEM Fellows report that they don’t perform the procedure often enough to maintain their confidence, and all critical care practitioners including anaesthetists worry about how they will manage in a difficult airway scenario.

For senior practitioners, years may have elapsed since they received supervised training in laryngoscopy. Theory, training techniques and airway equipment have all changed over the last decade. The CCAM Team has deconstructed laryngoscopy and tracheal intubation, taking all these changes into account, describing how the two-curve theory can be used to guide a three-stage, deliberate approach to TI.

Pre-oxygenation: There is emerging evidence that non-invasive ventilation may be superior for pre-oxygenation. If NIV is not used, pre-oxygenation should comprise head-up positioning, a tight-fitting face mask with PEEP and careful ventilation during the onset of neuromuscular blockade.

Videolaryngoscopy: There is good evidence that VL is superior to direct laryngoscopy. It should be used routinely for the first attempt at tracheal intubation.

Introducers: There is good evidence that the use of a bougie or stylet improves intubation success in critically ill patients. The BOUGIE trial, a multicenter, unblinded, randomised investigation involving 1106 critically ill adults undergoing first-attempt tracheal intubation, found no statistically significant difference in first-pass success rates between the bougie group and the stylet group.

Cricoid force: There is insufficient evidence to advise for or against the use of cricoid force. If it is used, it should be released in case of difficulty with airway management.

Apnoeic Oxygenation: There is no evidence to support the use of apnoeic oxygenation during attempts at intubation.

Known or suspected cervical spine injury: Patients should be positioned in a head-neutral position, which usually requires the use of an occipital pad/pillow. Cervical collars interfere with laryngoscopy and should be removed. The use of manual in-line stabilisation increases the difficulty of tracheal intubation and there is little evidence that it decreases secondary spinal cord injury. It should be removed in cases of difficult airway management.

Flattening the Curves – Airway Manoeuvres

A video showing the effect on the airway of lower cervical spine flexion

Acknowledgement: AIME Airway

Dynamic MRI showing the effect on the airway of upper cervical spine extension

Acknowledgement: Chris Kelly

Flattening the Curves – Laryngoscopy

Direct and standard VL blades flatten the primary curve by compressing and displacing the tongue. Lifting these blades in the axis of the handle helps to flatten the vestibule axis and secondary curve.

Hyperangulated VL (HAVL) blades follow the primary curve and do not significantly alter its shape. Lifting these blades vertically helps to flatten the vestibule axis and the secondary curve.

Comparative Analysis of Standard and Hyperangulated Blade Video laryngoscopes

Flattening the Curves – External Laryngeal Manipulation (ELM)

In some patients, ear-to-sternal notch positioning is limited.

In these cases, an up-sloping vestibule axis can be flattened using external laryngeal manipulation (also known as bimanual laryngoscopy), which can improve visualisation of the glottis and facilitate passage of the tube.

Stage 1: Laryngeal Exposure

• During stage 1, we are essentially negotiating the primary curve around the tongue. This is done in different ways depending on the device used (see Table below).
• Epiglottoscopy – the first landmark is the epiglottis
• Lift the epiglottis – gain a view of the glottis by either lifting the epiglottis directly (straight blade) or by deploying the hyo-epiglottic ligament with pressure in the vallecula (all other devices).
• Optimise view – lift the tongue and other anterior column tissues with upward force in the axis of the handle of the laryngoscope, or vertically if using hyperangulated videolaryngoscopy (HAVL).
• Optimise view – external laryngeal manipulation (not BURP – Back Up Right Pressure): intubator uses right hand to manipulate the larynx into view, assistant then holds larynx in the same position
• Optimise view – head lift
• Optimise VL view – create view with glottis in top half of screen – back off, tilt down (especially for HAVL).

Stage 2: Delivery of the Tube or Bougie to the Glottic Opening

• Performing stage 2 also depends on the device used: standard geometry and straight blade laryngoscopes, which flatten or bypass the primary curve, allow for tube delivery without an introducer
• For HAVL devices, which follow the primary curve, a curved introducer is mandatory (exception: channelled devices)
• During HAVL, place the glottis in the top half of the screen. This allows for visualisation of the tube or bougie approaching from below and eases their passage towards the glottis (by flattening the secondary curve).

The table below summarizes the use of different laryngoscopes across the first two stages of tracheal intubation:

Stage 3: Advancing the tube or bougie into the trachea

• Stage 3 offers pitfalls depending on the device used: during HAVL, the tube or bougie approaches the glottis at an angle where it is likely to impact on the anterior tracheal wall
• Bimanual laryngoscopy can flatten the vestibule axis, facilitating tube advancement
• Tube delivery is also helped by turning bevelled tubes 90 degrees clockwise at the level of the vocal cords (‘Right Turn for Rings’), and reverse loading of the tracheal tube onto a stylet.
• If the tube won’t pass over the bougie, rotate 90 degrees anti-clockwise (Bougie Left Turn, BLT), the chances are the bevel is stuck in the right piriform fossa

Should ongoing airway education be a mandatory component of continuing professional development for College of Intensive Care Medicine Fellows? – Brewster et al 2018.

Cochrane review: Videolaryngoscopy versus direct laryngoscopy for adults undergoing tracheal intubation.

Tracheal intubation in critically ill adults with a physiologically difficult airway. An international Delphi study.

Oxygenation during the apnoeic phase preceding intubation in adults in prehospital, emergency department, intensive care and operating theatre environments.