Intubation Guidelines for the Critically Ill
In this article, Dr Andy Higgs explains how Human Factors and Ergonomics (HFE) have been included in the Diffficult Airway Society (DAS), Intensive Care Society (ICS), Faculty of Intensive Care Medicine (FICM) and Royal College of Anaesthetists (RCoA) Intubation Guidelines for the Critically Ill.
In the previous step, we learnt how the challenges of airway management in the critically ill are partly due to the patient’s poor physiological reserve but also to logistical and environmental difficulties. Intubation may take place on the intensive care unit itself or almost anywhere else in the hospital, often in remote areas where skilled help and a full range of equipment are not available.
Sometimes there is time to plan and prepare but most airway interventions on ICU involve an urgent call to intubate a rapidly deteriorating patient. Having systems in place to manage the Human Factors and Ergonomics (HFE) aspects of caring for these patients helps communication and teamwork in time-pressured situations, as we will see as we go through Plans A-D of the Intubation Guidelines for the Critically Ill.
Plan A: preparation, oxygenation, induction, mask ventilation and intubation
The guidelines recommend that we use an intubation checklist in all but the most extreme circumstances (e.g. cardiac arrest). The checklist is designed to help us think about the patient, the clinical team, the equipment we might need and to be prepared for difficulties.
Airway team composition and role allocation
The team leader should assign roles and run through the strategy for Plans A, B/C and D. Each team member needs to know who is in charge, what is about to happen, what they have to do. This promotes the importance of teamwork, helps creates a shared ‘mental model’ and helps with clear communication. Roles may depend on the number of team members present, as in this diagram:
Can the patient be woken up?
Before induction of anaesthesia, the team should agree if waking the patient up if the intubation fails is an option. This is often the right choice for anaesthesia but may not be possible if the patient is critically ill.
The guidelines recommend PER-oxygenation.
The term PER-oxygenation describes how to maintain oxygenation throughout the intubation sequence.
Sit the patient as upright as possible to optimise oxygen reserve and functional residual capacity. Give 100% oxygen with a tight-fitting face mask that can deliver continuous positive pressure ventilation (CPAP), use a circuit with an adjustable valve and high oxygen flows of up to 15L/minute. Standard nasal cannulae at 5 L/min, high flow nasal oxygen systems (at up to 60L/minute) and non-invasive ventilation also help increase the time before desaturation.
2. Apnoeic oxygenation
As the patient loses consciousness, continue oxygenation during intubation, increase nasal cannulae flows to 15 L/min or use high flow nasal oxygenation, to prolong the safe apnoea time.
3. Maintenance oxygenation
After a failed attempt at intubation, Bag-Valve-Mask ventilation with CPAP may help re-oxygenate the patient before a second attempt. If cricoid pressure has been applied to protect against aspiration, it should be maintained unless it prevents effective ventilation.
A videolaryngoscope should be available for all intubations of critically ill patients. If difficult laryngoscopy is predicted (MACOCHA score 3 or more) it is advisable to use a videolaryngoscope for the first attempt.
Mallampati score III or IV
Apnoea syndrome (obstructive)
Cervical spine limitation
Opening mouth <3 cm
Scores: from 0 (easy) to 12 (very difficult). Score of 3 or more predicts a difficult airway.
Reproduced with permission of the American Thoracic Society. Copyright © 2019 American Thoracic Society
|Factors related to patient|
|Mallampati class III or IV||5|
|Obstructive Sleep Apnoea Syndrome||2|
|Reduced mobility of Cervical spine||1|
|Limited mouth Opening <3 cm||1|
|Factors related to pathology|
|Severe Hypoxaemia (SpO2 <80%)||1|
|Factor related to operator|
If there is a poor view of the larynx with a direct laryngoscope, use a videolaryngoscope for the next attempt.
During videolaryngoscopy the whole team can see the view. This improves
- external laryngeal manipulation (ELM)
Whilst Plan A follows the traditional DAS approach, 3 intubation attempts plus a single extra attempt by a more experienced clinician are allowed, it recommends that we should not keep trying to intubate the trachea using laryngoscopy if a ‘best effort’ attempt has failed.
A ‘best effort’ is an attempt to intubate which can’t be improved; in other words, the most experienced operator has used the most appropriate laryngoscope under optimal patient conditions (position, use of ELM, paralysis) and with optimal adjuncts, such as a bougie or stylet.
Further attempts at intubation are unlikely to succeed and delay the move to another approach to oxygenation such as supraglottic airway device (SAD) or face-mask (FM) oxygenation.
If critical desaturation occurs attempts to intubate the trachea should be abandoned.
Plan B/C: rescue oxygenation using SAD or FM after failed intubation
In the DAS Difficult Intubation 2015 Guidelines, Plans B and C (oxygenation using SAD and FM, respectively) are separate steps. The DAS Intubation Guidelines for the Critically Ill borrow from The Vortex Approach, so that if plan Plan A has failed, SADs or FMV can be used alternately to maintain oxygen levels.
Plan D: Emergency Front of Neck Airway (eFONA)
The Plan D step, is similar to the DAS Difficult Intubation 2015 Guidelines, but there are some important differences:
In a “Can’t Intubate, Can’t Oxygenate” situation, eFONA with a scalpel cricothyroidotomy technique is an option, percutaneous tracheostomy or a cannula-based technique may also be the first choice.
Also from The Vortex Approach is the concept of ‘Priming for CICO’. Distinct steps which are sequentially reached during unsuccessful attempts to intubate the trachea act as triggers for us to prepare ourselves and the team to perform eFONA.
As we work through the algorithm, the following steps trigger us to think about the possibility that attempts to oxygenate from above may ultimately fail:
- Failure at laryngoscopy
- Failure at a first mode of supraglottic oxygenation (e.g. SAD)
- Failure at a second mode of supraglottic oxygenation (e.g. FM)
How do you feel when you are called to provide urgent support to unstable patients in unfamiliar environments? Do you have access to guidelines or cognitive aids, such as the ones described below, to help you when this happens? Have a look at the whole algorithm. Where can you see that Human Factors and Ergonomics have been included?
© UCL, materials reproduced with permission from the Difficult Airway Society