Today, I link to, review, and excerpt from Difficult Airway Society guidelines for awake tracheal intubation (ATI) in adults [PubMed Abstract] [Full-Text HTML] [Full-Text PDF]. Anaesthesia. 2020 Apr;75(4):509-528. doi: 10.1111/anae.14904. Epub 2019 Nov 14.
All that follows is from the above resource.
Summary
Awake tracheal intubation has a high success rate and a favourable safety profile but is underused in cases of anticipated difficult airway management. These guidelines are a comprehensive document to support decision making, preparation and practical performance of awake tracheal intubation. We performed a systematic review of the literature seeking all of the available evidence for each element of awake tracheal intubation in order to make recommendations. In the absence of high‐quality evidence, expert consensus and a Delphi study were used to formulate recommendations. We highlight key areas of awake tracheal intubation in which specific recommendations were made, which included: indications; procedural setup; checklists; oxygenation; airway topicalisation; sedation; verification of tracheal tube position; complications; management of unsuccessful awake tracheal intubation; post‐tracheal intubation management; consent; and training. We recognise that there are a range of techniques and regimens that may be effective and one such example technique is included. Breaking down the key practical elements of awake tracheal intubation into sedation, topicalisation, oxygenation and performance might help practitioners to plan, perform and address complications. These guidelines aim to support clinical practice and help lower the threshold for performing awake tracheal intubation when indicated.
Keywords: airway management, bronchoscopy, laryngoscopy, tracheal intubation, training, videolaryngoscopy
Recommendations
Why were these guidelines developed?
Awake tracheal intubation (ATI) has a high success rate and a low‐risk profile and has been cited as the gold standard in airway management for a predicted difficult airway. However, ATI is reported to be used in as few as 0.2% of all tracheal intubations in the UK 1. There are barriers preventing broad uptake and use of awake techniques for securing the airway. We aimed to produce generalisable guidelines to improve patient safety by making ATI more accessible to all clinicians, trainers and institutions. Rather than inform expert practice, these guidelines aim to support the use of ATI by more clinicians, with a particular focus on those that do not regularly perform ATI. There remains heterogeneity in clinical practice, underscoring the need for a more consistent approach using the available evidence, which these guidelines aim to deliver.
Disclaimer
These guidelines are not intended to represent a minimum standard of practice, nor are they to be regarded as a substitute for good clinical judgement. They present key principles and suggested strategies for preparation, performance, consent and training to inform clinical practice. This document is intended to guide appropriately trained operators.
Introduction
A strategy for difficult airway management is necessary when facemask ventilation, supraglottic airway device (SAD) placement or ventilation, tracheal intubation or insertion of a front‐of‐neck airway (FONA) is predicted to be challenging. The incidence of difficult facemask ventilation is 0.66–2.5% 14, 15, 16, 17, difficult SAD placement or ventilation 0.5–4.7% 18, 19, 20, 21, 22, difficult tracheal intubation 1.9–10% 14, 16, 23, 24, 25 and combined difficulty in both facemask and tracheal intubation 0.3–0.4% 16. As a rescue technique after failed tracheal intubation, one study reported that SADs have a success rate as low as 65% in difficult airway management 26. The reported incidence of requirement for emergency FONA and death due to airway management are 0.002–0.07% (1:50,000–1:1400) 1, 27, 28 and 0.0006–0.04% (1:180,000–1:2800), respectively 1, 28. The risk and severity of adverse outcomes during difficult airway management is highlighted by the plethora of guidelines and cognitive aids for airway rescue 29.
Awake tracheal intubation involves placing a tracheal tube in an awake, spontaneously‐breathing patient, most commonly with flexible bronchoscopy (ATI:FB) or videolaryngoscopy (ATI:VL, Table 1). This allows the airway to be secured before induction of general anaesthesia, avoiding the potential risks and consequences of difficult airway management in an anaesthetised patient 30.
Awake tracheal intubation has a favourable safety profile because both spontaneous ventilation and intrinsic airway tone are maintained until the trachea is intubated 31, 32, 33, 34, 35. Awake tracheal intubation can be unsuccessful in 1–2% of cases, but this rarely leads to airway rescue strategies or death 33, 34, 35. These guidelines aim to increase the use of ATI by providing clear guidance for clinicians to support decision making, preparation and performance of ATI in the setting of a predicted difficult airway.
Indications
Prediction of difficult airway management is unreliable 14, 23, 42, but there are common features that have been identified in patients requiring ATI. These include, but are not limited to: patients with head and neck pathology (including malignancy, previous surgery or radiotherapy); reduced mouth opening; limited neck extension; obstructive sleep apnoea; morbid obesity; and progressive airway compromise 32, 33, 35, 43, 44. There is limited evidence for any individual, validated, predictive assessment tool developed specifically for ATI. Airway assessment including history, examination and appropriate investigations, is indicated for all patients 1, 2, 7, 45 (Grade D). Awake tracheal intubation must be considered in the presence of predictors of difficult airway management (Grade D). In an elective setting the patient should be appropriately fasted (Grade D). In the non‐fasted patient, the potential for regurgitation or aspiration of gastric contents still exists even with ATI. There are few relative contra‐indications to ATI (e.g. local anaesthetic allergy, airway bleeding, unco‐operative patients) but the only absolute contra‐indication is patient refusal.
Procedural setup
Awake tracheal intubation can be associated with the greatest operator‐related physical, mental and psychological stress of all elective airway management interventions 46. These stressors may be associated with suboptimal performance 47, 48, increasing the risk of complications including failure.
When ATI is performed outside of the theatre environment (e.g. in the critical care unit or the emergency department), the same standards of care should apply (Grade D) 52.
Monitoring patients’ physiological parameters during anaesthetic care mitigates risks and may alert operators to impending complications 53, 54, 55, 56, 57.
In accordance with Association of Anaesthetists’ guidelines for patients receiving sedation 62, it is recommended that ECG, non‐invasive blood pressure, pulse oximetry and continuous end‐tidal carbon dioxide monitoring are used throughout the process of ATI (Grade C). It is acknowledged that end‐tidal carbon dioxide monitoring during ATI may be challenging in current practice.
There is no consensus on the ideal operator or patient position 64, 65, 66, 67, but there are physiological and anatomical advantages to having patients sitting up 68, 69, 70.
Complications or unsuccessful ATI, although uncommon, should be prepared for 33, 34, 35, and immediate access to emergency drugs, staff and equipment is essential (Grade C). A plan for unsuccessful ATI, including possible postponement, FONA or high‐risk general anaesthesia, should be discussed explicitly and agreed on by all team members before beginning the procedure (Grade D).
It is important to select an appropriate route for tracheal intubation, visualisation device and tracheal tube.
Awake tracheal intubation using videolaryngoscopy has a comparable success rate and safety profile to ATI:FB (98.3% each) 31. Choosing between techniques is based on patient factors, operator skills and availability of equipment (Grade A). For example, in patients with limited mouth opening, a large tongue or fixed flexion deformity of the neck, ATI:FB may be more appropriate. Conversely, patients with airway bleeding may be more suitable for an ATI:VL technique. If the chosen ATI technique is unsuccessful, practitioners should consider using an alternative (e.g. ATI:FB if ATI:VL is unsuccessful or vice versa; Grade D). A combined approach to ATI using both VL and FB has been described 72, 73, 74 and could be considered in complex clinical scenarios (Grade D). In a well‐topicalised patient, insertion of an SAD as a conduit for ATI:FB has also been described 75, 76, and may provide the benefit of maintaining airway patency. Single‐use flexible bronchoscopes are associated with a similar safety profile to re‐usable ones 77. Operators should defer to local availability and personal experience in determining which flexible bronchoscope to use (Grade B). There is currently no evidence or consensus to support the safety or efficacy of any individual videolaryngoscope. For ATI:VL practitioners should use videolaryngoscopes with which they are most familiar (Grade B).
Careful selection of tracheal tube is integral to the success of any ATI technique. This should factor in size (internal and external diameter), shape, length, tip design and material. For ATI:FB, reinforced, Parker Flex‐Tip™ (Bridgewater, CN, USA) and intubating laryngeal mask airway tubes (LMA® Fastrach™ ETT, Teleflex, Beaconsfield, UK) have been shown to be superior to standard polyvinylchloride (PVC) tracheal tubes in terms of ease of tracheal intubation, railroading (advancing the tracheal tube over the flexible bronchoscope) and decreasing laryngeal impingement 78, 79, 80, 81, 82, 83, 84, 85, 86. Therefore, the use of a standard PVC tracheal tube is not recommended (Grade A). Using the smallest appropriate external diameter tracheal tube is advisable, as this may reduce the incidence of impingement 87 (Grade B). Positioning the bevel of the tracheal tube posteriorly is recommended 80, 82, 86 (Grade A). For ATI:VL, tracheal tube selection is similar to that in an asleep patient and is influenced by the VL selected.
Careful selection of tracheal tube is integral to the success of any ATI technique. This should factor in size (internal and external diameter), shape, length, tip design and material. For ATI:FB, reinforced, Parker Flex‐Tip™ (Bridgewater, CN, USA) and intubating laryngeal mask airway tubes (LMA® Fastrach™ ETT, Teleflex, Beaconsfield, UK) have been shown to be superior to standard polyvinylchloride (PVC) tracheal tubes in terms of ease of tracheal intubation, railroading (advancing the tracheal tube over the flexible bronchoscope) and decreasing laryngeal impingement 78, 79, 80, 81, 82, 83, 84, 85, 86. Therefore, the use of a standard PVC tracheal tube is not recommended (Grade A). Using the smallest appropriate external diameter tracheal tube is advisable, as this may reduce the incidence of impingement 87 (Grade B). Positioning the bevel of the tracheal tube posteriorly is recommended 80, 82, 86 (Grade A). For ATI:VL, tracheal tube selection is similar to that in an asleep patient and is influenced by the VL selected.
Checklists
In the peri‐operative setting the use of cognitive aids, such as checklists, improves inter‐professional communication, teamwork and patient outcomes 88, 89, 90, 91. In anaesthetic practice, cognitive aids enhance performance in simulated emergency scenarios 92, 93, and their use been recommended in elective airway management 1. Given the potential benefits, we recommend a cognitive aid such as a checklist before and during performance of ATI (Grade D; Supporting Information, Appendix S2). The key components of ATI are sedation, topicalisation, oxygenation and performance (sTOP; Fig. 2). The ‘s’ is in lower case to emphasise the optional nature of sedation.
[Remember that muscle tone may be critical to maintaining a problematic 0pen airway and that sedation may disasterously minimize muscle tone.]
Oxygenation
The reported incidence of desaturation (SpO2 ≤ 90%) with low‐flow (< 30 l.min−1) oxygen techniques during ATI ranges between 12% and 16% 58, 94, 95. When warmed and humidified high‐flow nasal oxygen is used, the reported incidence of desaturation is 0–1.5% 33, 96; this was the most common oxygenation strategy used by experts responding to our survey. Although there are no randomised controlled trials comparing air vs. oxygen during ATI, data from bronchoscopy studies demonstrate that there is a significant difference in the incidence and severity of desaturation 97, 98. In patients receiving sedation in a variety of settings, administration of oxygen has been shown to reduce the incidence of desaturation when compared with air 97, 99, 100, 101, 102. United Kingdom, European and North American recommendations for sedation all suggest the use of supplemental oxygen 103, 104, 105. Whilst airway topicalisation alone may rarely be associated with desaturation and airway obstruction 59, 106, there is no significant difference in the incidence of desaturation between ATI:FB and ATI:VL techniques, and therefore the recommendations apply to both approaches 31. The administration of supplemental oxygen during ATI is recommended (Grade B). This should be started on patient arrival for the procedure and continued throughout (Grade D). If available, high‐flow nasal oxygen should be the technique of choice (Grade C).
