Difficult Airway Society guidelines for awake tracheal intubation (ATI) in adults

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.

## Recommendations
1 Awake tracheal intubation must be considered in the presence of predictors of difficult airway management.
2 A cognitive aid such as a checklist is recommended before and during performance of awake tracheal intubation.
3 Supplemental oxygen should always be administered during awake tracheal intubation.
4 Effective topicalisation must be established and tested.
The maximum dose of lidocaine should not exceed 9 mg.kg A1 lean body weight. 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 [bib_ref] 4th National Audit Project of the Royal College of Anaesthetists and the..., Cook [/bib_ref]. 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.

## What other guidelines exist?
Although there are many guidelines on unanticipated difficult airway management [bib_ref] Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in..., Frerk [/bib_ref] [bib_ref] Obstetric Anaesthetists' Association and Difficult Airway Society guidelines for the management of..., Mushambi [/bib_ref] [bib_ref] Recommendations for airway control and difficult airway management, Petrini [/bib_ref] [bib_ref] The difficult airway with recommendations for management -Part 1 -Intubation encountered in..., Law [/bib_ref] [bib_ref] Practice guidelines for management of the difficult airway: an updated report by..., Apfelbaum [/bib_ref] [bib_ref] All India Difficult Airway Association 2016 guidelines for the management of unanticipated..., Myatra [/bib_ref] [bib_ref] All India difficult airway association 2016 guidelines for the management of unanticipated..., Ramkumar [/bib_ref] [bib_ref] Difficult intubation and extubation in adult anaesthesia, Langeron [/bib_ref] [bib_ref] Scandinavian SSAI clinical practice guideline on pre-hospital airway management, Rehn [/bib_ref] [bib_ref] S1-Leitlinie Atemwegsmanagement: Leitlinie der Deutschen Gesellschaft f ur An asthesiologie und Intensivmedizin..., Piepho [/bib_ref] [bib_ref] airway management guideline 2014: to improve the safety of induction of anesthesia, Anon [/bib_ref] , there are few that specifically focus on the anticipated difficult airway. The ASA, Canadian Airway Focus Group, French Society for Anesthesia and Intensive Care and German Society for Anesthesiology and Intensive Care describe clinical decision making in the anticipated difficult airway [bib_ref] The difficult airway with recommendations for management -Part 1 -Intubation encountered in..., Law [/bib_ref] [bib_ref] Practice guidelines for management of the difficult airway: an updated report by..., Apfelbaum [/bib_ref] [bib_ref] Difficult intubation and extubation in adult anaesthesia, Langeron [/bib_ref] [bib_ref] S1-Leitlinie Atemwegsmanagement: Leitlinie der Deutschen Gesellschaft f ur An asthesiologie und Intensivmedizin..., Piepho [/bib_ref].
How do these guidelines differ from existing guidelines?
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% [bib_ref] Diagnostic accuracy of anaesthesiologists' prediction of difficult airway management in daily clinical..., Nrskov [/bib_ref] [bib_ref] Prediction of difficult mask ventilation using a systematic assessment of risk factors..., Nrskov [/bib_ref] [bib_ref] Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy:..., Kheterpal [/bib_ref] [bib_ref] Prediction and outcomes of impossible mask ventilation: a review of 50,000 anesthetics, Kheterpal [/bib_ref] , difficult SAD placement or ventilation 0.5-4.7% [bib_ref] Survey of laryngeal mask airway usage in 11,910 patients: safety and efficacy..., Verghese [/bib_ref] [bib_ref] Incidence of and risk factors for difficult ventilation via a supraglottic airway..., Saito [/bib_ref] [bib_ref] A comparison of the i-gel with the LMA-Unique in non-paralysed anaesthetised adult..., Francksen [/bib_ref] [bib_ref] The airway: problems and predictions in 18,500 patients, Rose [/bib_ref] [bib_ref] A randomised comparison of the Portex Softseal TM laryngeal mask airway with..., Cook [/bib_ref] , difficult tracheal intubation 1.9-10% [bib_ref] Diagnostic accuracy of anaesthesiologists' prediction of difficult airway management in daily clinical..., Nrskov [/bib_ref] [bib_ref] Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy:..., Kheterpal [/bib_ref] [bib_ref] Predicting difficult intubation in apparently normal patients: a meta-analysis of bedside screening..., Shiga [/bib_ref] [bib_ref] A documented previous difficult tracheal intubation as a prognostic test for a..., Lundstrm [/bib_ref] [bib_ref] Will this patient be difficult to intubate? the rational clinical examination systematic..., Detsky [/bib_ref] and combined difficulty in both facemask and tracheal intubation 0.3-0.4% [bib_ref] Incidence, predictors, and outcome of difficult mask ventilation combined with difficult laryngoscopy:..., Kheterpal [/bib_ref]. 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 [bib_ref] Supraglottic airway devices in difficult airway management: a retrospective cohort study of..., Thomsen [/bib_ref]. The reported incidence of requirement for emergency FONA and death due to airway management are 0.002-0.07% (1:50,000-1:1400) [bib_ref] 4th National Audit Project of the Royal College of Anaesthetists and the..., Cook [/bib_ref] [bib_ref] Danish Anaesthesia Database. Emergency surgical airway management in Denmark: a cohort study..., Rosenstock [/bib_ref] [bib_ref] A prospective, cohort evaluation of major and minor airway management complications during..., Huitink [/bib_ref] and 0.0006-0.04% (1:180,000-1:2800), respectively [bib_ref] 4th National Audit Project of the Royal College of Anaesthetists and the..., Cook [/bib_ref] [bib_ref] A prospective, cohort evaluation of major and minor airway management complications during..., Huitink [/bib_ref]. The risk and severity of adverse outcomes during difficult airway management is highlighted by the plethora of guidelines and cognitive aids for airway rescue [bib_ref] Difficult airway management algorithms: a directed review, Edelman [/bib_ref].
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, . 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 [bib_ref] Strategies for the prevention of airway complications -a narrative review, Cook [/bib_ref].
Awake tracheal intubation has a favourable safety profile because both spontaneous ventilation and intrinsic airway tone are maintained until the trachea is intubated [bib_ref] Videolaryngoscopy vs. fibreoptic bronchoscopy for awake tracheal intubation: a systematic review and..., Alhomary [/bib_ref] [bib_ref] A study of flexible fiberoptic bronchoscopy aided tracheal intubation for patients undergoing..., Ajay [/bib_ref] [bib_ref] A prospective cohort study of awake fibreoptic intubation practice at a tertiary..., El-Boghdadly [/bib_ref] [bib_ref] The incidence, success rate, and complications of awake tracheal intubation in 1,554..., Law [/bib_ref] [bib_ref] A retrospective study of success, failure, and time needed to perform awake..., Joseph [/bib_ref]. Awake tracheal intubation can be unsuccessful in 1-2% of cases, but this rarely leads to airway rescue strategies or death [bib_ref] A prospective cohort study of awake fibreoptic intubation practice at a tertiary..., El-Boghdadly [/bib_ref] [bib_ref] The incidence, success rate, and complications of awake tracheal intubation in 1,554..., Law [/bib_ref] [bib_ref] A retrospective study of success, failure, and time needed to perform awake..., Joseph [/bib_ref]. 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.

# Methods
The development of these guidelines followed the appraisal of guidelines for research and evaluation (AGREE) reporting checklist [bib_ref] The AGREE Reporting Checklist: a tool to improve reporting of clinical practice..., Brouwers [/bib_ref]. To ensure these guidelines are supported by best evidence, a systematic review adhering to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) recommendations [bib_ref] The PRISMA statement for reporting systematic reviews and meta-analyses of studies that..., Liberati [/bib_ref] [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.
Workspace ergonomics have an impact on performance and safety [bib_ref] Safer anaesthetic rooms: human factors/ergonomics analysis of work practices, Davis [/bib_ref] [bib_ref] Human factors and ergonomics as a patient safety practice, Carayon [/bib_ref] , and should be considered before starting the procedure (Grade D; [fig_ref] Figure 1: Grade D [/fig_ref] ; Supporting
Information, Appendix S2) [bib_ref] Guidelines for the management of tracheal intubation in critically ill adults, Higgs [/bib_ref]. This includes optimising the position of patient, operator and assistants, as well as location of equipment and monitors, which should be in the direct line of sight of the operator. There is no consensus on the ideal operator or patient position [bib_ref] Airway management in adult patients with deep neck infections: a case series..., Ovassapian [/bib_ref] [bib_ref] Influence of patient posture on oxygen saturation during fibre-optic bronchoscopy, Meghjee [/bib_ref] [bib_ref] Flexible bronchoscopy in supine or sitting position, Van Zwam [/bib_ref] [bib_ref] Posture influences patient cough rate, sedative requirement and comfort during bronchoscopy: an..., Ling [/bib_ref] , but there are physiological and anatomical advantages to having patients sitting up [bib_ref] Preoxygenation in the obese patient: effects of position on tolerance to apnoea, Altermatt [/bib_ref] [bib_ref] Sitting posture decreases collapsibility of the passive pharynx in anesthetized paralyzed patients..., Isono [/bib_ref] [bib_ref] The effects of head and body positioning on upper airway collapsibility in..., Ikeda [/bib_ref].
Complications or unsuccessful ATI, although uncommon, should be prepared for [bib_ref] A prospective cohort study of awake fibreoptic intubation practice at a tertiary..., El-Boghdadly [/bib_ref] [bib_ref] The incidence, success rate, and complications of awake tracheal intubation in 1,554..., Law [/bib_ref] [bib_ref] A retrospective study of success, failure, and time needed to perform awake..., Joseph [/bib_ref] , 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

## Checklists
In the peri-operative setting the use of cognitive aids, such as checklists, improves inter-professional communication, teamwork and patient outcomes [bib_ref] Simulation-based trial of surgical-crisis checklists, Arriaga [/bib_ref] [bib_ref] Crisis checklists for the operating room: development and pilot testing, Ziewacz [/bib_ref] [bib_ref] Do safety checklists improve teamwork and communication in the operating room? A..., Russ [/bib_ref] [bib_ref] A surgical safety checklist to reduce morbidity and mortality in a global..., Haynes [/bib_ref]. In anaesthetic practice, cognitive aids enhance performance in simulated emergency scenarios [bib_ref] The impact of didactic read-aloud action cards on the performance of cannula..., Harvey [/bib_ref] [bib_ref] The effects of a displayed cognitive aid on non-technical skills in a..., Marshall [/bib_ref] , and their use been recommended in elective airway management [bib_ref] 4th National Audit Project of the Royal College of Anaesthetists and the..., Cook [/bib_ref]. 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_ref] Figure 2: The Difficult Airway Society awake tracheal intubation [/fig_ref]. The 's' is in lower case to emphasise the optional nature of sedation.

## Oxygenation
The reported incidence of desaturation (S p O 2  90%) with low-flow (< 30 l.min A1 ) oxygen techniques during ATI ranges between 12% and 16% [bib_ref] Awake fiberoptic or awake video laryngoscopic tracheal intubation in patients with anticipated..., Rosenstock [/bib_ref] [bib_ref] A technique of awake fibreoptic intubation. Experience in patients with cervical spine..., Sidhu [/bib_ref] [bib_ref] Fiberoptic intubation in 327 neurosurgical patients with lesions of the cervical spine, Fuchs [/bib_ref]. When warmed and humidified high-flow nasal oxygen is used, the reported incidence of desaturation is 0-1.5% [bib_ref] A prospective cohort study of awake fibreoptic intubation practice at a tertiary..., El-Boghdadly [/bib_ref] [bib_ref] Optimizing oxygenation and intubation conditions during awake fibreoptic intubation using a high-flow..., Badiger [/bib_ref] ; 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 [bib_ref] Supplemental oxygen during moderate sedation and the occurrence of clinically significant desaturation..., Rozario [/bib_ref] [bib_ref] Pulse oximetry during fibreoptic bronchoscopy in local anaesthesia: frequency of hypoxaemia and..., Milman [/bib_ref]. 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 [bib_ref] Supplemental oxygen during moderate sedation and the occurrence of clinically significant desaturation..., Rozario [/bib_ref] [bib_ref] Effects of sedation and supplemental oxygen during upper alimentary tract endoscopy, Reed [/bib_ref] [bib_ref] A prospective study evaluating the usefulness of continuous supplemental oxygen in various..., Reshef [/bib_ref] [bib_ref] The utility of high-flow oxygen during emergency department procedural sedation and analgesia..., Deitch [/bib_ref] [bib_ref] The utility of supplemental oxygen during emergency department procedural sedation and analgesia..., Deitch [/bib_ref]. United Kingdom, European and North American recommendations for sedation all suggest the use of supplemental oxygen [bib_ref] European Society of Anaesthesiology and European Board of Anaesthesiology guidelines for procedural..., Hinkelbein [/bib_ref] [bib_ref] Practice guidelines for moderate procedural sedation and analgesia 2018: a Report by..., Surgeons [/bib_ref] [bib_ref] Guidance on the provision of sedation services 2016. In: Royal College of..., Newton [/bib_ref]. Whilst airway topicalisation alone may rarely be associated with desaturation and airway obstruction [bib_ref] Complications of awake fibreoptic intubation without sedation in 200 healthy anaesthetists attending..., Woodall [/bib_ref] [bib_ref] Total airway obstruction during local anesthesia in a non-sedated patient with a..., Ho [/bib_ref] , 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 [bib_ref] Videolaryngoscopy vs. fibreoptic bronchoscopy for awake tracheal intubation: a systematic review and..., Alhomary [/bib_ref].

## Airway topicalisation
The success of ATI depends on effective topical application of local anaesthetic to the airway. Vasoconstriction of the nasal passage reduces the incidence of epistaxis [bib_ref] A comparison of the effects of epinephrine and xylometazoline in decreasing nasal..., Song [/bib_ref] [bib_ref] Epistaxis and nasotracheal intubation-prevention with vasoconstrictor spray, O&apos;hanlon [/bib_ref].
The use of topical nasal vasoconstrictors before nasotracheal intubation is recommended (Grade A).
Lidocaine has theoretical safety benefits over other local anaesthetic agents due to a favourable cardiovascular and systemic toxicity risk profile [bib_ref] Local anesthetic systemic toxicity: current perspectives, El-Boghdadly [/bib_ref] ; this is the most commonly used local anaesthetic agent for ATI. Following airway topicalisation, clinical evidence of toxicity or levels exceeding toxic plasma concentrations have been shown with lidocaine doses of 6.0-9.3 mg.kg A1 lean body weight [bib_ref] Serum concentrations of lignocaine and its metabolite monoethylglycinexylidide during fibre-optic bronchoscopy in..., Milman [/bib_ref] [bib_ref] Randomized-controlled trial to study the equivalence of 1% versus 2% lignocaine in..., Hasmoni [/bib_ref] [bib_ref] Absorption of lidocaine during aspiration anesthesia of the airway, Mainland [/bib_ref] [bib_ref] Plasma concentrations of lignocaine during fibreoptic bronchoscopy, Efthimiou [/bib_ref] [bib_ref] Combined nebulization and spray-as-you-go topical local anaesthesia of the airway, Williams [/bib_ref]. The dose of topical lidocaine should not exceed 9 mg.kg A1 lean body weight (Grade C) [bib_ref] Dose adjustment of anaesthetics in the morbidly obese, Ingrande [/bib_ref]. The recommendation of 9 mg.kg A1 rather than 9.3 mg.kg A1 is a pragmatic decision to allow ease of calculation.
Practitioners should recognise that this is not a target but a maximum dose, and in practice this is rarely required. The total dose of all local anaesthetics administered, regardless of route (e.g. regional anaesthesia or surgical infiltration), [bib_ref] Intratracheal cocaine induced myocardial infarction: an unusual complication of fibreoptic bronchoscopy, Osula [/bib_ref] [bib_ref] Systematic review of topical vasoconstrictors in endoscopic sinus surgery, Higgins [/bib_ref] [bib_ref] Coronary spasm after the topical use of cocaine in nasal surgery, Lenders [/bib_ref] , while its analgesic efficacy during nasotracheal tube insertion is no better than co-phenylcaine (2.5 ml lidocaine 5%/ phenylephrine 0.5%) [bib_ref] Pain during awake nasal intubation after topical cocaine or phenylephrine/lidocaine spray, Cara [/bib_ref]. Cocaine in this setting is therefore not advised, and phenylephrine in combination with lidocaine is more appropriate (Grade A).
Depending on the delivery device used, there is variable local anaesthetic absorption [bib_ref] The pharmacokinetics of atomized lidocaine administered via the trachea: a randomized trial, Takaenoki [/bib_ref] but this should not affect the maximal dose calculation. There is insufficient evidence to recommend any individual topicalisation technique (e.g. mucosal atomisation, spray-as-you-go, transtracheal injection, nebulisation) [bib_ref] Awake fiberoptic intubation protocols in the operating room for anticipated difficult airway:..., Cabrini [/bib_ref]. However, blocks of the glossopharyngeal and superior laryngeal nerves have been associated with higher plasma concentrations of local anaesthetic [bib_ref] A comparison of anesthetic techniques for awake intubation in neurosurgical patients, Reasoner [/bib_ref] , local anaesthetic systemic toxicity [bib_ref] Hypotension and bradycardia following superior laryngeal nerve block, Wiles [/bib_ref] and lower patient comfort [bib_ref] Local anesthetic administration for awake direct laryngoscopy. Are glossopharyngeal nerve blocks superior?, Sitzman [/bib_ref]. Invasive techniques should therefore be reserved for those with expertise in their performance (Grade B). Nebulised lidocaine can be used but absorption is variable [bib_ref] The science of nebulised drug delivery, O&apos;callaghan [/bib_ref] ; consequently higher doses have been used to compensate for this [bib_ref] Complications of awake fibreoptic intubation without sedation in 200 healthy anaesthetists attending..., Woodall [/bib_ref]. Regardless of technique used, the adequacy of topicalisation should be tested in an atraumatic manner before airway instrumentation [bib_ref] Local anaesthesia for awake fibreoptic nasotracheal intubation, Kundra [/bib_ref] (Grade D), for example, with a soft suction catheter or Yankauer sucker.
The use of an antisialogogue is not mandatory in the performance of ATI and may be associated with undesirable clinical consequences (Grade D; [fig_ref] Table 3: Characteristics of drugs used commonly during ATI [/fig_ref] [bib_ref] pharmacokinetics and some pharmacodynamics findings, Ali-Melkkila [/bib_ref]. There is limited evidence to support their use in ATI, but in anaesthetised patients the clarity of a visual field through a flexible bronchoscope may be improved [bib_ref] Anticholinergics improve fibreoptic intubating conditions during general anaesthesia, Brookman [/bib_ref]. If used, intramuscular antisialogogues should be injected 40-60 min before performing ATI, for peak mucosal drying effect, but there are few data on the intravenous (i.v.) route in this setting.

## Sedation
Awake tracheal intubation may be safely and effectively performed without sedation [bib_ref] A prospective cohort study of awake fibreoptic intubation practice at a tertiary..., El-Boghdadly [/bib_ref] [bib_ref] Complications of awake fibreoptic intubation without sedation in 200 healthy anaesthetists attending..., Woodall [/bib_ref] [bib_ref] Training course in local anaesthesia of the airway and fibreoptic intubation using..., Patil [/bib_ref]. However, its use during ATI can reduce patient anxiety and discomfort and increase procedural tolerance [bib_ref] Conscious sedation for awake fibreoptic intubation: a review of the literature, Johnston [/bib_ref]. Minimal sedation is defined as "a drug-induced state during which the patient responds normally to verbal commands, whilst the airway, spontaneous ventilation and cardiovascular function are unaffected". Sedative drugs can produce a number of effects which may be considered desirable (e.g. amnesia) or detrimental (e.g. over-sedation). The risk of over-sedation and its sequelae, including respiratory depression, airway loss, hypoxia, aspiration and cardiovascular instability, make the presence of an independent anaesthetist delivering, monitoring and titrating sedation desirable [bib_ref] 4th National Audit Project of the Royal College of Anaesthetists and the..., Cook [/bib_ref] (Grade D). In certain patient populations, the risk of over-sedation is particularly hazardous, thus an independent practitioner delivering sedation is strongly recommended (Grade D; [fig_ref] Table 4: Special circumstances that may affect standard performance of ATI with suggested management... [/fig_ref]. If required, we recommend the cautious use of minimal sedation (Grade D).
Remifentanil and dexmedetomidine are associated with high levels of patient satisfaction and low risk of oversedation and airway obstruction when used for ATI [bib_ref] Conscious sedation for awake fibreoptic intubation: a review of the literature, Johnston [/bib_ref]. A single-agent strategy is safest for the non-expert, and if used, remifentanil or dexmedetomidine are appropriate (Grade A). As a sole sedative agent, propofol is associated with a greater risk of over-sedation, coughing and airway obstruction than remifentanil [bib_ref] Remifentanil target-controlled infusion vs propofol target-controlled infusion for conscious sedation for awake..., Rai [/bib_ref] [bib_ref] A comparison of propofol and remifentanil target-controlled infusions to facilitate fiberoptic nasotracheal..., Lallo [/bib_ref] [bib_ref] TCI remifentanil vs. TCI propofol for awake fiber-optic intubation with limited topical..., Zhang [/bib_ref] and is therefore not advisable in this setting (Grade A) [bib_ref] Conscious sedation for awake fibreoptic intubation: a review of the literature, Johnston [/bib_ref]. If co-administration of sedative agents is to be performed, remifentanil and midazolam are both reversible and therefore appropriate, recognising the increased risk of over-sedation (Grade D).
Sedation should not be used as a substitute for inadequate airway topicalisation (Grade D) [bib_ref] Awake fiberoptic intubation protocols in the operating room for anticipated difficult airway:..., Cabrini [/bib_ref]. A suggested sedation regimen is presented in [fig_ref] Figure 2: The Difficult Airway Society awake tracheal intubation [/fig_ref].

## Two-point check of tracheal tube placement

## Difficult airway society ati technique
An example of a practical approach to the sTOP ATI technique is shown in [fig_ref] Figure 2: The Difficult Airway Society awake tracheal intubation [/fig_ref]. This technique has been specifically considered for simplicity and generalisability.
We recognise that there are a range of different techniques and regimens which also address the key sTOP components that will be equally effective.

## Special circumstances
Specific patient pathophysiology may dictate modifications to the performance of ATI that must be considered and planned for. As with all other aspects of ATI, these modifications can be categorised based on sTOP. Examples of suggested changes to technique are presented in [fig_ref] Table 4: Special circumstances that may affect standard performance of ATI with suggested management... [/fig_ref].

## Managing complications
The reported overall complication rate in patients undergoing ATI either flexible bronchoscopic or videolaryngoscopic, is up to 18% .
Complications during ATI occur due to inadequate sTOP. In the event of a complication, its aetiology should be determined and appropriately managed (Grade D; [fig_ref] Figure 3: Managing procedural complications during awake tracheal intubation [/fig_ref].
We define an unsuccessful attempt at ATI as the If airway management is deemed essential, the preferred option for securing the airway after unsuccessful ATI:VL or ATI:FB should be ATI using FONA (ATI:FONA),

## Post-tracheal intubation management
Patients who have had ATI due to predicted difficult airway management are at high risk of complications at tracheal extubation [bib_ref] 4th National Audit Project of the Royal College of Anaesthetists and the..., Cook [/bib_ref] [bib_ref] Difficult Airway Society Guidelines for the management of tracheal extubation, Popat [/bib_ref] , and require an appropriate tracheal extubation strategy. Planning, preparation, performing and post-tracheal extubation care should follow DAS guidelines [bib_ref] Difficult Airway Society Guidelines for the management of tracheal extubation, Popat [/bib_ref] (Grade D).
Before tracheal extubation, laryngoscopy, either with a direct laryngoscope or videolaryngoscope, may provide useful information for risk stratification of tracheal extubation and any subsequent airway management. The view at laryngoscopy may be altered by the presence of a tracheal tube [bib_ref] Difficult Airway Society Guidelines for the management of tracheal extubation, Popat [/bib_ref]. Therefore, verification of laryngoscopy grade may rule out, but not rule in, easy subsequent asleep tracheal intubation.
Topical lidocaine has a dose-dependent duration of analgesic action of up to 40 min although this may vary with concentration and method of administration [bib_ref] Physiologic effects and serum lidocaine concentrations after inhalation of lidocaine from a..., Kirkpatrick [/bib_ref] [bib_ref] Onset and duration of hypoalgesia of lidocaine spray applied to oral mucosa..., Schnemann [/bib_ref].
However, the time to return of laryngeal reflexes can be longer [bib_ref] Lignocaine topicalization of the pediatric airway, Roberts [/bib_ref]. Given that the terminal elimination half-life of lidocaine is up to 2 h, patients should remain nil by mouth for at least 2 h following airway topicalisation for ATI (Grade D).
Documentation of ATI in clinical records is necessary to inform and guide future patient management [bib_ref] 4th National Audit Project of the Royal College of Anaesthetists and the..., Cook [/bib_ref]. This

## Consent
Clinicians should adhere to the Association of Anaesthetists' guidelines on consent for anaesthesia [bib_ref] Association of Anaesthetists: consent for anaesthesia 2017, Yentis [/bib_ref] (Grade D). Informed consent must be taken, with patients being given information (ideally including a patient information leafletin a timely manner (Grade D).
The risks of ATI and its alternative (induction of general anaesthesia before securing the airway) should be discussed [fig_ref] Table 5: Incidence of complications when asleep or awake tracheal intubation is performed [/fig_ref] 

## Training
Successful performance of ATI has been shown to be independent of seniority, but related to experience [bib_ref] A prospective cohort study of awake fibreoptic intubation practice at a tertiary..., El-Boghdadly [/bib_ref].
There are many strategies used for training in the technical aspects of ATI, including the use of manikins, simulators, cadavers and patients [bib_ref] Complications of awake fibreoptic intubation without sedation in 200 healthy anaesthetists attending..., Woodall [/bib_ref] [bib_ref] Effective nonanatomical endoscopy training produces clinical airway endoscopy proficiency, Martin [/bib_ref] [bib_ref] Evaluating the ORSIM a simulator for assessment of anaesthetists' skills in flexible..., Baker [/bib_ref] [bib_ref] Development and initial evaluation of a novel, ultraportable, virtual reality bronchoscopy simulator, Casso [/bib_ref] [bib_ref] Comparison of the efficacy and efficiency of the use of virtual reality..., Jiang [/bib_ref] [bib_ref] Proficient manipulation of fibreoptic bronchoscope to carina by novices on first clinical..., Marsland [/bib_ref] [bib_ref] Fiberoptic intubation using anesthetized, paralyzed, apneic patients results of a resident training..., Cole [/bib_ref] [bib_ref] Virtual airway simulation to improve dexterity among novices performing fibreoptic intubation, Oliveira [/bib_ref]. All anaesthetists should seek every opportunity to attain and maintain skills in ATI and all departments should support this [bib_ref] 4th National Audit Project of the Royal College of Anaesthetists and the..., Cook [/bib_ref] (Grade C).
Awake tracheal intubation is a skill in the compulsory higher training curriculum of the Royal College of Anaesthetists, but opportunities for training are known to be limited [bib_ref] Perception of training needs and opportunities in advanced airway skills: a survey..., Mcnarry [/bib_ref] [bib_ref] Difficult airway management practice patterns among anesthesiologists practicing in the United States:..., Ezri [/bib_ref] [bib_ref] An audit of fibreoptic intubation training opportunities in a UK teaching hospital, Wiles [/bib_ref] [bib_ref] Fibreoptic intubation skills among anaesthetists in New Zealand, Dawson [/bib_ref] [bib_ref] Airway management practices at German university and university-affiliated teaching hospitals -Equipment, techniques..., Goldmann [/bib_ref]. These guidelines provide a common stem for

# Discussion
The primary aims of these guidelines are to provide practitioners with a comprehensive document on ATI. These guidelines should support clinical practice and lower the performance threshold thereby increasing the use of ATI when indicated. The quality of evidence supporting many recommendations is limited, with interventions and outcomes being highly heterogeneous. This is likely influenced by the fact that ATI can be successfully performed in a wide range of settings and patients with varying techniques [bib_ref] Awake fiberoptic intubation protocols in the operating room for anticipated difficult airway:..., Cabrini [/bib_ref]. For example, the use of SADs as a conduit to ATI or optical stylets in awake patients have not been well-described but warrant future investigation as their role becomes more defined. Similarly, the lack of previously published specific guidelines means that research in ATI is disparate and inconsistent [bib_ref] From evidence based on practice to evidence-based practice: time for a difficult..., Ahmad [/bib_ref]. However, we have sought and appraised the available evidence in ATI, and in its absence we have incorporated the practical and theoretical experience of international experts. We have involved patients, DAS members and international experts in order to further understand current practice and the need for these guidelines. Formal resource implication analysis has not been conducted; however, the tools to practically perform ATI are available widely, and thus we expect the resource impact to be modest.
These guidelines prioritise patient safety and provide recommendations for best clinical practice. It is hoped that they will lead to a paradigm shift in clinical practice and improve the care of patients with predicted difficult airway management in the UK and beyond.
C. Rosenstock and L. Lundstrm for data provided from the Danish Anaesthesia Database in [fig_ref] Table 5: Incidence of complications when asleep or awake tracheal intubation is performed [/fig_ref] 
[fig] 5: Cautious use of minimal sedation can be beneficial. This should ideally be administered by an independent practitioner. Sedation should not be used as a substitute for inadequate airway topicalisation. 6 The number of attempts should be limited to three, with one further attempt by a more experienced operator (3 + 1). 7 Anaesthesia should only be induced after a two-point check (visual confirmation and capnography) has confirmed correct tracheal tube position. 8 All departments should support anaesthetists to attain competency and maintain skills in awake tracheal intubation. [/fig]
[fig] Figure 1: Grade D). It is important to select an appropriate route for tracheal intubation, visualisation device and tracheal tube. The route for tracheal intubation should take into account patient anatomy, surgical access and tracheal extubation plan (Grade D). For example, in patients with limited mouth opening, the nasal approach may be the only option, while in patients having nasal surgery, the oral approach may be the preferred route. There is no evidence or consensus Examples of ergonomics for awake tracheal intubation (ATI). The primary operator should have a direct line of sight of the patient, video monitor and patient monitor, as well as immediate access to infusion pumps, anaesthetic machine, suction and oxygen delivery device. If a second anaesthetist is present, they should be positioned with a direct line of sight of the patient and have immediate access to infusion pumps, as well as be able to access all other equipment. The anaesthetic assistant's primary position should be with immediate access to the airway trolley, and in proximity to the operator. (a) Awake tracheal intubation performed with the operator positioned facing the patient who is in a sitting up position. (b) Awake tracheal intubation performed with the operator positioned behind the supine/semi-recumbent patient. This figure forms part of the Difficult Airway Society guidelines for ATI in adults and should be used in conjunction with the text. Difficult Airway Society 2019. [/fig]
[fig] Figure 2: The Difficult Airway Society awake tracheal intubation (ATI) technique. This figure forms part of the Difficult Airway Society guidelines for ATI in adults and should be used in conjunction with the text. HFNO, high-flow nasal oxygen; LA, local anaesthetic; FB, flexible bronchoscopy; MAD, mucosal atomising device; TCI, target-controlled infusion; Ce, effect-site concentration; VL, videolaryngoscopy. Difficult Airway Society 2019. [/fig]
[fig] Figure 3: Managing procedural complications during awake tracheal intubation (ATI). This provides a framework for managing complications, but is not meant to be a comprehensive guide. This figure forms part of the Difficult Airway Society guidelines for ATI in adults and should be used in conjunction with the text. F I O 2 , fractional inspired concentration of oxygen; O 2 , oxygen Difficult Airway Society 2019. 520 [/fig]
[fig] Figure 4: The Difficult Airway Society management of unsuccessful awake tracheal intubation (ATI) in adults. This algorithm forms part of the Difficult Airway Society guidelines for ATI in adults and should be used in conjunction with the text. HFNO, high-flow nasal oxygen; SAD, supraglottic airway device; FONA, front-of-neck airway; GA, general anaesthesia. Difficult Airway Society 2019. attempts; and any complications or notes (Grade D; Supporting Information, Appendix S3). [/fig]
[table] Table 2: Grading of recommendations based on the level of evidence available. [/table]
[table] Table 3: Characteristics of drugs used commonly during ATI. [/table]
[table] Table 4: Special circumstances that may affect standard performance of ATI with suggested management options. [/table]