The difficult airway: the DAS 2025 guidelines

July 15, 2026 · Read 12 min

Difficult airway guidelines have existed for more than three decades; the 2015 version from the Difficult Airway Society organized the response to failed intubation. The 2025 version, published in the British Journal of Anaesthesia, keeps that linear algorithm but shifts the center of gravity: the goal is no longer to avoid and manage failure but to maximize the likelihood of success at the first attempt. What changes is not a device, but the philosophy: the first attempt should be the best attempt, because a suboptimal attempt is a wasted attempt.

1. A change of philosophy

The structure the anesthesiologist already knows is unchanged; what changes is the hierarchy of priorities. Where previous versions emphasized how to rescue a deteriorating situation, the 2025 version concentrates the effort on ensuring the first attempt takes place under the best conditions, and on moving on decisively when a technique fails, with oxygen throughout the process and capnography confirming every step.

Three principles support it. Transitioning —recognizing that a plan has failed and immediately moving on to the next— is often poorly executed owing to task fixation or to persisting with a technique that is not working, which adds trauma and brings the cannot intubate, cannot oxygenate scenario closer; each transition is declared out loud to the whole team and is guided by the number of attempts, the time elapsed and the physiological response. Calling for help is warranted whenever any difficulty is encountered, regardless of hierarchy; the team decides during the brief who will be called and assigns that task to someone other than the airway assistant. The third principle is the most decisive: each successive attempt increases trauma and reduces success, so the best conditions are reserved for the first.

2. The decision begins before induction

Safety is decided before induction of anesthesia. Airway assessment —history, bedside tests and, where appropriate, relevant investigations— identifies anticipated difficulty with facemask ventilation, the supraglottic airway device, tracheal intubation or the front-of-neck airway, and allows an airway strategy to be built as a series of plans. The earlier it is performed, the more time there is to formulate that strategy, obtain the equipment and communicate with the team.

Predicting difficulty remains difficult

No single bedside test reliably rules out difficulty; the upper lip bite test has the greatest diagnostic accuracy and combining several tests improves sensitivity. Obstructive sleep apnea and snoring are more reliable predictors than obesity in isolation, whose independent value remains uncertain, and perhaps the most reliable is a previous history of difficult airway management: it is prudent to review the medical record and any difficult airway alert cards that some patients carry. Assessment also includes screening for a physiologically difficult airway.

The cricothyroid membrane is located now, not in the crisis

An operational change in 2025: the cricothyroid membrane is identified —by visual assessment, palpation or ultrasound, ideally with the neck fully extended— during assessment, not during the crisis, which informs the front-of-neck airway technique in advance. Because palpation is unreliable even in elective conditions, the decision about palpability is made and verbalized early.

When difficulty is anticipated: awake

When a difficult airway is anticipated, awake tracheal intubation —with a flexible bronchoscope or videolaryngoscope— is associated with lower failure and fewer complications than asleep techniques; it should be considered when difficulty is anticipated in any of Plans A to D, and awake tracheostomy is another option depending on the case.

Equipment, environment and monitoring

Equipment for Plans A to D must be immediately available in every area where the airway is managed, and airway management out of hours or outside the operating room, which carries greater risk, warrants seeking senior input from the outset and using a checklist for emergency tracheal intubation. Before induction, the monitors are prepared: waveform capnography checked, audible SpO2 tones enabled and adequate neuromuscular block confirmed with quantitative monitoring. Continuous capnography is maintained throughout all phases.

3. Peroxygenation: oxygen from start to finish

The term peroxygenation names the principle the guidelines place at the center: continuous oxygen delivery from before induction (preoxygenation), during apnea (apneic oxygenation) and throughout the attempts, until the airway is secured. Preoxygenation prolongs the safe apnea time, increases the oxygen reserve and allows more time for laryngoscopy, tracheal intubation and rescue.

The head-up position and positive pressure during preoxygenation increase functional residual capacity and the oxygen available during apnea, so the most effective strategy combines both, with high-flow nasal oxygen, noninvasive ventilation or a facemask with continuous positive airway pressure. After induction, oxygen delivery continues through the facemask and, during laryngoscopy, when facemask ventilation is not possible, through low- or high-flow nasal cannulae with a patent airway.

High-flow nasal oxygen delivers a flow rate that exceeds peak inspiratory flow, typically greater than 30 L/min, but it only delays hypoxemia without always preventing it and should not be started as a rescue technique once facemask ventilation has failed. Apneic oxygenation, ideally with high flow, matters particularly when there is a risk of an anatomically or physiologically difficult airway, because of how rapidly desaturation occurs.

4. Plan A: the first attempt is the best attempt

The essence of Plan A is successful tracheal intubation —confirmed with waveform capnography— at the first attempt and without complications, limiting the number and duration of attempts while maintaining oxygenation.

Videolaryngoscopy is recommended first line whenever possible: compared with direct laryngoscopy it improves safety and efficacy, increases first-attempt success and reduces hypoxemia and esophageal intubation. There is no strong evidence favoring one blade design, but hyperangulated and Macintosh-type blades require different techniques; with a hyperangulated blade, a stylet, a bougie or a flexible bronchoscope should be used, shaped appropriately before use.

Blind bougie insertion with a Cormack-Lehane grade 3 or 4 view can cause trauma or device misplacement, and relying on the hold-up sign —which can indicate passage into the bronchial tree— carries a risk of perforation; both should be avoided. When the glottic view is poor, external laryngeal manipulation by a trained assistant is useful: backward, upward and rightward pressure on the thyroid cartilage, or the BURP maneuver.

The guidelines maintain the principle of 3+1: a maximum of three attempts, with a fourth and final attempt undertaken by a more experienced colleague. Each attempt incorporates a change that increases the likelihood of success —head and neck position, blade or blade size, introducer, operator, external laryngeal manipulation, suction, removal of cricoid force or optimization of neuromuscular block. If hypoxemia occurs, the attempt is abandoned in order to oxygenate with the facemask, which is maintained between attempts along with anesthesia. Failure of Plan A can be declared at any time, even after the first attempt, when no change would improve the outcome or when persisting would cause complications; once the 3+1 attempts are exhausted, failed intubation is declared, Plan B begins and the eFONA kit is made immediately accessible.

The confirmation that is never skipped

Confirmation of tracheal intubation requires two variables: waveform capnography with sustained exhaled carbon dioxide and visualization of the tube passing through the vocal cords or within the trachea. Sustained carbon dioxide excludes esophageal intubation but does not by itself confirm tracheal placement —the tube can be in a bronchus or in the pharynx— and clinical tests used in isolation (tube misting, chest rise, auscultation) are unreliable.

Facemask ventilation is a core skill throughout the algorithm; difficulty with it increases the risk of failed tracheal intubation more than tenfold, although it remains difficult to predict. Neuromuscular block makes it easier, so its administration should not be delayed in order to check facemask ventilation first. When difficulty arises, it is communicated to the team, help is sought immediately and the technique is adjusted: an oropharyngeal or nasopharyngeal airway, a two-person technique and a good seal.

5. When A fails: B, C and D

When tracheal intubation fails, the immediate objective is to maintain oxygenation and progress through the algorithm without delay.

Plan B: oxygenate and reassess

Plan B maintains oxygenation with a supraglottic airway device, ideally second generation —lower risk of aspiration and a better conduit—, which can rescue 60-65 % of difficult or failed intubations and remains underutilized. It is limited to three attempts, each with a change (size or type of device, full neuromuscular block), with facemask ventilation between them. Once oxygenation is achieved, the rule is to stop, think and communicate: by default, discontinue anesthesia and wake the patient up, the safest way to preserve control of the airway. The remaining options —continuing with the device, intubating through it or a planned front-of-neck airway— are high risk and require a more experienced clinician; intubation through the device is always performed under visualization, for example with a flexible bronchoscope, never blindly.

Plan C: final attempt with the facemask

Plan C is the final attempt at facemask ventilation after failed tracheal intubation and failed supraglottic airway device ventilation. Trauma and edema from repeated instrumentation may have made it more difficult, so every condition is optimized: full neuromuscular block, adequate depth of anesthesia, correct positioning, an oropharyngeal or nasopharyngeal airway and a two-person technique. Rapid progression to Plan D should be anticipated: if ventilation is effective, management is decided with senior input; if it is not, a cannot intubate, cannot oxygenate scenario is declared, roles are allocated and Plan D begins immediately.

Plan D: emergency front-of-neck airway

Plan D arises when oxygenation has failed by all previous means. The default choice is a vertical skin incision —it serves for both a palpable and an impalpable cricothyroid membrane—; the transverse stab incision is appropriate only when the membrane is identified with certainty by palpation or has been marked with ultrasound. Palpability should have been decided during assessment and verbalized by the end of Plan A, and when there is any uncertainty the vertical incision is preferred. The procedure requires maximal neck extension and full neuromuscular block; if Sugammadex has already been administered, a neuromuscular blocking agent other than Rocuronium or Vecuronium will likely be required. Throughout the procedure, oxygen is applied to the upper airway by facemask, nasal cannula or supraglottic airway device.

6. Physiology, populations and human factors

The physiologically difficult airway

Management must consider, alongside anatomy, physiological (advanced age, pregnancy) and pathophysiological (sepsis, heart failure) alterations, which increase the risk of hypoxemia, pulmonary aspiration and hemodynamic instability on transition to positive pressure ventilation. That instability is the most common life-threatening complication of tracheal intubation in the critically ill patient, and is often predictable and preventable: this is why assessment and optimization before induction are decisive —fluids, vasopressors and choice of induction agent— and why it is essential to have a team member dedicated to hemodynamics while the anesthesiologist focuses on the airway. Propofol can worsen it, which makes careful dosing necessary; Ketamine, Etomidate and Remimazolam have a role in these patients. Because multiple attempts increase adverse events, first-attempt success matters even more.

Cricoid force and rapid sequence induction

Cricoid force aims to reduce the risk of aspiration —classically 10 N before induction and 30 N once consciousness is lost—, although its use is variable and the evidence on safety and efficacy is limited; it does not affect first-attempt success with videolaryngoscopy, although it can make tube advancement more difficult. The pragmatic recommendation: use it only when the risk of pulmonary aspiration is particularly high, and remove it if difficulty with laryngoscopy or tracheal intubation is encountered, if a supraglottic airway device is inserted in Plan B or if active vomiting occurs. The growing use of GLP-1 receptor agonists, which delay gastric emptying and increase the risk of aspiration, is a change in practice that preoperative assessment should take into account. Rapid sequence induction and intubation shares the general principles, with the considerations summarized below; these patients may also have a physiologically difficult airway.

Obesity

Obesity raises the risk of airway complications: facemask and supraglottic airway device ventilation can be more difficult, the front-of-neck airway more complex, and the reduced functional residual capacity together with higher oxygen consumption accelerates desaturation. It is therefore reasonable to consider awake tracheal intubation, high-flow nasal oxygen for peroxygenation, early use of a supraglottic airway device and a head-up position of 30° or greater, which improves preoxygenation, ventilation and intubation. The 2025 recommendations from the Society for Obesity and Bariatric Anaesthesia (SOBA) set out the comprehensive package of measures, and calling for help earlier is advisable.

Human factors, ultrasound and documentation

The guidelines place human factors at the center. Priming —preparing the eFONA kit in parallel with Plans A to C— ensures that it is immediately available and that appropriately skilled staff are ready: it is left accessible when failed intubation is declared, and the assistant opens it after a maximum of three attempts with the supraglottic airway device. The airway assistant plays a central role —confirming sustained exhaled carbon dioxide, maintaining situational and time awareness, prompting the transition after the maximum number of attempts and knowing when to seek help— supported by graded assertiveness tools. Point-of-care ultrasound is increasingly used to assess the airway, localize the cricothyroid membrane and evaluate gastric contents.

Finally, documentation: when airway management is considered difficult, in addition to recording it in the medical record, it is communicated verbally and in writing to the patient and to their primary care provider, with appropriate diagnostic coding.