The Difficult Airway Society (DAS) guidelines are tested in both the FRCA Primary (anatomy and airway management principles) and the FRCA Final (clinical application and crisis management). The 2015 DAS guidelines for management of unanticipated difficult intubation in adults remain the core reference, supplemented by the 2015 DAS guidelines for failed tracheal intubation in obstetrics and DAS/AAGBI guidance for awake tracheal intubation.
The four-plan approach
The DAS guidelines structure airway management as a four-plan sequential approach. The plans are not alternatives — they are escalation steps. You proceed to the next plan only when the current plan has failed.
Plan A — Facemask ventilation and tracheal intubation. Optimise positioning (ramped position, ear-to-sternal notch alignment), pre-oxygenate thoroughly, administer induction agents, and attempt direct or video laryngoscopy. A maximum of three intubation attempts is recommended (plus one further attempt by a more experienced colleague if available) — four total. Excessive intubation attempts increase the risk of airway trauma, oedema, and cannot-intubate-cannot-oxygenate (CICO) situations.
If intubation fails after the maximum attempts, declare failed intubation and move to Plan B.
Plan B — Maintaining oxygenation via a supraglottic airway device. Insert a second-generation supraglottic airway device (such as i-gel or LMA ProSeal). A maximum of three insertion attempts is recommended. If the SAD is successfully placed and ventilation is achieved, you have time — you can either wake the patient, proceed with surgery via the SAD if appropriate, or attempt intubation through the SAD.
If SAD insertion fails or ventilation through the SAD is inadequate, move to Plan C.
Plan C — Final attempt at facemask ventilation. This is a deliberate pause to attempt facemask ventilation before proceeding to the surgical airway. Optimise facemask technique — two-person technique, jaw thrust, oral and nasal airways, reduce cricoid pressure if applied. This step exists because facemask ventilation may now be easier than at initial induction (muscle relaxation is more complete, positioning may have been optimised).
If facemask ventilation fails, you are in a CICO situation. Move to Plan D.
Plan D — Emergency front-of-neck access (FONA). This is the rescue step for CICO — the patient cannot be intubated and cannot be oxygenated by any non-invasive means. The recommended technique is scalpel cricothyroidotomy — a vertical skin incision, horizontal stab through the cricothyroid membrane, bougie insertion, and railroading a size 6.0 cuffed tracheal tube. Needle cricothyroidotomy (using a large-bore cannula) is an alternative but is associated with a higher failure rate and is now considered a secondary option.
The DAS guidelines emphasise that FONA should not be delayed. When you are in CICO, every second of hypoxia causes harm. The decision to proceed to FONA should be made explicitly and communicated clearly to the team — "this is a CICO situation, I am performing an emergency cricothyroidotomy."
What the exam tests
FRCA questions on DAS guidelines typically test the escalation logic — when to move from one plan to the next, the maximum number of attempts at each stage, and the specific technique for Plan D. Common errors include continuing intubation attempts beyond the recommended maximum, failing to declare CICO when ventilation has failed, and choosing needle cricothyroidotomy over scalpel cricothyroidotomy as the primary FONA technique.
Questions may also present specific clinical contexts — the obstetric patient (where a modified approach applies due to the dual patient consideration and the higher incidence of difficult airways), the paediatric patient (different anatomy, different equipment sizing), or the patient with known difficult airway features (where awake fibreoptic intubation should be planned electively rather than discovering difficulty after induction).
Awake fibreoptic intubation
Awake fibreoptic intubation is indicated when a difficult airway is anticipated and the risks of induction before securing the airway outweigh the risks of an awake technique. Indications include known difficult airway (previous failed intubation, Mallampati 4, limited mouth opening, cervical spine instability), predicted difficult facemask ventilation (obesity, beard, edentulous, radiation changes), and unstable cervical spine where neck movement must be minimised.
The technique involves topical anaesthesia of the airway (lidocaine spray and nebulisation), sedation (typically remifentanil TCI or low-dose midazolam — maintaining spontaneous ventilation and patient cooperation), and passage of a flexible bronchoscope through the nose or mouth into the trachea, followed by railroading the tracheal tube over the scope.
The key exam points are the indications (anticipate difficulty and plan), the importance of maintaining spontaneous ventilation (do not abolish it with deep sedation), and the topical anaesthesia technique.
Obstetric modification
The DAS/OAA guidelines for failed intubation in obstetrics follow the same four-plan structure but with specific modifications. The key differences are that the decision after failed intubation includes whether to wake the patient or proceed with surgery via SAD — a decision that depends on the urgency of delivery (category 1 caesarean for fetal distress may justify proceeding via SAD rather than waking). Cricoid pressure may impair laryngoscopy and should be released if it is not aiding intubation. Maternal positioning (left lateral tilt) must be maintained throughout to prevent aortocaval compression.
iatroX's FRCA Primary and Final banks include DAS guideline questions covering all four plans, the CICO decision point, FONA technique, awake fibreoptic intubation indications, and the obstetric modifications. All included at £29 per month or £99 per year.