The Expect-it study aims to accompany the development and clinical implementation process of a new algorithm for the management of expected difficult intubation. The new algorithm is designed to allocate patients to specific tracheal intubation techniques. After assessing the status quo (non-algorithm-based decision-making) the new algorithm-based allocation will be compared with this clinical standard within a confirmatory diagnostic accuracy study (post-implementation).

Difficult tracheal intubation is one of the major reasons for anesthesia-related adverse events. Patients undergoing ear, nose & throat (ENT) or oral and maxillofacial (OMS) surgery often require tracheal intubation for general anesthesia but are at increased risk for difficult tracheal intubation. Currently, existing preoperative tests for the prediction of difficult intubation show low diagnostic accuracy. Moreover, as the results of these prediction tests are not coupled with concrete treatment recommendations, they cannot be used targeted within preventive concepts. An evidence based rational algorithm for the management of expected difficult intubation has not been developed yet. It is unknown, if an algorithm-based allocation to an intubation approach might be advantageous compared with a non-algorithm-based allocation strategy.

The Expect-it study aims to accompany the development and clinical implementation process of a new algorithm for the management of expected difficult intubation. This new algorithm is designed to provide an evidence-based decision-making tool for a rational pre-choice of tracheal intubation techniques, anesthetized intubation by direct laryngoscopy (DL) or videolaryngoscopy (VL) or awake tracheal intubation (ATI). In the first study phase the status quo (clinical standard, non-algorithm-based decision-making) will be assessed (three-month period with an approximated case number of up to 600 patients). The Expect-it algorithm will be implemented thereafter. Between both study phases, the algorithm will be updated (based on the findings of the first phase), sensitivity and specificity of the clinical standard will be calculated, sample size will critically be appraised and readjusted (approximately 600 within at least three months), if appropriate. The second study phase is a confirmatory diagnostic accuracy study for the new algorithm with a single test study design, that aims to proof, if the new Expect-it algorithm is superior or at least non-inferior to the clinical standard, defined as superiority in either the specificity or sensitivity and non-inferiority in the other co-primary endpoint in each domain (ATI, DL, VL) (pre-planned preliminary analysis of the first study phase; IRB amendment 2021-10459_2-BO-ff, December 3, 2021). Sensitivity and specificity are considered co-primary endpoints. Study planning and conduction is in accordance with the Standards for Reporting Diagnostic accuracy studies (STARD) statement. The Expect-it study will further include two surveys among anesthetist in the study center in order to evaluate challenges and obstacles associated with the implementation process and possible clinical implications of the algorithm. An additional analysis will be performed to test a core data set for an 'anesthesia alert card'.

Inclusion Criteria:

• Patients undergoing ENT or OMS surgery that require general anesthesia with tracheal intubation (either DL, VL or ATI)
• Age ≥ 18 years

Exclusion Criteria:

• Denial of consent
• Planned intubation technique is not designated in the study protocol as it differs from either DL, VL, ATI (e.g. primary tracheotomy or rigid bronchoscopy)

Consecutive sampling: Adult patients that undergo ENT or OMS surgery in a tertiary care hospital who require tracheal intubation and consent to participate within two predefined study periods of at least 3 months.