The unanticipated difficult airway with recommendations for managementPurpose: To review the current literature and generate recommendations on the role of newer technology in the management of the unanticipated difficult airway. Methods: A literature search using key words and filters of English language and English abstracted publications from contained in the Medline, Current Contents and Biological Abstracts databases was carried out. The literature was reviewed and condensed and a series of evidence-based recommendations were evolved. Conclusions: The unanticipated difficult airway occurs with a low but consistent incidence in anaesthesia practice. Difficult direct laryngoscopy occurs in 1,5 -8.5% of general anaesthetics and difficult intubation occurs with a similar incidence. Failed inubation occurs in 0.13-0.3% general anaesthetics. Current techniques for predicting difficulty with laryngoscopy and intubation are sensitive, non-specific and have a low positive predictive value. Assessment techniques which utilize multiple characteristics to derive a risk factor tend to be more accurate predictors. Devices such as the laryngeal mask, lighted styler and rigid fibreoptic laryngoscopes, in the setting of unanticipated difficult airway, are effective in establishing a patent airway, may reduce morbidity and are occasionally lifesaving. Evidence supports their use in this setting as either alternatives to facemask and bag ventilation, when it is inadequate to support oxygenation, or to the direct laryngoscope, when tracheal intubation has failed, Specifically, the laryngeal mask and Combitube TM have proved to be effective in establishing and maintaining a patent airway in "cannot ventilate" situations. The lighted stylet and Bullard (rigid) fibreoptic scope are effective in many instances where the direct laryngoscope has failed to facilitate tracheal intubation. The data also support integration of these devices into strategies to manage difficult airway as the new standard of care. Training programmes should ensure graduate physicians are trained in the use of these alternatives. Continuing medical education courses should allow physicians in practice the opportunity to train with these alternative devices.Objectif : Passer en revue la documentation courante et fournir des recommandations sur le r61e de la nou velle technologie dans la conduite ~ tenir Iors d'une intubation difficile. M~thodes : On a procEdE ~ une recherche documentaire selon des mots-clEs et des filtres de langue anglaise et des publications de rEsumEs anglais de 1990 ~ 1996, contenus dans les bases de donnEes de Medline, Current Contents et Biolo~colAbstracts.La littErature a ErE revue et r&umEe et une sErie de recommandations basEes sur les fairs ont ErE ElaborEes. Conclusion : Les dit~cultEs d'intubation non prEvues surviennent selon une incidence faible, mais constante, clans la pratique de I'anesthEsie, Des probl~mes de laryngoscopie directe et des difficult& d'intubation ont lieu dans 1,5 -8,5 % des anesth&ies gEnErales. E&hec de I'...

BackgroundPreviously active in the mid-1990s, the Canadian Airway Focus Group (CAFG) studied the unanticipated difficult airway and made recommendations on management in a 1998 publication. The CAFG has since reconvened to examine more recent scientific literature on airway management. The Focus Group’s mandate for this article was to arrive at updated practice recommendations for management of the unconscious/induced patient in whom difficult or failed tracheal intubation is encountered. MethodsNineteen clinicians with backgrounds in anesthesia, emergency medicine, and intensive care joined this iteration of the CAFG. Each member was assigned topics and conducted reviews of Medline, EMBASE, and Cochrane databases. Results were presented and discussed during multiple teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made together with assigned levels of evidence modelled after previously published criteria.ConclusionsThe clinician must be aware of the potential for harm to the patient that can occur with multiple attempts at tracheal intubation. This likelihood can be minimized by moving early from an unsuccessful primary intubation technique to an alternative “Plan B” technique if oxygenation by face mask or ventilation using a supraglottic device is non-problematic. Irrespective of the technique(s) used, failure to achieve successful tracheal intubation in a maximum of three attempts defines failed tracheal intubation and signals the need to engage an exit strategy. Failure to oxygenate by face mask or supraglottic device ventilation occurring in conjunction with failed tracheal intubation defines a failed oxygenation, “cannot intubate, cannot oxygenate” situation. Cricothyrotomy must then be undertaken without delay, although if not already tried, an expedited and concurrent attempt can be made to place a supraglottic device.

BackgroundAppropriate planning is crucial to avoid morbidity and mortality when difficulty is anticipated with airway management. Many guidelines developed by national societies have focused on management of difficulty encountered in the unconscious patient; however, little guidance appears in the literature on how best to approach the patient with an anticipated difficult airway.MethodsTo review this and other subjects, the Canadian Airway Focus Group (CAFG) was re-formed. With representation from anesthesiology, emergency medicine, and critical care, CAFG members were assigned topics for review. As literature reviews were completed, results were presented and discussed during teleconferences and two face-to-face meetings. When appropriate, evidence- or consensus-based recommendations were made, and levels of evidence were assigned.Principal findingsPreviously published predictors of difficult direct laryngoscopy are widely known. More recent studies report predictors of difficult face mask ventilation, video laryngoscopy, use of a supraglottic device, and cricothyrotomy. All are important facets of a complete airway evaluation and must be considered when difficulty is anticipated with airway management. Many studies now document the increasing patient morbidity that occurs with multiple attempts at tracheal intubation. Therefore, when difficulty is anticipated, tracheal intubation after induction of general anesthesia should be considered only when success with the chosen device(s) can be predicted in a maximum of three attempts. Concomitant predicted difficulty using oxygenation by face mask or supraglottic device ventilation as a fallback makes an awake approach advisable. Contextual issues, such as patient cooperation, availability of additional skilled help, and the clinician’s experience, must also be considered in deciding the appropriate strategy.ConclusionsWith an appropriate airway evaluation and consideration of relevant contextual issues, a rational decision can be made on whether an awake approach to tracheal intubation will maximize patient safety or if airway management can safely proceed after induction of general anesthesia. With predicted difficulty, close attention should be paid to details of implementing the chosen approach. This should include having a plan in case of the failure of tracheal intubation or patient oxygenation.

Summary We compared the McGrath® Series 5 videolaryngoscope with the Macintosh laryngoscope in a simulated difficult airway, using manual in‐line stabilisation in 88 anaesthestised patients of ASA physical status 1‐2. The primary outcome was laryngoscopic view. Secondary outcomes included rates of successful tracheal intubation and complications. A Cormack and Lehane grade‐1 or ‐2 view was found in all patients when using the McGrath compared with 45 (51%, p < 0.0001) using the Macintosh laryngoscopes. The mean (SD) percentage of glottic opening was 82 (23)% using the McGrath compared with 13 (23)% using the Macintosh (p < 0.0001). In 66 out of 88 patients (75%), the McGrath improved the glottic view by one to three grades compared with the Macintosh (p < 0.001). Intubation of the trachea was successful in all patients using the McGrath, while the Macintosh was successful in 26 (59%, p < 0.001). There was no significant difference in the complication rates between the devices.

Purpose Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the published airway management literature has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This second of two articles addresses airway evaluation, decision-making, and safe implementation of an airway management strategy when difficulty is anticipated. Source Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence is lacking, statements are based on group consensus. Findings and key recommendations Prior to airway management, a documented strategy should be formulated for every patient, based on airway evaluation. Bedside examination should seek predictors of difficulty with face-mask ventilation (FMV), tracheal intubation using video- or direct laryngoscopy (VL or DL), supraglottic airway use, as well as emergency front of neck airway access. Patient physiology and contextual issues should also be assessed. Predicted difficulty should prompt careful decision-making on how most safely to proceed with airway management. Awake tracheal intubation may provide an extra margin of safety when impossible VL or DL is predicted, when difficulty is predicted with more than one mode of airway management (e.g., tracheal intubation and FMV), or when predicted difficulty coincides with significant physiologic or contextual issues. If managing the patient after the induction of general anesthesia despite predicted difficulty, team briefing should include triggers for moving from one technique to the next, expert assistance should be sourced, and required equipment should be present. Unanticipated difficulty with airway management can always occur, so the airway manager should have a strategy for difficulty occurring in every patient, and the institution must make difficult airway equipment readily available. Tracheal extubation of the at-risk patient must also be carefully planned, including assessment of the patient’s tolerance for withdrawal of airway support and whether re-intubation might be difficult.

Purpose Since the last Canadian Airway Focus Group (CAFG) guidelines were published in 2013, the literature on airway management has expanded substantially. The CAFG therefore re-convened to examine this literature and update practice recommendations. This first of two articles addresses difficulty encountered with airway management in an unconscious patient. Source Canadian Airway Focus Group members, including anesthesia, emergency medicine, and critical care physicians, were assigned topics to search. Searches were run in the Medline, EMBASE, Cochrane Central Register of Controlled Trials, and CINAHL databases. Results were presented to the group and discussed during video conferences every two weeks from April 2018 to July 2020. These CAFG recommendations are based on the best available published evidence. Where high-quality evidence was lacking, statements are based on group consensus. Findings and key recommendations Most studies comparing video laryngoscopy (VL) with direct laryngoscopy indicate a higher first attempt and overall success rate with VL, and lower complication rates. Thus, resources allowing, the CAFG now recommends use of VL with appropriately selected blade type to facilitate all tracheal intubations. If a first attempt at tracheal intubation or supraglottic airway (SGA) placement is unsuccessful, further attempts can be made as long as patient ventilation and oxygenation is maintained. Nevertheless, total attempts should be limited (to three or fewer) before declaring failure and pausing to consider “exit strategy” options. For failed intubation, exit strategy options in the still-oxygenated patient include awakening (if feasible), temporizing with an SGA, a single further attempt at tracheal intubation using a different technique, or front-of-neck airway access (FONA). Failure of tracheal intubation, face-mask ventilation, and SGA ventilation together with current or imminent hypoxemia defines a “cannot ventilate, cannot oxygenate” emergency. Neuromuscular blockade should be confirmed or established, and a single final attempt at face-mask ventilation, SGA placement, or tracheal intubation with hyper-angulated blade VL can be made, if it had not already been attempted. If ventilation remains impossible, emergency FONA should occur without delay using a scalpel-bougie-tube technique (in the adult patient). The CAFG recommends all institutions designate an individual as “airway lead” to help institute difficult airway protocols, ensure adequate training and equipment, and help with airway-related quality reviews.

While extracorporeal membrane oxygenation (ECMO) is an effective method of oxygenation for patients with respiratory failure, further refinement of its incorporation into airway guidelines is needed. We present a case of severe glottic stenosis from advanced thyroid carcinoma in which gas exchange was facilitated by veno-arterial ECMO prior to achieving a definitive airway. We also conducted a systematic review of the MEDLINE, EMBASE, CINAHL, and Web of Science databases, using the keywords "airway/ tracheal obstruction", "anesthesia", "extracorporeal", and "cardiopulmonary bypass" to identify reports where ECMO was initiated as the a priori method of oxygenation during difficult airway management.Thirty-six papers were retrieved discussing the use of ECMO or cardiopulmonary bypass (CPB) for the management of critical airway obstruction. Forty-five patients underwent pre-induction of anesthesia institution of CPB or ECMO for airway obstruction. The patients presenting with critical airway obstruction had a range of airway pathologies with tracheal tumours (31%), tracheal stenosis (20%), and head and neck cancers (20%) being the most common. All cases reported a favourable patient outcome with all patients surviving to hospital discharge without significant complications.While most practitioners are familiar with the fundamental airway techniques of bag-mask ventilation, supraglottic airway use, tracheal intubation, and front-of-neck airway access for oxygenation, these techniques have limitations in managing patients with pre-existing severe airway obstruction. The use of ECMO should be considered in patients with severe (or near-complete) airway obstruction secondary to anterior neck or tracheal disease. This approach can provide essential tissue oxygenation while attempts to secure a definitive airway are carried out in a controlled environment.

Lightwands have been used to assist in the tracheal intubation of patients with difficult airways for many years. A new lightwand (~achlight, f~ } with a brighter light source and a flexible styler permits both oral and nasal intubation under ambient light. This study reports the effectiveness of the Trachlight'~ in tracheal intubation