A significant number of patients with short VCD in our study group could be at risk of endobronchial intubation with many of the tracheal tubes. Patient height and thyrosternal distance can be useful in predicting short tracheas.

A two-curve theory is proposed as a basis for explaining airway configuration. The changes in these curves with head and neck positioning support the sniffing position as optimal for direct laryngoscopy. Application of this new concept to other forms of laryngoscopy should be investigated.

'Can't intubate, can't oxygenate' scenarios are rare but are often poorly managed, with potentially disastrous consequences. In our opinion, all doctors should be able to create a surgical airway if necessary. More practically, at least all anaesthetists should have this ability. There should be a change in culture to one that encourages and facilitates the performance of a life-saving emergency surgical airway when required. In this regard, an understanding of the human factors that influence the decision to perform an emergency surgical airway is as important as technical skill. Standardisation of difficult airway equipment in areas where anaesthesia is performed is a step toward ensuring that an emergency surgical airway will be performed appropriately. Information on the incidence and clinical management of 'can't intubate, can't oxygenate' scenarios should be compiled through various sources, including national coronial inquest databases and anaesthetic critical incident reporting systems. A systematic approach to teaching and maintaining human factors in airway crisis management and emergency surgical airway skills to anaesthetic trainees and specialists should be developed: in our opinion participation should be mandatory. Importantly, the view that performing an emergency surgical airway is an admission of anaesthetist failure should be strongly countered.

SummaryIn airway management, poor judgment, education and training are leading causes of patient morbidity and mortality. The traditional model of medical education, which relies on experiential learning in the clinical environment, is inconsistent and often inadequate. Curriculum change is underway in many medical organisations in an effort to correct these problems, and airway management is likely to be explicitly addressed as a clinical fundamental within any new anaesthetic curriculum. Competency‐based medical education with regular assessment of clinical ability is likely to be introduced for all anaesthetists engaged in airway management. Essential clinical competencies need to be defined and improvements in training techniques can be expected based on medical education research. Practitioners need to understand their equipment and diversify their airway skills to cope with a variety of clinical presentations. Expertise stems from deliberate practice and a desire constantly to improve performance with a career‐long commitment to education.

In 1913, Chevalier Jackson [1] described his method of laryngoscopy while his assistant Boyce supported the patient's head and neck in an elevated position ('BoyceJackson position'). Magill [2] in 1936 suggested the term the 'sniffing position', which has since gained wide acceptance as the best position for direct laryngoscopy. Later, Bannister and Macbeth [3] proposed the need for aligning the mouth, pharyngeal and laryngeal axes.However, Adnet and workers [4][5][6][7] criticised the 'sniffing position' and found no significant improvement over simple extension of the head and neck, unless the patient was obese or had reduced neck mobility. Furthermore, previous studies have proven that it has been challenging to find a reliable pre-operative predictor for difficult laryngoscopy and tracheal intubation [8][9][10][11]. The problem arises from variations in investigators' assessments, as well as a variety of definitions for different aspects of difficult airway management [12,13].I attempt to reassess these issues, initially analysing how laryngoscopy succeeds in the 'normal' patient, and then proposing a new model describing the mechanism for successful direct laryngoscopy. Such a model aims to explain how extremes in the normal population, including particular pathological conditions, cause failures in the performance of direct laryngoscopy. Dynamic phase of laryngoscopySeparate from the static component of upper airway axes alignment, the dynamic phase of direct laryngoscopy is the second essential component to successful laryngoscopy. Boidin [14] argued that the hyoid formed the boundary between two parts of the airway -the pharynx and larynx.Anteroposterior shift of the hyoid leads to changes in the position of the epiglottis that may obstruct air flow within the airway. Further work by Horton and workers [15] showed that during laryngoscopy with a curved Macintosh blade in awake patients, the hyoid is drawn forward and downwards with a variable length of epiglottis.If the hyoid is unusually low in the neck, leading to a long mandibulohyoid distance, a large portion of the tongue mass is situated in the hypopharynx rather than in the oral cavity [16,17]. Chou and Wu [18] postulated that, under general anaesthesia, this large hypopharyngeal tongue creates a narrowed air space and the epiglottis frequently falls against the posterior pharyngeal wall [16], resulting in difficult ventilation, difficult intubation and obstructive sleep apnoea [18]. The hypopharyngeal tongue leads to a reduction in the submandibular compliance, making tongue displacement difficult when lifting the laryngoscope blade.A short mandibular ramus may lead to difficult laryngoscopy. First, the tongue will occupy more of the oral cavity and, consequently, there will be difficulty aligning the oral and pharyngeal axes during direct laryngoscopy. The short ramus may also lead to an increased mandibulohyoid distance and problems of a hypopharyngeal tongue, as mentioned above. It is therefore possible that the relationship of the three meas...

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SummaryA randomised study was carried out in 60 anaesthetised patients with no evidence of airway difficulties, to compare the Williams Airway Intubator and the Ovassapian Fibreoptic Intubating Airway for bronchoscopic view and ease of railroading a tracheal tube during fibreoptic orotracheal intubation. The Williams Airway Intubator provided a better view of the glottis (41 (68.3%) unobstructed views) than the Ovassapian Fibreoptic Intubating Airway (15 (25%) unobstructed views; p < 0.0001) and a shorter time was needed to complete bronchoscopy (median (95% CI) difference 4 s (1-7); p = 0.01). Four (6.7%) bronchoscopies failed using the Williams Airway Intubator compared with 26 (43.3%) using the Ovassapian Fibreoptic Intubating Airway (p < 0.0001). Both airways provided similar intubating conditions when the glottis was visible.

SummarySixty patients with no clinical indicators of a difficult airway were selected to undergo a fibreoptic assessment after induction of general anaesthesia using both the Berman Intubating Airway and the Williams Airway Intubator. The bronchoscopic view and ease of railroading a tracheal tube during fibreoptic orotracheal intubation were studied. The bronchoscopic views obtained by the Berman Airway and the Williams Airway were significantly different (p < 0.008, test of symmetry). The estimated odds ratio of obtaining an obstructed path was 3.06 times higher for the Berman than the Williams Airway. However, if the glottis could be reached with the bronchoscope, there was no significant difference in the degree of ease of intubation between the two airways.