Difficult Airway Society guidelines for management of the unanticipated difficult intubation

Problems with tracheal intubation are infrequent but are the most common cause of anaesthetic death or brain damage. The clinical situation is not always managed well. The Difficult Airway Society (DAS) has developed guidelines for management of the unanticipated difficult tracheal intubation in the non-obstetric adult patient without upper airway obstruction. These guidelines have been developed by consensus and are based on evidence and experience. We have produced flow-charts for three scenarios: routine induction; rapid sequence induction; and failed intubation, increasing hypoxaemia and difficult ventilation in the paralysed, anaesthetised patient. The flow-charts are simple, clear and definitive. They can be fully implemented only when the necessary equipment and training are available. The guidelines received overwhelming support from the membership of the DAS. Disclaimer: It is not intended that these guidelines should constitute a minimum standard of practice, nor are they to be regarded as a substitute for good clinical judgement.     

Difficult tracheal intubation: a retrospective study

This is a retrospective study of patients whose tracheas were impossible to intubate on a previous occasion. There is a correlation between the degree of difficulty and the anatomy of the oropharynx in the same patient. The study was initially on obstetric patients but was extended to nonobstetric surgical patients in order to increase the number of cases investigated. The incidence of failed intubations in the obstetric group over a 3-year period was seven out of 1980 cases, whereas in the surgical group the results were six out of 13,380 patients. Any screening test which adds to our ability to predict difficulty in intubation must be welcomed, as failure to intubate can potentially lead to fatality.     

Alternative techniques for tracheal intubation

Conventional direct laryngoscopy with the curved Macintosh blade is a fundamental skill for all anaesthetists and has been the cornerstone of airway management for many years. This technique relies upon the operator aligning the oro-pharyngo-laryngeal structures and inserting a tracheal tube into the trachea under direct vision. However, there is a recognized failure rate with this technique, thus alternative techniques for tracheal intubation are available and should be considered. Awake fibreoptic intubation remains the ‘gold standard’ method for securing the airway in an anticipated difficult airway. Advances in optical technology over recent years have led to the development of several rigid indirect devices, which improve glottic visualization by enabling the operator to ‘see around the corner’. With improved views at laryngoscopy these devices have emerged as important tools in airway management and are useful teaching and training aids.     

Failed intubation secondary to complete tracheal rings: a case report and literature review

Unanticipated difficult intubation in asymptomatic infants is a rare event. Most infants with congenital tracheal anomalies will present with airway problems. We present a case of failed intubation in an asymptomatic 8-day-old infant with complete tracheal rings. The infant could be ventilated with an LMA and surgery for placement of a ventricular-peritoneum shunt was completed. This is a report of the case and review of the literature.     

Comparison of a new video-optical intubation stylet versus the conventional malleable stylet in simulated difficult tracheal intubation

Handling and efficacy of a new video-optical intubation stylet were assessed in a simulated difficult tracheal intubation setting and compared with a conventional malleable stylet. Forty-five anaesthetists performed 10 tracheal intubations using both techniques. Laryngoscopy was performed by the observer, who created a grade 3 view according the classification by Cormack and Lehane. The time taken to place the tracheal tube and the final tracheal tube positions were documented. Mean (SD) intubation time for the video-optical stylet was 20.4 (7.7) s and for the malleable stylet 10.2 (3.3) s (p<0.01). With the video-optical stylet the trachea was correctly intubated in all 225 attempts; with the malleable stylet 44 (19.6%) oesophageal and 44 (19.6%) endobronchial intubations occurred (p<0.01). The video-optical intubation stylet enabled us to recognise inappropriate tracheal tube positions and to correct them immediately. This equipment can be considered a reliable and effective tool for management of the difficult airway.     

Identification of the difficult airway

Nearly all patients who are seriously difficult to manage are easily identified because they have grossly obvious abnormalities. Conversely, it is difficult to identify the few normal-looking patients that are difficult to manage.     

Alternative techniques for tracheal intubation

Conventional direct laryngoscopy with the curved Macintosh blade is a fundamental skill for all anaesthetists and has been the cornerstone of airway management for many years. This technique relies on the operator aligning the oro-pharyngo-laryngeal structures and inserting an endotracheal tube into the trachea under direct vision. There is a recognized failure rate with this technique and thus alternative techniques for tracheal intubation should be available for use in difficult situations. Awake fibreoptic intubation (AFOI) remains the ‘gold standard’ method for securing the airway in an anticipated difficult intubation. Advances in optical technology over recent years have lead to the development of several rigid indirect devices, which improve glottic visualization by enabling the operator to ‘see around the corner’. With improved views at laryngoscopy these videolaryngoscopes are emerging as important tools in airway management and useful teaching and training aids.     

视频喉镜在气道管理中应用的进展

视频喉镜是能够提供上呼吸道间接视野的新型气管插管设备。在困难气道管理处理方面．与直接喉镜相比．视频喉镜能够改善声门显露的Cormack—Lehane分级,并能在较短时间内达到相同或更高的气管插管成功率。尽管视频喉镜可获得非常好的声门显露．但是应用视频喉镜时插入和推进气管导管有时可发生失败。到目前为止,尚无确切证据表明在正常或困难气道患者视频喉镜应取代直接喉镜。     

Alternative techniques for tracheal intubation

Conventional direct laryngoscopy with the curved Macintosh blade is a fundamental skill for all anaesthetists and has been the cornerstone of airway management for many years. This technique relies on the operator aligning the oro-pharyngo-laryngeal structures and inserting an endotracheal tube into the trachea under direct vision. There is a recognized failure rate with this technique and thus alternative techniques for tracheal intubation should be available for use in difficult situations. Awake fibreoptic intubation (AFOI) remains the ‘gold standard’ method for securing the airway in an anticipated difficult intubation. Advances in optical technology over recent years have lead to the development of several rigid indirect devices, which improve glottic visualization by enabling the operator to ‘see around the corner’. With improved views at laryngoscopy these videolaryngoscopes are emerging as important tools in airway management and useful teaching and training aids.     

Obstetric Anaesthetists' Association and Difficult Airway Society guidelines for the management of difficult and failed tracheal intubation in obstetrics

The Obstetric Anaesthetists' Association and Difficult Airway Society have developed the first national obstetric guidelines for the safe management of difficult and failed tracheal intubation during general anaesthesia. They comprise four algorithms and two tables. A master algorithm provides an overview. Algorithm 1 gives a framework on how to optimise a safe general anaesthetic technique in the obstetric patient, and emphasises: planning and multidisciplinary communication; how to prevent the rapid oxygen desaturation seen in pregnant women by advocating nasal oxygenation and mask ventilation immediately after induction; limiting intubation attempts to two; and consideration of early release of cricoid pressure if difficulties are encountered. Algorithm 2 summarises the management after declaring failed tracheal intubation with clear decision points, and encourages early insertion of a (preferably second‐generation) supraglottic airway device if appropriate. Algorithm 3 covers the management of the ‘can't intubate, can't oxygenate’ situation and emergency front‐of‐neck airway access, including the necessity for timely perimortem caesarean section if maternal oxygenation cannot be achieved. Table 1 gives a structure for assessing the individual factors relevant in the decision to awaken or proceed should intubation fail, which include: urgency related to maternal or fetal factors; seniority of the anaesthetist; obesity of the patient; surgical complexity; aspiration risk; potential difficulty with provision of alternative anaesthesia; and post‐induction airway device and airway patency. This decision should be considered by the team in advance of performing a general anaesthetic to make a provisional plan should failed intubation occur. The table is also intended to be used as a teaching tool to facilitate discussion and learning regarding the complex nature of decision‐making when faced with a failed intubation. Table 2 gives practical considerations of how to awaken or proceed with surgery. The background paper covers recommendations on drugs, new equipment, teaching and training.     

The Management of difficult intubation in children

This article looks at the current techniques and equipment recommended for the management of the difficult intubation scenario in pediatric practice. We discuss the general considerations including preoperative preparation, the preferred anesthetic technique and the use of both rigid laryngoscopic and fiberoptic techniques for intubation. The unanticipated scenario is also discussed.     

The performance of rigid scopes for tracheal intubation: a randomised,controlled trial in patients with a simulated difficult airway

We compared the Bonfils^? and SensaScope^? rigid fibreoptic scopes in 200 patients with a simulated difficult airway randomised to one of the two devices. A cervical collar inhibited neck movement and reduced mouth opening to a mean (SD) of 23 (3) mm. The primary outcome parameter was overall success of tracheal intubation; secondary outcomes included first‐attempt success, intubation times, difficulty of intubation, fibreoptic view and side‐effects. The mean (95% CI) overall success rate was 88 (80–94)% for the Bonfils and 89 (81–94)% for the SensaScope (p = 0.83). First‐attempt intubation success rates were 63 (53–72)% for the Bonfils and 72 (62–81)% for the SensaScope (p = 0.17). Median (IQR [range]) intubation time was significantly shorter with the SensaScope (34 (20–84 [5–240]) s vs. 45 (25–134 [12–230]) s), and fibreoptic view was significantly better with the SensaScope (full view of the glottis in 79% with the SensaScope vs. 61% with the Bonfils). This might be explained by its steerable tip and the S‐formed shape, contributing to better manoeuvrability. There were no differences in the difficulty of intubation or side‐effects.     

Lightwand光棒插管在整形外科手术中的应用

目的：观察1ightwand光棒用于整形外科手术患者常规气管插管的安全性,和有效性以及在预测困难气管插管的可行性。方法：选择152例ASA Ⅰ或IⅡ级全麻下行择期整形外科手术的患者,其中124例为正常气道,根据光棒前端弯曲角度不同随机分为A组（60°）和B组（90°）,28例预测有困难气管插管为C组（90°）。记录各组插管时间、插管次数、插管的成功率、插管期间血流动力学变化以及术后并发症情况。结果：A、B和C组的一次插管成功率分别为100％、95．2％和85．7％,三组的插管总成功率均为100％;A、B和C组完成插管时间分别为（11．8±4．9）s、（14．0±5．4）S和（17．4±8．1）s,A组的光点寻找时间、光棒退出时间和气管插管时间均较B、C组缩短;光棒插管对循环功能的干扰小,术后并发症少。结论：lightwand光棒用于整形外科手术的常规气管插管及预测困难气管插管,插管成功率高、耗时短,对血流动力学影响较小,插管并发症少。     

Strategies and algorithms for management of the difficult airway

We have some good evidence but no proof regarding the usefulness of algorithms and guidelines for management of the difficult airway. Therefore, it is logical that there are no mandatory standards (yet) but only voluntary recommendations. Airway management is a practical matter, and a sufficient range of proven techniques should be practiced every day to facilitate successful use in emergencies.     

The laryngeal mask airway in the difficult paediatric airway: an assessment of positioning and use in fibreoptic intubation

The laryngeal mask airway (LMA) was used in 34 children who presented with difficult airways and difficulty in intubation. All 34 children were a grade 3 or grade 4 Cormack and Leehane view at conventional laryngoscopy. The laryngeal mask airway was used as part of the anaesthetic technique. It was either used as the method of airway maintenance during a short procedure or as an aid to fibreoptic intubation. The results of its use in this group of patients showed that overall a good airway was obtained in 73% of patients and an adequate airway in 27%, and in no patient was a poor airway obtained. The fibreoptic positioning of the LMA, taken from the distal aperture of the laryngeal mask airway showed that, overall, in 29.5% of patients a full view of the glottis (grade 1) was obtained, in 29.5% of patients a partial view of the glottis (grade 2) was obtained and in 41% a view of the epiglottis only (grade 3) was obtained. In no patient was a view excluding the epiglottis obtained. In children with a mucopolysaccharide disorder, the number of children who had a grade 3 view increased to 54%. Children with a disorder other than mucopolysaccharidosis had a grade 3 view in only 17% of cases. Children with mucopolysaccharidoses had a grade 1 view in only 14% of cases compared with 58% in the group with other disorders. Of the 34 patients, 21 patients were intubated on 31 separate occasions. There were no failures. The complications of the fibreoptic intubation technique described are outlined.     

Guidelines for the management of tracheal intubation in critically ill adults

These guidelines describe a comprehensive strategy to optimize oxygenation, airway management, and tracheal intubation in critically ill patients, in all hospital locations. They are a direct response to the 4^th National Audit Project of the Royal College of Anaesthetists and Difficult Airway Society, which highlighted deficient management of these extremely vulnerable patients leading to major complications and avoidable deaths. They are founded on robust evidence where available, supplemented by expert consensus opinion where it is not. These guidelines recognize that improved outcomes of emergency airway management require closer attention to human factors, rather than simply introduction of new devices or improved technical proficiency. They stress the role of the airway team, a shared mental model, planning, and communication throughout airway management. The primacy of oxygenation including pre- and peroxygenation is emphasized. A modified rapid sequence approach is recommended. Optimal management is presented in an algorithm that combines Plans B and C, incorporating elements of the Vortex approach. To avoid delays and task fixation, the importance of limiting procedural attempts, promptly recognizing failure, and transitioning to the next algorithm step are emphasized. The guidelines recommend early use of a videolaryngoscope, with a screen visible to all, and second generation supraglottic airways for airway rescue. Recommendations for emergency front of neck airway are for a scalpel–bougie–tube technique while acknowledging the value of other techniques performed by trained experts. As most critical care airway catastrophes occur after intubation, from dislodged or blocked tubes, essential methods to avoid these complications are also emphasized.