The Difficult Airway Society ‘ADEPT’ Guidance on selecting airway devices: the basis of a strategy for equipment evaluation

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 Tulip GT® airway versus the facemask and Guedel airway: a randomised, controlled, cross-over study by Basic Life Support-trained airway providers in anaesthetised patients

We performed a randomised, controlled, cross-over study of lung ventilation by Basic Life Support-trained providers using either the Tulip GT® airway or a facemask with a Guedel airway in 60 anaesthetised patients. Successful ventilation was achieved if the provider produced an end-tidal CO2 > 3.5 kPa and a tidal volume > 250 ml in two of the first three breaths, within 60 sec and within two attempts. Fifty-seven (95%) providers achieved successful ventilation using the Tulip GT compared with 35 (58%) using the facemask (p < 0.0001). Comparing the Tulip GT and facemask, the mean (SD) end-tidal CO2 was 5.0 (0.7) kPa vs 2.5 (1.5) kPa, tidal volume was 494 (175) ml vs 286 (186) ml and peak inspiratory pressure was 18.3 (3.4) cmH2 O vs 13.6 (7) cmH2 O respectively (all p < 0.0001). Forty-seven (78%) users favoured the Tulip GT airway. These results are similar to a previous manikin study using the same protocol, suggesting a close correlation between human and manikin studies for this airway device. We conclude that the Tulip GT should be considered as an adjunct to airway management both within and outside hospitals when ventilation is being undertaken by Basic Life Support-trained airway providers.

Radical evolution: the 2015 Difficult Airway Society guidelines for managing unanticipated difficult or failed tracheal intubation

There is little doubt that these guidelines incorporate advances made in airway management since 2004. They will change day-to-day practice of anaesthesia, as outlined above, from pre-operative airway assessment, to integrating the WHO team briefing, to the use and provision of equipment and drugs, and the recording of information on the anaesthesia chart. They will inform the later analysis of any critical airway incidents, especially as documentation and postoperative management are addressed, and they will encourage training in a range of techniques. Taken together, not quite a revolution but certainly a very 'radical evolution'.Assessment of the utility of the new guidelines should consider if they can be used as tools to enhance knowledge and training, or in addition as a prosthesis to bridge the gap between the requirements of and our abilities during emergencies. Formal testing may reveal which aspects of their design, complex as it is, may distract from, rather than enhance, airway management during crises.All guidelines represent a standard of care or a normative approach to a clinical problem. As such, they not only help guide clinicians, but they also provide the broader community with the opportunity to improve standards, to ensure equipment is available, and that training for the skills and processes required are in place to ensure successful adoption.

Evaluation of a novel Surgicric® cricothyroidotomy device for emergency tracheal access in a porcine model

A can't intubate, can't ventilate scenario can result in morbidity and death. Although a rare occurrence (1:50 000 general anaesthetics), it is crucial that anaesthetists maintain the skills necessary to perform cricothyroidotomy, and are well-equipped with appropriate tools. We undertook a bench study comparing a new device, Surgicric(®) , with two established techniques; the Melker Emergency Cricothyroidotomy, and a surgical technique. Twenty-five anaesthetists performed simulated emergency cricothyroidotomy on a porcine model, with the primary outcome measure being insertion time. Secondary outcomes included success rate, tracheal trauma and ease of use. The surgical technique was fastest. The median (IQR [range]) was 81 (62-126 [37-300]) s, followed by the Melker 124 (100-217 [71-300]) s, and the Surgicric 127 (68-171 [43-300]), p = 0.003. The Surgicric device was the most traumatic, as evaluated by a blinded Ear, Nose and Throat surgeon. Subsequently, the authors contacted the device manufacturer, who has now modified the kit in the hope that its clinical application might be improved. Further studies are required to evaluate the revised model.

A comparison of the ease of tracheal intubation using a McGrath MAC(®) laryngoscope and a standard Macintosh laryngoscope

We compared the McGrath MAC(®) videolaryngoscope when used as both a direct and an indirect laryngoscope with a standard Macintosh laryngoscope in patients without predictors of a difficult tracheal intubation. We found higher median Intubation Difficulty Scores with the McGrath MAC as a direct laryngoscope, 1 (0-3 [0-5]) than when using it as an indirect videolaryngoscope, 0 (0-1 [0-5]) or when using the Macintosh laryngoscope, 0 (0-1 [0-5]), p = 0.04. This was mirrored in the subjective user reporting, scored out of 10, of difficulty for each method 3.0 (2.0-3.4 [0.5-80]); 2.0 (1.0-3.9 [0-70]) and 2.0 (1.0-3.3 [0-70]), respectively (p = 0.01). This difficulty is in part explained by the poorer laryngeal views recorded using the Cormack and Lehane classification system (p < 0.001) and reflected in the higher than normal operator force required (25%, 4%, 8% for each method, respectively, p < 0.001) and the increased use of rigid intubation aids (21%, 6%, 2%, respectively, p < 0.001). There was no difference between the groups in time taken to intubate or incidence of complications. There was no statistical difference in the performances as measured between the McGrath MAC used as an indirect videolaryngoscope and the Macintosh laryngoscope. We cannot recommend that the McGrath videolaryngoscope be used as a direct laryngscopic device in place of the Macintosh.

Preparedness and education in airway management

A prepared airway practitioner performs safe airway management, displaying skill, knowledge, and a full awareness of human factors, within a culture of safety. The education of prepared practitioners should include deliberate practice and distributed learning and should aim for expertise rather than mere competence. Translational outcomes from improved education and training can significantly decrease patient morbidity and mortality.

The Availability of Advanced Airway Equipment and Experience with Videolaryngoscopy in the UK: Two UK Surveys

Fibreoptic intubation, high frequency jet ventilation, and videolaryngoscopy form part of the Royal College of Anaesthetists compulsory higher airway training module. Curriculum delivery requires equipment availability and competent trainers. We sought to establish (1) availability of advanced airway equipment in UK hospitals (Survey I) and (2) if those interested in airway management (Difficult Airway Society (DAS) members) had access to videolaryngoscopes, their basic skill levels and teaching competence with these devices and if they believed that videolaryngoscopy was replacing conventional or fibreoptic laryngoscopy (Survey II). Data was obtained from 212 hospitals (73.1%) and 554 DAS members (27.6%). Most hospitals (202, 99%) owned a fiberscope, 119 (57.5%) had a videolaryngoscope, yet only 62 (29.5%) had high frequency jet ventilators. DAS members had variable access to videolaryngoscopes with Airtraq 319 (59.6%) and Glidescope 176 (32.9%) being the most common. More DAS members were happy to teach or use videolaryngoscopes in a difficult airway than those who had used them more than ten times. The majority rated Macintosh laryngoscopy as the most important airway skill. Members rated fibreoptic intubation and videolaryngoscopy skills equally. Our surveys demonstrate widespread availability of fibreoptic scopes, limited availability of videolaryngoscopes, and limited numbers of experienced videolaryngoscope tutors.

A review of video laryngoscopes relevant to the intensive care unit

The incidence of difficult direct intubation in the intensive care unit (ICU) is estimated to be as high as 20%. Recent advances in video-technology have led to the development of video laryngoscopes as new intubation devices to assist in difficult airway management. Clinical studies indicate superiority of video laryngoscopes relative to conventional direct laryngoscopy in selected patients. They are therefore an important addition to the armamentarium of any clinician performing endotracheal intubation. We present a practical review of commonly available video laryngoscopes with respect to design, clinical efficacy, and safety aspects relevant to their use in the ICU.

A pilot study to examine the effect of the Tulip oropharyngeal airway on ventilation immediately after mask ventilation following the induction of anaesthesia

The Tulip airway is an adult, disposable, single-sized oropharyngeal airway, that is connectable to an anaesthetic circuit. After a standardised induction of anaesthesia in 75 patients, the ease of insertion, intracuff pressure and intracuff volume were measured, as were the end-tidal carbon dioxide levels, airway pressures and tidal volumes over three breaths. Successful first-time insertion was achieved in 72 patients (96%, CI 88.8-99.2%) and after two attempts in 74 patients (99%, CI 92.8-100%). There was outright failure only in one patient. In 60 patients (80%, CI 72.2-90.4%), the Tulip airway provided a patent airway without additional manoeuvres, but in 14 patients, jaw thrust or head extension was necessary for airway patency. The main need for these adjuncts appeared to be an initial under-inflation of the cuff. These promising results are consistent with recent manikin studies using this device.

Extraglottic airway devices: A review

Extraglottic airway devices (EAD) have become an integral part of anesthetic care since their introduction into clinical practice 25 years ago and have been used safely hundreds of millions of times, worldwide. They are an important first option for difficult ventilation during both in-hospital and out-of-hospital difficult airway management and can be utilized as a conduit for tracheal intubation either blindly or assisted by another technology (fiberoptic endoscopy, lightwand). Thus, the EAD may be the most versatile single airway technique in the airway management toolbox. However, despite their utility, knowledge regarding specific devices and the supporting data for their use is of paramount importance to patient's safety. In this review, number of commercially available EADs are discussed and the reported benefits and potential pitfalls are highlighted.

Making endotracheal intubation easy and successful, particularly in unexpected difficult airway

Background:

Difficult intubation, most often due to poor view of the vocal cords on laryngoscopy is an intermittent and often challenging problem for clinically practicing anesthesiologists, maxillofacial surgeons, ear nose, and throat (ENT), emergency, and critical care physicians.

Purpose:

We present a new approach for facilitating difficult intubation and evaluate its efficacy in a retrospective observational study.

Settings and Design:

Operating room, emergency department, intensive care unit (ICU), retrospective observational study.

Materials and Methods:

A semirigid 5.6 Rüsch tracheal tube introducer (bougie) with its soft tip protruding at least 6 cm (=4 digits) beyond the distal end of the tube was used. After its insertion through the larynx under laryngoscopy, the tube was gently advanced upon rotation at 360° clockwise.

Statistical Analysis:

Descriptive.

Results:

Anesthesia services were analyzed on 10,363 patients over 12 months. In 2453 patients (23.7%) (Group A) intubated in the usual way, difficulties were encountered in 63 patients (2.6%). They were managed either with tube rotation technique (n = 60) or Bonfils endoscope (n = 3). In contrast, 2807 patients (27.1%) (Group B) were intubated using tube rotation technique with introducer. Difficult intubations occurred only in three patients (0.11%) who could be managed with tube rotation by experienced consultant anesthesiologists.

Conclusions:

The tube rotation technique for intubation was introduced during the Gulf War and has been practiced for the past 19 years without any obvious damage to the trachea in Germany. However, it should be used only by physicians being well familiar with this technique. In addition, well designed controlled studies are needed.

[Rare problem with the insertion of a Supreme™ laryngeal mask airway device. Case of the trimester]

A breast tumor was resected under general anesthesia. After induction, the airway was managed with a Supreme™ laryngeal mask airway device. The insertion of the laryngeal mask airway device, the insertion of the orogastric tube through the drain tube, as well as the mechanical ventilation, were very difficult from the beginning. On removing the laryngeal mask airway device to solve the problem, it was observed that the drain tube was broken, and the orogastric tube had passed into the anterior, laryngeal part of the device through the split. It was later found out that the laryngeal mask airway device, as well as the whole manufacturing batch, had suffered a design modification: the cuff was constructed with a softer material without reinforcement in the tip, and the drain tube had a heat-sealing defect that facilitated the break. The incident was reported to the local supplier and the manufacturer, and the defective batch of laryngeal mask airway devices was recalled. The incident was also reported to other hospitals via SENSAR, to warn other users of the potential dangers of the design modification in the Supreme™ laryngeal mask airway.

A randomized trial comparing the Ambu ® Aura-i ™ with the air-Q ™ intubating laryngeal airway as conduits for tracheal intubation in children

OBJECTIVES

To assess the clinical performance of the Ambu Aura-i (Aura-i) in children.

AIM

To compare the Aura-i with the air-Q intubating laryngeal airway (air-Q) for the purposes of fiberoptic-guided tracheal intubation.

BACKGROUND

The Aura-i is a new supraglottic airway designed for tracheal intubation.

MATERIALS/METHODS

One hundred twenty children, ages 1 month to 6 years, were randomized to receive either the Aura-i or air-Q, and divided into three equal subgroups (Group 1, 2, 3) based on weight. The time for successful tracheal intubation was primarily assessed. The ease, time, and number of attempts for successful device insertion, leak pressures, fiberoptic grade of laryngeal view, number of attempts time for removal of the device after tracheal intubation, and complications were secondarily assessed.

RESULTS

Device placement, tracheal intubation, and removal after tracheal intubation were successful in all patients. There were no differences in the time to successful tracheal intubation through the Aura-i (32.9 ± 13.3 s), and the air-Q (33.9 ± 13 s; P = 0.68), or fiberoptic grade of view between devices. There was not a statistically significant correlation between the time to intubation and the fiberoptic grade of laryngeal view in any of the groups. There were no statistically significant differences in the overall leak pressures, air-Q (18.3 ± 6.1 cm H(2) O) vs Aura-i (16 ± 5.1 cm H(2) O; P = 0.05). In Group 1 (5-10 kg), leak pressures were higher with the air-Q (23.4 ± 7.2 cm H(2) O) than the Aura-i (16.1 ± 5.2 cm H(2) O; P = 0.001). There were no statistically significant differences in the time for removal between the two devices (P = 0.11). However, with the size 1.5 Aura-i, the pilot balloon of the tracheal tube was removed in order to facilitate the removal of the device after tracheal intubation.

CONCLUSIONS

Both devices served as effective conduits for fiberoptic-guided tracheal intubation. The limitation of the narrower proximal airway tube of the size 1.5 Aura-i should be considered if cuffed tracheal tubes are to be utilized.

A randomised comparison of InnoScope and Macintosh laryngoscope in simulated difficult tracheal intubation in manikins

We conducted a crossover randomised study to evaluate the performance of a novel optical stylet, the InnoScope, for tracheal intubation in simulated normal and difficult airways. Twenty-five anaesthetists attempted tracheal intubation on a SimMan 3G simulator using the InnoScope first followed by the Macintosh laryngoscope or vice versa. Three airway scenarios were tested: (1) normal airway; (2) difficult airway with swollen pharynx; and (3) limited neck movement. In each scenario, the laryngeal view, duration of and success rate for tracheal intubation were recorded. Compared with the Macintosh laryngoscope, the use of InnoScope increased the percentage of glottic opening seen by 17% in normal airway, 23% in the difficult airway and 32% with limited neck movement, p < 0.01. Despite this better laryngeal view, successful tracheal intubation achieved with the InnoScope (88.0%) was lower than that for the Macintosh laryngoscope (98.7%), p = 0.008. Using the InnoScope, tracheal intubation during the first attempt was only successful in 48% of cases with difficult airway. In this scenario, the median (interquartile range [range]) duration of tracheal intubation was significantly longer with [corrected] InnoScope compared with the Macintosh laryngoscope, (70 (19-120 [15-120)] s vs 30 [21-58 (15-120)] s, [corrected] p = 0.01. We conclude that an improved laryngeal view with the use of the InnoScope did not translate into better conditions for tracheal intubation.

An observational study of the Baska® mask: a novel supraglottic airway

The Baska mask is a novel supraglottic airway device. We conducted an initial observational study to assess this device in 30 low-risk female patients. All Baska masks were inserted by a single investigator. The overall success rate for device insertion was 96.7% (95% CI 82.8-99.9%), while the success rate for the first insertion attempt was 76.7% (95% CI 57.7-90.1%). The device was easy to insert, with a mean (SD) difficulty score of 0.9 (1.6) on a 10-cm scale. The mean (SD) airway leak pressure was 35.7 (13.3) cmH(2) O. The incidence of throat pain, dysphonia and dysphagia was low. We conclude that the Baska mask demonstrates a level of utility as an alternative supraglottic airway that is worthy of further clinical study.

Non-Luer connectors: are we nearly there yet?

The Department of Health aims to eliminate the use of devices with a Luer connector firstly from 'single shot' neuraxial procedures (April 2012) and subsequently from all neuraxial and regional anaesthesia procedures (April 2013). This initiative is important for all anaesthetists, oncologists, paediatricians and neurologists. Once achieved, non-Luer connectors for neuraxial procedures will create one more barrier to wrong-route errors. The period until full implementation and market stability remains problematic. Avoidance of unintended consequences requires professional and individual attention to detail. Considerable progress has been made by manufacturers in the last year in improving the quality and range of equipment available, but despite this not all the necessary equipment is available and there remains a lack of independent evaluation, which is urgently needed to enable clinicians to judge the absolute and relative performance of different connectors. Initial evaluation of devices with new connectors can (and should) take place in a laboratory with rigs and manikins, with patient-based evaluation following after the results of the technical and usability evaluations are available. A structured evaluation of all five current connectors is urgently needed. Non-Luer connectors, however successful, will not create barriers to several type of wrong-route error and solutions to these should also be actively sought. It is clear that the initiative has been more complex than the Health Select Committee, the National Patient Safety Agency and the External Reference Group anticipated, but while there is still much work to be done, we should acknowledge that much progress has been made.

A randomised, controlled trial comparing the Airtraq™ optical laryngoscope with conventional laryngoscopy in infants and children

The Airtraq(™) optical laryngoscope became available in paediatric sizes in the UK in May 2008. We conducted a randomised, controlled trial comparing the Airtraq with conventional laryngoscopy during routine anaesthesia in children. We hypothesised that the Airtraq laryngoscope would perform as well as conventional laryngoscopy. Sixty patients (20 infants and 40 children) were recruited. The mean (SD) intubation time using the Airtraq was longer than conventional laryngoscopy overall (47.3 (32.6) vs 26.3 (11.5) s; p=0.002), though the difference was only significant for children (p=0.003) and not for infants (p=0.29). The Airtraq provided a better view of the larynx compared with conventional laryngoscopy (in infants (percentage of glottic opening scores 100 (95-100 [90-100]) vs 77 (50-90 [40-100]), respectively; p=0.001; visual analogue scores for field of view 9.2 (9.2-9.5 [8.2-10.0]) vs 6.8 (5.1-8.0 [4.7-10.0]), respectively; p=0.001). In children, the Airtraq provided a similar view of the larynx (percentage of glottic opening scores 100 (100-100 [40-100]) vs 100 (90-100 [50-100]), respectively; visual analogue scores for field of view 9.2 (8.6-10.0 [7.0-10.0]) vs 9.2 (8.6-10.0 [5.6-10.0]), respectively; both p>0.05), compared with conventional laryngoscopy.

Evidence for benefit vs novelty in new intubation equipment

A myriad of new intubation equipment has been introduced commercially since the appearance of Macintosh/Miller blades in the 1940s. We review the role of devices that are relevant to current clinical practice based on their presence in the scientific literature. The comparative performance of new vs traditional direct laryngoscopes, their complications, their use in awake intubation techniques and the prediction of unsuccessful intubation with new devices are reviewed. Manikin studies are of limited value in this area. We conclude that in both predicted and unpredicted difficult or failed intubation, carefully selected new intubation equipment has a high success rate for tracheal intubation. Ideally, such devices should be available in all settings where tracheal intubation is performed. Most importantly, experience and competence with any of the new devices are critical for their successful use in any clinical setting.