Use of the bougie in simulated difficult intubation. 2. Comparison of single-use bougie with multiple-use bougie

New guidelines for research in airway device evaluation: time for an updated approach (ADEPT-2) to the Difficult Airway Society's 'ADEPT' strategy?

In this article we present the learning from a clinical study of airway device evaluation, conducted under the framework of the Difficult Airway Society (DAS, UK) 'ADEPT' (airway device evaluation project team) strategy. We recommend a change in emphasis from small scale randomised controlled trials conducted as research, to larger-scale observational, post-marketing evaluation audits as a way of obtaining more meaningful information.

An assessment of introducers used for airway management

Different introducers are available to assist with tracheal intubation. Subtle differences in the design of introducers can have a marked effect on safety and performance. The Difficult Airway Society's Airway Device Evaluation Project Team proposal states that devices should only be purchased for which there is at least a case-control study on patients assessing airway devices. However, resources are not currently available to carry out a case-control study on all introducers available on the market. This study comprised a laboratory and manikin-based investigation to identify introducers that could be suitable for clinical investigation. We included six different introducers in laboratory-based assessments (design characteristics) and manikin-based assessments involving the participation of 30 anaesthetists. Each anaesthetist attempted placement in the manikin's trachea with each of the six introducers in a random order. Outcomes included first-time insertion success rate; insertion success rate; number of attempts; time to placement; and distance placed. Each anaesthetist also completed a questionnaire. First-time insertion success rate depended significantly on the introducer used (p = 0.0016) and varied from 47% (Armstrong and P3) to 77% (Intersurgical and Frova). Median time to placement (including oesophageal placement) varied from 10 s (Eschmann and Frova) to 20 s (P3) (p = 0.0025). Median time to successful placement in the trachea varied from 9 s (Frova) to 22 s (Armstrong) (p = 0.037). We found that the Armstrong and P3 devices were not as acceptable as other introducers and, without significant improvements to their design and characteristics, the use of these devices in studies on patients is questionable. The study protocol is suitable for differentiating between different introducers and could be used as a basis for assessing other types of devices.

Double-lumen tracheal tubes and bougies: a bench study to investigate factors that influence the risk of shearing

Tracheal intubation with a double-lumen tube can be more challenging than with a single-lumen tube. A bougie can be used to facilitate intubation. Case reports have described fragment shearing from bougies when they are removed from the tube after intubation. These fragments have the potential to cause harm. It has even been suggested that bougies and double-lumen tubes should not be used together. We conducted a benchtop trial to investigate factors that influence the risk of shearing. We investigated three brands of double-lumen tube (each in three sizes and both lateralities) and four brands of bougie. We simulated one intubation and 29 further insertions/removals of bougie with every bougie-double-lumen tube combination. We inspected the inside of the tube for evidence of shearing after first, tenth and thirtieth removals. We found that brand of bougie, brand of double-lumen tube and size of double-lumen tube (but not its laterality) all influenced the degree of shearing. Certain bougie-double-lumen tube combinations produced a particularly high degree of shearing, so these should be avoided.

Comparison of the AMBU® Laryngeal Mask and the LMA Classic in Anaesthetised, Spontaneously Breathing Patients

There may be a role for single-use laryngeal mask airways with concerns about inability to adequately sterilise laryngeal mask airways to eradicate prion proteins. A single-blinded prospective randomised controlled trial was conducted to compare the clinical performance of the single-use AMBU®LMA with the reuseable LMA Classic. There was no difference in time to insertion, successful insertion at first attempt, oropharyngeal leak pressure, haemodynamic response to insertion or complications of placement. The AMBU®LMA was easier to insert. There was a suggestion of reduced postoperative sore throat and pharyngeal trauma for the AMBU® LMA group. The AMBU®LMA is a viable alternative to the LMA Classic for airway management in spontaneously breathing patients.

Comparison of laryngeal morbidities with modified reinforced silicone tube intubation guided over a bougie vs. a guidewire: novel assessment with voice analysis

Semi-rigid flexible introducer-guided tracheal intubation is associated with pharyngolaryngeal morbidities. We compared the practice of railroading a newly described modified reinforced silicone tracheal tube with a built-in guide channel in its wall over a non-kinking guidewire with railroading the same tube over a disposable bougie, with respect to pharyngolaryngeal morbidities. One hundred and twenty-four ASA 1 and 2 adults were randomly assigned to undergo bougie-guided (n = 62) or wire-guided (n = 62) intubation under general anaesthesia. All patients were assessed for postoperative pharyngolaryngeal complaints. In addition, voice parameters (fundamental frequency, shimmer, jitter and harmonic noise ratio) with vowels 'a' and 'i' were analysed pre-operatively and 24 h postoperatively. The success of first-attempt intubation and the associated haemodynamic response were also recorded. A higher incidence of pharyngolaryngeal complaints was seen in the bougie group, 48.3%, 95%CI (35.9-60.9%) when compared with wire-guided group 28.3%, 95%CI (18.0-40.6%), p = 0.01. Postoperatively, all the voice parameters were significantly more affected when compared with their pre-operative value in the bougie-guided group (p < 0.05) but not in the wire-guided group. The success of first-attempt intubation was similar in both groups. Wire-guided orotracheal intubation was associated with a lower incidence of pharyngolaryngeal complaints and effect on voice when compared with bougie-guided intubation.

A before-and-after observational study of a protocol for use of the C-MAC videolaryngoscope with a Frova introducer in pre-hospital rapid sequence intubation

Results using videolaryngoscopy in pre-hospital rapid sequence intubation are mixed. A bougie is not commonly used with videolaryngoscopy. We hypothesised that using videolaryngoscopy and a bougie as core elements of a standardised protocol that includes a drugs and a laryngoscopy algorithm would result in a high first-pass tracheal intubation success rate. We employed videolaryngoscopy (C-MAC) combined with a bougie (Frova intubating introducer) in an anaesthetist-staffed helicopter emergency medical service. Data for adult tracheal intubation were collected prospectively as part of the airway registry of our unit for 22 months after implementation of the protocol (n = 543) and compared with controls (n = 238) treated in the previous year before the implementation. The mean first-pass success rate (95%CI) was 98.2% (96.6-99.0%) in the study group and 85.7% (80.7-89.6%) in the control group, p < 0.0001. Combining C-MAC videolaryngoscopy and bougie with a standardised rapid sequence induction protocol leads to a high first attempt intubation success rate when performed by an anaesthetist-led helicopter emergency medical service team.

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.

Difficulties with gum elastic bougie intubation in an academic emergency department

BACKGROUND

The difficulties with gum elastic bougie (GEB) use in the emergency department (ED) have never been studied prospectively.

OBJECTIVES

To determine the most common difficulties associated with endotracheal intubation using a GEB in the ED.

METHODS

We conducted a prospective, observational study of GEB practices in our two affiliated urban EDs with a 3-year residency training program and an annual census of 150,000 patients. Laryngoscopists performing a GEB-assisted intubation completed a structured data form after laryngoscopy, recording patient characteristics, grade of laryngeal view (using the modified Cormack-Lehane classification), reason for GEB use, and problems encountered. Data were analyzed using standard statistical methods and 95% confidence intervals.

RESULTS

A GEB was used for 88 patients. The overall success rate was 70/88 (79.6%; 95% confidence interval [CI] 71.1-88.0%). The GEB failure rate of the first laryngoscopist was 25/88 (28.4%; 95% CI 21.0-40.3%), with the two most common reasons being: inability to insert the bougie past the hypopharynx in 13 (52%; 95% CI 32.4-71.6%) and inability to pass the endotracheal tube over the bougie in six (24%; 95% CI 7.3-40.7).

CONCLUSIONS

The GEB is a helpful rescue airway device, but emergency care providers should be aware that failure rates are relatively high at a teaching institution.

Effect of cardiopulmonary resuscitation on intubation using a Macintosh laryngoscope, the AirWay Scope, and the gum elastic bougie: A manikin study

BACKGROUND

Physicians could encounter difficult intubation during cardiopulmonary resuscitation (CPR) in trauma patients due to the patient's movement from continuous chest compression and to cervical stabilisation. Therefore, first, we evaluated the impact of chest compression with or without cervical stabilisation on intubation with a Macintosh laryngoscope. Next, we compared difficulty in intubation among the Macintosh laryngoscope, AirWay Scope (AWS), and gum elastic bougie (GEB) with the Macintosh laryngoscope in three simulated CPR scenarios in a randomised, controlled, cross-over study design.

METHODS

Twenty-three anaesthetists intubated the trachea of a manikin (ALS Skill Master, Laerdal Medical Japan, Tokyo, Japan) using the Macintosh laryngoscope, AWS, and GEB in the control scenario, chest compression scenario, and chest compression with cervical stabilisation scenario. Difficulty in intubation was rated on a 5-point scale and the intubation time was measured.

RESULTS

Continuous chest compression increased difficulty in intubation with the Macintosh laryngoscope, compared with the control scenario. Concurrent application of cervical stabilisation further increased the difficulty, compared with application of chest compression alone. Of the three devices compared, the AWS facilitated the easiest intubation, and the GEB facilitated the second-easiest intubation in all scenarios, though the intubation time was slightly longer with the GEB than with other devices.

CONCLUSION

CPR employing continuous chest compression with or without cervical stabilisation caused difficult intubation with the Macintosh laryngoscope. The AWS and GEB facilitated the easiest and second-easiest intubation, respectively, even during CPR employing continuous chest compression with or without cervical stabilisation in a manikin.

Difficult and failed intubation in 3430 obstetric general anaesthetics

A retrospective audit was performed of all obstetric general anaesthetics in our hospital over an 8 year period to determine the incidence of difficult and failed intubation. Data was collected from a number of sources to ensure accuracy. A total of 3430 rapid sequence anaesthetics were given. None of the patients had a failed or oesophageal intubation (95% CI, 0-1:1143). There were 23 difficult intubations (95% CI, 1:238-1:100). This was anticipated in nine cases, requiring awake fibreoptic intubation in three cases. Consultants or specialist registrars were involved in the management of all cases. We attribute the low incidence of airway complications to the above average rate of general anaesthesia in our hospital, senior cover and specialised anaesthetic operating department assistants.

Intubation bougie dissection of tracheal mucosa and intratracheal airway obstruction

Intubation bougies are commonly used to aid in intubation when an optimal view of the larynx is not obtained. We describe a case of tracheal perforation using a disposable intubation bougie resulting in a complete intratracheal airway obstruction relieved by cricothyrotomy. Disposable intubation bougies may have mechanical properties that differ from their nondisposable counterparts making complications more likely.

Evaluation of clinical effectiveness of the Frova single-use tracheal tube introducer

A prospective observational study design was used to evaluate the clinical effectiveness of the Frova single-use tracheal tube introducer. Data were collected from 203 patients. Consultants and trainee anaesthetists completed 61 (30%) and 142 (70%) forms respectively, when the Frova introducer was used. It was successfully placed in the trachea in 194/203 (96%) of patients with two attempts at placement by the first clinician. The first clinician failed to either pass the Frova introducer or railroad the tube in six (3%) and 10 (5%) of the 203 patients respectively. The success rate by the first clinician was significantly influenced by the laryngeal view obtained (p < 0.0001). There was only one failure to place the Frova introducer in the trachea by either the first or second clinician. Airway trauma was detected in 11/203 (5%) patients. In six of these 11 patients blood was detected on tracheal suction; 'distal hold up' was elicited in five of these six. The Frova introducer has a high success rate for tracheal placement but has noteworthy potential to produce airway trauma.

Comparison of the Levitan FPS Scope and the single-use bougie for simulated difficult intubation in anaesthetised patients

A randomised cross-over study was performed in 34 patients with no evidence of airway difficulties, following induction of general anaesthesia, to compare the efficacy of the Levitan FPS scope (LFPS) and the single-use bougie for tracheal intubation during simulated grade IIIa laryngoscopy. Success rates for intratracheal placement of the device, and the time required for insertion and tracheal intubation were recorded. Both devices were equally successful (31/34 for the LFPS vs 29/34 for the bougie) for insertion into the glottis. The mean insertion time for the LFPS was statistically longer than that for the bougie (4.4-12.5 s) but this difference was not clinically relevant. Intubation times were similar between the two devices. Major problems hindering successful intubation using the LFPS were the presence of a narrow epiglottic-pharyngeal wall space and copious secretions. An inability to maintain the desired shape was the principal cause of failure with the bougie.

The use of single-use devices in anaesthesia: balancing the risks to patient safety

Single-use devices are designed, manufactured and sold to be used once and then discarded. This paper addresses growing concerns about the quality of some devices. Single-use devices, manufactured at a lower cost to justify their disposal, are perceived to have a lesser efficacy, which may threaten patient safety through iatrogenic harm. There is, in addition, growing scepticism about the actual risk of contracting variant Creutzfeldt-Jakob disease and other blood-borne diseases from reused surgical instruments. Interview data suggests that when choosing to use a single-use device, clinicians balance concerns about the risk of infection against those about the risk of injury. However, despite reservations about induced harm and the unknown risk of an iatrogenic disease, most clinicians would want single-use devices used on themselves and their family if they were patients.

A comparison of the use of Trachlight and Eschmann multiple-use introducer in simulated difficult intubation

BACKGROUND AND OBJECTIVE

The Eschmann multiple-use introducer is widely used in the management of difficult intubations. Transillumination of the neck is less commonly used. We conducted a randomized crossover study comparing the Trachlight lightwand and Eschmann multiple-use introducer in simulated difficult intubation.

METHODS

Sixty-four healthy patients were studied using a standard anaesthetic and full muscle relaxation assessed by train of four. A Macintosh laryngoscope was then inserted and then lowered to simulate a Grade 3 view. Tracheal placement was attempted with both Trachlight lightwand and Eschmann multiple-use introducer in a randomized order. Anaesthetists placing the devices had extensive experience with the Eschmann multiple-use introducer, but only 15 previous uses of the Trachlight. Success rates and time for tracheal placement were recorded.

RESULTS

The Eschmann multiple-use introducer and Trachlight were successfully placed in 96.8% and 93.7%, respectively (n.s.). Mean (SD) time to intubation for Eschmann multiple-use introducer and Trachlight were 15(6) and *21(13), respectively (*P < 0.001).

CONCLUSION

The Trachlight is a potentially useful alternative to the Eschmann multiple-use introducer in difficult intubation.

Prehospital airway management in Ambulance Services in the United Kingdom

A postal survey of the 38 Ambulance Services in the United Kingdom was undertaken to find out what equipment is provided for paramedic crews to aid tracheal intubation and to confirm tracheal placement. The response rate to our survey was 100%. Fourteen (37%) ambulance services provided neither stylet nor bougie to facilitate difficult intubation. The laryngeal mask airway was available to 15 (40%) ambulance services. Seventeen (45%) ambulance services had use of a needle cricothyroidotomy set. Twenty-nine (76%) ambulance services had no type of device other than a stethoscope to confirm tracheal tube placement. This survey showed wide variations in the equipment for airway management available to paramedic crews in the United Kingdom. We recommend provision of a standard set of airway management equipment to all paramedic crews in the United Kingdom together with introduction of appropriate training programmes.

Evaluation of Frova, single-use intubation introducer, in a manikin. Comparison with Eschmann multiple-use introducer and Portex single-use introducer

In a randomised cross-over study, 48 anaesthetists attempted to place a Frova single-use introducer, an Eschmann multiple-use introducer and a Portex single-use introducer in the trachea of a manikin set up to simulate a grade 3 laryngoscopic view. The anaesthetists were blinded to success (tracheal placement) or failure (oesophageal placement). Successful placement (proportion, 95% confidence interval) of either the Frova introducer (65%, 50-77%) or the Eschmann introducer (60%, 46-73%) was significantly more likely than with the Portex introducer (8%, 3-20%). There were no significant differences between the success rates for the Frova and the Eschmann introducers. A separate experiment revealed that the peak force exerted by the Frova and Portex introducers was two to three times greater than that which could be exerted by the Eschmann introducer, p < 0.0001, indicating that the single-use introducers are more likely to cause tissue trauma during placement.

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.

Use of the bougie in simulated difficult intubation. 1. Comparison of the single-use bougie with the fibrescope

We studied the success rates for tracheal intubation in 64 healthy patients during simulated grade III laryngoscopy after induction of anaesthesia, using either the single-use bougie or oral flexible intubating fibrescope, both in conjunction with conventional Macintosh laryngoscopy. Patients were randomly allocated to either simulated grade IIIa or grade IIIb laryngoscopy, and also to one of the two study devices. Success rates for tracheal intubation (primary outcome measure) and times taken to achieve intubation (secondary outcome measure) were recorded. For the simulated grade IIIa laryngoscopy group, the fibreoptic scope was more successful than the bougie (16/16 successful intubations vs. 8/16; p = 0.02). For the simulated grade IIIb laryngoscopy group, the fibreoptic scope was also more successful than the bougie (8/16 successful intubations vs. 1/16; p = 0.02), but clearly use of the fibreoptic scope was not as successful as it had been in simulated grade IIIa laryngoscopy (p = 0.04). With either device, median (range) total tracheal intubation times for successful attempts with either grade of laryngoscopy were less than 60 s (19-109) and there were no clinically important differences. We conclude that the fibrescope used in conjunction with Macintosh laryngoscopy is a more reliable method of tracheal intubation than the single-use bougie in both types of grade III laryngoscopy. This finding has implications for the management of patients in whom grade III laryngoscopy is encountered unexpectedly after induction of anaesthesia, and also for the management of patients previously known to have grade III view at laryngoscopy.