Written by: Amanda Randolph, MD (NUEM PGY-3) Edited by: Katie Colton, MD (NUEM ‘19) Expert commentary by: Howard Kim, MD
Introduction:
Endotracheal intubation is one of the most common and life-saving procedures performed in the Emergency Department (ED), though it is not without risk – approximately 12% of ED intubations result in an adverse event. First-pass success has been linked to improved outcomes, but in the case of a difficult airway, this goal can be challenging. The bougie is typically reserved as a rescue device in these situations. However, a study recently published in JAMA questions this approach, and instead asks whether the routine use of a bougie during all difficult airway attempts would improve first-pass success.
The Study:
Driver BE, Prekker ME, Klein LR, et al. Effect of Use of a Bougie vs Endotracheal Tube and Stylet on First-Attempt Intubation Success Among Patients With Difficult Airways Undergoing Emergency Intubation: A Randomized Clinical Trial. JAMA. 2018;319(21):2179–2189. doi:10.1001/jama.2018.6496
Study Design:
This study was a randomized clinical trial performed at Hennepin County Medical Center, an urban academic Emergency Department.
Population:
Investigators enrolled consecutive patients 18 years and older whom the attending emergency physician planned to intubate using a Macintosh laryngoscope blade (direct or video).
Exclusion criteria included known anatomic distortion of the upper airway (ie angioedema, epiglottitis, laryngeal mass, or malignancy), as the bougie has already been proven more effective in these patients in previous studies. Prisoners and pregnant patients were also excluded.
After intubation, the physician recorded whether any difficult airway features were present: body fluids obscuring the laryngeal view, airway obstruction or edema, obesity, short neck, small mandible, large tongue, facial trauma, or cervical spine immobilization. Patients were then subcategorized based on the presence of 1 or more difficult airway characteristics.
Intervention Protocol:
To optimize a balanced study population, eligible patients were first sorted into 2 strata – those with obesity or cervical immobilization, and those without these features. From that point, patients from each stratum was randomized 1:1 to either bougie or endotracheal tube (ET tube) + stylet for the first attempt.
The intubating physician was free to direct the procedure as they saw fit, including patient positioning, pre-oxygenation, the use of RSI, and cricoid pressure. The physician could choose between direct laryngoscopy using a Macintosh blade, or video laryngoscopy using a C-MAC or GlideScope. If video laryngoscopy was chosen, the physician could elect whether to view the video screen.
In the bougie group, the physician inserted the bougie into the trachea, an assistant loaded the ET tube, and the operator guided the tube through the vocal cords. If resistance was met, the physician retracted the tube 2cm, rotated 90 degrees and re-advanced.
In the ET tube + stylet group, a straight to cuff shape was used. If resistance was encountered, the physician could reshape the tube/stylet as needed.
If intubation was unsuccessful on the first attempt, the physician was free to change any equipment or devices. Correct tube placement was determined by waveform capnography.
Outcome Measures:
Primary outcome: first-pass intubation success
Successful intubation on the first laryngoscopy attempt with device as previously randomized (bougie or ET tube)
Secondary outcomes:
Hypoxemia (sat < 90%, or > 10% desat during intubation if already hypoxemic)
First attempt time elapsed (laryngoscope insertion to removal)
Esophageal intubation
Results:
In patients randomized to the bougie arm, there was a 14% absolute increase in the rate of first-pass success in patients with at least one difficult airway feature (96% vs 82% bougie vs ET tube +stylet).
The bougie approach was superior in subsets of patients with predictors of airway difficulty including C-spine immobilization, obesity, and Cormak-Lehane grades 2-4.
Even in patients not predicted to have a difficult airway, there was a 7% absolute increase in first-pass success with the bougie approach (99% vs 92% with ET tube + stylet).
There was a small but significant increase in the time elapsed on first-pass success with the bougie (38 seconds) vs ET tube + stylet (34 seconds).
A more extensive summary of the results is depicted in Table 3:
Interpretation:
This study concludes that the bougie improves first-pass success rate both in difficult airways and standard airways. The small increase in time to first-pass success when using a bougie is outweighed by the need to fall back on rescue techniques more frequently when starting with an ET tube and stylet. Therefore, authors propose the use of a bougie as a routine primary intubation device for all patients. This argument is compelling and potentially practice-changing. Most EDs including NMH have adopted the practice of using a bougie right away when there is an obviously difficult airway (laryngeal mass, neck hematoma etc), but otherwise the bougie is often reserved for backup after one or more failed attempts. This relies on a perhaps now invalid model of an algorithmic approach to the difficult airway in which operators progress through a series of rescue devices and maneuvers. In light of this study, it may be time for a culture shift in EM toward routine bougie use.
Strengths:
This is a well-designed randomized controlled trial, with a total of 752 patients studied, generating enough power to provide meaningful results. The methodology of using the bougie and the ET tube + stylet was highly standardized. At the same time, the physicians were free to direct the remainder of the intubation strategy, including preoxygenation, medications, patient positioning, operator training, laryngoscope type, and video assistance. This is a realistic approach that would be generalizable to the typical ED experience. The power of this study was sufficient to then create subgroup analyses for each of these factors, and prove they were not confounders.
Weaknesses:
This study is primarily limited by its single center design and thus may not be generalizable to all Emergency Departments. This particular hospital had been using the bougie routinely prior to this study, which is uncommon. This may have led to overestimation of the bougie’s benefit. Further studies involving multi-centered trials are needed to affirm generalizability. Finally, this study by design could not be blinded, which could have led to biased results.
Take Home Points:
This was a single center randomized controlled trial of bougie vs ET tube + stylet for first-pass intubation
The bougie was significantly more effective in all patients, with or without difficult airway features
This study is potentially practice-changing and suggests the bougie should be used as a routine primary intubation device for all patients in the ED
Further studies including a multi-centered trial would be helpful to affirm generalizability
Expert Commentary
Thank you for the excellent review of this randomized trial of a bougie-first intubation strategy. I agree that this study is potentially practice-changing, with the important caveat that your initial mileage may vary due to the study setting of a single ED with an existing culture of utilizing the bougie. Still, the demonstrated 11% absolute difference in first-pass success among all-comers (including patients with and without difficult airway characteristics) is compelling.
Intuitively, routine use of the bougie should be a familiar concept to ED physicians. We regularly utilize Seldinger technique in the placement of various vascular access devices, and the bougie can be thought of as the Seldinger technique of the airway. Anecdotally, I feel that the primary benefits of the bougie are improved visualization of the glottic inlet and tactile feedback from tracheal clicks and holdup. Many of us will encounter airways that we do not initially perceive to be difficult based on anatomic features (e.g., non-obese, reassuring Mallampati) only to be perplexed by the visual appearance of the glottic inlet after blade placement (see Kovacs et al., 2017) or complete obscuring of the glottic inlet by rapidly re-accumulating blood or vomitus. In these scenarios, tactile feedback can be reassuring of proper tube placement.
Importantly, use of the bougie requires the operator to understand three key points: first, many novice users instinctively remove the intubating blade after the bougie is placed but prior to railroading the endotracheal (ET) tube over the bougie; this makes ET tube placement difficult but can be addressed by re-inserting the intubating blade (and confirming that the bougie remains in the correct position). Second, as the study authors point out, the bevel tip of the endotracheal tube can get caught on the arytenoids. This can be addressed by rotating the ET tube and re-attempting insertion. Finally, bougie placement can be difficult with hyper-angulated devices, such as the traditional GlideScope blade or the “D-Blade” for the C-MAC – hence the reason for excluding these devices in the trial. These hyper-angulated devices require the ET tube (and bougie) to navigate a hyper-acute angle for delivery, which is why they come with a special hyper-angulated metal stylet.
Finally, while I am an advocate of a bougie-first intubation strategy, I would emphasize that it is important not to become too infatuated with or dependent on a single airway technique. For example, a bougie cannot solve the dilemma of a small, restricted mouth that will not accommodate blade placement (e.g., advanced scleroderma), nor will it allow you to navigate an edematous tongue that occludes the entire oropharynx (e.g., severe angioedema). The best airway technicians are facile in a number of airway techniques, are always cognizant of the potential for their primary approach to be unsuccessful, and have a clear algorithm for how to respond to potential obstacles. This requires learning as many airway techniques as possible during your training (e.g. video, direct, LMA, bougie, fiber-optic).
References:
Kovacs G, Duggan LV, Brindley PG. Glottic Impersonation. Can J Anaesth. 2017 Mar;64(3):320. PMID 28028675.
Howard S. Kim, MD MS
Assistant Professor
Department of Emergency Medicine
Northwestern University Feinberg School of Medicine
How To Cite This Post
[Peer-Reviewed, Web Publication] Randolph A, Colton K. (2019, Nov 25). Bougie Journal Club. [NUEM Blog. Expert Commentary by Kim H]. Retrieved from http://www.nuemblog.com/blog/bougie.
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