SGEM#271: Bougie Wonderland for First Pass Success

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Date: October 17th, 2019

Reference: Driver 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 May 2018

Guest Skeptic: Missy Carter, former City of Bremerton Firefighter/Paramedic, currently a physician assistant practicing in emergency medicine in the Seattle area and an adjunct faculty member with the Tacoma Community College paramedic program.

Case: You are preparing for a rapid sequence intubation in a patient suffering from respiratory distress. While doing your airway assessment you notice some difficult airway characteristics (obese patient with a small mouth opening). In the past you’ve had failed first pasts attempts on a similar patient and used a bougie as your back up device. You wonder if this time you would be more successful using the bougie for your first attempt.

Background: We have covered airway a number of times on the SGEM. This has included supraglottic airways for OHCA (SGEM#247), POCUS for confirming endotracheal tube placement (SGEM#249) and non-invasive positive pressure ventilation for OCHA (SGEM#96) just to name a few. However, we have never covered the issue of using a bougie for intubation.

For many years the bougie has been considered a back up or “rescue” airway tool and only pulled out after one or even several failed intubation attempts. Many studies have shown that multiple intubation attempts can increase mortality and morbidity, so we are always striving to increase our first pass intubation success rates to improve patient care.

Clinical Question: Does using a bougie increase first pass intubation success?

Reference: Driver et al. The Bougie and First-Pass Success in the Emergency Department. Annals of Emergency Medicine 2017

Population: Adult patients (age > 17 years) who underwent intubation in the emergency department
- Excluded: Patients with missing videos that recorded the intubation, cases in which a bougie was used with a hyper angulated video laryngoscope blade (GlideScope) or were intubated before arrival to the emergency department
Intervention: Bougie with Macintosh or CMAC laryngoscope
Comparison: Intubation with endotracheal tube and stylet
Outcome:
- Primary Outcome: First-pass success rates
- Secondary: Duration of attempts, hypoxia and esophageal intubations

Authors’ Conclusions: “Bougie was associated with increased first-pass intubation success. Bougie use may be helpful in ED intubation.”

Quality Checklist for Observational Study:

Did the study address a clearly focused issue? Yes
Did the authors use an appropriate method to answer their question? Yes
Was the cohort recruited in an acceptable way? Yes
Was the exposure accurately measured to minimize bias? Yes
Was the outcome accurately measured to minimize bias? Yes
Have the authors identified all-important confounding factors? Yes
Was the follow up of subjects complete enough? Yes
How precise are the results? Fairly precise given the small sample size
Do you believe the results? Yes
Can the results be applied to the local population? Unsure
Do the results of this study fit with other available evidence? Yes

Key Results: There were 543 patients included in this cohort. The median age was in the late 40’s and more than two-thirds were male. The vast majority (~95%) of the intubations were performed by a senior resident.

First-pass success was greater with than without bougie

Primary Outcome: First-pass success
- 95% with bougie vs. 86% without bougie
- Absolute difference 9% (95% CI; 2% to 16%)
Secondary Outcomes:
- Median first-attempt duration was higher with than without bougie (40 seconds vs. 27 seconds) with a difference of 13 seconds (95% CI; 11 to 16).
- Hypoxia 17% with and 13% without bougie
- Esophageal intubation 1 with and 1 without bougie

1. External Validity: This is clearly a bougie center of excellence. Of the 543 intubations included in this study, 435 used the bougie as the first-time airway tool. This raises the question of generalizability. If providers in this center are more proficient with the use of a bougie than the average emergency medicine clinician, would we see different results if we put the bougie in the hands of someone who does not use it regularly?

In addition, 95% of the intubations were done by residents. Does this have external validity to non-teaching sites where the attending physician is performing the intubations?

2. Missing Data: Although these cases were consecutive; 83 cases had to be excluded due to missing video. The videos in addition to chart review were the primary data collection tools. The authors addressed this limitation with a sensitivity analysis that showed the bougie would still be superior.

3. Associations: The retrospective nature of this study makes it difficult to eliminate bias. The reviewers did their best to mitigate this by using multiple reviewers for the videos looking from multiple angles. Three separate investigators watched all cases from three cameras. They were blinded to the study goals and simply reported information on a standardized form. However, it was not a randomized trial and so we cannot claim causation only association between bougie and first pass success rates.

4. Why Use the Bougie: It is unknown why the bougie was used in each case. The authors’ attempted to identify difficult airway characteristics (obesity, cervical spine immobilization, presence of abnormal anatomy, facial trauma, masses, and body fluids) that could have influenced the operators’ decision. They also screened for hypoxia and esophageal intubations. These characteristics were about the same between groups which suggests the providers used bougie as first line device regardless of difficult airway characteristics.

5. Patient-Oriented Outcomes: They used first pass success rates, duration and hypoxia as surrogate markers. Important patient-oriented outcomes would have been survival and survival with good neurological function.

While there was a longer time for ETT insertion with a bougie than without (13 seconds) it is unlikely this was a clinically important difference.

Rates of hypoxia among the two groups were similar (13% with bougie and 17% without). Unfortunately, there is missing data on hypoxia in a total of 181 cases (114 missed on video feed and 67 were missed due to poor wave forms). It’s possible that this missing information may have shown a significant increase in hypoxia for our bougie patients.

Comment on Authors’ Conclusion Compared to SGEM Conclusion: We agree with the authors’ conclusions.

SGEM Bottom Line: The use of a bougie is associated with increased first pass success rates for intubations in the emergency department but an RCT is needed to further explore this topic.

Clinical Application: But wait there is more. We are going to do two papers today on the SGEM. The second paper is a randomized control trial looking at this issue by the same lead author.

Population: Adult patients (>17 years of age) who underwent intubation in the emergency department and the attending emergency physician planned to use a Macintosh laryngoscope blade on the first attempt
- Exclusions:Prisoners, suspected or known pregnant patients and patients with known distortion of the upper airway or glottic structures
Intervention: Bougie with Macintosh or CMAC laryngoscope
Comparison: Intubation with endotracheal tube and stylet
Outcome:
- Primary Outcome: First-attempt intubation success
- Secondary Outcomes: Duration of attempts, hypoxemia (SpO2 <90% or a 10% decrease) and esophageal intubation

Authors’ Conclusions: “In this emergency department, use of a bougie compared with an endotracheal tube + stylet resulted in significantly higher first-attempt intubation success among patients undergoing emergency endotracheal intubation. However, these findings should be considered provisional until the generalizability is assessed in other institutions and settings.”

Quality Checklist for Randomized Clinical Trials:

The study population included or focused on those in the emergency department. Yes
The patients were adequately randomized. Yes
The randomization process was concealed. Yes
The patients were analyzed in the groups to which they were randomized. Yes
The study patients were recruited consecutively (i.e. no selection bias). Yes
The patients in both groups were similar with respect to prognostic factors. Yes
All participants (patients, clinicians, outcome assessors) were unaware of group allocation. No
All groups were treated equally except for the intervention. Yes
Follow-up was complete (i.e. at least 80% for both groups). Yes
All patient-important outcomes were considered. No
The treatment effect was large enough and precise enough to be clinically significant. Yes

Key Results: They enrolled 757 patients that included 380 with a difficult airway characteristic. The mean age was in the mid-40’s with more than two-thirds being male. The vast majority (85%) were intubated by a senior resident or fellow. Only 1% were intubated by emergency medicine faculty. The rest were intubated by junior residents.

First-pass success was greater with than without bougie

Primary Outcome: First-attempt intubation success
- 96% with bougie group and 82% without bougie
- Absolute difference of 14% (95% CI; 8-20)
Secondary Outcomes:
- Median first-attempt duration was similar (38 seconds vs 36 seconds)
- Hypoxemia was similar (13% vs 14%)
- Esophageal intubations (0 vs 3)

1. External Validity: The big money question we all have here is about generalizability. This trial was performed in a single center that has a known love affair with the bougie so healthy skepticism for bias is warranted. This raises the question if adding the bougie in a center which is unfamiliar with the device would be beneficial. Sometimes the best method is simply the method you know best.

Another thing is that only 1% of the intubations were done by the attending physician. Would the bougie be as helpful to a seasoned physician working in a non-teaching community setting.

Perhaps the bougie would help the rural clinician in the critical access hospital who does not intubate often?

2. Intention-to-Treat Analysis: This was an ITT analysis with 98% adherence in the bougie arm and 92% adherence in the stylet arm, meaning some physicians in the stylet arm chose bougie for first pass attempt due to their clinical judgement. There were 25 cases of crossover from stylet to bougie and only 4 cases of crossover to stylet from the bougie arm. This was a 7% protocol violation in favor of using bougie for difficult airways or need for rapid intubation per the article. This did not affect the study’s final results as these intubations had high first pass success for the stylet group.

3. Secondary Outcomes: Various secondary outcomes were explored including hypoxia and incidence of pneumothorax were assessed in this trial. Unlike the observational trial which raised concern for hypoxia in the bougie group this study did not show a difference between the groups. There have been previous studies suggesting an association between bougie use and pneumothorax due to trauma while inserting to the carina.Those trials used a straight bougie whereas this trial used a coude’ tip. In this study complications were rare, pneumothorax after intubation without known cause was seen in in 9 patients in each group, esophageal intubation was seen in 3 patients in the stylet group and 0 in the bougie group. None of these complications were significant (table 5)

4. Subgroup Analyses: Although the trial was powered for success rates with difficult intubations, they did an interesting sub-group analysis of success rates as follows: Patients without difficult characteristics (99% vs. 92%), in-line immobilization (100% vs. 78%), obese patients (96% vs. 75%), and patients with Cormack-Lehane grades 2-4 (97% vs. 60%). Each favored the bougie suggesting routine bougie use as beneficial in all airways but some much more than others.

5. Patient-Oriented Outcomes: The outcomes were only measured until 1 minute after the end of the first intubation attempt. Again, they used first pass success rates, duration and hypoxia as surrogate markers. Patients may have considered mortality or survival with good neurological function more patient-oriented.

Comment on Authors’ Conclusion Compared to SGEM Conclusion: We generally agree with the authors’ conclusions.

SGEM Bottom Line: Consider using a bougie to improve your first pass success rates in routine intubations and in those patients with difficult airway characteristics.

Missy Carter

Case Resolution: You decide to use the bougie on your first attempt for this patient in hope you will get the tube on your first attempt. You make sure your team is ready with the ETT. You visualize a grade 2 view and slip the coude’ tip under the epiglottis and through the cords. You feel the rumble strips as you advance to the hold up at the carina. The respiratory therapist slides the tube over the bougie, and you advance it to the proper depth. You have equal lung sounds on both sides and confirmation with wave form capnography.

Clinical Application: It all depends. I personally use a bougie only as a rescue device and have only missed one airway in 24 years. There is one doctor in my shop who uses it all the time. I think if you are comfortable with it and having great success then carry on with what works. If you have struggled in the past and found yourself reaching for the bougie more often than you would like as a rescue device than consider using it for the first attempt.

What Do I Tell My Patient? Probably not a whole lot to tell your patient since they are likely preoccupied with breathing or are unresponsive.

Keener Kontest: Last weeks’ winner was Dr. Robert Allen a PGY2 EM resident from SUNY Downstate/Kings County Hospital Center. Robby knew that TXA was first made in 1962.

Listen to the SGEM podcast to hear this weeks’ question. If you think you know the answer, send an email to TheSGEM@gmail.com with “keener” in the subject line. The first correct answer will receive a cool skeptical prize.

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