Background: In 2018, the BEAM Trial, a small single-center randomized clinical trial, conducted in the emergency department at Hennepin County Medical Center, demonstrated that bougie use significantly increased the first-attempt intubation success rate compared to the endotracheal tube with stylet (98% vs 87% (absolute difference, 11% [95% CI, 7% to 14%]).¹ Conversely, the 2021 BOUGIE trial—a larger, multicenter randomized clinical trial conducted by the same investigators—found no significant difference in first-attempt intubation success between the bougie and an endotracheal tube with stylet among critically ill adults.² Moreover, the American Society of Anesthesiologists’ 2022 Practice Guidelines for Management of the Difficult Airway recommend the use of adjuncts like bougies in anticipated difficult airways but stop short of endorsing their routine universal use.³ The question of whether bougies should be used as the primary approach for all intubations remains unresolved. The systematic review and meta-analysis covered here aims to provide clarity by pooling clinical trial data to obtain a single point estimate. 

Paper: von Hellmann R, Fuhr N, Maia IWA, et al. Effect of Bougie Use on First-Attempt Success in Tracheal Intubations: A Systemic Review and Meta-Analysis. Ann Emerg Med. 2024 Feb 83(2):132-144. PMID: 37725023

Clinical Question: In adult patients requiring tracheal intubation, does the use of a bougie compared to a stylet improve the first-attempt success rate?

What they did:

• The authors performed a systematic review and meta-analysis  utilizing the PRISMA guidelines.
• A medical librarian with expertise in systematic reviews, searched Cochrane, Embase, Medline, Scopus, and Web of Science for relevant randomized controlled trials and comparative observational studies from inception to June 2023.
• Included patients from out-of-hospital, emergency department, intensive care unit, and operating-room intubations.
• Researchers used the Cochrane Risk of Bias Tool to assess bias in randomized controlled trials, and observational studies were assessed with the modified Newcastle-Ottawa scale.
• The Grade methodology was utilized to asses the level of certainty.
• Registered at PROSPERO (CRD42023403212)

Population:

Inclusion criteria:

• Adult intubation using a bougie as an intervention compared to usual care (intubation with or without a stylet).
• Intubation performed in all settings (out-of-hospital, emergency department, ICU, and operating room).
• Studies that report the outcome of first-attempt intubation success for both bougie and non-bougie groups.
• Randomized controlled trials or comparative non-randomized observational studies.

Exclusion criteria:

• Manikin and cadaver studies.
• Studies using only hyper-angulated video laryngoscopy or channeled laryngoscopic devices (e.g., airway scope).
• Studies comparing different types of bougies.
• Studies published in languages other than English, Portuguese, or Spanish.
• Conference abstracts.
• Studies lacking a control group or that do not report first-attempt success for both bougie and non-bougie groups.

Intervention: Intubation performed using a bougie..

Comparator: Intubation performed using a standard stylet or no introducer at all.

Outcomes: 

Primary Outcome: First-attempt intubation success

• The successful placement of the endotracheal tube on the first laryngoscope insertion.

Secondary Outcomes: 

• First-attempt success without clinically important complications (e.g., hypotension, hypoxemia).
• Incidence of hypoxemia, defined as oxygen saturation <90%.
• Postintubation arrest.
• Duration of intubation.
• Incidence of intubation-related injuries, such as airway trauma.
• Occurrence of esophageal intubations.
• Occurrence of postprocedural sore throat.

Results:

Article selection:

• 3915 studies identified.
  • 1217 duplicated removed.
• 2699 studies screened for review.
  • 2565 studies excluded after reviewing titles and abstracts.
• 134 full-text articles were assessed for eligibility.
  • 116 studies excluded based on eligibility criteria.
• 18 studies were included:
  • 12 randomized controlled trials
  • 6 observational studies
• The papers included a total of 9151 intubated patients.

Primary outcome: First-attempt intubation success: 

• The use of bougie during intubation was associated with increased first-attempt success, with a relative risk of 1.11, 95% confidence interval (1.06-1.17,  I² =83%)

Secondary outcomes:

• First-attempt success without clinically important complications: Only two studies reported this outcome. Those intubated with a bougie had higher success than those intubated with a stylet (80.5% for the bougie group vs. 65.9% for the control group).
• Incidence of hypoxemia: In the meta-analysis of six studies, the use of a bougie was not associated with a significant increase in hypoxemia (RR 0.93, 95% CI 0.66 to 1.31). However, the confidence interval was wide, indicating uncertainty about the effect.
• Postintubation arrest: Two studies reported this outcome, with similar rates of postintubation arrest between the bougie group and control group (1.8% in both groups in one study, and 1.1% vs. 0.9% in another study).
• Duration of intubation: Nine of thirteen studies reported slightly longer intubation times with a bougie, with a maximum average increase of 13 seconds in ED–based studies.
• Incidence of intubation-related injuries: There was a higher incidence of intubation-related injuries (such as oral and airway trauma) in the bougie group compared to controls (RR 1.55, 95% CI 1.00 to 2.39). However, in emergency department studies, there were no direct airway injuries related to bougie use.
• Occurrence of esophageal intubations: There was no statistically significant difference in the rate of esophageal intubations between the bougie and control groups (RR 0.59, 95% CI 0.25 to 1.36).
• Adverse events: 6 studies comprising 3576 patients, showed more frequent intubation-related injuries with a bougie and had a relative risk 1.55, 95% confidence interval (1.00-2.39), and I² 0%

Strengths:

• Comprehensive Literature Review: The study conducted a thorough search across multiple major databases, including Ovid Cochrane Central, Ovid Embase, Ovid Medline, Scopus, and Web of Science, ensuring a robust and comprehensive search for relevant literature. They utilized an experienced research librarian which increases the likelihood of finding all relevant articles.
• Inclusion of RCTs: The study included a number of RCTs (12 out of 18 studies), which strengthens the overall reliability of the evidence, as RCTs are the gold standard for evaluating interventions.
• GRADE Approach for Certainty Assessment: The authors utilized the GRADE approach to evaluate the certainty of evidence, lending transparency and rigor to the assessment of evidence quality.
• Large Sample Size: The study pooled data from 9,151 patients, enhancing the power of the findings and the potential to detect statistically significant differences between groups.
• Detailed Risk of Bias Assessment: The study used both the Cochrane risk of bias tool for RCTs and the Newcastle-Ottawa scale for observational studies, providing a structured evaluation of study quality and limitations.
• Relevant Secondary Outcomes: The inclusion of secondary outcomes, such as hypoxemia, postintubation arrest, and intubation-related injuries, helps provide a more comprehensive view of the clinical implications of bougie use beyond first-attempt success.

Limitations:

• Primary Outcome is Not Patient-oriented: The primary outcome, first-attempt intubation success, is not patient-oriented. However, studying first-attempt success is essential as it allows for comparison among the preponderance of existing evidence.
• Clinically Diverse Patient Population: The study included patients from varied clinical settings (ED, ICU, OR, and pre-hospital). While this approach increases sample size, the clinical diversity may make it challenging for clinicians to comfortably interpret a single pooled estimate across such different patient populations, potentially limiting the practical applicability of the results.
• Lack of Gray Literature Search: Gray literature was not systematically searched, which could limit the comprehensiveness of the review and potentially exclude relevant studies.
• No Reporting of Agreement Metrics: The authors did not report kappa or agreement metrics on study inclusion, reducing transparency around inter-reviewer reliability.
• No Third-Party Arbitrator for Disagreements: Commonly used in systematic reviews, a third-party arbitrator to resolve disagreements was not employed, which could affect the objectivity of study selection and data extraction processes.
• Pediatric Patients:: Although the study population was defined as adults, one RCT included patients aged 12–17 years, and another RCT and an observational study included patients aged 16–17. Since, the vast majority of patients were adults, we don’t know how this data applies to pediatric patients
• Lack of Data on Intubator Experience: Insufficient information on the intubator’s experience with bougie use limits the ability to assess how varying levels of expertise might influence success rates.
• Variability in Laryngoscopy Techniques: Among the included studies, 11 utilized direct laryngoscopy (DL), while 7 used video laryngoscopy (VL). This variation in techniques may contribute to inconsistencies in outcomes and limit generalizability.
• Limited Reporting on Complications: The analysis focused primarily on first-attempt success rates, with minimal reporting on clinically significant complications, making it difficult to evaluate the safety profile of bougie use comprehensively.
• Risk of Bias: Out of the 18 studies included, 6 were comparative observational studies, which inherently increases the risk of bias. Overall the risk of bias was high making certainty of evidence low.
• High Statistical Heterogeneity: The meta-analyses exhibited high statistical heterogeneity (I²), leading to reduced certainty in the evidence due to inconsistency among study results.
• Potential Publication Bias: Funnel plot analysis indicated asymmetry, suggesting a potential for publication bias, although the exact impact on findings remains unclear.

Discussion:

Inside the Numbers: Bougie use during intubation was associated with a modest improvement in first-attempt success, with a relative risk of 1.11 (95% CI, 1.06-1.17). Despite limitations in the study, this small benefit seems probable. The effect is greater in patients with Cormack-Lehane grade III or IV views, where the relative risk increased to 1.60 (95% CI, 1.40-1.80). However, only 5 of the 18 studies, covering 585 patients, reported results for those with poorly visualized anatomy. It’s unclear how many patients had grade III or IV views in the remaining studies, but a large amount could skew the results toward bougie use. Still, most patients undergoing intubation probably have well-visualized anatomy. A subgroup analysis focusing on patients with Cormack-Lehane grade I or II views would be valuable. In such cases, the potential for increased intubation-related injuries associated with bougie use (RR 1.55, 95% CI 1.00 to 2.39) might outweigh the benefits.

The Patients: The systemic review and meta-analysis included patients from a wide range of clinical settings. Including out-of-hospital, emergency department, intensive care unit, and operating-room intubations complicates the interpretation of data. While increasing generalizability, the results become less applicable to specific clinical situations. For example, there are significant differences between undifferentiated ED patients needing emergency intubation, critically ill ICU patients with an established diagnosis, and OR patients who are typically medically optimized and NPO. Pooling these distinct groups to obtain a single point estimate is problematic and contributed to the very high heterogeneity observed in this paper (I2=83%).

Missing information: The authors did not collect Important information about preoxygenation methods and specific medicines and dosages used for induction and paralysis. The paper also lacks crucial details regarding experience of the physicians performing the intubations. How many intubations had they completed? How familiar were the clinicians with using a bougie? What bougie grip did they use for insertion? There are clear and obvious differences in skill between a first-year resident and seasoned intensivists, emergency physician, or anesthesiologists and this level of detail is essential for interpreting the data accurately. For highly experienced resuscitationists, the choice of device may matter less. This was evident in the DEVICE trial, which found that as providers became more proficient, the performance gap between video and direct laryngoscopy narrowed.⁵ Similarly, experienced intubators are likely better equipped to plan their approach and anticipate potential challenges.

State of the Evidence: The BEAM trial demonstrated a significant increase in first-attempt intubation success when using a bougie, achieving a 98% success rate. However, the subsequent multicenter BOUGIE trial did not replicate these results, showing no significant difference between bougie and endotracheal tube and stylet use. The BEAM trial was conducted at a single center where clinicians were highly experienced with bougie use, which may have contributed to the higher success rates observed. In contrast, the BOUGIE trial included multiple centers with varying levels of clinician experience, potentially diluting the effect seen in the BEAM trial.^1,2 These findings suggest that while the bougie can be highly effective in skilled hands, its advantage diminishes without adequate training and experience. 

Pragmatic Approach: The success of any procedure lies in the preparation. Resuscitationists should devise an airway plan with multiple contingencies. Advocates for bougie-first intubation will highlight the challenge of predicting which patients will have difficult airways and poor anatomical views. However, for contrarians, it is simple enough to prepare a bougie and a styletted endotracheal tube, as well as any other useful airway adjuncts. Once the anatomy comes into view, the resuscitationist can determine which device is needed and ask for the tool for the job at hand. There will likely never be a once-size-fits-all-all airway tool. We have to adapt our plan to fit the patient’s needs.

Author’s Conclusion: “The bougie as an aid in the first intubation attempt was associated with increased success.”

Our Conclusion:

The data suggest that the use of a bougie may slightly increase first-attempt success rate when performing endotracheal intubation in adult patients. However, due to the inclusion of papers with a high risk of bias, statistical heterogeneity was high and the certainty of evidence was low. While the evidence strongly supports bougie use for patients with poorly visualized airway anatomy, the benefit of routine bougie use for all intubations remains up for debate. Ultimately, the effectiveness of any device depends on the skill of the practitioner. Adopting a bougie-first intubation approach can help clinicians develop and maintain proficiency, ensuring confidence when managing patients with difficult airways.

References:

1. 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. PMID: 29800096
2. Driver BE et al. Effect of Use of a Bougie vs Endotracheal Tube with Stylet on Successful Intubation on the First Attempt Among Critically Ill Patients Undergoing Tracheal Intubation: A Randomized Clinical Trial (BOUGIE Trial). JAMA 2021. PMID: 34879143
3. Apfelbaum JL, Hagberg CA, Connis RT, et al. 2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway. Anesthesiology. 2022;136(1):31-81. PMID: 34762729
4. von Hellmann R, Fuhr N, Maia IWA, et al. Effect of Bougie Use on First-Attempt Success in Tracheal Intubations: A Systemic Review and Meta-Analysis. Ann Emerg Med. 2024 Feb 83(2):132-144. PMID: 37725023
5. Prekker ME, Driver BE, Trent SA, et al. Video versus Direct Laryngoscopy for Tracheal Intubation of Critically Ill Adults [published online ahead of print, 2023 Jun 16]. N Engl J Med. 2023;10.1056/NEJMoa2301601. PMID: 37326325

Post Peer Reviewed By: Anand Swaminathan, MD (Twitter/X: @EMSwami)