So rarely is a study published that directly and effortlessly translates into clinical practice. Very few of these studies examine the nuances of everyday practice in the fast paced milieu of the Emergency Department. Given the infrequency of such studies, I am continually amazed by the work put forth by Brian Driver and colleagues at the Hennepin County Emergency Department.
The most recent of his clinical gems, 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, was just published in JAMA (1). The authors randomized patients 18 years or older presenting to a single Emergency Department, required emergent endotracheal intubation in whom the attending physician planned to use a standard geometry direct or video laryngoscope on the first attempt. All patients in whom the treating clinician planned to utilize a hyperangulated video laryngoscope on the initial attempt, were excluded from the study, as use of such a laryngoscope without a custom hyperangulated rigid stylet has been associated with added difficulty. Patients were randomized to either the use of a bougie or an endotracheal tube plus a traditional moldable stylet for the initial attempt. Other decisions integral to the intubation procedure, including patient positioning, preoxygenation strategy, use of neuromuscular blockade, cricoid pressure, choice of laryngoscope, and whether to view the video screen, were left to the discretion of the treating physician.
The authors enrolled a total of 757 patients. Of these, 380 were determined to have at least one difficulty airway characteristic (defined as body fluid(s) obscuring the laryngeal view, airway obstruction or edema, obesity, short neck, small mandible, large tongue, facial trauma, or cervical spine immobilization). In patients randomized to the bougie-first approach, the authors found a 14% absolute increase in their primary outcome, the rate of first pass success in patients with at least one difficulty airway characteristic. A similar 11% absolute benefit in favor of the bougie-first method was noted in the entire 757 patient cohort. Even in the subset of patients who were not predicted to be a difficult airway, a 7% absolute increase in the rate of FPS was observed. In fact, the authors were unable to find any interaction between the presence of difficult airway predictors and efficacy of the bougie. The bougie also proved itself superior to the traditional ETT and stylet approach in a number of subsets of patients, including patients requiring cervical in-line immobilization (100% vs 78%,), obese patients (96% vs 75%), and patients with incomplete glottic views on laryngoscopy corresponding to Cormack-Lehane grades 2 to 4 (97% vs 60%).
The Driver et al study also serves to discredit some of the arguments commonly cited against the use of a bougie-first strategy. For instance, It takes longer to intubate the patient, which will lead to a clinically significant amount of needless desaturation events. Overall time to intubation was far shorter in the patients that were randomized to the bougie-first strategy. This temporal benefit was entirely powered by the higher rate of FPS observed in the bougie-first group. When the authors examined the subset of patients who were successfully intubated on first attempt, they noted a 4-second delay in time to intubation associated with the use of the bougie. And while this difference is statistically significant it has little clinical meaning especially given the overall improvement in FPS. In addition even this small difference in time to intubation is likely to be avoided by any of the many preloaded bougie techniques which were not utilized in this study, but provide a much swifter tube delivery mechanism. The bougie can cause an airway injury as its distal tip is wedged in the small airways during the intubation process. The authors found no difference in overall complication rate, the rate of direct airway trauma, or the incidence of pneumothorax following intubation. There is often significant difficulty passing the tube over a bougie, as it will frequently get stuck in the arytenoid cartilages. Resistance to tube passage occurred in only 7% of patients, and all but one was resolved by simply turning the tube 90 degrees counter-clockwise prior to insertion.
While this trial has a number of methodological limitations, Driver et al present a strong argument in favor of a bougie-first approach in Emergency Department patients requiring endotracheal intubation. The strength of the authors conclusions lie in the consistency with which the bougie demonstrated its efficacy. Not only was the bougie superior to the more traditional stylet based approach for intubations predicted to be difficult by the Emergency Physician, but it also improved FPS in patients in whom a difficult airway was not suspected. We have traditionally applied the concepts of non-emergent airway management to the Emergency Department setting, with the assumption that if it is good enough for the OR it is certainly sufficient for the Emergency Department. But time and time again such assumptions have been proven false. Given the findings reported by Driver et al it is time we re-examine our assumption regarding the management of the emergent airway, specifically our view of rescue equipment, and the belief that their use should be utilized only when more traditional measures have failed. No longer should we progress through a failed airway algorithm in a neat linear path, advancing to the next step only after the previous one is unsuccessful. Rather in the emergent intubation where time and failure incur more dire consequences, rescue strategies, including the use of a bougie, should be deployed in parallel.
- 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. Published online May 16, 2018. doi:10.1001/jama.2018.6496