Gum Elastic Bougie is Useful Adjunct For Difficult Airways

Abstract & Commentary

Dr. Ufberg is Assistant Professor of Emergency Medicine, Residency Program Director, Department of Emergency Medicine, Temple University School of Medicine, Philadelphia, PA. Dr Ufberg is a researcher for Pfizer Pharmaceuticals. Dr. Grauer is sole proprietor of KG/EKG Press.

Source: Jabre P, et al. Use of gum elastic bougie for prehospital difficult intubation. Am J Emerg Med 2005;23:552-555.

The gum elastic bougie (GEB) is an established tool that has gained increased usage during difficult endotracheal intubation scenarios during the last several years. The GEB is a 60-cm tracheal tube introducer with a smoothly angled tip. If the glottis is not visualized fully during direct laryngoscopy, the GEB may be passed blindly (or with partial visualization) behind the epiglottis. The operator confirms tracheal placement through "clicks" felt as the tip of the bougie passes over the tracheal rings, and feels the progress of the GEB become difficult as it reaches the carina. After placement of the GEB, the tracheal tube is passed over the GEB during direct laryngoscopy.

The authors of this study attempted to assess the effectiveness of the GEB in prehospital cases of difficult endotracheal intubation. This study was performed in the suburbs of Paris, where the emergency medical service (EMS) response systems are quite different than in the United States. The EMS system involved consisted of five mobile intensive care units (MICUs), which responded to about 10,000 calls per year at the time of the study. The MICU is composed of a driver, a nurse anesthetist, and either a senior emergency physician (in > 90% of MICUs) or a senior anesthesiologist. Field intubations in this system always are performed or supervised by a physician.

Forty-five intubators (23 EPs, five anesthesiologists, and 17 nurse anesthetists) participated in this study. A senior anesthesiologist always was on call to respond to the scene in cases of difficult or impossible intubation. All participants initially were trained in GEB usage with classroom and mannequin didactics. After training, all MICUs were equipped with GEBs, and GEB was used as the first line alternative technique in cases of difficult intubation (defined by more than two failed attempts under direct laryngoscopy with optimal head positioning and external laryngeal manipulation). If two attempts with GEB assistance failed, the operators used another method based upon preference and experience. A senior anesthesiologist was called if GEB-assisted intubation failed, or if a difficult ventilation scenario arose.

Patients were enrolled into the study if tracheal access was not achieved after two direct laryngoscopy attempts, and data forms were completed immediately after the airway management process. Data collected included Cormack and Leane laryngeal view classification (grade 1, whole larynx visible; grade 2, partial view of vocal cords; grade 3, only epiglottis visible; grade 4, no part of larynx visible), clinical characteristics, a validated intubation difficulty score, patient height and weight, history of ENT disease, objective cervical mobility, cervical immobilization, history of maxillofacial disease, clinical risk factors for difficult intubation (e.g., morbid obesity, reduced cervical mobility, upper airway distortion, or maxillofacial trauma), and success or failure of GEB-assisted intubation.

During the study period, 1442 patients required prehospital intubation. Of these, 640 were cardiac arrest victims, and 802 had cardiac activity. Of the 802 with cardiac activity, 95% received paralytic agents before intubation. Forty-three patients (3%) required GEB-assisted intubation. These patients had a median Cormack and Leane score of 4, and high median scores for difficulty of intubation. GEB assistance allowed rapid (rapid was not defined in the study) intubation of 33 of the 41 (80%) failed intubations, 24 with one attempt and 9 requiring two attempts using GEB assistance. Seven patients were intubated after GEB failure (intubating LMA [1], retrograde intubation [1], blind nasal intubation [1], senior anesthesiologist rescue using direct laryngoscopy [4]), and one patient required cricothyroidotomy. Most failed GEB-assisted intubations occurred in patients with ENT malignancies. No complications associated with GEB use were encountered.

The authors mentioned several factors that may have contributed to this success rate, which is lower than in previous studies performed in operating rooms and EDs. Some previous studies excluded anticipated difficult airways, while the patients in this study were selected for their difficulty. Also, the environmental conditions of prehospital intubation often are much more difficult than those in the hospital. Almost half of the patients in this study were intubated while supine on the ground.

Commentary

American EMS systems do not include physicians on-scene, and the performance of European physicians using this device cannot be assumed to correlate to American paramedics with far less training and experience than the operators in this study.

That being said, this study did highlight the utility of the GEB as a simple, inexpensive device that can be a handy addition to our difficulty airway armamentarium. Many physicians, myself included, consider this the first line of defense after direct laryngoscopy has failed. The GEB can be used effectively with very little training, and the reported success rates are high.

One interesting aspect is the study's high success rate despite the median laryngeal view score being a 4 (no part of larynx visible). Traditionally, the bougie has been most useful for patients in whom at least the epiglottis is visible. Twenty-seven of the 41 patients enrolled had a grade 4 airway upon initial laryngoscopy, so evidently the GEB also may be useful for blind intubation.