According to the American Society of Anesthesiologists’ Practice Guidelines for Management of a Difficult Airway, an awake intubation is considered the primary method to secure a suspected difficult airway.1 Traditionally, an awake intubation is performed by flexible fiberoptic laryngoscopy. However, within the last decade, many new devices have been developed to assist anesthesiologists in managing patients with difficult airways. Among these devices are rigid fiberoptic stylets, one of which is the Bonfils Retromolar Intubation Fiberscope™ (Bonfils; Karl Storz Endoscopy, Tuttlingen, Germany).2,3
The Bonfils (Fig. 1) is a 40 cm long, semi-rigid optical stylet with an external diameter of 5.0 mm and a fixed anterior tip curvature of 40 degrees. Its fiberoptic bundle is encased in a stainless steel tube that provides 15,000 pixel resolution and is manufactured with (outside of United States) and without a 1.2 mm working channel. The adult stylet can accommodate 6.5 mm endotracheal tubes or larger3 and the pediatric stylet, the Brambrink Intubation Endoscope™ (Brambrink; Karl Storz Endoscopy, Tuttlingen, Germany), can accommodate 2.5–6.0 mm endotracheal tubes. There are two versions of each stylet. One version has an adjustable eyepiece, allowing for direct visualization during intubation. The other version has a “Direct Coupled Interface” that displays the image directly on a video monitor. The eyepiece can also be converted to project the image onto a remote monitor to provide better visualization and enhance teaching. There is an adaptor “slide cone” for fixation of the endotracheal tube. This adaptor has a side port that allows oxygen insufflation or instillation of local anesthetic.2,3
The Bonfils fiberscope was developed more than 20 years ago for use by ear-nose-throat surgeons.4 Anesthesiologists became interested in the device in the mid-1990s for management of patients with difficult airways.5 It has been successfully used to intubate patients with normal airways, as well as patients with difficult airways (expected or unexpected), including those who failed direct laryngoscopic intubation.6–8 It is also useful in patients with limited neck mobility, patients with cervical spine injuries,9,10 and for endoscopic guidance during percutaneous tracheostomies.4
The use of the Shikani Optical Stylet (Clarus Medical LLC, Minneapolis, MN) for awake fiberoptic intubation was recently reported in the emergency medicine literature.11 To date, there are no reports of the Bonfils as a device to perform awake intubation. We present this case series in which the Bonfils Retromolar Intubation Fiberscope was used to accomplish awake intubation using the “spray as you go” technique12 in five patients with anticipated difficult airways.
The first patient was a 49-yr-old 96 kg man with a history of stroke complicated by severe residual spasticity who was scheduled to undergo implantation in the prone position of an intrathecal baclofen pump. Physical examination of the airway revealed a 2 cm mouth opening, short thick neck, very limited neck extension, and Mallampati class 4 airway.
The second patient was a 29-yr-old 79 kg man with a history of motor vehicle accident resulting in blunt trauma to the abdomen who was scheduled for an exploratory laparotomy. On arrival to the operating room, the patient was alert and complaining of severe neck pain. Adequate imaging of the cervical spine had not been obtained because of the urgent nature of the case. Physician examination of his airway revealed a 3 cm mouth opening and Mallampati class 3 airway. The decision was made by the staff anesthesiologist to perform an awake intubation with the rigid cervical collar in place.
The third patient was a 67-yr-old 75 kg man with destructive lesions of his C1–2 vertebral bodies secondary to a fall 4 yr previously who was scheduled for posterior fusion of the occiput through C4. His chief complaint was neck pain, as well as neuropathic pain in his upper extremities. Computed tomography imaging of his cervical spine revealed a type 3 dens fracture, as well as anterior subluxation of C1 upon C2. Any neck extension elicited a painful response. Physical examination of his airway revealed a 4 cm mouth opening and Mallampati class was 3 airway.
The fourth patient was a 20-yr-old 68 kg man with a history of polysubstance abuse who sustained a C5–6 dislocation injury after diving into a shallow swimming pool. The patient was initially placed in a halo device and subsequently taken to the operating room for cervical stabilization. His neurologic status was significant for neck pain and decreased sensation in both lower extremities. His airway examination was significant for no neck mobility, a 3 cm mouth opening, and a Mallampati class 2 airway.
The fifth patient was a 22-yr-old 95 kg man admitted after a vehicle accident scheduled for elevation of a frontotemporal depressed skull fracture. He had sustained multiple facial fractures including fractures of the left zygomatic arch, nasal bones, and the maxillary sinus. His airway examination revealed normal neck mobility, a 1.5 cm mouth opening, and a Mallampati class 4 airway.
All five patients were placed supine with their head and neck maintained in a neutral position. The patients received IV glycopyrrolate 0.2–0.4 mg, midazolam 1–2 mg, droperidol 2.5 mg, and incremental doses of fentanyl (50–200 μg) or sufentanil (10–20 μg) for sedation. The oropharynx was topically anesthetized with 4 mL of 4% lidocaine administered via an atomizer (EZ-Spray; Intertex Research, Inc., Houston, TX). Each patient was administered oxygen with 8L O2 for 3 min. After sedation, administration of topical lidocaine, and oxygen administration, the patients were instructed to open their mouths and stick out their tongues. Although a midline approach is possible, the Bonfils (preloaded with an 8.0 mm cuffed endotracheal tube) was advanced via the retromolar technique to the hypopharynx and advanced towards the posterior pharynx (Fig. 2). When the Bonfils was positioned immediately in front of the vocal cords, an additional 4 mL of 4% lidocaine was injected onto the cords via the tube adapter. After waiting 30–60 s, the Bonfils was advanced further until the tip of the scope just passed the glottic opening. An additional 4 mL of 4% lidocaine was then injected into the trachea. All patients received <7 mg/kg lidocaine in order to prevent the risk of systemic toxicity. After another 30–60 s delay, the endotracheal tube was advanced over the scope. The Bonfils was then removed, leaving the endotracheal tube in place. End-tidal capnography confirmed tracheal placement and an abbreviated neurologic assessment was performed, followed by routine IV induction.
All five patients maintained spontaneous ventilation and meaningful contact throughout the procedure. All intubations were performed by CA-3 anesthesiology residents and took <3 min from the time the scope was placed into the mouth until intubation was completed. Although it is possible to administer oxygen through the special adapter attached to the shaft of the scope, it was not necessary in any of these cases. Additionally, there was no need to remove the Bonfils for a second attempt. One patient did complain of discomfort on initial insertion of the scope and the resident needed to reposition the scope more anteriorly and additional sedation (sufentanil 20 μg in two divided doses) was administered. No evidence of trauma was noted upon visual inspection of the oropharynx performed immediately after the procedure. There were no perioperative complications related to airway management in any patient.
It has been demonstrated that the Bonfils is a reliable and atraumatic device for difficult airway management.5,6 It is useful in patients after unsuccessful laryngoscopy8 and those with limited or no neck mobility.9,10 It is also helpful in patients who have limited mouth opening capacity. Its rigid structure allows a large floppy epiglottis to be physically lifted. Similarly, the design allows easy navigation through the oral cavity of patients with a large tongue or large tonsils. Additionally, it allows for a faster intubation than other difficult airway devices.7 An awake intubation technique usually implies an indirect fiberoptic technique. For years, flexible fiberoptic laryngoscopy has been advocated as a necessary and effective tool for managing the predicted difficult airway.13 Nevertheless, surveys have demonstrated that anesthesiologists have limited skill with this technique.14 As with the Shikani Optical Stylet, the endotracheal tube is preloaded directly on the stylet. Once the glottis is viewed, the tip of the device can either remain just in front of or pass just through the vocal cords and the endotracheal tube advanced over the stylet into proper position. Both of these devices may be easier and take less time to navigate to the larynx than the flexible fiberoptic laryngoscope, especially by those who are inexperienced, such as residents, first-time users, and non-anesthesiologists. When using the Bonfils for an awake intubation, patients should be prepared in a similar fashion as awake flexible fiberoptic laryngoscopic procedures. Patients should be premedicated with an anti-sialagogue and sedated, if appropriate, and the patient’s upper airway should be anesthetized either topically or with appropriate nerve blocks.
Since the Bonfils has a fiberoptic lens, it shares some of the disadvantages as other devices with fiberoptic lenses. Secretions and blood can obscure the view and therefore an anti-sialagogue, such as glycopyrrolate should be administered 10–15 min before the procedure, unless contraindicated. Thorough suctioning of the posterior pharynx should be performed before insertion of the instrument. Fogging may be avoided by placing the tip of the scope in either a warm bottle of saline or water, applying an anti-fogging agent to the lens, and/or administering oxygen through the system.3 Although the 5 mm Bonfils Stylet is manufactured with a 1.2 mm working channel, this version is not available in the United States. Thus, a special external tube adapter allows for suctioning, delivery of oxygen, and administration of local anesthetic. Unlike the flexible fiberoptic laryngoscope, the Bonfils cannot be used for nasotracheal intubation. As with any airway device, skill should be obtained before its use in difficult situations. Practice should occur on patients with normal airways under general anesthesia before using it for more difficult patients, including those requiring an awake intubation.
This case series demonstrates that the Bonfils Retromolar Intubation Fiberscope™ can be used effectively to accomplish an awake fiberoptic intubation in patients with a suspected or known difficult airway. The device offers certain advantages over the flexible fiberoptic laryngoscope and should be considered when intubating patients with a difficult airway.
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