Airway management in patients with unstable occipito-cervical and upper cervical (C1-C2) junctions presents a challenge to the anesthesiologist because intubation may produce pathological cervical spine motion, thus putting the spinal cord at risk of injury.1 Intubation with direct laryngoscopy1,2 and other intubation methods, such as the Bullard Laryngoscope®,3–5 GlideScope®,6,7 and light wand,6 produce varying degrees of extension at the occipito-cervical junction.
Fiberoptic intubation (FOI) is used frequently in patients with unstable occipito-C1-C2 because it is associated with minimal spine motion. However, the laryngeal inlet can be displaced and/or difficult to access with the fiberoptic bronchoscope in such patients because of severe spinal deformity or traction. Consequently, conventional FOI may occasionally fail in these patients because of difficulty in threading either the fiberoptic bronchoscope or the oral endotracheal tube (OET) into the trachea.8 Two reports by Aoyama et al. and Takenaka et al.8,9 have described using the fiberoptic scope to obtain a view of the glottis, with the OET being inserted independently, guided by the fiberoptic view. In this report, we describe our experience with a variation of this technique in five patients with occipito-C1-C2 junctions instabilities and deformities.
The IRB of the University of Iowa granted permission to publish this clinical report and waived the requirement to obtain written informed consent from the legal guardians of children and from the adult patients in this report.
Preanesthetic Assessments and Preparations
Five patients with diagnoses of advanced occipito-cervical and upper cervical junction instabilities were preoperatively evaluated, indicating the need for FOI to secure their airways. The demographics, clinical diagnoses, and summaries of anesthetic management of these patients are shown in Table 1.
All patients were monitored as per the standards of the American Society of Anesthesiologists.10 Patients 1 and 2 were children in whom FOI under general anesthesia was planned (Table 1). After anesthesia was induced by inhaling of sevoflurane and oxygen by mask, IV access was obtained before proceeding with FOI. Patients 3, 4, and 5 were adults and FOI while awake was indicated and planned. Conscious sedation and effective topical anesthesia were established in these patients before beginning FOI. The absence of gag and superficial and deep pressure sensations in the airway of the awake patients were tested by pressing the base of the tongue against the posterior pharyngeal wall with a tongue depressor.
Conduct of Fiberoptic Intubations
Appropriately sized OETs were used based on patient age. The fiberoptic bronchoscopes were lubricated before use and were easily moving and sliding within the OET before starting FOI. Intubating airways were not used during FOI in these patients as per the preference of the corresponding author (MAM).
In the pediatric patients, manual in-line stabilizations, jaw thrusts, and careful manual anterior pulling of the tongue were maintained during FOI. FOI was initially attempted using a pediatric fiberoptic bronchoscope (Pentax Model F1-10P2, Pentax Precision Corporation, Orangeburg, NY). In the adult patients, a fiberoptic bronchoscope (Olympus GP-4, Olympus America, Melville, NY) was initially used. In all patients we were unable to introduce the tip of the bronchoscope between the vocal cords into the trachea despite clear visualization of the vocal cords and multiple attempts. Thus, we did not have the opportunity to attempt to thread the tube into the trachea, and it was not surgically feasible to use the nasal fiberoptic approach.
As an alternative approach, another fiberoptic scope (Olympus BF-P240, Melville, NY) that was connected to a video monitor was inserted orally and positioned superiorly in the laryngopharynx to obtain a wide view of the larynx. While maintaining a view of the glottis, a styletted and appropriately angulated OET (Sheridan HVT, Hudson RCI, Temecula, CA), was successfully inserted between the vocal cords into the trachea of the pediatric patients (Fig. 1). In the adult patients, maintaining a wide view of the glottis allowed an appropriately angled introducer (Endotracheal Tube Introducer, Sun Med, Largo, FL, USA, or a Portex Tracheal Tube Guide, O.D. = 15 Fr., length = 70 cm, Smiths Industries Medical Systems, Keene, NH) to be orally inserted into the trachea. Thereafter, an OET was threaded over the introducer and into the trachea with continued guidance provided by the video monitor. In all patients, anesthesia and surgery proceeded uneventfully thereafter. None of the patients had new neurological injuries postoperatively (Fig. 1).
Although elective FOI is almost always successful,11 there are a few patients in whom this technique may fail or not be possible because of laryngeal pathologies or abnormalities.8,9
When FOI fails in patients with anomalous or injured occipito-cervical junctions, the options of intubation methods that avoid spinal cord and brainstem injury become limited. Direct laryngoscopy results in movement of the cervical spine in humans.2,3,6 Use of devices, such as the Bullard Laryngoscope,3–5 GlideScope,6,7 intubating laryngeal mask airway and light wand,3,5 also results in movement of the occipito-cervical junction. Recent reports by Turkstra et al. and Robitaille et al. suggested that laryngoscopy with a Macintosh blade or GlideScope® produces similar degrees of occiput-C1 and C1-C2 extensions.6,7 Intubations by direct laryngoscopy seem to be associated with postoperative neurological injury in four case reports of patients with congenital unstable occipito-cervical junctions.12 Thus, intubation methods that involve various degrees of lifting of airway tissues with metal or rigid plastic laryngoscope blades to obtain a view of the glottis may subject the spinal cord to injury in the population of patients described in this report. We did not examine cervical spine motion in our patients. However, absence of a clinically assessable neck motion suggests that the method of intubation described in this report may be safe to use in children and adult patients with unstable occipito-cervical and upper cervical junctions when conventional FOI fails.
Cervical spine surgeries in patients with advanced unstable craniovertebral junctions of congenital or metabolic etiologies are not commonly encountered. Furthermore, failure of FOI is also not a common occurrence in such patients. Our case series consists of only five patients who had FOI with different sedation/anesthesia techniques (two pediatric patients had FOI under general anesthesia, whereas three patients had FOI while under conscious sedation). Even though our patients’ postoperative neurological outcomes were favorable, caution should be exercised in making firm recommendations with regard to the safety of this technique since the number of patients in this case series is small (n = 5). The uncorrected confidence interval for 0/5 incidence reported is (0, 0.435).
The method we used differs from a conventional oral FOI in that the OET is not threaded over the fiberoptic bronchoscope. Instead, the OET is independently inserted through the mouth, guided by the view provided by the fiberscope. This technique enabled intubation of the trachea without moving the neck because the distal ends of the styletted OET or introducer may be fashioned as needed to access the glottis and trachea (Fig. 1). In contrast to conventional FOI, this technique also allows insertion of the OET between the vocal folds under direct visualization thus avoiding impingement of the OET onto laryngeal structures and the potential for laryngeal injury (a risk in traditional FOI).13,14 The technique also lends itself to more OET maneuverability versus conventional FOI. One disadvantage of this technique is that it requires a coordinated group effort by at least two anesthesiologists with aptitude in fiberoptic techniques. A challenge while using this method is that the fiberoptic scope can be displaced while inserting the styletted OET or introducer into the airway, thus losing the panoramic laryngeal view on the video monitor. A potential disadvantage of this method may be increased stimulation of the gag reflex by the additional instruments in the pharynx and larynx. However, in our patients with congenital spine malformations, gag reflex was markedly diminished or even absent because of basilar settling and compression of the brainstem by deformed odontoid processes.
Previous reports have described this technique with the fiberscope being introduced via the nose.8,9 In this report, we introduced the fiberscope orally for several reasons. First, the nasal approach for FOI was not a possible option in our patients because of surgical reasons. Second, by using the oral route, we were able to use a larger adult-sized fiberscope in small children. This was an advantage because larger adult-sized fiberscopes contain a suction channel, whereas most pediatric fiberscopes do not. Because a clear view of the glottis is central to this technique, the ability to remove secretions is essential.
In our patients, failure to intubate using traditional FOI was not because of failure to thread the OET over the fiberoptic bronchoscope into the trachea. It occurred because we could not introduce the tip of the bronchoscope between the vocal cords into the trachea despite clear visualization of the vocal cords and multiple attempts. Therefore, we did not have the opportunity to attempt to thread the tube into the trachea. There may be three reasons for failure of FOI in this series. First, our patients had either unstable craniovertebral junctions or were in traction. Therefore, we could not manipulate the neck for optimal positioning for FOI. Second, syndromes of congenital spine malformations have been reported to be sometimes associated with abnormalities of the airway, simultaneous displacement of airway in multiple planes secondary to severe cervical spine deformity or difficult airway management.15–22 Third, failure of FOI could have been simply due to our inability to do so. This possibility is unlikely considering the collective experience in airway fiberoptic endoscopy of the attending faculty members that were involved in the care of these patients.
In summary, we describe an alternative method of intubation in patients in whom traditional FOI failed because of craniovertebral and atlantoaxial junction pathologies and laryngeal displacements. The potential advantages of this technique include avoidance of clinically assessable neck movement during intubation in patients with unstable occiput-cervical spine junctions and visualization of the OET as it is entering the larynx thus avoiding potential laryngeal injury.
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