Tracheal Intubation Using a Flexible Fiberoptic Bronchoscope
Tracheal Intubation Using a Flexible Fiberoptic Bronchoscope
While tracheal intubation using a flexible fiberoptic bronchoscope or fiberoptic intubation in short can be performed either under general anesthesia or awake under topical anesthesia. This narrative will only discuss the awake fiberoptic intubation.
Modern flexible bronchoscopes include fiberoptic bronchoscopes, video bronchoscopes, and hybrid designs.
Flexible fiberoptic bronchoscopes are also available with battery operated light sources, which greatly improve portability. The handle of the bronchoscope is fitted with a lever, which controls flexion and extension of the tip of the bronchoscope in a single plane. The handle also contains the proximal port of the working channel, which extends distally to the tip of the scope.
This channel can be used to pass various instruments into the airway and can be used for irrigation, administration of medications, and suction. Profound regional anesthesia of the airway to facilitate awake fiberoptic intubation can be achieved using the following technique. IV glycopyrrolate should be administered 20 minutes prior to airway manipulation.
Local anesthesia of the upper airway begins with gargling 50 milliliters of 4% lidocaine solution in several aliquots.
The longer the patient gargles, the better the anesthesia can be achieved. The lidocaine solution is then expectorated into a kidney basin. If the patient cannot gargle, an alternate topical anesthetic technique should be employed by either applying 5% lidocaine ointment to the back of the tongue with a tongue depressor or using a 10% lidocaine spray directed to the relevant structures.
This is followed by the use of DeVilbiss atomizer attached to oxygen tubing with eight liters per minute of oxygen flow. The DeVilbiss atomizer is filled with 12 milliliters of 3% lidocaine using 4% lidocaine solution diluted with water. The patient's cooperation with respiratory effort is essential while using the DeVilbiss atomizer.
If nasal tracheal intubation is anticipated, the application of the local anesthetic should begin with the selected nostril. The DeVilbiss atomizer is applied with the patient's breathing in a coordinated fashion as shown in this video. If an orotracheal intubation is anticipated, the DeVilbiss atomizer should be applied through the oropharynx with nose closed as shown.
The intensity of the block can be supplemented with superior laryngeal nerve blocking using Jackson Crossover Forceps holding a cotton pledget soaked with 4% lidocaine solution. The tip of the forceps is placed at each piriform fossa for approximately 60 seconds. This will provide intense block of the superior laryngeal nerve. The endotracheal tube can be precut to a desired length to maximize the length of the insertion cord beyond the tube and thereby optimize maneuverability.
The inside of the tube can be lubricated and the tube ensleeved proximally and fitted to the handle with an elastic band. A lubricant jelly placed on the cuff of the tube may facilitate glottic entry. Lubricating the shaft of the scope may be unnecessary and makes it difficult to handle. The lens of the bronchoscope can be defogged using silicone solution or simply by holding the tip of the scope in warm water or against the buccal mucosa for a few seconds prior to use.
The scope is held such that the right thumb is on top of the flexion lever. Moving the lever downward flexes the tip of the scope. Upward, toward the 12 o'clock position. Conversely moving the lever upward flexes the tip downward toward the 6 o'clock position. To flex the tip in any other plane the entire scope must be rotated clockwise or counterclockwise. Many bronchoscopes have a triangular marker or a divot located at the 12 o'clock position at the periphery of the scope's field of vision.
This marker helps the practitioner maintain spatial orientation as the tip of the scope always flexes in the diametrical plane of the marker. When a video camera is coupled to a fiberoptic bronchoscope, the divot must be adjusted to the 12 o'clock position to maintain correct orientation. The practitioner's non-dominant hand holds the shaft or the bronchoscope between the thumb and the index finger a few centimeters proximal to the tip.
The patient is placed in a semi-sitting position. Extension at the atlanto-occipital joint moves the epiglottis anteriorly away from the posterior pharyngeal wall and facilitates passage of the bronchoscope through the pharynx. It is our preference to perform the intubation facing the patient, as standing at the patient's right side facilities negotiation of the natural C-shaped curve of the airway with the scope, permits easy visualization of the patient monitors, and maintains eye contact with the patient.
To elevate the epiglottis, gentle tongue traction with a gauze is provided by an assistant. The scope is inserted into the oral cavity in the midline and then advanced slowly over the tongue towards the uvula. Gently resting the hand, holding the shaft of the scope on the patient's chin, may help keep the scope in the midline. The scope is advanced past the uvula and flexed caudally to visualize the epiglottis.
If the epiglottis is oriented posteriorly or is in contact with the posterior pharyngeal wall, the patient can be instructed to take a deep breath and thereby move the epiglottis anteriorly. The scope is then passed posterior to the epiglottis to visualize the vocal cords. If the bronchoscope is off midline at the level of the epiglottis, the approach to the larynx can be much more difficult.
The scope is then advanced in the midline through the glottis and positioned proximal to the carina. As the scope is advanced through the larynx, the patient is again instructed to take a deep breath to maximally abduct the vocal cords and thereby facilitate passage of the scope. Having positioned the tip of the bronchoscope in the trachea, the practitioner should advance the endotracheal tube over the scope to follow the natural curve of the airway.
As the tube is advanced, the patient should be instructed to take a deep breath to maximally abduct the vocal cords. The correct position of the endotracheal tube is confirmed endoscopically before the scope is removed and can be further confirmed by movement of gas through the circuit and capnography.
Segment:4 Trouble Shooting.
Difficulty in passing the ensleeved endotracheal tube through the larynx maybe encountered.
Rotation of the tube 90 degrees counterclockwise may improve passage of the tube through the larynx. The larger the discrepancy between the outside diameter of the bronchoscope shaft and the internal diameter of the ensleeved tube, the greater is the chance that the tube may impinge on laryngeal structures. Therefore, this discrepancy should be minimized if at all possible.
Laryngeal cannulation may also be facilitated by using a tube with a modified tip design, such as the intubating LMA tube with a soft hemispherical bevel, or the Parker Flex-Tip tube. Various oral intubating airways can also be used during fiberoptic intubation. These may help to keep the bronchoscope in the midline and align it with the glottic opening.
Displace the tongue anteriorly and the soft palate superiorly, thus opening the pharyngeal space and to protect the scope from bite damage. These include the Berman Intubating Pharyngeal Airway, the Williams Airway Intubator, and the Ovassapian Fiberoptic Intubating Airway. While these airway intubators may be helpful, the emphasis should be on the development of skill with bronchoscopic manipulation, positioning, and regional anesthesia of the airway.
In summary, awake fiberoptic intubation can be rapidly achieved with good topical anesthesia. Fiberoptic intubation is an invaluable alternate technique in the management of the difficult airway. It should be mastered by all airway practitioners.