Michael F. Murphy
Peter M. C. DeBlieux
Description
Endotracheal intubation over a fiberoptic bronchoscope has emerged as an invaluable technique in airway management, particularly in patients for whom standard laryngoscopy and orotracheal intubation have failed or are anticipated to be difficult or impossible. No discussion of difficult or emergency airway management is complete without a review of the use of fiberoptic devices to perform diagnostic procedures in the upper airway and endotracheal intubation.
Although fiberoptic bronchoscopes are becoming more widely available in emergency departments (EDs), and published studies have described their use in the ED, few emergency practitioners have extensive experience with them for diagnostic procedures in the upper airway, and fewer still have done fiberoptic intubations.
Indications and Contraindications
Indications for fiberoptic endoscopy in emergency airway management include the following:
· Intubation of the patient who is predicted to be a difficult intubation. The most frequent candidates are those with supraglottic causes of upper airway obstruction such as angioedema, oropharyngeal abscess or hematoma, or Ludwig's angina, or those with slowly progressive laryngeal lesions such as lingual and laryngeal cancers.
· Direct vision laryngoscopy and intubation is recommended for patients with laryngeal trauma and tracheal disruption. The fiberscope meets this indication.
· Cervical spine immobility required, particularly if the airway is predicted to be difficult.
· Anatomical abnormalities, such as patients with restricted mouth opening or severely hypoplastic mandibles, or the morbidly obese.
· Failed intubation in the “can't intubate, can oxygenate” scenario, when continuing deterioration of the airway is not anticipated.
Contraindications to fiberoptic intubation are mostly relative and may include the following:
· Excessive blood and secretions in the upper airway, which have the great potential to obscure the view and reduce the success rate with the fiberoptic technique. Some experienced bronchoscopists use the fiberscope like a Trachlight (see Chapter 11) in situations such as these, using transillumination to indicate entry into the trachea and only then looking through the scope to verify the position of the fiberscope in the trachea.
· High-grade upper-airway obstruction (due to foreign bodies or other lesions), where the procedure may precipitate total airway obstruction. If a patient has a high-grade supraglottic airway obstruction, the delays and risks of precipitating complete airway obstruction or laryngospasm argue strongly against fiberoptic intubation and in favor of cricothyrotomy.
· Inadequate oxygenation by bag and mask does not permit fiberoptic intubation because of the time required (“can't intubate, can't oxygenate”).
Technique
Overview
Fiberoptic intubation is a technical challenge that requires initial training, and then skill maintenance activities to maintain speed and success. Manual dexterity in manipulating the fiberscope is essential to performing fiberoptic intubation in a timely fashion. This skill is best learned by attending fiberoptic intubation workshops with expert instruction, and then practicing on intubation manikins or high-fidelity human patient simulators before one attempts to intubate a patient. This is particularly true of patients with difficult airways. The manufacturers of fiberscopes can usually provide training videos, product support personnel, and manikins to support this endeavor.
The requisite psychomotor skills cannot be developed without practice, and lack of training, practice, and experience constitute the most common cause of failed fiberoptic intubation. A reasonable level of dexterity in bronchoscopic manipulation can be achieved within 3 to 4 hours of independent practice using an intubation model. Recent studies have shown that the technique can also be learned in real-life situations by the performance of upper airway endoscopy when diagnostic opportunities, such as searching for foreign bodies and evaluating the causes of hoarseness, severe sore throat, and other upper airway conditions, present themselves. As is the case with many of the specialized airway techniques, semiemergent intubations, such as overdose victims without anticipated difficult airways and those who are easily ventilated with normal oxygen saturation, may be appropriate candidates for fiberoptic intubation. Because success depends on familiarity and skill in using the device, gaining experience in routine cases is invaluable before one is required to perform a difficult fiberoptic intubation in a crisis.
Preparation
Although the emergency difficult or failed airway situation often does not permit lengthy preparation and a methodical approach, maximal success with this technique requires both psychological and pharmacological patient preparation. When the procedure is to be done “awake” (see Chapter 8), optimizing the chances for success includes the following:
· Educate the patient as to what to expect.
· Administer an antisialogogue, such as glycopyrrolate 0.01 mg/kg, at least 20 minutes in advance of the procedure to minimize obscuring secretions and to maximize the effect of topically applied local anesthesia.
· Achieve profound local anesthesia of the airway. A fiberoptic intubation requires as much sedation and topical anesthesia as is necessary for awake direct laryngoscopy.
· Administer adequate sedation (see Chapter 8).
Scope Selection
Instrument selection for the ED is an important issue. Affordable and durable scopes are easily available from a variety of manufacturers. Selection of a manufacturer may be guided by existing service contracts in your specific institution. These instruments, although expensive, find several uses in the ED to justify such an expenditure:
· Endotracheal intubation, both nasal and oral
· Diagnostic laryngoscopy
· Oropharyngeal foreign body location and extraction
· Pulmonary toilette, particularly when intensive care unit patients are “held over” in the ED
The scope should be of sufficient caliber and stiffness to guide the passage of an endotracheal tube (ETT) over itself through the angles of the airway without kinking and resist being flipped out of the trachea, while maintaining flexibility and ease of manipulation. Most fiberscope manufacturers produce intubation-specific devices that have the added stiffness of the fiber bundle to allow ETTs to be guided into the trachea over the scope. This feature allows scopes that are small enough (3 to 4 mm tip diameter) to be painlessly and atraumatically passed through a topically anesthetized nose for diagnostic work to also be used for fiberoptic intubation. Neonatal and pediatric fiberscopes (2 to 3 mm tip diameter) are also available.
The fiberoptic bundle should be long enough (600 mm) to allow bronchoscopy and airway toilette in the ED. Standard bronchoscopes are 600 mm in length. Some manufacturers produce 400-mm intubating fiberscopes that are not long enough for pulmonary care. A separate channel for the injection of local anesthetic or saline and suctioning is essential, although the smaller neonatal and pediatric fiberscopes may not have them owing to their small size. A formerly recommended practice, the insufflation of oxygen through the suction apparatus to maintain saturations and blow secretions out of the way, is now contraindicated following several cases of gastric insufflation, perforation, and death. A new generation of fiberoptic scopes with battery-powered, portable, self-contained light sources promises to be much more compact and may be preferable for ED applications.
Care of the Instrument
Some general precautions to prevent damage to the scope and its relatively delicate fiberoptic bundles are as follows:
· Do not drop the scope.
· Use a bite-block (e.g., oral airway) to protect the scope. Most oral fiberoptic intubation guides incorporate this feature (e.g., the Berman intubating/pharyngeal airway, also called the “Berman breakaway airway”) and are invaluable aids to successful oral fiberoptic intubation (Fig. 12-1).
· Avoid acute bending or kinking of the fiber bundle, especially when sliding the ETT over the scope into the trachea.
· If rotation of the ETT during intubation is necessary, rotate both the ETT and the scope to avoid damage to the fibers.
· Lubricate the ETT by spraying local anesthetic agent or other water-soluble material down the tube to allow easy removal of the scope after the ETT is in place. Lubricating the scope makes it slippery and difficult to manipulate.
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Figure 12-1 • Three Oral Fiberoptic Intubation Aids are on The Market: the Williams (left), the Berman intubating/pharyngeal airway (center), and the Ovassapian guide (right). The Williams and the Berman serve a “bite-block” function. |
· Clean the device, including the working channel, immediately after use. The best routine is to suction 1 L of saline through the device immediately after use. Manufacturers and endoscopy units will provide instructions for acceptable cleaning routines.
· Do not flex the tip against undue resistance to manipulate the direction of an ETT or use it to move tissue out of the way.
Technique of Fiberoptic Intubation
The fiberscope has two main components: a body (handpiece) housing the controls and accessories and a fiber bundle (Fig. 12-2). Scope tip control is simple: flexion forward and backward is achieved with the thumb toggle on the body of the fiberscope, whereas rotation clockwise and counterclockwise is done by rotating the wrist of the hand that is holding the body of the fiberscope (not the entire upper body).
The vast majority of EDs will not have a video-capable system, so this description assumes the operator is holding the eyepiece to his or her eye. When looking through the eyepiece of the fiberscope, select visual targets as you advance the scope using the hand holding the fiber bundle to pull the hand holding the body of the scope along. Move toward these targets slowly but steadily using small manipulations forward and back (toggle) and left and right (wrist flexion and extension) to keep successive targets in the center of the visual image. The hand-eye coordination needed for successful fiberoptic intubation has been likened to the kind of hand-eye coordination used to play a video game.
Preparation for the task depends on how much time is available. Generally, most things should be in a state of instantaneous readiness on the difficult and failed airway cart:
1. Gather all your equipment (usually preassembled on a tray):
a. Topical airway anesthesia supplies and equipment, including three 5-mL syringes loaded with 4% lidocaine to inject into the airway through the scope as needed
b. Fiberscope, ETTs, airways, bite-blocks
c. Tonsil suction
d. Lubricant and silicone liquid drops (prevents fogging)
e. Additional airway management equipment as indicated in case of patient deterioration and need for rapid intervention
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Figure 12-2 • Body of a Fiberoptic Bronchoscope. |
2. Obtain an able and knowledgeable assistant.
3. Prepare the patient:
a. Antisialogogue, such as glycopyrrolate 0.01 mg/kg intramuscularly or intravneously
b. Vasoconstrictor for the nose (if nasal route chosen)
c. Local airway anesthesia
d. Sedation as appropriate
e. Preoxygenate the patient as for rapid sequence intubation (see Chapter 3) as much as is possible
4. Lubricate the tube and slide it over the scope up to the handpiece. Press the ETT connector to the handpiece firmly to hold it in place or tape it there. Lubricating the scope makes it slippery and too hard to manipulate.
5. Put a drop of silicone liquid on the tip of the scope or place the tip of the fiber bundle in a bottle of warmed saline (usually available in the warming cabinets of most EDs) for 1 minute to prevent fogging.
6. Insert a bite-block if the oral route is chosen, or, preferably, use an intubating guide such as a Berman intubating/pharyngeal airway. If a Berman guide is used, mount the ETT in the guide, ensuring that the tip of the ETT is at the end of the tubular portion of the airway before inserting the guide into the mouth, and then insert the fiberscope through the ETT.
7. Stand up straight, either at the head of, the side of, or facing the patient. Operator positioning is mostly a matter of personal preference and patient tolerance.
8. Oral technique: Stay in the midline, stay in the midline, stay in the midline! The best way is to place the long or ring finger in the middle of the upper lip to maintain a reference point and hold the fiber bundle with the index finger and thumb. Gentle traction on the tongue by an assistant using a gauze bandage helps open the airway and prevent the patient from using the tongue to obstruct access to the airway. Custom made airways, such as the Berman intubating/pharyngeal airway, are helpful in keeping the scope in the midline and obviate the need for the tongue traction maneuver. If such an adjunct is used, insert the ETT into the airway and then insert the scope through the airway/ETT combination, obviating the need to jam or tape the ETT connector onto the scope handpiece.
Nasal technique: Soften the nasotracheal tube by placing the ETT in a bottle of warmed saline or sterile water from the warming closet for 3 to 5 minutes before inserting the ETT through the nostril. It is helpful to dilate the chosen anesthetized nostril by gently and slowly inserting increasingly large nasopharyngeal airways or a lubricated and gloved small finger into the nostril as far as possible immediately before inserting the ETT. Advance the lubricated nasal tube to the nasopharynx, and then pass the scope through the tube.
9. Hold the body of the fiberscope in the same hand as your dominant eye. This allows one to turn slightly to the side when using the scope, an important detail in keeping the fiber bundle of the scope straight during the procedure for reasons described later. Some advocate holding the body of the scope in the left hand to facilitate clearance of the light source cable and suction tubing, which exit the body of the scope on its left side (Fig. 12-2). Use your thumb to toggle the tip control lever up and down. The index finger can be used to depress and activate the suction feature. Flexing and extending the wrist moves the tip of the fiber bundle left and right, although the fiber bundle must be held straight with mild tension between the two hands to optimize this maneuver. Slackness in the fiber bundle will not permit wrist motion to rotate its tip. The nondominant hand advances, withdraws, and manipulates the fiber bundle, and maintains a midline oral position if the oral route is chosen. The operator should move the hands and arms, not the whole torso, to manipulate the fiber bundle into the airway.
10. The assistant should have tonsil suction available to aspirate oral secretions and blood. The working channel of the scope may provide insufficient suction to clear the volume of secretions that may be present during the procedure. If the tip becomes soiled or fogged and obscures clear vision, bouncing the tip gently against the mucosa may be sufficient to clear it.
11. Get your bearings. At the head of the bed, the base of the tongue is up; beside or in front of the patient, it is down. Advance slowly while flexing the tip up to pass over the back of the tongue. The epiglottis comes into view. Keep it above you. You will see the white cords opening and closing with respiration.
12. It may be difficult to coordinate it, but attempt to advance the scope through the vocal cords during inspiration when they are open. You may need to inject 5 mL of 4% lidocaine through the working channel onto the larynx to obtund the cough or closure reflex and permit entry into the trachea.
13. If you get lost, withdraw to the oropharynx and find a landmark.
14. Once the tip of the fiber bundle is through the vocal cords, advance the scope almost to the carina. Then slowly advance the ETT over the scope into the trachea, being careful not to kink the scope. A laryngoscope may be useful to straighten out the angle of approach to the glottis. Gentle rotation of the scope/tube unit through 180 degrees may be necessary if the ETT catches on the cords. Newer ETT tip designs may facilitate passage of the ETT through the cords (e.g., Parker tube).
15. If coughing is a persistent problem, inject 5 mL of lidocaine 4% aqueous through the scope.
16. After the ETT has been successfully passed into the trachea, the scope can be used to correctly position the ETT in the midportion of the trachea. Push the tip of the scope through the ETT until it is just distal to the end of the ETT and flex it gently forward. Grasp both the fiberscope and the ETT, and move them together until light transilluminates the sternal notch. The light is shining forward immediately beyond the tip of the ETT, so this corresponds to the midtracheal position.
Complications
Patient complications with this technique are uncommon and include mucosal damage to the airway and epistaxis. As with all techniques, damage to the vocal apparatus is possible but rare. The most frequent complication is damage to the scope from biting, twisting, kinking, or dropping. In the past, it was taught that oxygen ought to be insufflated down the working channel of the scope to blow secretions out of the way and provide an element of oxygenation for the patient. This practice has been associated with gastric insufflation and rupture leading to death, and thus is no longer recommended.
Evidence
Intubating over a fiberoptic bronchoscope, nasally and orally, is a well-established technique for managing difficult airways (1,2,3,4). It has been demonstrated that the technique is easily learned and the skill maintained (5), and that nonhuman models are useful in teaching the manipulative skills that are key to successful intubation (6). It is recognized as a skill important to the training of residents in emergency medicine (7). Levitan et al. (8) surveyed academic EDs in 1999, attempting to determine what alternative airway management devices were available for difficult airway management. Sixty-four percent of them had fiberoptic bronchoscopes. Several studies have demonstrated a success rate for ED fiberoptic intubation by emergency physicians in the 70% to 99% range, depending on training and frequency of use (9,10,11,12,13). Both fiberoptic nasal (adults and children) and oral intubation in the ED have been described in the literature (14,15). Emergency fiberoptic intubation has been used in blunt and penetrating head and neck trauma, laryngeal malignancies, tracheal stenosis, and other difficult airway situations (16,17,18,19,20). As mentioned previously, the practice of insufflating oxygen down the working channel of the scope has been associated with gastric insufflation and rupture leading to death (21) and is no longer recommended (22).
Finally, no discussion of fiberoptic intubation would be complete without at least mentioning the uncommon but real risk of sudden and total airway obstruction in patients undergoing topical anesthesia for awake fiberoptic intubation (23,24,25,26) (see Chapter 8). This factor simply serves to reinforce the need for preparedness for any eventuality when one is managing an airway in an emergency.
References
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16. Mulder DS, Wallace DH, Woolhouse FM. The use of the fiberoptic bronchoscope to facilitate endotracheal intubation following head and neck trauma. J Trauma 1975;15:638–640.
17. Wei WI, Siu KF, Lau WF, et al. Emergency endotracheal intubation under fiberoptic endoscopic guidance for malignant laryngeal obstruction. Otolaryngol Head Neck Surg 1988;98:10–13.
18. Wei WI, Siu KF, Lau WF, et al. Emergency endotracheal intubation under fiberoptic endoscopic guidance for stenosis of the trachea. Surg Gynecol Obstet 1987;165:547–548.
19. Mandavia DP, Qualls S, Rokos I. Emergency airway management in penetrating neck injury. Ann Emerg Med 2000;35:221–225.
20. Edens ET, Sia RL. Flexible fiberoptic endoscopy in difficult intubations. Ann Otol Rhinol Laryngol 1981;90:307–309.
21. Hershey MD, Hannenberg AA. Gastric distention and rupture from oxygen insufflation during fiberoptic intubation. Anesthesiology 1996;85:1479–1480.
22. Ovassapian A, Mesnick PS, Hannenberg AA, et al. Oxygen insufflation through the fiberscope to assist intubation is not recommended. Anesthesiology 1997;87:183–184.
23. Ho AM, Chung DC, To EW, et al. Total airway obstruction during local anesthesia in a non-sedated patient with a compromised airway. Can J Anaesth 2004;51:838–841.
24. Shaw IC, Welchew EA, Harrison BJ, et al. Complete airway obstruction during awake fibreoptic intubation. Anaesthesia 1997;52:582–585.
25. McGuire G, el-Beheiry H. Complete upper airway obstruction during awake fibreoptic intubation in patients with unstable cervical spine fractures. Can J Anaesth 1999;46:176–178.
26. Donlon JV Jr. Anesthetic management of patients with compromised airways. Anesth Rev 1980;7:22–31.
