FIBEROPTIC INTUBATION AND THE DIFFICULT AIRWAY
Charles Beattie, Ph.D., M.D.

The fiberoptic bronchoscope can be a powerful tool in the hands of a skillful operator. Multiple articles and reviews(1) have outlined its utility in airway examination(2), double lumen tube placement(3), pulmonary lavage(4), etc. Two recent books are recommended(5,6). The most valuable application is in securing an airway in two classes of patients:

1) individuals who carry the history of difficult intubation or who have conditions known to dispose to difficult intubation (e.g. Treacher-Collins Syndrome(7), ankylosing spondylitis, achondroplasia(8), etc.

2) patients with compromised airways who may decompensate if trauma occurs during a failed direct or blind intubation attempt (tumor, trauma(9), abscess(10))

Individuals and departments who wish to develop a fiberoptic capability may consider the drawbacks of such a decision. These include initial expense, breakdowns, storage, cleaning, training of staff, and certification. We will review some of these issues.

Many of the high quality fiberoptic scopes are designed for use by bronchoscopists who need the ability to achieve sharp angulation of the tip and to lock the angle while passing biopsy forceps. Both of these features increase the expense and decrease durability. In the past, attempts to produce a more rugged and affordable scope have compromised optics and lighting far too much for practicality. However, instruments now on the market have solved virtually all of the earlier problems. They are moderately priced, have quality optics and lighting, a small diameter (4.0 mm) and are quite durable.

A special area for cleaning scopes must be designated and universal precautions employed to prevent transmission of disease(11). The following routine is suggested: 1) the instrument is cleaned immediately after the procedure is completed in order to remove superficial debris, 2) the scope is then soaked for 10 minutes in a cidex bath - with aspiration and injection of cidex through the suction port, and 3) the scope is rinsed in two separate baths of sterile water, again with aspiration and injection of cleaning solution. The scope is then wiped dry and stored in a designated cabinet.

A rather awkward issue has recently arisen secondary to medical-legal considerations and the increasing influence of regulatory bodies. This concerns the matter of certification of individuals who perform fiberoptic procedures. While there are no accepted standards at the present time, each group or institution should develop their own policies and procedures.

Fiberoptic intubation is simple in principle, but with potential difficulties in practical application. It requires practice to learn. In addition, whereas it is often arguably the "best" way to proceed, it is infrequently an absolute necessity. The combination of these factors make it unlikely that more than a small percentage of any group will master its use. For those who are interested, there is one basic suggestion; use the scope frequently - at least whenever a nasal intubation is planned. Finally, as one becomes identified as the in-house fiberoptic expert, resist requests of colleagues to "stand-by" while they try a known difficult intubation by standard methods. Insist on committing to a fiberoptic procedure from the outset.

HOW TO DO IT

Familiarity with the scope features and practice in manipulation should be obtained before clinical use. Tip control is quite simple, up/down motion is adjusted with the deflection lever; right/left motion is accomplished by clockwise/counter-clockwise rotation of the entire scope-handle and shaft. Trying to effect this rotation by turning the handle alone (without simultaneous rotation of the shaft with the other hand) produces torque which the smaller scopes may not tolerate - especially if they are passing through a snug fitting endotracheal tube. This twisting is one of the most common causes of scope damage. Be sure to rotate the entire scope as a unit. Direction changes should be made with very small movements of the lever. Do not attempt to deflect the endotracheal tube tip by scope deflections as cable damage may ensue.

There are a number of procedural options regarding the route (oral vs nasal), patient condition (awake, anesthetized, spontaneous vs controlled ventilation) and intubation technique (scope-first vs tube-first). The relevant factors that determine choice will be evaluated throughout the text. In this author's experience, the most straight forward combination is a nasal intubation, using the tubefirst technique, in a spontaneously breathing patient. We shall discuss this approach in greater detail.

Patient Preparation:

Adequate preparation is frequently the key to success. Secretions are the enemy of the endoscopist. An antisialogogue, administered in sufficient time to work, is imperative. Scopolamine, atropine or glycopyrrolate may be used. We routinely use glycopyrrolate because it is non-sedative and results in fewer hemodynamic side effects than atropine. The nasal passage (if the nasal route is chosen) and the oropharynx, cords, and trachea should be topicalized with lidocaine or cocaine. Superior laryngeal and transtracheal blocks are described elsewhere. Whereas nerve blocks can be valuable under special circumstances, many experienced clinicians use simple topicalization. I prefer a good atomizer and use 4% lidocaine. One must limit the total amount used to 5 mg/kg and be alert for signs of toxicity. The patient is asked to breathe deeply, while inhaling a mist sprayed into the open airway. This can be done repeatedly as other aspects of patient preparation are underway. The local anesthetic is distributed over the laryngeal surfaces and, in conjunction with sedation, usually produces very satisfactory intubating conditions. The nasal passage is first topicalized with spray then with cotton swabs coated with 2% lidocaine jelly. Vasoconstriction is very important and is accomplished by using 5% cocaine as the anesthetic or by adding phenylephrine to 2% lidocaine jelly. The swab may be passed along the floor of the nasal passage directly back until it hits the posterior wall of the nasopharynx. The ease of passage gives a feel for the patency. If necessary, the other nostril is treated. The nasal passage is then dilated starting with small, and then with progressively larger, soft nasal airways coated with the lidocaine jelly, phenylephrine mixture. This should be done patiently and carefully with additional anesthetic used as necessary. The largest airway which can be introduced then serves as a guide to the acceptable maximum endotracheal tube size. The largest nasal airway is left in for a few minutes to compress turbinates in preparation to receive the endotracheal tube. Sedation is quite desirable during this period of preparation. I find small doses of droperidol and fentanyl to be ideal, even in children. Of course it must not be overdone, especially when there is doubt of the ability to manage the airway with a mask should it become necessary. This supplemental sedation should be started early (soon after arrival in O.R.), given slowly, and titrated to effect.

Intubation:

After sedation, topicalization, and dilatation an appropriate endotracheal tube (softened by heat) is introduced through the nose and gently advanced just until the bend is made at the posterior nasopharynx. This is signaled by a sudden "give" after an initial resistance. It is important to stop immediately at this point to avoid passing the tube too far. It is useful to introduce a flexible suction catheter (14 F) down the tube to clear all secretions. If the suction catheter does not pass out of the tube, the latter should be repositioned (usually rotated or withdrawn slightly) until it does. After the scope has been prefocused and lubricated, it is passed through the tube and the glottic opening is sought. The sequence to this point describes the tube-first technique. The alternative method is called the scope-first technique, wherein the endotracheal tube is first passed over the scope up to the base of the handle. The scope tip is then passed through the nostril and manipulated through the naso and oropharynx to the glottic opening. There are both advantages and disadvantages associated with each technique. When the tube is passed first, it acts as a clean conduit and as a stint for scope support and orientation. On the negative side, there is a tendency to pass the tube too far. Also, the tip of the endotracheal tube may be buried in pharyngeal tissue. If recognizable anatomy is not seen, then the tube is slowly withdrawn. It is claimed that this sequence carries the hazard of induced bleeding which might obscure the field of vision. In my experience this problem virtually disappears with proper dilatation, vasoconstriction, and tube size selection described above. The scope is manipulated through the cords and advanced well into the trachea. Then, both the tube and the scope are advanced as a unit until the tube is within trachea. The scope is then withdrawn with continued visualization to assure that the tube is not inadvertently pulled out of the trachea. Again, this maneuver differs from the scope-first method wherein the tube is advanced over the scope during tracheal placement. I feel that advancing the two together reduces (while not eliminating) the probability of kinking or buckling of the scope when bends must be negotiated during insertion. The problem of kinking can be serious and not only prevents a successful intubation, but can cause scope damage and airway obstruction. It arises because some of the smaller bronchoscopes are too compliant to guide a stiff tube through small radius curves, or because of "hang-up" on the cords or arytenoids.

The lists below show the comparative issues when choosing the oral or nasal route, provided the patient's anatomy and surgical procedure allows such choice.

Nasal

Oral

* Whereas it is preferable to perform oral intubation in patients who are anticoagulated, the nasal route may be safely used,by performing the nasal preparatory procedures very carefully, and using a small, soft endotracheal tube.

** Two oral airways are available. The Williams Airway Intubator and the Ovassapian Fiberoptic Airway. These are designed differently and may each be useful in different circumstances.

Awake vs. Asleep:

Fiberoptic intubations are, in my experience, easier when done awake and by the nasal route. In increasing order of awkwardness are:

awake - nasal

awake - oral

asleep - nasal - spontaneous ventilation

asleep - nasal - controlled ventilation

asleep - oral - spontaneous ventilation

asleep - oral - controlled ventilation

The procedure is performed under anesthesia some means of assisting or controlling ventilation usually must be instituted. This may be accomplished with special devices manufactured for the purpose. Anesthesia masks are available equipped with separate openings for ventilation and tube insertion. We have refined a feasible alternative, wherein ventilation is controlled or assisted via a nasal airway (with adaptor) introduced through one nostril while the tube-first intubation sequence proceeds through the other nostril. When the scope is passed through a nasally placed tube there is usually minimal leak through the annular space thus created. The mouth is easily held shut to form a tight seal and fiberoptic intubation can proceed under calm and controlled circumstances. We have used this technique multiple times in both emergency settings and in failed direct intubations in patients who were anesthetized and paralyzed(12).

Tricks, Tips, Hints:

I. Lubrication and tube size/scope diameter:

Lubrication with a generous coating of mild soap to the scope shaft and removal of the endotracheal tube connector (don't lose it!) allows a full one half size smaller tube to be used with any given scope. For example, a 4.9 mm O.D. scope rated as permissible for use with a 6.0 I.D. tube will smoothly pass through a 5.5 I.D. tube using a soap lubricant and removing the adaptor.

II. Manipulation through the glottic opening:

The scope does not necessarily follow the tip when it is advanced, especially in a supine patient. You may be frustrated to find that you can see the target but not hit it. This often occurs with the extremely anterior larynx. In this circumstance, the natural anterior curve of the ETT may be used to direct the scope (provided, of course, the tube has already been advanced through the nares as suggested) toward the larynx and then a posterior bend applied to actually enter the trachea. Alternately, some practitioners advocate a patient-sitting position for the entire intubation procedure. This greatly facilitates visualization in most cases, but the position is not always practical.

III. Avoiding scope damage:

a. Never try to angulate the scope tip while the end is still in the endotracheal tube; the cables may stretch or break.

b. Never try to remove the scope from the tube while locking mechanism is engaged. The locking feature should be eliminated from scopes used for intubation.

c. Scope rotation to effect left/right orientation is rather more difficult using the tube first technique - especially if anatomy or equipment constraints have resulted in a snug scope/tube fit. Rotation is achieved in this case by turning the tube and scope together.

In spite of the drawbacks it seems reasonable that, as putative airway "experts", anesthesiologists (or some group representative) should develop a fiberoptic capability and provide this advanced dimension of patient care.

REFERENCES

  1. Watson CB: Fiberoptic bronchoscopy for anesthesia. Anesthesiology Review IX:17-26, 1982.
  2. Lindholm C, Ollman B, Snyder J, et al: Flexible fiberoptic bronchoscopy. Critical Care Medicine 2(5): 250-261, 1974.
  3. Shapiro S, Watson CB, Bowe EA, Klein EF: Bronchoscopic placement of the double-lumen endotracheal tube for independent lung ventilation. Critical Care Medicine 9(3): 189, 1981.
  4. Tahin AH, Yarbrough WM, Adriani J: Bronchofiberscope as an aid to endotracheal intubation and respiratory care in surgical patients. Southern Medical Journal 66:772-774, 1973.
  5. Ovassapian A: Fiberoptic airway endoscopy in anesthesia and critical care medicine. New York: Raven Press, 1990.
  6. Norton ML: Atlas of the difficult airway. St. Louis, Missouri: Mosby Year Book, 1991.
  7. Sklar GS, King BD: Endotracheal intubation and Treacher-Collins Syndrome. Anesthesiology 44:247-249, 1976.
  8. Mather JS: Impossible direct laryngoscopy in achondroplasia. Anaesthesia 21:244-248, 1966.
  9. Mulder DS, Wallace DH, Woolhouse FM: The use of the fiberoptic bronchoscope to facilitate endotracheal intubation following head and neck trauma. Journal of Trauma 15: 638-640, 1975
  10. Ludwig's Angina: Use of fiberoptic laryngoscopy to avoid tracheostomy. J Oral Surgery 2:608-611, 1974.
  11. Bond WW: Virus transmission via fiberoptic endoscope: Recommended disinfection JAMA 257(6): 843-844, 1987
  12. Mark LJ, Beattie C, Ferrell L, Trempy G, Dorman T, Schauble J: The Difficult Airway: Mechanisms for Effective Dissemination of Critical Information. J. Clin Anes 4:247-251, 1992.



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