Office evaluation of the tracheobronchial tree.

The development of the flexible endoscope permanently changed the way we evaluate the tracheobronchial tree. Until the late 1960s, the only adequate way to examine the airways was via rigid endoscopy, which was usually performed in the operating room with general anesthesia. With improvements in design and optics, flexible endoscopes have become the standard instruments for the evaluation and, in many cases, the treatment of airway-related disorders.

Part of the reason for the popularity of flexible endoscopy, particularly in the evaluation of the tracheobronchial tree, relates to our ability to conduct an evaluation without the need for general anesthesia. Often, depending on the indication, we can examine this area with the use of topical anesthesia alone.

Patient selection and indications

Office tracheobronchoscopy can be performed routinely and safely to obtain anatomic information relating to the tracheobronchial tree in most adults. Common indications include the evaluation of patients with chronic cough and subglottic or tracheal stenosis. Its use, however, might need to be limited in patients with cardiac and broncho-constrictive disease because the risk of complications may be higher in these groups.

Effects on cardiovascular function. The hemodynamic effects of bronchoscopy have been studied in patients who have received local anesthesia and in those who have received sedation.

Local anesthesia. Lundgren et al studied 10 cardiovascularly stable patients who underwent bronchoscopy under topical anesthesia. (1) They observed significant hemodynamic changes that were associated with the delivery of the topical anesthetic, the passage of the endoscope through the larynx, and suctioning. In addition, they noted that significant deoxygenation occurred during suctioning. Their study suggests the need for caution in the use of bronchoscopy in those patients who do have cardiac disease.

Sedation. Matot et al studied 29 patients of varying health status who underwent bronchoscopy under sedation. (2) Although they found no changes in blood pressure, they did note a significant increase in heart rate and a fall in oxygenation, a combination that increases myocardial ischemia in patients at risk. Moreover, the authors suggested that the sedation itself might lead to respiratory depression and consequent arterial desaturation. Finally, they found some indication (although not statistically significant) that the length of a procedure may be a factor in increasing the risk of ischemia.

Effects on pulmonary function. Peacock et al studied the effects of bronchoscopy on pulmonary function in 21 patients. (3) The researchers concluded that the insertion and maintenance of the bronchoscope in the airways had no effect on pulmonary function, but the application of topical lidocaine did cause significant decreases in forced expiratory volume in 1 second (FE[V.sub.1]), forced vital capacity, peak expiratory flow, and peak inspiratory flow. The same responses were noted by McAlpine and Thomson. (4)

Other cautions. The practitioner should also know that there are limitations to the use of nonsedated tracheobronchoscopy performed in the office. This technique is not typically used to conduct an extensive investigation into the distal airways because of the length of time required and the degree of patient discomfort it causes. Extensive investigation also increases the need for topical anesthetics, which in turn increases the risk of complications.

Topicalization

A routine cursory evaluation of the upper trachea itself requires little if any additional anesthesia beyond that given during standard nasolaryngoscopy. However, when the clinician needs to perform a more detailed evaluation (e.g., examination of the lower trachea and distal airways), additional anesthesia is necessary. The clinician has several options, including (1) topical 4% lidocaine spray, usually delivered through the side channel of an endoscope or through an Abraham cannula, (2) nebulized lidocaine, and (3) lidocaine instillation through a cricothyroid puncture.

In our experience, the topical spray technique for anesthetizing the larynx and upper trachea is the easiest, although the transcricoid technique has been shown to be better tolerated and may require less topical anesthetic. (5) With the spray technique, the nose is topicalized in the standard Fashion for nasolaryngoscopy with lidocaine and phenylephrine sprays. Next, the flexible endoscope is passed transnasally and positioned over the laryngeal inlet (figure 1). While the patient is phonating, approximately 2 to 3 ml of 4% lidocaine is delivered to the larynx through the side channel of the endoscope. The application may have to be repeated until the patient demonstrates little or no response to the presence of the lidocaine in the laryngeal inlet. The endoscope is then advanced through the glottis; additional topical lidocaine is applied only as needed.

[FIGURE 1 OMITTED]

An alternative method involves the use of an Abraham cannula, through which lidocaine can be delivered via a transoral approach. (This technique is described in the first article in this supplement, "Topical anesthesia of the airway and esophagus," page 2.) The recommended total dose of 4% lidocaine is typically 300 mg (or 7 to 8 ml).

In patients who have undergone a tracheotomy or who have a permanent tracheal stoma, topical anesthetic can be applied directly to the tracheal mucosa via a nebulizer. These patients tolerate tracheobronchoscopy extremely well, and they require little anesthesia.

Equipment

An adequate examination of the trachea and lower airways requires a flexible endoscope and a recording system with video-capture capabilities, such as a videocassette recorder (VCR) with slow-motion and freeze-frame options. The video recording is necessary not only for documentation purposes, but also to allow for more careful study through later review in a situation where the length of the examination itself is often limited; the use of a VCR allows the endoscopist to perform a fairly quick investigation, thereby reducing the risk of side effects and complications. Finally, a video tower is useful during a biopsy or bronchoalveolar lavage because it allows the assistant to watch the procedure, as well. (The video tower is described in the first article in this supplement, "Topical anesthesia of the airway and esophagus," page 2).

When only the proximal trachea is to be examined, a standard nasolaryngoscope usually can be used. However, when a prolonged examination is necessary or a biopsy is planned, a flexible endoscope with a side channel is usually necessary. If this is not available, the endoscopist can use a Slide-On sheath (Vision Sciences; Natick, Mass.) that fits over an endoscope (figure 2). The sheath is equipped with built-in side channels that can be used to biopsy or to deliver a topical anesthetic.

[FIGURE 2 OMITTED]

To examine the distal trachea or lower airway, it is necessary to use a longer flexible endoscope, such as a bronchoscope or a transnasal esophagoscope. Again, a side channel is required for delivery of topical anesthetic, biopsy, or suctioning.

Technique

Tracheoscopy alone. Tracheoscopy can be performed fairly routinely in the office setting without the need for additional anesthesia--that is, an amount beyond what is required for standard nasolaryngoscopy. At the onset of the procedure, the patient should be warned that he or she will experience a coughing and/or choking sensation for a few seconds. The scope is advanced to a location just above the vocal folds. The video-capture device is activated, and the patient is asked to inhale through the nose. When the vocal folds are abducted, the scope is quickly advanced through the laryngeal inlet and into the upper trachea.

After the lesion or area of concern has been visualized for 2 or 3 seconds, the scope is withdrawn as the patient coughs. The video recording can then be reviewed in slow motion or frame by frame, by using the jog shuttle function (figure 3).

[FIGURE 3 OMITTED]

Bronchoscopy. Additional anesthesia is usually required for bronchoscopy. As the endoscope is advanced into the lower airways, attention should be paid to the bronchoscopic landmarks because it is easy to become disoriented. It is also important to avoid excess suctioning, which has been shown to cause oxygen desaturation. (1)

Practical considerations

In general, office tracheobronchoscopy with topical anesthesia is safe and effective. It has been used extensively with relatively few complications; a large retrospective study showed that its complication rate was similar to that associated with tracheobronchoscopy under sedation. (6) In addition, this procedure is significantly less expensive than bronchoscopy performed under sedation because it obviates the costs associated with facility-based services.

Certain precautions should be kept in mind, however. As mentioned earlier, patients should be screened for the presence of cardiac and bronchoconstrictive disease. In addition, consideration should be given to routine monitoring when performing lengthy procedures in the tracheobronchial tree. Many authors have recommended the routine use of pulse oximetry, (7,8) but the need for cardiac monitoring is less clear. (6)

In our practice, we perform tracheobronchoscopy mainly as a screening tool. This typically limits the duration of our procedures to less than 3 minutes. When more extensive investigation is necessary, we often schedule our patients to undergo bronchoscopy in the operating room or we refer them to a pulmonologist for bronchoscopy under sedation. Using this protocol, we have been able to avoid any serious complications.

References

(1.) Lundgren R, Haggmark S, Reiz S. Hemodynamic effects of flexible fiberoptic bronchoscopy performed under topical anesthesia. Chest 1982;82:295-9.

(2.) Matot I, Kramer MR, Glantz L, et al. Myocardial ischemia in sedated patients undergoing fiberoptic bronchoscopy. Chest 1997; 112: 1454-8.

(3.) Peacock AJ, Benson-Mitchell R, Godfrey R. Effect of fibreoptic bronchoscopy on pulmonary function. Thorax 1990;45:38-41.

(4.) McAlpine LG, Thomson NC. Lidocaine-induced bronchoconstriction in asthmatic patients. Relation to histamine airway responsiveness and effect of preservative. Chest 1989;96: 1012-15.

(5.) Webb AR, Fernando SS, Dalton HR, et al. Local anaesthesia for fibreoptic bronchoscopy: Transcricoid injection or the "spray as you go" technique? Thorax 1990;45:474-7.

(6.) Colt HG, Morris JF. Fiberoptic bronchoscopy without premedication. A retrospective study. Chest 1990;98:1327-30.

(7.) Milman N, Faurschou P, Grode G, Jorgensen A. Pulse oximetry during fibreoptic bronchoscopy in local anaesthesia: Frequency of hypoxaemia and effect of oxygen supplementation. Respiration 1994;61:342-7.

(8.) Jones AM, O'Driscoll R. Do all patients require supplemental oxygen during flexible bronchoscopy? Chest 2001;119:1906-9.