Pitfalls in the Use of the Flexible Bronchoscope in Pediatric Patients: INSTRUMENTATION FOR ENDOSCOPY
use of inappropriate instruments for bronchoscopy is a major potential pitfall. Flexible bronchoscopes at least partially obstruct the airway, and the instrument used should be small enough to allow adequate ventilation if possible. On the other hand, it is also possible to employ an instrument which is inappropriately small for the task at hand. The “ultra- thin” flexible bronchoscopes do not have suction channels, and it may therefore be very difficult to adequately visualize the airways with such an instrument if there are excessive secretions. The bronchoscopist must be certain that the appropriate structures have been adequately visualized.
A more insidious problem is the use of a flexible bronchoscope when a rigid instrument should be used instead. While in general I believe that the flexible instruments are superior for diagnostic purposes, there are several distinct situations in which use of the rigid bronchoscope may be essential to reach an accurate diagnosis. The rigid instrument approaches the glottis from the anterior aspect, and it is often difficult to adequately evaluate the anterior aspect of the glottis with a rigid instrument. On the other hand, the flexible instrument approaches the glottis (via the transnasal route) from the posterior aspect, and must be flexed anteriorly to view the glottis. Thus, it may be difficult to adequately evaluate the posterior aspect of the glottis with a flexible instrument. Therefore, the examination of a patient with suspected H-type tracheoesophageal fistula or a suspected laryngeal cleft is probably best performed with a rigid bronchoscope. The lens of the flexible bronchoscope is at the extreme distal end of the instrument; this makes it very difficult to manipulate the tissues under direct vision, as can be done with a rigid bronchoscope or laryngoscope. Vocal cord movement is most appropriately evaluated under topical anesthesia (and sedation) rather than general anesthesia, and the flexible instruments are usually adequate. However, if the vocal cords do not abduct, the problem may be either paralysis or interarytenoid fixation. These possibilities can best be distinguished with a rigid instrument, since the cords can be separated by the tip of the bronchoscope while their movement is observed through the telescope.
Another inappropriate use of the flexible bronchoscope is the attempted removal of foreign bodies. Although some small forceps and baskets are available which will pass through the pediatric (or adult) flexible scope, foreign body extraction is sufficiently difficult and risky that it should rarely, if ever, be attempted with a flexible bronchoscope unless attempts with a rigid instrument have failed and the flexible instrument offers some distinct advantage in the specific situation. levitra plus
Flexible bronchoscopes are expensive (>$8,000 at current prices) and there is great temptation to utilize less expensive instruments, such as a nasopharyngo- scope. The nasopharyngoscope has many legitimate uses but can lead to problems in routine use in pediatric patients. It has no suction channel, so that it may be more difficult to achieve adequate laryngeal anesthesia, thus tempting the operator either to not examine the larynx or to examine it from some distance. I have seen several infants with large subglottic masses who, prior to referral to my institution, had been examined by competent otolaryngologists with a nasopharyngoscope without making the correct diagnosis. The lack of a suction channel also may cause great problems in the presence of excess secretions. Another inexpensive instrument is the semidisposable “optical catheter.” These instruments do provide a reasonable image, but since they lack effective distal angulation, can only be passed through an endotracheal or tracheostomy tube. Once the tip of the instrument reaches the end of the artificial airway, it is very difficult to manipulate it to visualize the anatomic structures. All flexible instruments have a wide-angle lens, which produces substantial optical distortion, with poor perception of depth and relative size. Therefore, if a nonsteerable instrument is passed through an endotracheal tube which is positioned in the right main bronchus, it is very easy to mistake the right middle lobe bronchus for the left main bronchus. Only if one can manipulate the tip of the instrument so that all the major anatomic landmarks can be unequivocally identified can one be certain of the location of the tip of the instrument.
Flexible bronchoscopes are expensive and fragile, and there are many potential pitfalls which lead to their damage or destruction. Untrained assistants may easily break the image or light bundles, while exposure to high temperatures (inadvertent autoclaving or gas sterilization at too high a temperature) may destroy the bronchoscope. Newer models are immersible and do not require gas sterilization. However, they must be fitted with an exhaust valve to prevent damage from increased pressures within the instrument during sterilization. Another major risk is associated with oral passage of the instrument; bite blocks are essential, even in intubated patients who appear to be unconscious.
Nosocomial infection is a constant risk if the bronchoscope is not adequately cleaned and disinfected prior to use.® Even with immersion in sterilizing solutions, microbial agents may survive beneath mucus adherent to the interior of suction valves or the suction channel. It is important to thoroughly clean and brush the entire instrument with each cleaning. Suction valves must be disassembled for cleaning. The suction side arm must also be brushed clean; contamination here may not infect the patient but it may well lead to erroneous diagnostic results.
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