Pitfalls in the Use of the Flexible Bronchoscope in Pediatric Patients: THE PROBLEM OF CONCURRENT LESIONS
Bronchoscopists, especially pediatric bronchoscopists, cannot be medical unitarians. Children frequently have multiple abnormalities in their airways. Even when a finding explains the child’s symptoms, other abnormalities may lurk around the corner. For example, in 15 percent of children whom I have examined for stridor and in whom a plausible explanation for the stridor was found at the subglottis or above, there was in addition a significant lesion in the trachea or bronchi. Unless there are good reasons not to do so, a thorough examination should be made of the entire airway during each examination.
When multiple lesions are found, it can sometimes be difficult to determine which lesion is most important or contributes most to the patients problem. This may usually be resolved by careful observation under conditions which most nearly mimic those under which the symptoms occur and by paying careful attention to physiologic principles.
Technical Problems
Finally, there are a number of technical problems which merit mention in the context of pitfalls. buy viagra professional
The Difficult Nasal Passage
Almost everyone’s nasal airways are somewhat asymmetric. While the amount of pressure which can safely and reasonably be used to insert a flexible bronchoscope is a matter of some experience and learning, one should not hesitate to attempt to pass through the opposite nostril if difficulty is encountered initially. The nostril should be gently but thoroughly aspirated of secretions prior to attempted insertion of the bronchoscope, and the use of a topical vasoconstrictor may be of benefit. In general, the middle meatus, between the middle and lower turbinates, usually affords the easiest passage for the bronchoscope. The bronchoscope should be inserted parallel to the floor of the nose, and not directed upwards toward the glabella. If the light from the tip of the bronchoscope can be seen near the glabella, it is likely that the instrument is directed in the wrong direction. I have encountered only three patients in whom transnasal passage of the flexible bronchoscope was not possible. Even infants as small as 700 g easily admit the 3.5mm pediatric flexible bronchoscope through their noses.
Pharyngeal Hypotonia
Patients with tracheostomies or who have decreased muscle tone because of muscle or CNS disease often have pharyngeal hypotonia. This may make it very difficult to find the larynx. Obstruction of the tracheostomy tube for several breaths will force the patient to make increased inspiratory effort, recruiting the hypopharyngeal musculature, and often dramatically opening the supraglottic airway. Alternatively, oxygen can be insufflated through the suction channel of the bronchoscope (at a rate of 1 to 3 L/min in infants) to distend the hypopharynx. If one is using an ultrathin instrument without a suction channel, a suction catheter can be inserted through the opposite nostril and oxygen passed through the catheter to achieve the same result. Care must be taken not to pass the catheter down the esophagus, distending the stomach and abdomen, and thus embarrassing ventilation. Yet another technique is to ventilate the patient through a nasopharyngeal tube while passing the bronchoscope through the other nostril. An orogastric tube may be used to relieve gastric distention in this technique. In extremis, one may expose the larynx with a rigid laryngoscope while passing the flexible bronchoscope through the nostril.
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Nasotracheal Intubation
In my personal experience, it has rarely required more than 30 s to accomplish nasotracheal intubation with a flexible bronchoscope. The smallest of the ultrathin instruments with distal angulation (2.2 mm, Olympus PF22) will pass through a 2.5-mm endotracheal tube, so this technique is at least in theory available to every patient. A common pitfall in this technique is to pass the endotracheal tube into the posterior nasopharynx prior to passage of the bronchoscope into the tube. This severely restricts the mobility of the tip of the bronchoscope and the ability to identify the laryngeal structures. Instead, the endotracheal tube should be placed over the bronchoscope and positioned as far proximally on the shaft of the instrument as possible. The tip of the bronchoscope should first be passed to the carina and then the endotracheal tube passed through the nostril and glottis into the trachea. Unless the operator keeps the carina in view during the entire procedure, the tip of the bronchoscope may inadvertently slip into the esophagus as the endotracheal tube is positioned. A rotating motion should be used as the tube traverses the nose and larynx; this reduces friction against the bronchoscope and facilitates safe and effective passage through the nose and especially the glottis. If an endotracheal tube is used which is relatively large in relation to the bronchoscope, it may be difficult to cannulate the glottis, since the tip of the tube may hang up on the vocal cords or arytenoids. Furthermore, small flexible bronchoscopes may be damaged if they are used with larger endotracheal tubes. The 3.5-mm flexible bronchoscope should be used with tubes ranging in size from 4.5 to 6 mm in diameter, the 4.9mm flexible bronchoscope (standard adult size) with tubes larger than 6 mm, and ultrathin instruments for tubes 4.0 mm or smaller.
Thick Secretions
The suction channel of the 3.5-mm pediatric flexible bronchoscope (Olympus BF3C4/10/20) is only 1.2 mm in diameter, and thick secretions may obstruct the channel. Direct suctioning of the nose and pharynx with a catheter prior to insertion of the bronchoscope is helpful. Once in the lower airways, thick secretions must be manipulated with the bronchoscope. Small volume saline solution lavage (3 to 5 ml) may loosen secretions and facilitate their removal. However, mucous plugs may have the consistency of dry rubber cement; on rare occasions I have had to resort to a rigid bronchoscope for removal of extremely tenacious central mucus plugs. If the tip of the bronchoscope is placed onto the mucus plug and suction applied continuously, then the bronchoscope is slowly withdrawn, and the mucus plug may be removed from the airway along with the bronchoscope. I have often retrieved mucus plugs much larger in diameter than the bronchoscope itself in this fashion. If the patient is very small and is not ventilating well, this procedure must be completed within 30 s or so. Frequently, the mucous plug will dislodge itself from the suction channel, and another attempt must be made. As long as nothing is visible through the lens of the bronchoscope as it is being continuously withdrawn, there is mucus on the end of the instrument.
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Mucolytic agents (eg, N-acetylcysteine) can be instilled through the bronchoscope to facilitate bronchial toilet. However, solutions more concentrated than 1 percent are hypertonic and very irritating; large volumes should not be used.
