Abstract
Bronchoscopy is a powerful (and often underutilized) tool for the diagnosis and management of airway and pulmonary problems in infants and children. Both rigid and flexible instruments are available for diagnostic and/or therapeutic bronchoscopic procedures; each has special advantages and limitations, and in many patients, the use of both modalities may enable more effective and accurate assessment/treatment. This chapter reviews the instrumentation, indications, and techniques for bronchoscopy and for bronchoalveolar lavage, as well as anesthetic and airway management considerations. Special techniques for diagnostic and therapeutic interventions are reviewed. Bronchoscopy in children is not considered to be a high risk procedure, but it must be done carefully and thoughtfully, as the most serious complication, other than death of the patient, is cognitive—to have done the procedure and obtained the wrong answer.
Keywords
flexible bronchoscopy, rigid bronchoscopy, bronchoalveolar lavage, processing of bronchoalveolar lavage samples, anesthesia for bronchoscopy, indications for diagnostic bronchoscopy, contraindications for diagnostic bronchoscopy, complications of bronchoscopy, bronchial biopsy, bronchial brushing
Visualization of the interior of the body is often the most effective and efficient way to evaluate a patient’s problem. As an old Chinese proverb says, “A picture is worth a thousand words.” Advances in endoscopic techniques and instrumentation have greatly enhanced the pulmonary specialist’s ability to visualize the interior of the respiratory tract. This in turn has led to improvements in diagnosis and treatment.
Bronchoscopy—the visual examination of the airways—is usually performed for diagnostic purposes but is also useful for certain therapeutic maneuvers. Bronchoscopy may be performed with either rigid or flexible (fiberoptic) instruments depending on the particular needs of the patient and the skills and instrumentation available to the bronchoscopist. In general, most things that can be done with a rigid bronchoscope can be done with a flexible instrument and vice versa. However, there are some notable exceptions. For example, a rigid instrument cannot be passed around a curve into the apices of the lungs or very far into the peripheral bronchi, while a flexible instrument is quite unsuited for removal of aspirated foreign bodies from the lungs of children. For the most effective care of pediatric patients, both rigid and flexible instruments must be available, and there must be practitioners trained in the use of each type of instrument (although not necessarily the same person). In many patients, the combined use of both instruments may yield the most optimal result.
In addition to visualization, bronchoscopes also provide an effective means to obtain specimens from the lungs and airways. Tissue samples may be obtained by biopsy forceps, secretions can be aspirated from the airways, and bronchoalveolar lavage (BAL) yields samples of the fluid resident on the surfaces of the alveoli and distal airways. Bronchoscopy is primarily a clinical tool but is increasingly being used for investigational purposes as well. Although pediatric patients present special challenges (technical as well as ethical) to the investigative use of bronchoscopy, age alone is no contraindication to the use of bronchoscopy for research.
Bronchoscopy involves the examination of at least part of the upper airway as well as the trachea and bronchi; this is especially true with (and an advantage of) flexible instruments. Rigid bronchoscopes are generally passed through the patient’s mouth, while flexible bronchoscopes are generally passed through the patient’s nose. Bronchoscopes may also be used to examine just the upper airway, although the high incidence of concurrent upper and lower airway lesions makes it wise to examine both upper and lower airways unless there is a good reason not to do so.
Instrumentation
Rigid Bronchoscopes
The rigid (“open tube”) bronchoscope consists of a metal tube of appropriate diameter and length that is passed into the trachea and through which the operator may look and the patient may breathe. The instrument is not a simple metal tube; it is equipped to deliver anesthetic gasses and light to the distal tip.
The large open channel, through which instruments may be passed, is one of the major advantages of rigid bronchoscopes. However, visualization is challenging, especially when passing an instrument (such as a biopsy forceps). A major advance in bronchoscopic technique came with the development of the glass rod telescope. This device yields exceptionally fine optical performance, and various instruments such as biopsy and grasping forceps have been designed specifically to work with the telescopes. Rigid bronchoscopes have holes in the side along the distal tip to allow ventilation of the contralateral lung when the bronchoscope is advanced into one main-stem bronchus.
The rigid bronchoscope must be an appropriate size for the patient. Therefore, a variety of instruments must be available to the pediatric bronchoscopist ranging in diameters from 3 to 7 mm or larger and in length from 20 to 50 cm. There must be a full range of telescope lengths and diameters for the different bronchoscopes. In addition, glass rod telescopes may be made with a prism on the distal end to facilitate observation of the upper lobes (typically, 30, 70, or even 120 degrees).
Likewise, the auxiliary instruments (e.g., biopsy or grasping forceps) must match the telescopes and/or bronchoscopes. A large variety of forceps and other devices has been devised for specialized purposes. Perhaps the most valuable are the “optical forceps,” which are matched with a glass rod telescope and allow the bronchoscopist to operate the forceps under close and direct visualization.
The nomenclature of bronchoscope sizes can be confusing. In general, rigid instruments are defined by the diameter of the largest instrument that will pass through the bronchoscope, while flexible bronchoscopes are defined by their outer diameter. For example, a 3.5-mm flexible bronchoscope will easily pass through a “3.5-mm” rigid bronchoscope.
Flexible Bronchoscopes
The flexible bronchoscope is essentially a solid instrument composed of thousands of glass fibers that carry the light for illumination and the image. The tip of the instrument can be deflected to guide it into the desired path or location. Most flexible bronchoscopes have a small suction channel through which secretions may be aspirated, fluids may be delivered to the airways, or small flexible instruments may be passed.
The typical pediatric flexible bronchoscopes in use today are 2.8 mm in diameter and with a suction channel approximately 1.2 mm in diameter. Smaller instruments (2.2 mm) have no suction channel, and therefore have somewhat limited utility when there are secretions or blood in the airways; they also cannot be used to obtain diagnostic specimens. Larger instruments, ranging from 4.2 to 6.3 mm in diameter, are used in adults. These instruments have suction channels ranging from 2.0 to 3.2 mm in diameter.
In contrast to the rigid bronchoscope, through which the patient breathes (either spontaneously or by positive pressure); the flexible bronchoscope forces the patient to breathe around the instrument. Therefore, the instrument must be small enough not only to fit into the airway but also to allow the patient to breathe. Most infants as large as 1.5 kg can breathe spontaneously around the 2.8-mm bronchoscope, but great care must be taken to ensure the adequacy of ventilation during procedures.
Flexible bronchoscopes are quite limited in their capacity to accommodate instruments. The most common instruments used with flexible bronchoscopes are flexible biopsy forceps and cytology or microbiology brushes. Small grasping forceps and folding retrieval baskets are also available but have limited usefulness, especially in pediatric patients. Suctioning is done directly with the bronchoscope rather than by passing a device through the channel, as is the case with rigid bronchoscopes.
Flexible bronchoscopes are limited in their optical performance by the number of glass fibers, which conduct the image. While larger, adult-size instruments now mostly utilize a video chip at the working tip (and thus generate an image of much higher resolution), pediatric instruments, because of their small diameter, continue to rely on glass fibers to transmit the image. While the images obtained by flexible instruments are quite satisfactory for most clinical purposes, the glass rod telescopes and video scopes provide much greater resolution and image quality.
Care and Maintenance of Bronchoscopes
Bronchoscopy is not a sterile procedure, since the instruments pass through a nonsterile area (the nose or mouth). However, bronchoscopes and associated instruments must be cleaned and sterilized before use in a patient. Transmission of infectious agents from patient to patient due to inadequate cleaning or sterilization procedures has been well documented. In general, bronchoscopic equipment should be cleaned as soon as possible after use, as dried blood or mucus is much more difficult to remove and will prevent adequate sterilization by any method. At a minimum, the instruments should be flushed with water immediately after use and, if possible, soaked in an enzymatic detergent until formal cleaning can be done.
Rigid bronchoscopes are cleaned by vigorous brushing with detergent, followed by rinsing; they may be sterilized by steam autoclaving. Glass rod telescopes (unless specially marked) may not be exposed to steam, however, and must be sterilized with ethylene oxide or with liquid agents such as glutaraldehyde or peracetic acid.
Flexible bronchoscopes are cleaned by careful scrubbing of the exterior with a soft cloth and enzymatic detergent. The suction channel must be cleaned by multiple passes of an appropriate cleaning brush. Thorough rinsing is followed by high-level disinfection (with glutaraldehyde or peracetic acid) or sterilization (with ethylene oxide). Flexible bronchoscopes will melt in a steam autoclave…
The lenses of rigid telescopes and flexible bronchoscopes must be carefully scrubbed and polished with a soft cloth during cleaning. Otherwise, small amounts of protein left on the lens will accumulate over time, making the image progressively less satisfactory. Flexible bronchoscopes and glass rod telescopes are made of glass and are fragile (not to mention expensive). They must never be dropped and must not be subjected to forces that will cause breakage. Flexible bronchoscopes should never be passed through a patient’s mouth unless protected by a rigid bite block, since an endotracheal tube will not protect the bronchoscope from severe damage by teeth. The care with which instruments are cleaned and handled must match the care with which they are utilized in the patient’s airway. Individuals responsible for cleaning and preparing the instruments must be well trained and supervised.
Techniques for Bronchoscopy
Facilities for Bronchoscopy
It is important that bronchoscopy be performed in a suitable venue. Because of the need for general anesthesia, rigid bronchoscopy is almost always performed in an operating room. The relative ease with which flexible bronchoscopy can be done makes it tempting to use the instrument in unconventional places such as at the bedside or in an emergency room. However, while there are clearly circumstances in which such practice is justified, bronchoscopy is a serious procedure with the potential for lethal complications and should be performed only by physicians who are well trained, with the necessary cognitive and technical skills, and with full preparation for all contingencies. Therefore, a fully equipped and staffed endoscopy suite or operating room is the most appropriate venue. With suitable preparation, bronchoscopy (rigid or flexible) can be performed at the bedside in an intensive care unit, but this may still place the bronchoscopist at a disadvantage in terms of access to equipment and supplies in the event of difficulties. If bronchoscopy is performed in an intensive care unit, the bronchoscopist must take along everything that will possibly be needed and have it readily at hand.
Rigid Bronchoscopy
The appropriate rigid bronchoscope (length and diameter) is chosen for the patient. Under a satisfactory level of anesthesia, the patient is positioned supine with the shoulders supported and the head slightly extended. The larynx is exposed with a laryngoscope and the tip of the bronchoscope is gently advanced through the glottis and into the trachea. With the proximal end of the bronchoscope closed with a lens cap or with a telescope in place, the side port is attached to the anesthesia circuit, and the patient can be ventilated with positive pressure.
The bronchoscope is manipulated to visualize the tracheal and bronchial anatomy; the head and neck may be turned to help direct the bronchoscope into the right or left main bronchi. Telescopes greatly facilitate inspection and can be used in conjunction with a video camera. Angulated telescopes make it much easier to visualize the upper lobe segments. The telescope must be removed and cleaned if the lens becomes covered with secretions; suctioning is performed with a suction pipe or a suction catheter. During these times, ventilation is momentarily interrupted. It is also possible to work for extended periods with an open proximal end while maintaining ventilation with a Venturi jet injector.
When instrumentation is required, such as for the removal of a foreign body, the instruments may be passed through the open channel of the bronchoscope. Unfortunately, this significantly impairs the view of the operative site, as the instruments obstruct the line of vision. Optical forceps, which incorporate the glass rod telescope and allow direct visualization of the operative site, is the preferred instrument for biopsy and for foreign body extraction. Very small flexible forceps can also be passed through a side arm and alongside the telescope, but the tips of these instruments may be difficult to control.
In our practice, at Cincinnati Children’s Hospital, the vast majority of rigid bronchoscopic procedures (including foreign body removal) are performed using only the glass rod telescopes; the open tube sheath is employed in special circumstances. This technique requires that the patient breathe spontaneously, so anesthetic technique is critical, but it is much easier to evaluate airway dynamics. Because the overall size of the instruments is smaller, mechanical complications are less frequent.
Flexible Bronchoscopy
Most diagnostic procedures in pediatric patients can be performed with the standard 2.8 mm or 3.5-mm pediatric flexible instruments. In older children, a small “adult” instrument may be used (especially if a larger suction channel is needed); while in very small infants, it may be appropriate to use a 2.2-mm ultrathin bronchoscope. The patient is properly prepared for the procedure and positioned supine with the head and neck in a neutral position. It is also possible to perform flexible bronchoscopy in a sitting or some other position in special circumstances.
Flexible bronchoscopes are usually inserted transnasally. This avoids the potential for the patient to bite (and thus destroy) the instrument and also affords a view of the nasal and nasopharyngeal anatomy. Another advantage of this approach is that the bronchoscope does not contact the tongue; the tongue is a very powerful muscle and can readily move the bronchoscope in ways contrary to the intent of the bronchoscopist. A flexible bronchoscope may also be inserted orally if desired, always with a suitable bite block, even with the patient under general anesthesia, or through an artificial airway such as an endotracheal tube (with a bite block), a tracheostomy tube or a laryngeal mask airway (LMA).
The tip of the flexible bronchoscope can be flexed or extended in a single plane; movement to one side or another is accomplished by rotation. The instrument is directed to the site of interest by advancing the shaft while controlling the angulation and rotation at the tip. This combination of three simultaneous movements requires good hand-eye coordination on the part of the bronchoscopist. In contrast to glass rod telescopes, the image rotates as the instrument is rotated; this may produce disorientation on the part of operators unaccustomed to using flexible instruments. As the instrument is advanced through the airway, secretions may be removed by suctioning, and topical anesthetic can be applied, also through the suction channel.
The patient must be able to breathe around the instrument; most infants 3 kg or larger can breathe satisfactorily around the 3.5-mm pediatric flexible bronchoscope (infants larger than about 1.5 kg can usually breathe around the 2.8 mm instrument). Smaller infants will not be able to do so, and their procedures must be performed with an ultrathin instrument or with an apneic technique. If the patient is intubated, the bronchoscope must be small enough to readily pass through the tube ( Table 9.1 ).
| Instrument Diameter (mm) | Smallest Tube That Can Be Used (mm) a | Smallest Tube for Assisted Ventilation (mm) | Smallest Tube for Spontaneous Ventilation (mm) |
|---|---|---|---|
| 2.2 | 2.5 | 3.0 | 3.5 |
| 2.8 | 3.0 (not recommended) | 3.5 | 4.0 |
| 3.5 | 4.5 | 5.0 | 5.5 |
| 4.2 | 5.0 | 5.5 | 6.5 |
| 4.9 | 5.5 | 6.0 | 7.0 |
Flexible bronchoscopes are much smaller than rigid instruments (although the glass rod telescopes, if used alone, are equally small) and can be advanced much farther into the distal airways. Depending on the instrument used and the size of the patient, airways as small as 2 mm and as far as 14 to 16 generations from the carina may be inspected.
The instruments that can be passed through a flexible bronchoscope are quite limited, because of the small diameter of the suction channel (1.2 mm in pediatric instruments, 2.0 to 3.2 mm in “adult” instruments). Cup or “alligator” biopsy forceps, brushes, grasping forceps, expandable basket retrieval devices, balloon catheters (for dilation of stenoses), monopolar electrodes, and laser fibers are the most common such instruments.
Anesthesia for Bronchoscopy
Safe and effective bronchoscopy requires that the patient be comfortable and reasonably still during the procedure. Adequate oxygenation and ventilation must be maintained, and the patient must be carefully and continuously monitored. These criteria can be met with either general anesthesia (administered by an anesthesiologist) or with sedation (usually performed by the intravenous administration of a narcotic and/or a benzodiazepine, and administered by the bronchoscopist or sedation nurse) depending on the individual child’s situation and the procedure planned. Sedation and general anesthesia are merely points on a continuum between the fully awake state and surgical anesthesia; it matters little how the desired, safe state is achieved. Deep sedation and light “general anesthesia” are virtually indistinguishable. An advantage of general anesthesia is that an anesthesiologist takes full responsibility for monitoring the patient. Current practice guidelines for sedation mandate the presence of a trained individual whose sole responsibility is to monitor the patient, although this person does not have to be an anesthesiologist. Our current practice at Cincinnati Children’s Hospital is to utilize an anesthesiologist, and the child is sedated with general anesthetic agents (inhaled or given intravenously) to a point that maintains spontaneous breathing but ensures safe comfort. A significant advantage of using “general anesthetic” agents for sedation is rapid induction and relatively rapid emergence, as well as the ability to quickly change the degree of sedation (and therefore respiratory effort) during the procedure.
Sedation and anesthesia diminish or abolish protective reflexes. To reduce the risk for aspiration of gastric contents, patients should be given nothing by mouth for several hours prior to the procedure. Clear liquids may be given up to 2 hours before the procedure. It is prudent to aspirate the stomach with a catheter before proceeding with the bronchoscopy. Young infants may become dehydrated or hypoglycemic if kept NPO for too long, and intravenous fluid may be necessary prior to a procedure.
When general anesthesia is utilized for diagnostic bronchoscopy, careful attention must be given to airway dynamics. If the patient does not breathe spontaneously, then the usual airway dynamics are reversed—airway pressure during inspiration exceeds that during expiration. This may result in diagnostic confusion in patients with tracheomalacia and/or bronchomalacia. During therapeutic procedures, deeper anesthesia and positive-pressure ventilation are often utilized.
Flexible bronchoscopes are small enough that the patient can usually breathe around them. Spontaneous breathing is the rule for most flexible procedures. Oxygen can be supplied through an oral airway or a mask. Many practitioners routinely utilize an LMA; this, while providing a secure airway, requires deeper sedation, eliminates the ability to evaluate the anatomy and dynamics of the upper airway, and may mask tracheomalacia or bronchomalacia. It is therefore not recommended as a routine practice.
Sedation, similar to general anesthesia, may be produced by a variety of agents and techniques. Important principles of sedation include careful preparation of the patient, the use of fractional doses of relatively short acting agents with titration of total dose to the needed effect, appropriate monitoring before, during, and after the procedure, and careful selection of agents.
Sedative/anesthetic agents have a variety of physiologic effects in addition to reducing the level of consciousness. The most important of these is depression of respiratory drive, and this effect may last longer than the sedation. Children who have undergone sedation for procedures may be at greater risk after the procedure is completed than during the procedure itself, as there is no longer the stimulation of the procedure, and staff awareness and alertness may be diminished. Effective monitoring must be continued until all the effects of sedation have resolved.
Pharmacologic agents to reverse the effect of narcotics and benzodiazepines are available, and some physicians have utilized these agents routinely at the completion of procedures. This is not necessarily a good idea, however, as their effect is considerably shorter than the respiratory depression induced by the sedative agents. Furthermore, patients awakened abruptly from sedation are often disturbed and may become combative. Monitoring must be continued regardless of whether a reversal agent has been given; indeed, it may be argued that monitoring must be continued longer after reversal than without it. On the other hand, such agents should always be readily available in the event of serious respiratory depression.
Sedation—no matter how administered—involves more than giving drugs. Children are often very responsive to suggestion—whether positive or negative, whether intentional or inadvertent. Simple distraction or more formal methods of focusing attention on something other than the procedure may be surprisingly effective in children, especially in the 3- to 8-year age group. Even infants respond to tone of voice and the atmosphere around them. Careful preparation of the child and the parents, focusing on positive aspects and creating positive expectations can be powerful adjuncts to chemical sedation. On the other hand, negative suggestions can make even the most powerful drugs less effective. A screaming, upset child will require much higher doses of virtually any agent to achieve effective sedation, and that child’s recovery will be prolonged. For this reason, presedation with oral drugs such as midazolam and careful attention to atmosphere and language can often facilitate deeper sedation with minimal doses of other agents.
Airway management during bronchoscopy can be a challenge. The anesthesiologist must understand the goals of the procedure and enable the bronchoscopist to accurately evaluate not only the anatomy, but also the dynamics of the upper and lower airways. During evaluation of the upper airway, it is best to have a native airway with no devices or support, as in many pediatric patients, the diagnostic finding of most interest is dynamic obstruction of the upper airway. Once this has been evaluated, an oral airway can be placed to secure the upper airway, and oxygen and anesthetic gas can be delivered through an endotracheal tube inserted into the oral airway ( Fig. 9.1 ). After the tracheal and bronchial dynamics have been evaluated, then if necessary, the bronchoscope can be removed and an LMA or endotracheal tube can be used for the remainder of the procedure.
Indications for Diagnostic Bronchoscopy
It is difficult to categorize the indications for diagnostic bronchoscopy without a great deal of overlap. In a given situation, there is often more than one indication for bronchoscopy (for example, a child with recurrent pneumonia may also be suspected of aspiration). In general, however, one may utilize a bronchoscope to define airway anatomy and airway dynamics, and to obtain specimens for further diagnostic study. The diagnostic result of a particular procedure may include anatomic findings, definition of airway dynamics, and the results of microbiologic and/or microscopic evaluation of specimens obtained during the procedure. Bronchoscopy performed for diagnostic purposes may also have therapeutic benefit, such as the removal of a mucus plug causing atelectasis.
It should be noted that there is often great value in a normal bronchoscopic examination; the definitive exclusion of suspected problems (such as foreign body aspiration, for example) may be as important as a specific diagnostic finding. Bronchoscopy (rather than simple laryngoscopy) is often performed in patients in whom the suspected lesion is in the upper airway. Since effective laryngoscopy in children usually requires sedation and laryngeal anesthesia, it adds very little to the risk of the procedure to continue the examination into the lower airways. Unsuspected lesions in the lower airways are not uncommonly found, even in patients in whom significant pathology, explaining the patient’s symptoms, is seen at or above the glottis.
Airway obstruction is one of the most common general indications for diagnostic bronchoscopy, and may involve the upper or lower airways or both. The extent of anatomic obstruction, especially fixed obstruction in the subglottic space, is often much greater than would be suspected from clinical examination. If a patient is stridulous during the examination, the vibrating structures causing the noise will always be visible, if one is looking in the right place.
Imaging techniques, such as CT or MRI scans, can yield considerable diagnostic information about the lungs and airways. In some cases, such techniques may make bronchoscopy unnecessary. However, imaging studies are quite limited and cannot provide specimens or (in most cases) adequately define abnormal airway dynamics. In general, radiologic studies should be performed prior to bronchoscopy, as it may be important to direct the focus of the bronchoscopy (e.g., BAL site) to a specific region of the lungs. In general, there is only one indication for diagnostic bronchoscopy—there is information in the lungs or airways necessary to the care of the patient, which is best obtained by bronchoscopy ( Table 9.2 ).
| Indication | Rigid Instruments | Flexible Instruments |
|---|---|---|
| Stridor | May alter airway dynamics | Preferred |
| Persistent wheeze (not responsive, or poorly responsive to bronchodilator therapy) | Preferred | |
| Atelectasis (persistent, recurrent, or massive) | May be needed to remove airway obstruction | |
| Localized hyperinflation | Preferred | |
Pneumonia
(e.g., immunocompromised patients) | Preferred (much better to obtain BAL specimens) | |
| Hemoptysis | May be best if there is brisk bleeding | Preferred to evaluate distal airways |
Foreign body aspiration
| Mandatory for removal of foreign bodies | May be useful to examine for the possibility of foreign body; rarely useful for removal |
| Cough (persistent) | Preferred | |
| Suspected aspiration | Preferred to evaluate posterior larynx and cervical trachea | Preferred to obtain BAL |
| Evaluation of patients with tracheostomies | Preferred to evaluate posterior larynx and subglottic space | Preferred to evaluate tube position and airway dynamics |
| Suspected mass or tumor | Preferred for laryngeal or tracheal lesions | Preferred for lesions in distal airways |
| Suspected airway anomalies | ||
| Complications of artificial airways |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
