Rigid Bronchoscopy

The initial bronchoscope, developed by Killian and further optimized by Chevalier Jackson, was a rigid metal tube that permitted either spontaneous or mechanical ventilation. Over the decades, rigid bronchoscopes of various lengths and sizes that are adaptable for diverse applications in children and adults have become available. Although the flexible bronchoscope has to a large extent replaced the rigid scope for most diagnostic and some therapeutic indications, rigid bronchoscopy still has vital therapeutic applications.

Both rigid and flexible modern systems are equipped with optic capabilities for airway observation alone. With the rigid scope, various types of telescopic rods, equipped with circumferential illumination, permit direct and magnified visualization (Figure 11-1). Specially designed telescopes allow viewing not only directly forward but also at oblique and lateral angles. Various diagnostic and therapeutic instruments can be inserted through the rigid scope while the patient remains ventilated. Rigid bronchoscopy allows a number of therapies such as laser photoresection, endobronchial stents, balloon dilation, electrocautery, argon beam coagulation, and cryotherapy to be performed safely and effectively. Perhaps most important, a rigid scope can be used to “core out” large bulky airway tumors and to dilate central airway strictures and areas of stenosis very effectively and efficiently. In addition, the rigid bronchoscope also can be used for the passage of a flexible scope, which may be necessary for dealing with tortuous airways or distal lesions.

Figure 11-1 A typical rigid bronchoscope (middle) with Hopkins rod rigid telescope (top) and optical biopsy forceps (bottom).

(Courtesy John Beamis, MD.)

Flexible Bronchoscopy

The flexible scope is used in most bronchoscopic procedures. Although initial flexible bronchoscopes used fiberoptic systems, most such instruments now use a charge-coupled device (CCD) camera at the tip that allows transmission of digital images to a monitor. The main advantages of flexible scopes include their ease of manipulation and greater flexibility, allowing a more complete tracheobronchial tree evaluation than with rigid bronchoscopy, and a less challenging path to expertise, permitting more rapid acquisition of skills (favorable learning curve), for use of these devices (Figure 11-2).

Figure 11-2 Flexible bronchoscope. The flexible distal tip permits easy maneuverability in all lobar and segmental bronchi.

(Courtesy Olympus Corporation of the Americas, Center Valley, Pennsylvania.)

Flexible scopes vary in size, ranging from ultrathin devices allowing for endoscopy in infants and neonates to larger, adult-sized therapeutic scopes. The working channel of the bronchoscope can be used for aspiration of secretions and to accommodate various diagnostic or therapeutic accessories. Four main diagnostic tools have been developed for use during bronchoscopy in order to obtain diagnostic material: bronchoalveolar lavage (BAL), brushings, forceps biopsy, and needle aspiration (Figure 11-3). Since the inception of bronchoscopy more than 100 years ago, these diagnostic modalities have been hampered by limited ability to ensure direct localization of pulmonary nodules, masses, infiltrates, or lymph nodes. However, recent technologic developments in navigational technology and endoscopic ultrasound imaging have improved the ability to localize these lesions, to obtain diagnostic tissue, and to prevent unnecessary surgical intervention. The use of endobronchial ultrasound probes is discussed in Chapter 12.

Figure 11-3 Bronchoscopy brushes (A), needles (B), and biopsy forceps (C) are available in various sizes and types. B, Biopsy needles shown are the standard 21 G aspiration needle (top), and needle with side port (bottom), allowing for cell collection from the side and tip of the needle. C, Biopsy forceps shown (top to bottom) are alligator-jaw, alligator-jaw with needle, elongated, and standard cup forceps.

(Courtesy Olympus Corporation of the Americas, Center Valley, Pennsylvania.)

Biopsy forceps are available in various sizes and may have smooth or serrated edges. In some models, a small central needle is present between the cups for anchoring and stabilization. Smooth cup edges also may reduce tissue trauma and the concomitant bleeding risk. Lesions not accessible to direct forceps biopsy can be approached with a bronchial brush. This device consists of a rigid central wire surrounded by bristles of various size and shape. Repeated brush movement against the adjacent tissue produces minor trauma but enables collection of cellular specimens for cytologic or microbiologic analysis. Uncontaminated specimens from the lower respiratory tract can be collected with a brush protected by an additional sheath and tip. Needles of various sizes can be used to obtain both cytologic and histologic material from transbronchial lesions (e.g., lymph nodes, mediastinal masses) or from endobronchial and submucosal lesions.

Patient Preparation and Monitoring during Bronchoscopy

All patients undergoing bronchoscopy should undergo a complete prebronchoscopy evaluation, including a medical history, physical examination, and chest imaging (Box 11-1). Although routine laboratory tests are not required, each evaluation should be individualized on the basis of patients’ underlying conditions and the diagnostic and therapeutic procedures planned.

Most flexible bronchoscopy procedures are performed after patient sedation with any of a variety of pharmacologic agents. Most frequently, a combination of a short-acting benzodiazepine (e.g., midazolam) and a narcotic agent (e.g., fentanyl) are used for bronchoscopic sedation. Local anesthesia of the upper airway, larynx, and tracheobronchial tree is achieved with inhaled or bronchoscopically instilled lidocaine. Although rigid bronchoscopy initially was performed with use of minimal anesthesia and later with the patient under general anesthesia, the recent trend has been to perform the procedure with patients either breathing spontaneously or ventilated with a jet ventilator, often under total intravenous anesthesia (TIVA) with agents such as propofol and remifentanil. With appropriate monitoring, good oxygenation and adequate ventilation can be ensured.

Success of bronchoscopy, whether diagnostic or therapeutic, depends in large part on proper preparation of the patient, including relief of anxiety, muscle relaxation, cough suppression, and adequate anesthesia. Time spent in achieving these goals will be justified in reducing the complication risk and in increasing the ease of procedural performance.

Technique

The flexible bronchoscope usually is inserted nasally, orally, or through an endotracheal tube or a tracheotomy stoma. When necessary, it also can be inserted through a rigid bronchoscope. The nasal route often is preferred because the nasal passage often provides some resistance against the scope and allows for somewhat better control during airway inspection. When the oral route is used, a “bite block” should be inserted to prevent the patient from biting and damaging the scope. Supplemental oxygen should be administered to prevent hypoxemia, which is fairly common during bronchoscopy, particularly in patients with underlying lung disease.

The bronchoscopic evaluation should begin with a thorough examination of the upper airway, as well as assessment of the integrity and function of the larynx. The vocal cords should be examined for any abnormalities, such as polyps or tumors, and evaluated for paralysis during phonation.

Once the upper airway inspection is completed, a systematic evaluation of the lower respiratory tract should be performed, beginning with an evaluation of the trachea and then all segmental bronchi. Airway integrity should be assessed including thorough evaluation of the mucosal and delineation of carinal size and shape for any abnormalities with special attention paid to changes in dynamic airway caliber during either relaxed breathing or forced expiration and coughing.

It is important to distinguish among normal anatomy, anatomic variations without clinical significance, and frankly pathologic conditions. These considerations have important implications regarding potential diagnostic and therapeutic approaches. For example, an abnormal branching of a bronchus may be of no clinical significance. On the other hand, such an abnormality could explain frequent infections caused by impaired ventilation and drainage of the affected area. Bronchoscopy is particularly useful in documenting posttraumatic or postsurgical changes in bronchial integrity, such as bronchial rupture, tracheoesophageal or bronchopleural fistulas, or anastomotic complications after reconstructive or lung transplantation surgery. Similarly, bronchoscopy can be used to document tracheal injuries occurring in critically ill patients after prolonged intubation or tracheostomy. Although tracheal injuries have decreased in incidence over the past decade, tracheal stenosis, tracheomalacia, and tracheoinnominate artery fistula are still clinically important complications that must be considered and identified. Complications specific to the use of percutaneous tracheotomy include protrusion of ruptured cartilage into the tracheal lumen and extraluminal tracheostomy tube placement.

A thorough evaluation of the mucosal surface is an important part of the bronchoscopic examination. The most common abnormality is a change in mucosal coloration, with prominent hypervascular areas seen in patients with chronic bronchitis. The presence of granulation tissue can be due to reaction to a foreign body. Inflammatory mucosal reactions, although not very characteristic, should raise the possibility of mycobacterial infection, nonspecific viral and nonviral infections, and other granulomatous diseases, such as sarcoidosis (Figure 11-4). Mucosal ulcerations are more characteristic of Wegener granulomatosis or malignancy. Loss of the usual mucosal luster and presence of a roughened surface may be early signs of an infiltrative or neoplastic process.

Figure 11-4 Endobronchial sarcoidosis. Bronchoscopy demonstrates edematous airways with a “cobblestone” appearance, often seen in endobronchial sarcoidosis.

(Courtesy Meeta Prasad, MD.)

The trachea and bronchi are surrounded by mediastinal and parenchymal structures. Developmental or pathologic changes in these organs may be noted during bronchoscopic evaluation. An enlarged goiter or thymus can compress upper airways, resulting in airflow obstruction. Lymphadenopathy may produce structural changes, including widening of the main carina caused by subcarinal involvement, and compression of other bronchi—as, for example, in the right middle lobe syndrome. Peribronchial calcified lymph nodes may erode through the bronchial wall, resulting in broncholith formation. Such lesions are potential sources of obstruction, infection, or hemoptysis.

After the bronchoscopic inspection of the airways and surrounding structures has been performed, appropriate samplings should be obtained from the abnormalities identified. Aspirated secretions can be sent for microbiology cultures to determine the offending organism in cases of infection or suspected infection. Endobronchial lesions can be sampled with cytology brushes, biopsy forceps, or needles. Bronchoscopic lung biopsy can be performed for either focal abnormalities or diffuse lung diseases (Figure 11-5). For small or focal lesions, fluoroscopy helps guide peripheral forceps placement and improves the diagnostic yield of biopsies for focal lesions. The use of fluoroscopy also may obviate the need for routine chest radiography after transbronchoscopic lung biopsy. In the case of diffuse lung disease, such as sarcoidosis, use of fluoroscopy has not been demonstrated to improve the diagnostic yield of transbronchial biopsies. Fluoroscopy is useful, however, in providing information regarding the proximity of the forceps to the pleura and in more rapidly establishing the diagnosis of complications (e.g., pneumothorax). Transbronchoscopic needle aspiration (TBNA) and biopsy (TBNB) permit sampling of peribronchial lymph nodes. These transbronchial approaches provide cost-effective diagnostic modalities with less risk and a lower complication rate than with mediastinoscopy (see Chapter 17).

Figure 11-5 The mechanism by which bronchoscopic lung biopsy is obtained. The biopsy forceps pinches off the lung tissue located between two branches of terminal bronchi.

Bronchoalveolar lavage (BAL) is a useful and generally well-tolerated bronchoscopic sampling technique (Figure 11-6). BAL is safe, even in critically ill patients, when biopsy or brushing methods are not recommended because of bleeding risk. Normal saline solution, devoid of any bacteriostatic material, is instilled into distal air spaces through the “wedged” flexible scope and then aspirated through the instrument’s suction channel or from a sterile trap. The fluid collected can be analyzed for gross appearance to detect possible alveolar hemorrhage. The fluid also may be subjected to a variety of tests, depending on the clinical circumstances: microbiologic testing, specific cytologic analysis and cell count, immunologic parameters, presence of various biochemical mediators related to pathologic processes, tissue markers, polymerase chain reaction (PCR) assay, electron microscopy, flow cytometry, and DNA probes. The diagnostic yield of BAL very much depends on specific patient characteristics, the underlying pathologic process, and technical factors.

Figure 11-6 Bronchoalveolar lavage (BAL) is performed by wedging the tip of the flexible bronchoscope in the segmental bronchus leading to the parenchymal abnormalities detected by imaging techniques. Normal saline, 100 to 150 mL, in aliquots of 10 to 50 mL, is instilled through the bronchoscope channel and suctioned back into a container for analysis.

Chronic Cough

Chronic cough remains one of the most common reasons for patients to seek medical attention. Although flexible bronchoscopy frequently is used in the evaluation of chronic cough, its role has not been clearly defined, particularly in patients without other indications for the procedure. The routine use of bronchoscopy for investigation of chronic cough has a diagnostic yield of less than 5%. When chronic cough is associated with localizing signs and symptoms, such as hemoptysis, a focal wheeze, or abnormalities on an imaging study, a specific diagnosis by bronchoscopy is much more likely. In nonsmokers with normal findings on chest imaging, the most likely causes of cough are asthma, gastroesophageal reflux disease, and rhinitis. Bronchoscopy can be considered if these etiologic entities have been effectively ruled out by a combination of empirical treatment and diagnostic testing, including the use of spirometry, bronchoprovocation tests, sinus imaging, and esophageal pH probes.

Hemoptysis

Hemoptysis is a common clinical sign and one of the most frequent indications for bronchoscopic evaluation. The most common causes of scant hemoptysis include chronic bronchitis, tuberculosis, and bronchiectasis, whereas massive hemoptysis, usually defined as bleeding greater than 200 mL in a 24-hour period, most often is due to tuberculous cavities, lung cancer, mycetomas, or lung abscess (see Chapter 24). Bronchoscopy can be of help in localizing the site and cause of bleeding. Although the timing of the procedure should be dictated by clinical circumstances, studies have shown that early bronchoscopy (within 48 hours) is more likely to demonstrate active bleeding and allow for the determination of the bleeding site. Chest imaging, with either chest radiograph or computed tomography (CT) scan, can assist in bleeding site localization and, in stable patients without massive hemoptysis, should precede bronchoscopy. In patients with a normal appearance on the chest film, the prevalence of malignancy is approximately 5%, which in most cases is visible by CT scan. The yield of bronchoscopy in patients with normal findings on CT scan is extremely low, and a conservative approach consisting of observation and serial imaging should be considered. Beyond its role as a diagnostic tool, bronchoscopy often can be used to perform various therapeutic procedures in patients experiencing hemoptysis (see further on).

Pulmonary Infections

Bronchoscopy is a useful technique in the diagnosis of pulmonary infections, allowing for the collection of respiratory samples for evaluation with special stains and culture. Respiratory samples can be collected by one or more techniques, including bronchial washing, BAL, protected specimen brushing (PSB), bronchoscopic lung biopsy, and TBNA (Table 11-1).

Table 11-1 Bronchoscopic Techniques and Applications in Respiratory Infections

Bronchoscopy is not indicated for the diagnosis of community-acquired pneumonia, which is currently treated empirically with appropriate antibiotic therapy. Bronchoscopy is likely to be useful in cases of nonresolving pneumonia, ventilator-associated pneumonia (VAP), or new infiltrates in immunocompromised patients. Nonresolving pneumonia is defined as lack of improvement or worsening of symptoms despite a minimum of 10 days of antibiotic therapy or failure of radiographic abnormalities to resolve after 2 to 3 months. The causes of nonresolving pneumonia are myriad and include inadequate antibiotic therapy, resistant or highly virulent organisms, impaired host defenses, obstructing endobronchial lesions, or a noninfectious cause. Although controversial, bronchoscopy should be considered in these patients.

Mycobacterial Infections

In cases in which pulmonary tuberculosis is suspected, the initial diagnostic evaluation should consist of serial examination of sputum for the presence of acid-fast bacilli (AFB) in stained smears. Ideally, induced sputum samples should be obtained. If sputum study results are negative and tuberculosis is still suspected, bronchoscopy with BAL and biopsy should be performed. Both induced sputum collection and bronchoscopy should be performed with appropriate infection control precautions to minimize the risk of nosocomial transmission. A bronchoscopy may cause the patient to produce sputum for several days afterwards; these specimens also should be collected and analyzed, if possible. The utility of bronchoscopy varies widely in the literature, with reported diagnostic yields of 50% to 95%. The yield in patients with miliary tuberculosis, in whom sputum smears frequently are negative, is approximately 70%. Bronchoscopy also is useful in tuberculosis manifesting as an endobronchial lesion or with mediastinal and hilar adenopathy, in which case diagnostic tissue can be obtained with TBNA (Figure 11-7). The yield of diagnostic procedures, including bronchoscopy, can be expected to improve as newer interferon release assays and nucleic acid amplification techniques are incorporated into everyday practice (see Chapter 31).

Figure 11-7 Endobronchial tuberculosis involving distal trachea and main bronchi. Image on the left was obtained before chemotherapy; the posttherapy appearance is shown in image on the right. Endobronchial tuberculosis is commonly mistaken for bronchogenic carcinoma.

Bronchogenic Carcinoma

Diagnosis

Bronchoscopy most commonly is performed in the evaluation of patients with suspected lung cancer. It remains the most commonly used modality for the diagnosis of bronchogenic carcinoma and plays an important role in staging of the disease as well. Centrally located lesions generally can be approached using flexible bronchoscopy with minimal risk. Bronchogenic carcinoma of the central airways can manifest as exophytic mass lesions with partial or total bronchial lumen occlusion, as peribronchial tumors with extrinsic compression of the airway, as submucosal tumor infiltration, or as some combination of these entities. The mucosal abnormalities seen with peribronchial tumors or with submucosal infiltration often are subtle—the airways should be examined closely for characteristic changes such as erythema, loss of bronchial markings, and nodularity of the mucosal surface.

Central lesions usually are sampled with a combination of bronchial washes, bronchial brushings, and endobronchial biopsies. The yield of endobronchial biopsy is highest for exophytic lesions, with a diagnostic yield of approximately 80%. Attempts should be made to obtain the biopsy specimens from areas of the lesion that seem viable. Endobronchial needle aspiration (EBNA) to obtain a “core” biopsy from centrally located tumors should be considered, particularly if the lesion appears necrotic. For submucosal lesions, EBNA can be performed by inserting the needle into the submucosal plane at an oblique angle, and in patients with peribronchial disease causing extrinsic compression, the needle should be passed through the bronchial wall into the lesion. For all of these indications, EBNA has been shown to increase the diagnostic yield of conventional sampling methods.

Peripheral lesions usually are sampled with a combination of bronchial wash, brushes, transbronchial biopsy, and TBNA. The diagnostic yield of bronchoscopy for peripheral lesions depends on a number of factors, including lesion size, the distance of the lesion from the central airways, and the relationship between the lesion and bronchus. The yield of bronchoscopy for lesions smaller than 3 cm varies, ranging from 14% to 50%, compared with a diagnostic yield of 46% to 80% when the lesion is larger than 3 cm. The presence of a bronchus sign on chest CT predicts a much higher yield of bronchoscopy for peripheral lung lesions. In these cases, fluoroscopic guidance should be used to ensure proper positioning of the diagnostic accessory (Figure 11-8).

Figure 11-8 Bronchoscopic lung biopsy with fluoroscopic guidance. Fluoroscopy assists in the placement of the diagnostic accessory for investigation of small or focal lesions and improves the diagnostic yield.

Several newer methods have been developed for the evaluation of peripheral lung lesions, including endobronchial ultrasound (EBUS) imaging (see Chapter 12) and navigational bronchoscopy. The first U.S. Food and Drug Administration (FDA)-approved navigational system, the Electromagnetic Navigation Bronchoscopy (EMN) system (InReach System, SuperDimension, Inc., Minneapolis, Minnesota), uses an electromagnetic board to generate a magnetic field around the patient, a magnetic sensor probe, an extended working channel, and three-dimensional integration of CT scan reconstruction and flexible bronchoscope position (Figure 11-9). In essence, this navigational system works on the same triangulation principle as for a global positioning system and allows the bronchoscopist to direct the flexible scope through the airways to the target. Several studies have demonstrated EMN diagnostic sensitivity to range between 67% and 74%, independent of lesion size. Studies also show improved diagnostic yield with the combination of EMN with mini-ultrasound probes for sampling of small peripheral lesions. Beyond standard diagnostic utilization, novel navigational applications have been demonstrated in targeted therapeutic delivery, such as EMN-guided stereotactic radiosurgery fiducial placement or implantation of radiotherapy monitoring devices.

Figure 11-9 Electromagnetic Navigation Bronchoscopy (ENB) system: Representative images obtained at bronchoscopy performed using electromagnetic guidance. The parenchymal lesion is visible in sagittal, coronal, and axial views.

(Courtesy SuperDimension, Inc., Minneapolis, Minnesota.)

Several new navigational bronchoscopy systems have recently been introduced (LungPoint System, Broncus Technologies, Mountain View, California; SPiN Drive System, Veran Medical Technologies, St. Louis, Missouri; Bf-NAVI, Cybernet Systems, Tokyo, Japan). With LungPoint and Bf-NAVI, virtual bronchoscopic images are displayed adjacent to the actual procedural video, allowing an electronic pathway to be overlaid onto the endoscopic image. An image of the target lesion can be overlaid on the virtual bronchoscopy and actual video images for localization during biopsy.

Navigational bronchoscopy systems may be limited in general application by their high capital cost and training necessary for optimal utilization. These newer navigational technologies have not yet been rigorously evaluated but appear to offer improvements in diagnostic yield beyond that attainable with standard approaches. The lack of randomized, comparative studies with this technology raises concerns about its role relative to traditional or ultrasound-guided approaches.

Staging

Bronchoscopy is an important modality for establishing lung cancer stage. In patients with potentially resectable tumors, a thorough airway examination helps confirm the absence of a concomitant, radiographically occult lesion. For lesions that involve the central airways, it is important to document the extent of disease and the degree of involvement of “mainstem” bronchi and main carina.

TBNA has emerged as a valuable tool for the investigation of enlarged or metabolically active mediastinal lymph nodes (Figure 11-10). The procedure is particularly useful for evaluation of patients who are marginal or poor surgical candidates; in these patients, more invasive approaches, such as mediastinoscopy or mediastinotomy, may be obviated. TBNA has proved particularly useful with the use of rapid onsite evaluation (ROSE), whereby a cytopathologist working in or near the bronchoscopy suite can evaluate obtained specimens in real time (see Chapter 14).

Figure 11-10 Transbronchial needle aspiration (TBNA) of a precarinal lymph node.

Several precautions should be observed during the performance of TBNA to minimize the risk of false-positive results. The bronchoscope should be introduced into the bronchial tree without suction, and TBNA should be performed before distal airway inspection and before any other sampling procedures. N3 nodes should be sampled first, followed by N2 and N1 nodes.

Because of a relatively high false-negative rate (approximately 25%), a negative result with standard TBNA should prompt consideration of more invasive staging methods (i.e., mediastinoscopy). A positive result on TBNA is more likely with significant adenopathy on CT scanning, endoscopically visible tumors, subcarinal lymph nodes larger than 2 cm in diameter, or an abnormal-appearing carina. The use of image guidance with TBNA, such as ENB or EBUS, is promising and may provide higher diagnostic yields. This is particularly true of EBUS-TBNA.

Diffuse Lung Diseases

A wide range of acute and chronic pulmonary disorders are capable of causing diffuse interstitial lung diseases with more than 150 distinct clinical entities. These processes include infection, neoplasm, pulmonary edema, alveolar hemorrhage, alveolar proteinosis, occupational lung diseases, drug-induced disease, and various types of interstitial lung disease. In general, patients with diffuse lung disease should undergo high-resolution CT (HRCT) scanning, which helps to narrow the differential diagnosis and in some cases is virtually diagnostic of certain disorders. In many cases, it is still necessary to obtain samples for cytologic and histologic evaluation to confirm a specific diagnosis and to help exclude other possible disorders.

The most common bronchoscopic procedures used to help establish the diagnosis in diffuse lung disease are BAL and bronchoscopic lung biopsy. The findings on HRCT can be used to determine the best location for BAL or lung biopsy. In truly diffuse disease, the right middle lobe and the lingula are the best locations for BAL; with these sites, ease of access and good fluid retrieval are typical. BAL should be performed using a total of 100 to 200 mL of saline instilled in multiple aliquots. It is important to obtain a reasonable sampling of the alveolar spaces for the necessary cellular analysis.

Certain findings on BAL can be suggestive or virtually diagnostic of a number of interstitial lung diseases (Table 11-2). It is important that the BAL findings be correlated with the clinical and HRCT findings. For example, specific characteristics of the freshly retrieved lavage fluid can support the diagnosis of alveolar hemorrhage, pulmonary alveolar proteinosis, microlithiasis, or lipid aspiration. In patients with suspected eosinophilic pneumonia, a high eosinophil count is diagnostic, and in cases of pulmonary Langerhans cell histiocytosis, BAL flow cytometry should be performed to evaluate for CD1at cells.

Table 11-2 Bronchoalveolar Lavage (BAL) in Diffuse Interstitial Disease

DIP, diffuse interstitial pneumonia; PAS, periodic acid–Schiff; RBCs, red blood cells; RBILD, respiratory bronchiolitis–associated interstitial lung disease.

In a number of disorders, BAL findings may be suggestive, but additional diagnostic procedures probably will be required. Such diseases include sarcoidosis, hypersensitivity pneumonitis, and organizing pneumonia. Bronchoscopic lung biopsy should be considered in situations in which the diagnosis has not been established by HRCT and BAL. In many situations, bronchoscopic lung biopsy can establish the diagnosis and avoid the need for surgical lung biopsy (Box 11-4). For example, with pulmonary sarcoidosis, the diagnosis usually is established by a combination of BAL and biopsy findings. The BAL can be used to exclude the presence of tuberculosis and fungal infections and can demonstrate the characteristic high CD4⁺/CD8⁺ ratio seen in sarcoidosis, whereas bronchoscopic biopsy specimens may demonstrate the classic finding of noncaseating granulomas. In general, bronchoscopic biopsy should be performed in several affected areas, and at least five or six specimens should be taken. The sensitivity for diagnosis of sarcoidosis is only approximately 60% to 70%, and many patients require further invasive testing, such as surgical lung biopsy. Recently, the use of EBUS-TBNA has been extended to the diagnosis of sarcoidosis, especially in patients with mediastinal and hilar adenopathy. The addition of TBNA to transbronchial biopsy can provide the diagnosis in more than 85% of sarcoidosis cases.

Bronchoscopy has a limited role in the diagnosis of idiopathic pulmonary fibrosis (IPF). A nonspecific increase in levels of neutrophils, eosinophils, and, less commonly, lymphocytes has been documented in BAL fluid. Bronchoscopic biopsy is limited by the small size of the specimen obtained and the lack of histologic preservation because of mechanical crushing of the tissue. In the cases in which the diagnosis of IPF is probable or definite on the basis of clinical and HRCT criteria, bronchoscopy (and surgical lung biopsy) is not required. In situations in which the HRCT findings are “nondiagnostic,” bronchoscopy should be considered to evaluate for the presence of other potential etiologic disorders. If the specific diagnosis cannot be established on the basis of BAL and bronchoscopic biopsy findings, surgical lung biopsy should be considered.

Anesthesia and Related Blood Gas Abnormalities

The major complications of diagnostic bronchoscopy include respiratory depression, hypoventilation, hypotension, and syncope. Risk is significantly increased among elderly persons and in patients with serious concomitant illnesses, including cardiovascular disease, chronic pulmonary disease, renal and hepatic dysfunction, seizures, and altered mental status. In patients with underlying organ dysfunction, doses of sedative agents and topical anesthetics should be adjusted as appropriate. Conscious sedation techniques using short-acting benzodiazepines (e.g., midazolam) offer significant anterograde amnesia but less muscle relaxation and have reduced the incidence of potentially dangerous hypotension and respiratory depression.

Inadequate topical anesthesia potentiates coughing, gagging, and patient discomfort and increases the risk of injury during bronchoscopy. However, topical anesthetics such as lidocaine, the most frequently used agent, are absorbed systemically through the respiratory mucosa, increasing the risk of cardiac or central nervous system toxicity. These complications are more likely to occur in patients with underlying low cardiac output, hepatic dysfunction, and oropharyngeal candidiasis. Another, less frequent complication of excessive lidocaine use is methemoglobinemia and tissue hypoxia.

Introduction of the bronchoscope frequently results in a decrease in oxygenation and in hypoventilation with demonstrable increases in PaCO₂. In patients with underlying chronic lung disease, severe hypoxemia may occur, triggering life-threatening cardiac arrhythmias. All patients should, therefore, be monitored continuously (electrocardiogram, blood pressure, O₂ saturation, and, if indicated, expiratory CO₂ concentration) from initiation of topical anesthesia through recovery from conscious sedation. Use of supplemental oxygen during the procedure should be routine.

Fever and Infection

A variety of pulmonary procedures, including bronchoscopy, have been reported to cause transient bacteremia. However, data demonstrating a link between bronchoscopy and increased risk of infective endocarditis are lacking. For patients at high risk for this condition (e.g., those with prosthetic valves, history of previous endocarditis, or congenital heart disease), the American Heart Association does not recommend the use of prophylactic antibiotics before bronchoscopy unless the procedure involves incision of the respiratory tract mucosa. Antibiotic prophylaxis should be considered, however, in high-risk patients who are undergoing a procedure to treat an active infection, such as drainage of an abscess.

Transient fever after bronchoscopy is fairly common and generally does not require any therapy. However, persistent fever in the setting of progressive radiographic infiltrates necessitates antibiotic therapy. The incidence of fever is increased in elderly persons, in patients with underlying chronic pulmonary disease or documented endobronchial obstruction, and in those undergoing bronchoscopic interventions for malignancy. The incidence of fever and extension of pulmonary infiltrates increase with the volume of BAL fluid and the total number of pulmonary segments lavaged. The incidence of postbronchoscopic infection is higher in immunocompromised persons and in patients with chronic suppurative lung disease, such as cystic fibrosis.

Pneumothorax

Pneumothorax after transbronchial biopsy occurs in approximately 4% of cases, even when the procedure is done under fluoroscopic guidance (Figure 11-11). The impact of fluoroscopy on the incidence of pneumothorax remains controversial. Uncontrolled studies have not found a difference in the incidence of pneumothorax after transbronchial biopsy when performed with and without fluoroscopy.

Figure 11-11 Computed tomography (CT) image demonstrating a pneumothorax of the right lung that developed after transbronchial lung biopsy. An area of focal hemorrhage in the lateral right upper lobe (white arrow) as a result of biopsy also can be seen.

The incidence of pneumothorax is increased, however, in immunocompromised persons. This probably is due to the increased risk of pneumothorax associated with Pneumocystis infection. The risk also is elevated in mechanically ventilated patients, with peripheral lung biopsy, and in the presence of bullous lung disease. The risk of pneumothorax does not seem to be related to the size of the bronchoscopic biopsy forceps. In case of a significant pneumothorax, a chest tube should be inserted immediately to avoid oxygen desaturation and/or pathophysiologic changes in oxygen tension.

Hemorrhage

One of the most frequently reported complications related to bronchoscopy is hemorrhage. Patients with uremia or with underlying bleeding disorders, especially those caused by platelet dysfunction or thrombocytopenia, have an increased risk of bleeding during bronchoscopy. Bronchoscopic lung biopsy should not be performed if the platelet count is less than 50,000/μL, and aggressive interventional procedures (laser therapy, bronchoplasty, or stent placement) probably are safe only with platelet counts greater than 75,000/μL. Manipulation of the bronchoscope, mechanical trauma, vigorous suctioning, endobronchial brushing and biopsy may result in bleeding during bronchoscopy. In one large series, the overall rate of bleeding after transbronchial biopsy was 4.7%, although the risk of severe bleeding (defined as the need for a bronchus blocker, application of fibrin, critical care admission, or blood transfusion) was less than 1%. Hemorrhage also can occur with inadvertent perforation of pulmonary vessels during transbronchial needle aspiration or biopsy.

Ultrathin Bronchoscopy

Bronchoscopes with small external diameters (less than 3 mm), otherwise known as ultrathin bronchoscopes, were developed to deal with specific clinical situations, such as performing bronchoscopy in pediatric patients, investigating peripheral lung lesions, and evaluating tracheobronchial stenoses. The external diameter of traditional bronchoscopes generally is 5 to 6 mm, and these devices cannot easily examine beyond fourth- to fifth-order bronchi in adults. The use of ultrathin bronchoscopes with small working channels allowing for BAL and the use of a cytology brush have demonstrated promise in the diagnosis of peripheral lung lesions. The newest generations of ultrathin scopes have larger channels that can accommodate forceps and larger cytology brushes.

Virtual Bronchoscopy

Virtual bronchoscopy (VBS) is a novel radiographic reconstruction technique that exploits the versatility of helical (spiral) CT by transforming axial CT data into simulated three-dimensional intraluminal views of the airways. This form of perspective rendering has benefited enormously from continued advances in computing technology and currently is capable of providing images that in many ways mimic those obtained during conventional bronchoscopy (Figure 11-12). Although VBS has yet to find its place in routine clinical practice, it has nonetheless proved useful in the evaluation and management of a wide range of pulmonary diseases and conditions involving the tracheobronchial tree, including bronchogenic carcinoma, benign airway stenoses, tracheobronchomalacia, lung transplantation, and bronchiectasis. With this technique, which provides the bronchoscopist with a “virtual camera” inside the patient’s tracheobronchial tree, images and perspectives can be obtained and procedures can be planned before conventional bronchoscopy is undertaken. Specific advantages include examination of airways distal to a completely occluded bronchus, retroflexion of the bronchoscope, and en face views. Current limitations of VBS include its inability to adequately characterize mucosal abnormalities, identify subtle submucosal disease, or visualize small endobronchial lesions. Obviously, however, VBS can never completely replace conventional bronchoscopy because it does not allow biopsy or therapeutic intervention.

Figure 11-12 Endoluminal lesion obstructing the superior segment of the left lower lobe in a patient with metastatic melanoma. The images of this lesion (arrow) were obtained by flexible bronchoscopy (top left, A) and by virtual bronchoscopy (top middle, B).

(From Finkelstein SE, Schrump DS, Nguyen DM: Comparative evaluation of super high-resolution CT scan and virtual bronchoscopy for the detection of tracheobronchial malignancies, Chest 124:1834–1840, 2003.)

Autofluorescence and Narrow Band Imaging

The development of autofluorescence bronchoscopy (AFB) has improved the detection of dysplasia, carcinoma in situ, and invasive carcinoma of the central airways. AFB systems rely on the principle that infiltrating tumors disturb the fluorescence characteristics of normal tissue. Fluorophores, substances responsible for fluorescence, are variously concentrated within organs and may change according to prevailing conditions. When the bronchial tree is illuminated with blue light (442 nm in wavelength), subepithelial fluorophores within normal tissues emit light with a higher fluorescence intensity than that observed for pre-neoplastic or neoplastic lesions, especially in the green light emission spectrum. Reasons for the weaker green fluorescence in dysplasia, carcinoma in situ, and microinvasive carcinoma include epithelial thickening, tumor hyperemia, and reduced fluorophore concentrations. Thus, the intensity of the emitted light is weaker, and observed light shifts to the red spectrum.

Several recent studies have evaluated the utility of AFB as a screening tool for dysplasia or carcinoma of the central airways in comparison with white light bronchoscopy (WLB). These studies have included patients at high risk for such pathology (e.g., those with a history of asbestos exposure, smokers), with known or suspected lung cancer, and after surgical resection for lung tumors. Although the sensitivity for detecting high-grade dysplasia or carcinoma in situ was increased two- to six-fold on average, AFB has limited specificity. Furthermore, no accepted algorithm has emerged for management of the lesions identified by AFB, and the question of whether screening bronchoscopy improves cancer survival remains unanswered. An additional important consideration is the significant interobserver variability documented among AFB endoscopists and histopathologists.

Narrow band imaging (NBI) uses a unique filter to select light wavelengths that preferentially are absorbed by hemoglobin, thereby permitting superior microvasculature detection. Because angiogenesis preferentially occurs in dysplastic and neoplastic lesions, NBI may identify early dysplastic lesions better than WLB or AFB. Studies suggest similar sensitivity between AFB and NBI, but improved NBI specificity for detecting abnormal lesions. Although current clinical applications for AFB and NBI in the general pulmonary population are limited, they may play an important role in future risk stratification, prognostication, and chemoprevention trials in high-risk patients.

Optical Coherence Tomography

Optical coherence tomography (OCT) is the optical ultrasound analogue whereby near-infrared light transit time and reflection are used rather than sound waves and provides a macroscopic optical cross-sectional view of hollow organs. By using light instead of sound waves, OCT overcomes two major ultrasound limitations in the lung: (1) the inability to image through air and (2) poor spatial resolution. OCT resolution is between 4 and 20 nm, which is approximately 25 times higher than that of other modalities. In the airway, dysplastic, invasive cancer, or inflammatory changes appear to have unique OCT image patterns (Figure 11-13). The ability of OCT to provide an “optical biopsy” with information about microinvasive airway lesion evolution, airway wall remodeling in obstructive lung diseases, or interstitium alterations in idiopathic interstitial pneumonia (IIP) without the risk of tissue biopsy could provide a valuable bronchoscopic tool. Such data may provide diagnostic information, but more important, longitudinal evaluation in an individual patient may allow therapeutic tailoring in the future.

Figure 11-13 Optical coherence tomography images of bronchial mucosa in a patient with small cell carcinoma. A, Normal bronchial mucosa in uninvolved area of lung. Layers of epithelium (white arrow) and lamina propria (black arrow) can be seen. B, Within the tumor area, loss of identifiable microstructures is evident. The scale bars are 1 mm.

(From Ross RG, Kinawewitz GT, Fung KM, et al: Optical coherence tomography as an adjunct to flexible bronchoscopy in the diagnosis of lung cancer: a pilot study, Chest 138:984–988, 2010.)

Fibered Confocal Fluorescence Microscopy

Fibered confocal fluorescence microscopy (FCFM) is a modification of confocal microscopy that allows imaging of thin-section biologic specimens by replacing the microscope’s objective with a flexible fiberoptic miniprobe that can be introduced through a flexible bronchoscope. This technology does not rely on light reflectance, as in OCT, but rather is based on cellular and tissue autofluorescence on laser excitation. The predominant source of airway wall autofluorescence is the subepithelial elastin fibers, and alterations in this elastin network can be detected in microinvasive and invasive proximal airway lesions. FCFM can image alveolar and acinar elastin fiber alterations and alveolar macrophage accumulation in patients who smoke, compared with nonsmoking patients. Therefore, although available data are limited, this technology may have evolving applications in diagnosis and monitoring of therapeutic interventions in a variety of parenchymal lung diseases, including obstructive lung diseases, sarcoidosis, IIP, and microinvasive malignant lesions.

Rigid Bronchoscopic Debulking or Balloon Dilatation

The ideal tool for rapid reestablishment of airway patency in endoluminal obstruction is the rigid bronchoscope. Rigid bronchoscopes have beveled tips, which are ideal for “coring through” large airway tumors and for dilating strictures, and they have large internal diameters, which facilitates débridement of tumors, evacuation of clots, simultaneous insertion of multiple instruments, and concomitant ventilation. Despite advances in other adjunctive endoscopic techniques, rigid bronchoscopic recanalization remains the treatment of choice for life-threatening tracheobronchial obstruction.

Balloon dilation has become an attractive alternative to dissection with a blunt rigid bronchoscope in less urgent cases of obstruction caused by malignant tumors and benign strictures. High-pressure balloons of various lengths and diameters commonly were used in the past. There are now balloons designed specifically for tracheobronchial use that are expandable to specific diameters by application of defined positive pressure. These are inserted through the bronchoscope working channel under direct vision or fluoroscopic guidance. The balloon, filled with saline or radiopaque contrast media, is inflated at the site of interest until the desired diameter is attained. This technique often is used in combination with bronchoscopic thermal treatments (laser, argon plasma coagulation, electrocautery) and tracheobronchial stent placement for the treatment of airway stenosis (Figure 11-14).

Figure 11-14 Diagrammatic representation of bronchoscopic balloon dilatation of tracheal stenosis. This procedure can be accomplished using a flexible or rigid bronchoscope with graduated dilating balloons. After optimal dilatation, a silicone stent (far right), placed using a rigid bronchoscope, relieves airway obstruction.

Balloon bronchoplasty also has been used successfully to treat other disorders, including endobronchial tuberculosis, fibrosing mediastinitis, and strictures associated with lung transplantation or prolonged intubation. It is less successful when used alone to treat stenosis accompanied by extrinsic airway compression and generally is not beneficial in patients with tracheobronchomalacia.

Complications of balloon dilation of airway lesions include bronchospasm, chest pain, mucosal laceration, airway perforation, bleeding, postprocedure airway edema, pneumothorax, and pneumomediastinum.

Endobronchial Laser Therapy

Perhaps the most widely known technique in therapeutic bronchoscopy is laser photocoagulation or photoablation. Lasers produce a beam of monochromatic, coherent light that can induce tissue vaporization, coagulation, hemostasis, and necrosis. Although primarily useful in the ablation of endoluminal malignant tumors, bronchoscopic laser therapy also is beneficial for the treatment of other tracheobronchial disorders, including inflammatory strictures, obstructive granulation tissue, amyloidosis, and benign tumors such as hamartomas and lipomas.

Since the initial report of endobronchial laser ablation of an obstructive neoplasm by Laforet in 1976, several types of lasers have become available for the management of tracheobronchial obstruction. The carbon dioxide (CO₂) laser, used primarily by otolaryngologists, allows shallow penetration of tissue (to a depth of 0.1 to 0.5 mm) and highly precise cutting, but it has minimal hemostatic properties and traditionally was used through a rigid bronchoscope or with suspension laryngoscopy. More recently developed technology has facilitated the delivery of CO₂ laser energy by means of unique reflective fiberoptic probes allowing applications with flexible laryngoscopy and bronchoscopy. The CO₂ laser, with its fine control of tissue ablation, is ideal for the management of laryngeal lesions (e.g., webs, vocal cord nodules). For therapeutic bronchoscopy, neodymium:yttrium-aluminum-garnet (Nd:YAG) laser ablation is most commonly used and provides deeper tissue penetration (to a depth of 3 to 5 mm), superior coagulation, and improved hemostasis, but with less cutting precision. Nd:YAG laser procedures can be performed through a rigid or flexible bronchoscope. Success rates and complications directly related to laser therapy are not different when the procedure is performed through a rigid bronchoscope with the patient under general anesthesia or through a flexible bronchoscope with use of topical anesthesia and conscious sedation.

Nd:YAG laser photoablation therapy has demonstrated a single-modality recanalization rate greater than 90% for endobronchial obstruction of large central airways but is less successful for management of peripheral lesions or with associated extrinsic airway compression. Laser therapy may improve the chances of successful weaning from mechanical ventilation in patients with advanced endoluminal lung cancer presenting in respiratory failure. In addition, photocoagulation with an Nd:YAG laser is an invaluable treatment for patients with airway obstruction caused by benign endoluminal tumors.

Although endobronchial laser therapy generally is safe and well tolerated, it may be complicated by cardiac arrhythmias, airway perforation, pneumothorax, hemorrhage, hypoxemia, or endobronchial fire (ignition of the bronchoscope or endotracheal tube). The use of a laser in the tracheobronchial tree requires careful consideration of the anatomic location and configuration of the lesion. If the lesion is in close proximity to the esophagus or the pulmonary artery, endobronchial laser therapy carries a risk of fistula formation. Laser therapy in a patient with tracheobronchial narrowing caused by extrinsic compression may result in airway perforation. In rare cases, pulmonary edema or fatal pulmonary venous gas embolism has been reported. Patients with standard silicone endotracheal tubes or silicone tracheobronchial stents and those who require high concentrations of supplemental oxygen are at increased risk for endobronchial fire. Fortunately, the overall risk is less than 0.1%. The overall rate of mortality associated with endoscopic laser therapy is quite low, not exceeding 0.3% to 0.5% in several large series.

Endobronchial Cryotherapy and Electrocautery

Cryotherapy and electrocautery are cost-effective alternatives to laser therapy for the management of tracheobronchial obstruction. The depth of penetration and resulting injury are, however, much more difficult to control. As with the Nd:YAG laser, both electrocautery and cryotherapy can be administered through a rigid or flexible bronchoscope. The effects of electrocautery on tissue are similar to those of Nd:YAG laser, with tissue destruction induced by coagulative necrosis. Argon plasma coagulation (APC) is similar to electrocautery except that it uses argon gas to conduct the electrical current, rather than a contact probe. APC has a depth of penetration of only 1 to 3 mm and is therefore more suitable for the treatment of superficial and spreading lesions. In contrast with cautery or APC, cryotherapy probes induce tissue necrosis through hypothermic cellular crystallization and microthrombosis. Specially designed cryoprobes are inserted through the bronchoscope until they contact the target tissue. Through the probe in the bronchoscopy working channel, liquid nitrous oxide or liquid nitrogen is introduced through a small orifice under pressure, resulting in rapid cooling with creation of an “ice ball” (approximate temperature of −20° C) at the probe tip. This freezing effect is maintained for approximately 20 seconds; the area is then allowed to thaw. Cryotherapy treatment of an endobronchial lesion requires several freeze-thaw cycles.

Cryotherapy and electrocautery have been used successfully to relieve airway obstruction caused by benign tracheobronchial tumors, polyps, and granulation tissue. These techniques—cryotherapy in particular—may be superior to lasers for distal lesions because of the lower risk of airway perforation. Similarly, carcinoma in situ and mucosal dysplasia may be adequately treated with cryotherapy or electrocautery alone, although multiple treatments may be required for optimal results. Cryotherapy is effective in the removal of certain foreign bodies that can be frozen to the probe and extracted. Of interest, cryotherapy can very effectively freeze endobronchial blood clots and mucous plugs to the probe, which can be easily extracted from the airway.

Endobronchial cryotherapy generally is not effective for management of paucicellular lesions that are relatively impervious to freezing, such as fibrotic stenoses, cartilaginous or bony lesions, and lipomas. Furthermore, endobronchial cryotherapy, unlike either laser therapy or electrocautery, is inefficient in achieving rapid relief of symptomatic airway obstruction. The most common serious complication of both electrocautery and cryotherapy is bleeding secondary to disruption of endobronchial tumor without full coagulation of distal tissue and tumor vessels. The estimated incidence of clinically significant bleeding in patients treated with electrocautery is 2.5%.

Endobronchial Brachytherapy

Brachytherapy is the local treatment of tumors with radiation delivered internally through implanted radioactive seeds or in a circumferential fashion with inserted wires. This technique ensures the delivery of a maximal therapeutic radiation dose to the tumor with a minimal effect on normal surrounding tissues. Endobronchial brachytherapy involves the bronchoscopic insertion of a thin, hollow “afterloading” catheter through or parallel to a malignant obstruction under fluoroscopic guidance. A radioactive implant is then inserted into the catheter and left in position for a predetermined period (2 to 40 hours, depending on the dose rate).

In 1922, Yankauer described the use of rigid bronchoscopic brachytherapy for the palliation of airway obstruction caused by malignant tumors. Modern techniques, including the use of flexible bronchoscopes, polyethylene afterloading catheters, and iridium 192 implants, were first described in 1983. Since the development of techniques involving high dose-rate delivery in the 1980s, endobronchial brachytherapy has become an option for outpatient treatment of peribronchial tumors.

Relief of airway obstruction is the primary goal of endobronchial brachytherapy, although curative treatment may be attempted in conjunction with external beam irradiation in selected patients. For rapid and sustained airway recanalization in malignant airway obstruction, brachytherapy generally is used as an adjunct to thermal tumor ablation, endobronchial stent placement, or conventional external beam irradiation. Brachytherapy is safest and most effective for management of central airway lesions, although in one study, small peripheral tumors proved to be more responsive than bulkier central tumors. Among patients with malignant airway obstruction, rates of recanalization range from 60% to 90%, with decreased dyspnea, cessation of hemoptysis, and relief of cough in most cases. Endobronchial brachytherapy may require multiple treatments to be effective.

Serious complications of brachytherapy include massive hemoptysis and fistula formation secondary to necrosis of the airway wall and adjacent vascular structures. Because of the risk of fatal hemorrhage, every effort should be made to rule out central vascular involvement of the tumor before brachytherapy administration. The reported incidence of serious complications varies widely, with rates as low as zero to 10% in some of the largest studies and as high as 30% to 40% in smaller studies.

Photodynamic Therapy

Photodynamic therapy (PDT) currently is approved by the FDA for malignant airway obstruction palliation and as an alternative to surgery in select patients with minimally invasive central lung cancer. PDT works on the principle that certain compounds, such as hematoporphyrin derivatives (Photofrin) or aminolevulinic acid (ALA), function as photosensitizing agents, rendering malignant cells susceptible to damage from monochromatic light. Tumor necrosis occurs as a result of cellular destruction through the generation of oxygen free radicals or by ischemic necrosis mediated by vascular occlusion resulting from thromboxane A₂ release. The selective effect of PDT on malignant cells is thought to be due to the greater uptake and retention of photosensitizing agents in neoplastic cells compared with normal cells—with the exception of cells of the reticuloendothelial system, particularly those in the skin. This relative tumor selectivity effect seems to be most pronounced within 24 to 48 hours after photosensitizing agent infusion. For this reason, bronchoscopic treatment of target lesions often is performed 1 or 2 days after agent administration. In view of the delayed onset of PDT action, it is not useful in patients with acute respiratory distress from malignant airway obstruction. Follow-up “toilet” bronchoscopies are required to debride necrotic tissue.

Ideal candidates for PDT include patients with airway obstruction caused by malignant endobronchial masses with minimal extrinsic airway compression, and patients with minimally invasive tumors of the central airways. Although surgical resection remains the treatment of choice for early lung cancer, some patients refuse surgery or have tumors that are deemed inoperable because of high surgical risk. In such cases, PDT may represent an appropriate alternative. Response rates are highest in patients with small tumors and minimal depth of penetration. In patients with bulky tumors, endobronchial PDT may substantially reduce the obstruction, with objective increases in spirometric measurements and subjective improvements in dyspnea and the quality of life. Metastatic tumors also have been treated successfully with PDT. Complications include increased skin photosensitivity and hemoptysis resulting from extensive tumor necrosis. Cutaneous photosensitivity, similar to that seen with sunburn, occurs in up to 20% of patients in various reported series and can be obviated by adequate sunlight precautions. Sensitivity to sunlight after photosensitizer administration can persist for 6 weeks or longer.

Tracheobronchial Stenting

The medical term stent refers to any device designed to maintain the integrity of hollow tubular structures, such as the coronary arteries and the esophagus. Anecdotal reports of attempts to implant stents in the tracheobronchial tree date back to 1915. The Montgomery T tube, designed in the 1960s, was the first reliable, dedicated airway stent. However, stent implantation in the lower trachea and bronchi did not become standard medical practice until Dumon’s 1990 report on the safety and ease of placement of a dedicated airway stent made of silicone.

Two main types of endobronchial stents are in use today: tube stents made of silicone and self-expandable metallic stents (SEMSs). Silicone stents are placed by rigid bronchoscopy with the patient under general anesthesia. Silicone stents are relatively inexpensive (in the range of $400 to $500 USD) compared with SEMSs ($1800 to $2000 USD). Bifurcated silicone stents also are available for the palliation of distal tracheal and main carinal lesions. These stents have been effectively used in the management of carinal compression associated with malignant tumors, tracheoesophageal fistulas, and tracheobronchomalacia. Custom silicone stents can be designed by the treating bronchoscopist to deal with unique anatomic problems such as stump-related bronchopleural fistula after pneumonectomy. In one large single-center series, the complications of silicone stents included a 5% migration rate, a 10% incidence of granulation tissue formation, and a 27% incidence of partial stent occlusion by inspissated secretions.

Unlike silicone stents, SEMSs can be placed with flexible bronchoscopy, are less likely to migrate, and are more likely to preserve normal mucociliary clearance. However, if metal stents are misplaced in the airway, rigid bronchoscopy often is required for their removal. In addition, mucosal inflammation and the granulation tissue formation are common with uncovered SEMSs and at the proximal and distal ends of covered SEMSs, and repeated endoscopic intervention may be required to restore airway patency. For all these reasons, SEMSs have an FDA warning against their utilization in benign airway stenosis, unless all other treatment options, including silicone stenting, have been obviated. One exception to this rule is the development of dehiscence of the bronchial anastomosis in lung transplantation. In this setting, temporary uncovered SEMS insertion across the dehiscence has been used to induce focal granulation tissue formation, which promotes dehiscence closure.

Endobronchial stents have a critical role in multimodality endoscopic approaches to both benign and malignant airway obstruction. Airway obstruction caused by locally advanced bronchogenic carcinoma can be treated with a combination of thermal tumor ablation and stent implantation to regain and to preserve airway lumen diameter by preventing tumor ingrowth (Figure 11-15). Stent placement also can be used to maintain airway patency after endobronchial brachytherapy or can be combined with laser therapy and balloon dilation in the endoscopic management of benign fibrotic strictures. Most large studies of endobronchial stent placement have demonstrated impressive efficacy. Dumon and colleagues reported excellent clinical outcomes and few complications with silicone stent use in patients with malignant airway obstruction but a lower success rate among patients with tracheal stenosis caused by other disorders. Success rates, with “success” broadly defined as symptomatic relief, have ranged in limited studies between 78% and 98%, although none of the early trials used objective measures such as the Lung Cancer Symptom Score (LCSS) to determine efficacy. In two small studies in patients who were intubated because of respiratory failure secondary to unresectable tracheobronchial and mediastinal disease, stent placement facilitated extubation in most patients.

Figure 11-15 A, Endoluminal tumor with extrinsic compression treated with a combination of modalities: bronchoscopic laser therapy (B), balloon bronchoplasty (C), and stent placement (D).

The benefits of stent placement seem to persist in patients who survive for a period of several months or years after stent implantation. Long-term follow-up data, however, are derived from patients with benign disease, because the mean follow-up period in patients with malignant airway obstruction does not usually exceed 3 to 4 months, because of limited underlying disease survival. Some investigators have reported poor long-term results with the use of metal stents in patients with fibroinflammatory stenosis caused by nonmalignant disorders. In addition, there have been case reports of massive hemorrhage associated with the use of stents in patients with extrinsic compression attributable to aneurysmal dilatation or congenital aortic malformations.

Endoluminal Airway Obstruction

Endoluminal obstruction of the tracheobronchial tree may result from various benign and malignant processes. The most common cause of endobronchial obstruction is advanced bronchogenic carcinoma. In patients with inoperable central airway tumors, restoration of airway patency may provide palliation and may even prolong life, particularly in the case of impending respiratory failure or postobstructive pneumonia.

Signs and symptoms of central malignant airway obstruction vary but often include progressive dyspnea and functional limitation, wheezing, cough, stridor, hoarseness, hemoptysis, and chest pain. A careful pretreatment evaluation should be performed to distinguish symptoms attributable to focal tracheobronchial lesions from those related to underlying obstructive lung disease or parenchymal lung disease, or both. A mild obstruction, for example, may contribute only marginally to the dyspnea experienced by a patient with concomitant severe chronic obstructive pulmonary disease (COPD). Although pulmonary function testing and thoracic imaging techniques such as chest CT may be useful in the evaluation of a patient with suspected malignant airway obstruction, bronchoscopy, either rigid or flexible, remains the diagnostic and therapeutic “gold standard.” Increasingly, however, three-dimensional reconstruction CT imaging—so-called virtual bronchoscopy—is being applied as a reliable noninvasive method of assessing the nature and extent of malignant airway obstruction to allow preprocedural intervention planning.

The bronchoscopic approach to management of malignant airway obstruction depends on the lesion location, the presence or absence of associated extrinsic compression, and the degree of clinical urgency (Table 11-3). Rigid bronchoscopic debulking with adjunctive thermal ablation is recommended when airway recanalization must be performed on an emergency basis. If endobronchial obstruction is accompanied by marked extrinsic compression, stent placement may be beneficial (Figure 11-16).

Figure 11-16 A, Chest radiograph of an obstructing small cell carcinoma in right main bronchus, causing right lung atelectasis and mediastinal shift. B, Radiographic appearance after rigid bronchoscopic debulking of the lesion and placement of a Dumon silicone stent.

(A and B, Courtesy Colin Gillespie, MD.)

The complexity of a lesion is equally important in determining the best approach to resection. Benign tracheal webs often are managed by laser or electrocautery-mediated resection alone, whereas complex fibrotic strictures may warrant the combination of rigid bronchoscopic or balloon dilation, thermal incision, and stent placement. For focal tracheal stenosis in patients at low risk for complications, surgical resection with primary reanastomosis should remain the treatment of choice.

Extrinsic Airway Compression

Extrinsic airway compression usually results from malignant involvement of structures adjacent to the central airways, such as mediastinal lymph nodes or the esophagus, but it may be associated with a benign process, such as fibrosing mediastinitis, tuberculosis, aneurysmal dilatation of the aorta, or sarcoidosis. The clinical signs and symptoms of extrinsic airway compression often mimic those of endobronchial obstruction. The diagnosis is established on the basis of bronchoscopic detection of marked airway narrowing in the absence of an endoluminal mass.

Therapeutic options in the management of extrinsic airway compression are limited. Ablative endoscopic approaches such as laser therapy, cryotherapy, PDT, and electrocautery are contraindicated because of the lack of demonstrable benefit and risk of airway perforation. Although some patients with malignant disease may benefit from endobronchial brachytherapy, tracheobronchial stent placement is the palliative treatment of choice for patients with symptomatic extrinsic airway compression.

Tracheobronchomalacia

Diffuse or focal tracheobronchomalacia is perhaps the most challenging disorder encountered by the therapeutic bronchoscopist. Cartilaginous tracheobronchomalacia, as seen in patients with relapsing polychondritis, reflects a loss of the structural integrity of the trachea and/or main bronchi secondary to airway cartilaginous ring destruction. Membranous, or crescentic, tracheobronchomalacia, also known as excessive dynamic airway collapse (EDAC), is manifested by displacement of the posterior membrane toward the anterior tracheal wall during exhalation as a result of trachea and main bronchus posterior membrane laxity and usually is seen in patients with long-standing COPD. Focal tracheobronchomalacia may be a complication of long-standing intubation or an anastomotic complication after lung transplantation.

Tracheobronchomalacia is best diagnosed on the basis of findings on flexible bronchoscopy, performed with the patient breathing spontaneously (Figure 11-17, A), although dynamic CT scanning, with images obtained on inspiration and expiration, often is helpful. Tracheobronchomalacia should be distinguished from a saber sheath trachea, which is characterized by a fixed reduction of the transverse diameter of the intrathoracic portion of the trachea, in the presence of accentuation of the sagittal diameter (see Figure 11-17, B).

Figure 11-17 A, Tracheal buckling. In a patient presenting with dyspnea, cough, and stridor, bronchoscopic examination revealed localized upper tracheal buckling on hyperflexion of the neck. Symptoms cleared after three tracheal rings were resected. Histopathologic analysis showed localized tracheomalacia. B, “Saber sheath trachea.” Fixed reduction in coronal diameter with concomitant increase in sagittal diameter of the trachea results in the classic bronchoscopic appearance of this lesion.

The endoscopic treatment of choice for patients with diffuse tracheobronchomalacia is the insertion of a standard or bifurcated silicone tracheobronchial stent. This intervention is more likely to be successful in patients with the cartilaginous type of tracheobronchomalacia than in those with the membranous type. Patients with membranous tracheobronchomalacia may benefit from a trial of silicone stent placement. For those who benefit in terms of decreased respiratory symptoms and improved pulmonary function, surgical plication or buttressing of the posterior membrane, or both, can be performed, often with good results and with facilitation of stent removal. For many patients with focal tracheomalacia, particularly from postintubation injury, surgical resection with primary reanastomosis is the best therapeutic option. An alternative treatment for selected patients with diffuse tracheobronchomalacia is the “pneumatic stent” provided by noninvasive ventilatory techniques such as continuous positive airway pressure.

Control of Hemoptysis

In cases of hemoptysis, bronchoscopy may be of value not only for diagnosis but frequently for emergency management of endobronchial bleeding (Box 11-5). Because of difficulties with visualization, instruments with large and maximally effective suction channels should be used. Rigid bronchoscopy generally is preferred with massive bleeding and when the need to remove large clots is anticipated.

When continuous suctioning of blood fails to clear the airways, other means can be used. An iced saline solution can be instilled along with vasoactive drugs, such as epinephrine, to induce vasoconstriction. The bronchoscope itself can occlude the lumen of the bronchus from which the bleeding originates. The same effect, perhaps with better local control, can be achieved with bronchoscopic balloon catheters (Figure 11-18). Specially designed catheters have been developed for introduction through the working channel of the flexible bronchoscope, several permitting subsequent removal of the scope while the tamponading balloon remains in place, as well as the potential for suctioning beyond the balloon for clearance of blood from distal airways. Another effective method for control of visible sources of bleeding, particularly from endobronchial neoplasms, is Nd:YAG laser photocoagulation.

Figure 11-18 Placement of a Fogarty balloon catheter under bronchoscopic guidance to control massive hemorrhage from a segmental or lobar bronchus.

(From Lordan JL, Gascoigne A, Corris PA: The pulmonary physician in critical care: illustrative case 7: assessment and management of massive hemoptysis, Thorax 58:814-819, 2003.)

Recent reports have demonstrated the benefit of endobronchial packing, accomplished using either flexible or rigid bronchoscopy, with oxidized regenerated cellulose (Surgicel), which functions in multiple capacities, including local tamponade and isolation at the segmental or subsegmental bleeding site, absorption of blood, and promotion of endobronchial clot formation by induction of fibrin polymerization. This procedure may obviate the need for bronchial artery embolization or other, more invasive procedures.

Removal of Foreign Bodies

Foreign body aspiration is more likely to occur in children than in adults, with most occurring in children younger than 3 years. In children the obstruction most often involves a mainstem bronchus, whereas in adults most foreign bodies are wedged distally, most commonly in the right lower lobe. Before the development of bronchoscopy, most foreign body aspirations resulted in high morbidity and mortality, commonly from postobstructive pneumonia. Until the introduction of the flexible bronchoscope, all foreign body removals were accomplished with rigid bronchoscopy. Even at present, the rigid bronchoscope remains the tool of choice for the removal of foreign bodies, especially in children. The advantage of the rigid instrument resides in its larger access channel, permitting use of larger and more adaptable retrieval tools and ability to simultaneously provide and maintain ventilation. In adults, flexible bronchoscopy is the most common initial diagnostic tool for foreign body aspiration and allows for successful foreign body removal in most cases.

Various types of instruments have been developed for use with bronchoscopy for the removal of foreign bodies, including grasping forceps, balloon catheters, retrieval baskets, snares, and magnetic extractors. The instrument choice depends on the specifics of the type of foreign body and its location in the tracheobronchial tree. Grasping forceps may be helpful in the retrieval of hard objects with an irregular surface. Smooth objects or organic material (e.g., nuts, food particles) may require the use of expandable baskets or a combination of balloon catheters, suction devices, and grasping forceps. Fogarty balloon catheters frequently are used to dislodge a foreign body and bring it proximally into the trachea before its removal with other instruments.

Special attention should be paid to the period after removal of the foreign body, because serious complications can occur. Patients should be observed closely for any signs of hemoptysis, subcutaneous emphysema, or subglottic edema. Trauma inflicted during the extraction or forceful manipulation of instruments greatly accentuates the risk of postoperative complications, particularly if oversized instruments are used or if the bronchoscopy procedure is prolonged.

Aspiration of Secretions

According to a survey of bronchoscopists in the United States, removal of retained secretions is cited as a leading indication for therapeutic bronchoscopy. Bronchoscopic secretion aspiration may be indicated in patients presenting with respiratory muscle weakness (e.g., because of underlying neuromuscular disease or the postoperative state) or disorders leading to recurrent aspiration of food or excessive upper airway secretions. In critically ill or mechanically ventilated patients, removal of secretions and mucous plugs usually can be rapidly achieved through the flexible bronchoscope. A flexible scope with a large-diameter suction channel should be chosen for this procedure. The nature of the retained material—its consistency and viscosity—may dictate frequent bronchoscopy procedures to relieve segmental or lobar atelectasis because of inspissated mucous plugs. Underlying pulmonary diseases, such as bronchiectasis, may aggravate the airway secretion retention. Bronchoscopic secretion aspiration should not be considered “routine” in the postoperative period or in other conditions in which good chest physiotherapy and maintenance of adequate pulmonary toilet could be more effective.

Two specific disorders are worth highlighting in the context of therapeutic bronchoscopy: pulmonary alveolar proteinosis (PAP) and allergic bronchopulmonary aspergillosis (ABPA). In PAP, BAL has been used for therapeutic clearance of alveolar material, although the standard approach is whole-lung lavage that uses double-lumen endotracheal tube intubation. In ABPA, lavage with saline solution may be insufficient to remove tenacious impactions (described as “plastic bronchitis”). In these circumstances, use of bronchoscopic forceps or snare may prove helpful.

Closure of Bronchial Fistulas

Prolonged air leaks are a common problem associated with primary or secondary pneumothorax and are the most frequent complication after pulmonary resection, with the highest rate after lung volume reduction surgery (LVRS). The current management for prolonged air leaks usually includes prolonged chest tube drainage with Heimlich valve, attempts at surgical repair, and/or blood patch and pleurodesis.

Either flexible or rigid bronchoscopy can be a useful intervention in confirming suspected bronchopleural fistulas or alveolopleural fistulas and in specifying their precise location. The most common approach is to perform selective airway occlusion with a balloon catheter while observing the chest tube air leak rate or volume. Depending on the fistula location and the size, bronchoscopic procedures can be attempted with the goal of occlusion and sealing the bronchopleural fistulas. Small bronchial openings in an otherwise normal bronchus after thoracic surgery respond much better, with a higher rate of success of bronchoscopic sealing. It is much more difficult to achieve good obliteration of a fistula if it is infected or is due to an underlying malignancy. Many different techniques for permanent closure have been used, including introduction of bronchial mucosal irritants (e.g., silver nitrate), with the object of stimulating reactive granulation tissue formation. Several potentially useful agents have been described, including surgical gel (Gelfoam), autologous blood patch, cryoprecipitate, and thrombin injection to create fibrin clot. In addition, laser photocoagulation surrounding small, proximal bronchopleural fistulas has been reported to be beneficial. Recent case series suggest that the placement of one-way endobronchial valves leads to complete or partial resolution in the large majority of patients with prolonged air leaks from diverse causes.

Bronchoscopic Treatments for Emphysema

The risks associated with LVRS, in which diseased portions of emphysematous lung are resected through median sternotomy or with use of videothoracoscopy, including a perioperative mortality of 5% or greater, as well as substantial perioperative morbidity, have spurred the development of minimally invasive approaches for dyspnea palliation in patients with emphysema. The bronchoscopic lung volume reduction (BLVR) approaches evaluated have used a range of different techniques, including airway occlusion with silicone plugs (i.e., Endobronchial Watanabe Spigot [EWS]); insertion of one-way bronchial valves; and creation of artificial noncompressible communications (“bypass tracts”) between cartilaginous airways and emphysematous parenchyma. Endobronchial valves are designed to limit ventilation to the most severely emphysematous regions of lung and reduce dynamic hyperinflation. When placed correctly, the valves allow one-way flow of secretions and air out of the occluded pulmonary segment. The major advantage of the bronchial valve approach for emphysema palliation is the potential for reversibility—the valves generally are removable with minimal risk to the patient. The bane of the pulmonologist attempting to use bronchial valves in the treatment of emphysema is collateral ventilation, which inhibits induction of atelectasis, thereby preventing successful lung volume reduction. Results from the first randomized study of endobronchial valves, a double-blinded sham-controlled multicenter trial of the Zephyr endobronchial valve, demonstrated modest increases in forced expiratory ventilation in 1 second (FEV₁) and 6-minute walk distance at 6 months, but unfortunately with an increased rate of complications, including COPD exacerbations and hemoptysis.

The results from the randomized study of Airway Bypass also did not demonstrate statistically significant improvements in the primary end points of forced vital capacity (FVC) and dyspnea score. Studies evaluating the use of other novel endobronchial approaches are ongoing. These include the placement of airway implants (e.g., Nitinol coils); intrabronchial injection of steam to induce tissue necrosis resulting in loss of lung tissue, volume, and ventilation; and biologic restructuring of emphysematous lung parenchyma to induce tissue fibrosis, atelectasis, and contraction, with consequent lung volume reduction. The latter approach was inspired by numerous case reports of “medical” lung volume reduction, in which patients with heterogeneous emphysema achieved significant clinical and physiologic improvements in lung function after receiving external beam radiation therapy for an upper lobe non–small cell carcinoma or after developing infection or inflammation in an upper lobe bulla resulting in fibrosis and contraction of the bullous lung tissue after resolution of the infectious or inflammatory process. One of the major downsides of the biologic approach to lung volume reduction is the permanent destruction of lung tissue, with no option for reversibility in the event of worsening lung function.

Bronchial Thermoplasty

Chronic asthma is a major cause of morbidity and death and also a major contributor to rapidly rising health care costs. Bronchial thermoplasty (BT) is a new bronchoscopic procedure that delivers controlled thermal energy to the bronchial wall of conducting airways, with the intent to inhibit airway smooth muscle contractile function. This offers the potential to attenuate bronchoconstriction occurring during asthma exacerbations. BT is performed by use of a single-use radiofrequency device that delivers thermal energy to the bronchial wall during an outpatient bronchoscopic procedure. Three separate procedures are performed in order to treat all accessible upper and lower lobe airways, ranging from 3 to 10 mm in diameter. The initial randomized, multicenter Airway Intervention with Radiofrequency (AIR) trial in patients with moderate to severe disease demonstrated decreased asthma exacerbations in the group undergoing BT compared with those patients treated with standard medical treatment alone. This was followed by a randomized, sham-controlled multicenter trial (AIR2) demonstrating significant improvement in the primary end point, asthma-related quality of life. Although an increase was noted in early posttreatment asthma exacerbations requiring emergency department visits and hospitalizations, the long-term follow-up data showed decreased asthma-related health care utilization for patients undergoing BT as opposed to the sham procedure. On the basis of these data, BT should be considered for patients with severe asthma that is not well controlled by medication therapy. Studies are ongoing to collect additional safety data and to assess the durability of the BT treatment effect.

Complications of Therapeutic Bronchoscopic Techniques

The advent of interventional bronchoscopy has resulted in complications not ordinarily seen with diagnostic bronchoscopy. Inappropriate use of lasers has resulted in endobronchial burns and bronchial perforations associated with catastrophic bleeding, pneumomediastinum, or pneumothorax. Endobronchial edema and mucosal sloughing also may occur as a result of laser thermal effects.

As noted previously, the use of airway stents is associated with several complications. Stents may not be properly adapted to the diameter of the airway, resulting in either incomplete stent deployment or stent migration, possibly engendering life-threatening airway obstruction. The presence of an endoprosthesis in the airway may predispose the patient to difficulties with secretion clearance and accumulation of inspissated mucus. Placement of SEMSs may be followed by severe local airway reactions, with consequent formation of granulation tissue, hemorrhage, or bronchial perforation.