Bronchoscopy

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Chapter 11 Bronchoscopy

The first bronchoscopy was performed by Gustav Killian in 1897. Technologic advances during the next century facilitated development of bronchoscopy as a pivotal diagnostic and therapeutic tool in pulmonary medicine. Although a number of bronchoesophagologists contributed to refinement of the technique based on the use of a rigid instrument, the advent of flexible fiberoptic bronchoscopy, pioneered by Shigeto Ikeda in 1967, opened new horizons to clinicians. At the end of the 1980s, the development of videobronchoscopy brought significant improvements in imaging quality and data storage. Subsequently, several other bronchoscopic applications have been developed for both diagnostic and therapeutic purposes.

This chapter presents an overview of bronchoscopy and related techniques. After a general discussion of bronchoscopy and associated instrumentation, applications of the technique and patient preparation are considered, and safety factors, contraindications, and complications of bronchoscopy are reviewed. Finally, specific indications for diagnostic and therapeutic bronchoscopy are discussed.

Types of Bronchoscopy and General Instrumentation

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.

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).

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.

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.

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).

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.

Indications for Diagnostic Bronchoscopy

Many potential indications have been recognized for both diagnostic and therapeutic bronchoscopy, many of which are listed in Boxes 11-2 and 11-3. The most common reason for bronchoscopy remains the evaluation of a lung mass or nodule. Other major indications include investigation of pulmonary infiltrates, evaluation of opportunistic infections in immunocompromised persons, investigation of hemoptysis, assessment for suspected foreign body, and treatment of airway complications related to neoplasms in the tracheobronchial tree. Some of these indications are discussed next.

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

Technique Clinical Applications
Bronchoscopy—visualization Assessment of mucosal, intraluminal, and extraluminal pathology
Evaluation of endobronchial tuberculosis, mycoses, viral vesicles (in AIDS)
Evaluation of invasive tracheobronchial aspergillosis, candidiasis, and other conditions
Follow-up evaluation of endobronchial disease (e.g., tuberculosis)
Bronchial washing Culture for identification of mycobacteria, fungi, and viruses and Pneumocystis smears
Bronchoalveolar lavage Culture for identification of all organisms, especially mycobacteria, fungi, cytomegalovirus and other viruses and Pneumocystis smears
Protected specimen brushing Culture for aerobic and anaerobic bacteria
Nonprotected bronchial brushing Stains and culture for identification of mycobacteria, fungi, Pneumocystis, and viruses
Endobronchial biopsy Mucosal lesions caused by mycobacteria, fungi, protozoa
Removal of obstructing lesions responsible for infection (e.g., tumor, foreign body)
Drainage of lung abscess; piecemeal removal of mycetomas (aspergillomas, other fungus balls)
Bronchoscopic needle aspiration Stains and culture of extrabronchial lymph node specimens for identification of mycobacteria and fungi
Drainage of bronchogenic cyst and instillation of sclerosing agent
Bronchoscopic lung biopsy Stains and culture for identification of all organisms, especially Pneumocystis jiroveci, mycobacteria, and fungi
Detection of parasitic lung infections
Rigid or flexible bronchoscopy—therapeutic intervention Insertion of tracheobronchial prosthesis (stent) to overcome airway obstruction caused by intrinsic stenosis (posttuberculosis or fungal) or extrinsic compression caused by mediastinal fibrosis due to histoplasmosis

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).

Infections in Immunocompromised Patients

Pulmonary infection in immunocompromised patients is a frequent complication and represents an important contributor to mortality. Such infections are increasingly common, reflecting the expanding use of aggressive chemotherapeutic regimens and the ever-increasing number of solid organ and hematopoietic stem cell transplantations. The differential diagnosis of pulmonary infiltrates is broad in scope; however, most cases are caused by infectious agents, including bacterial, fungal, viral, and mycobacterial pathogens. Bronchoscopy is the most commonly used diagnostic procedure in these patients and should be performed as early as possible, because a delay in diagnosis of longer than 5 days has been shown to significantly increase mortality among these patients.

The sensitivity of bronchoscopy varies, depending on the immunocompromised population studied and the specific etiologic disorder. In non–human immunodeficiency virus (HIV)-infected patients, the yield of BAL for Pneumocystis jiroveci is approximately 80%, compared with a greater than 95% yield observed in HIV-seropositive patients. This difference is due to the much lower organism load present in non–HIV-seropositive subjects. Although empirical therapy often is initiated in patients suspected of having P. jiroveci infection, bronchoscopy should be performed in most cases to confirm the diagnosis. Bronchoscopic lung biopsy may increase the diagnostic yield of BAL for diagnosis of P. jiroveci infection, particularly in the non–HIV-infected population. Bronchoscopy also has a high diagnostic yield for cytomegalovirus (CMV); however, because CMV cultures from BAL are not specific, the diagnosis of CMV pneumonia should be limited to patients with pathologic evidence of CMV infection demonstrated by the presence of CMV inclusion bodies on BAL or biopsy. Although bronchoscopy also is useful for the diagnosis of aspergillosis—the sensitivity is approximately 50%—the disease often is peripheral and patchy and thus is not easily diagnosed by BAL or bronchoscopic biopsy. Overall, in immunocompromised patients with infiltrates, bronchoscopy is successful in establishing the diagnosis in as many as 80% of cases.

Human Immunodeficiency Virus Syndrome

The introduction of highly active antiretroviral therapy (HAART) led to a sharp decline in the incidence of opportunistic infections in HIV-infected patients. Nevertheless, infectious complications remain one of the most common indications for bronchoscopy in this population. Pneumocystis pneumonia remains the most frequent serious opportunistic infection in HIV-seropositive patients. Bronchoscopy with BAL remains the preferred diagnostic procedure for this disease, although in select centers, the use of sputum induction has had a relatively high diagnostic yield and may avoid the need for bronchoscopy. As previously mentioned, bronchoscopic lung biopsy may increase the diagnostic yield of BAL. Empirical therapy often is initiated in patients with suspected Pneumocystis infection; such therapy can impair the diagnostic yield of BAL if the procedure is not performed within 24 hours. In patients receiving pentamidine prophylaxis, the diagnostic yield is decreased unless the upper lobes are sampled. Several PCR assays have been tested on BAL fluid, induced sputum, and oral wash specimens; these generally have been more sensitive but less specific than traditional microbiologic methods.

Bronchoscopy also plays an important diagnostic role in HIV-positive patients with infections caused by mycobacteria, including tuberculosis, atypical bacterial pneumonias, and various fungal infections. Kaposi sarcoma, caused by human herpesvirus type 8 (HHV8), can manifest with violaceous endobronchial plaques that typically occur at airway bifurcations; pulmonary parenchymal involvement is characterized by lymphangitic infiltration of tumor, leading to the development of nodules and masses.

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).

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