Pulmonary Medicine

Diagnostic Bronchoscopy

General description of procedure, equipment, technique

This presentation provides a brief overview of diagnostic bronchoscopy, with a focus on the flexible fiberoptic technique.

The first direct endoscopic examination of the larynx was performed by Kirstein in 1895. Two years later, Gustav Killian, the "father of bronchoscopy,” investigated the lower trachea and main bronchi using Kirstein's laryngoscope.

In 1964, Dr. Shigeto Ikeda established standards for flexible fiberoptic bronchoscopy, and by 1966, bronchoscope prototypes had been developed. In 1968, the first commercially available flexible fiberoptic bronchoscope was introduced. In 1987, Dr. Ikeda introduced video bronchoscopy by replacing the bronchoscope's optical fiber bundle with a charge-coupled device (CCD), thereby providing improved image resolution.

Flexible fiberoptic bronchoscopy (FOB) is the most commonly performed method of bronchoscopy. Rigid bronchoscopy is performed under general anesthesia and is mainly therapeutic in nature.

During bronchoscopy, the operator visualizes the vocal cords, trachea, large proximal airways, and smaller distal airways to the level of the third or fourth generation of airways. FOB is used to sample and treat lesions in airways and to sample the lung parenchyma.

FOB is generally performed in a designated procedure room, with the patient under conscious sedation spontaneously breathing or with general anesthesia with laryngeal mask airway or an endotracheal tube. The bronchoscope consists of a flexible sheath that contains cables that allow the tip of the device to be flexed or extended. Images are transmitted using a CCD chip or through fiberoptic bundles. The bronchoscope includes a light source and a working channel for removal of secretions, insertion of biopsy forceps or aspirating needle, or performance of lung lavage.

Indications and patient selection

Bronchoscopy is used in evaluating a wide variety of clinical circumstances, including known or suspected malignancy (diagnosis, mediastinal staging, re-evaluation after treatment, and assessment of metastatic carcinoma); evaluation of interstitial lung diseases; evaluation of known or suspected respiratory infections, recurrent or unresolved pneumonia, assessment of infiltrates in an immuno-compromised host, exploration of cavitary lung lesions; diagnostic assessment of unexplained lung collapse; and evaluation of a variety of respiratory symptoms and signs, diagnosis and therapeutic management of hemoptysis, unexplained chronic cough, localized wheezing, and stridor.

Bronchoscopy is also used as a diagnostic and potential therapeutic approach in suspected or documented foreign body aspiration; in evaluation of unexplained pleural effusion; and as a diagnostic tool in lung transplantation, including donor assessment, evaluation of the transplanted organ for stricture or stenosis at the anastomotic site, or for infection or rejection.

In addition, bronchoscopy is used in patient evaluation in the setting of chest trauma, either blunt or penetrating; assessment for chemical or thermal lung injury; in conjunction with endotracheal intubation, including assistance in performing difficult intubations, confirmation of endotracheal tube or tracheostomy tube position, evaluation for tube-related injury, confirmation of transtracheal oxygen catheter position, or as an adjunct in performing percutaneous tracheostomy.

Other uses of bronchoscopy include visual assessment of bronchopleural, tracheo-esophageal, or broncho-esophageal fistulae; as part of the post-operative assessment of tracheal or bronchial anastomoses or determination of the integrity of the bronchial stump following lung resection; and as part of a program of pulmonary toilet in the setting of lobar or lung collapse, usually in the setting of excessive respiratory secretions.

Contraindications

Bronchoscopy must be carefully considered from the perspective of risk versus benefit. Absolute contraindications to the procedure include refractory hypoxemia, uncorrectable coagulopathy, unstable c-spine, severely ankylosed cervical spine, and restricted temporomandibular joint.

Additional, relative contraindications include malignant arrhythmia, unstable cardiac status, uremia, and untreated tuberculosis.

Factors associated with increased risk of complications from bronchoscopy include an uncooperative patient, recent or unstable angina without revascularization, moderate hypoxia, hypercarbia, uremia, lung abscess, immunosuppression, debility, advanced age, malnutrition, inadequately trained operator.

Basic Procedural Technique

The core elements in performing flexible bronchoscopy include administration of patient sedation, topical anesthesia, airway inspection, and sampling via various techniques. Conscious or moderate sedation commonly includes benzodiazepines like midazolam, though opiates such as fentanyl may also be employed synergistically. In certain circumstances deep sedation or general anesthesia may be necessary, as adequate sedation is important for patient comfort and providing a more controlled procedural environment.

Topical anesthesia is generally accomplished with 1% lidocaine. Prior to intravenous sedation, nebulized lidocaine may be used with or without a bronchodilator. Two percent lidocaine gel can be applied to the nares if the bronchoscope will be introduced nasally. Injection of a 1 percent lidocaine solution through the bronchoscope into the trachea, main carina, and large proximal airways helps with cough suppression. The maximum dose of lidocaine should be limited to 8.2 mg/kg in adults, with extra care exercised in the elderly and in those with liver or cardiac impairment. Lidocaine-related side effects include arrhythmias, seizures, cardiorespiratory arrest, and death. Plasma drug levels correlate with the total dose administered during bronchoscopy.

Patient monitoring during the procedure includes pulse oximetry, cardiac monitoring, and periodic measurement of blood pressure. Care should be taken to have appropriate sedation reversal agents including naloxone and flumazenil in the room if needed.

The bronchoscope may be inserted transnasally, orally, or via an artificial airway, including a laryngeal mask airway, endotracheal or tracheostomy tube. A complete bronchoscopic inspection of the trachea, large airways, and subsegments of both lungs should be performed, as this may help localize areas for sampling.

Bronchial washing may be performed for securing cytology specimens. Bronchoalveolar lavage (BAL) may be performed following airway inspection and prior to biopsy or brushing. BAL, which enables a “ liquid lung biopsy” from the distal airways and alveoli, differs from bronchial washing, in which secretions are aspirated from large airways directly or following the instillation of 10 to 30 ml of saline.

BAL is performed in the lung region with the most prominent radiographic involvement. In diffuse disease, the right middle lobe or lingula is usually lavaged due to slightly higher yields from these areas. Use of 100 ml fluid aliquots permits sampling of approximately one million alveoli (1.5 -3% of the lung). Prior to the lavage, the bronchoscope is advanced into a subsegmental bronchus until the lumen is occluded (the "wedged" position). A good wedge position is usually confirmed by noting slight airway collapse when gentle suction is applied. Poor wedge position allows leakage of lavage fluid.

Total fluid volume to be instilled has not been standardized but 100 to 240 ml of fluid in 20 to 60 ml aliquots is typically used. In evaluation of diffuse alveolar hemorrhage (DAH), three sequential lavages should be performed at the same site. Samples are visually inspected for any increase in hemorrhagic appearance from the first to the last specimen, and the procedure should be terminated if substantial distress (e.g., excessive coughing) or falling oxygen saturation are observed. Noting, while rare, BAL can result in pneumothorax.

Bronchial brush biopsy is performed by extending an initially retracted brush encased within a Teflon sheath into the airway of interest. The technique is useful in evaluating a visible endobronchial mass or suspected tumor.

Endobronchial biopsy utilizes forceps (including cup-, alligator-, and needle-type forceps) to obtain biopsies of visible endobronchial lesions or mucosa. The forceps are opened and applied directly to the lesion using gentle, firm pressure. As tissue is engaged, the forceps are closed and "tugged" before being withdrawn through the bronchoscope.

Transbronchial lung biopsy is performed by selecting the segmental bronchus through which the forceps are to be passed. As the forceps disappear from direct view through the bronchoscope, the operator may utilize fluoroscopic guidance to localize the forceps and takes care to avoid the visceral pleura. The forceps are anchored at the bifurcation of a respiratory bronchiole, closed, and then tugged. A sample of lung parenchyma is obtained by effectively tearing respiratory bronchioles. Optimally, 4-6 specimens should be obtained.

Endobronchial needle aspiration (EBNA) can be applied to visible endobronchial lesions using a hub, piggy back or jab technique with manual aspiration via a syringe allowing for a small footprint to minimize bleeding and it allows for depth of the given lesion for a more representative cytology sample.

Transbronchial needle aspirate (TBNA) can be applied to mediastinal and hilar adenopathy with conventional technique vs endobronchial ultrasound guidance. This can also be performed for acquisition of peripheral parenchymal nodules utilizing navigation bronchoscopy and /or radial probe endobronchial ultrasound guidance.

Interpretation of results

Accurate interpretation of cytologic, microbiologic, and pathologic findings from diagnostic bronchoscopy is critical to appropriate patient management.

Performance characteristics of the procedure (applies only to diagnostic procedures)

Diagnostic yield of FOB is generally increased by using a combination of sampling techniques including BAL, brush, endobronchial biopsy, and transbronchial biopsy. Overall yield for malignancy is as high as 85-90% when there is a visible endobronchial lesion, and lower if the tumor is submucosal or not visible on FOB. The yield of transbronchial biopsy for ILD is about 50-70% and may be increased by adding BAL. The yield of transbronchial biopsy for sarcoidosis increases with severity of disease and ranges 55-85%; adding endobronchial biopsy, even of normal appearing mucosa, increases the yield in this disease.

Outcomes (applies only to therapeutic procedures)

Not applicable.

Alternative and/or additional procedures to consider

Alternative diagnostic procedures may include surgical approaches like VATS lung biopsy, surgical mediastinal lymph node sampling, and transthoracic needle aspiration, all of which are discussed elsewhere.

Complications and their management

A number of well recognized complications of diagnostic bronchoscopy should be noted. Use of topical lidocaine anesthesia may result in complications when the dose exceeds 5 mg/kg. If methemoglobinemia is seen, it is treated with 1% methylene blue (1 mg/kg intravenously over 5-10 minutes, followed by a second dose at thirty minutes, along with ascorbic acid, 2 gm orally). Laryngospasm and bronchospasm are treated with aerosolized albuterol.

Bleeding exceeding 50 ml occurs in 1-4% of procedures, with mechanical trauma (from use of a sampling brush or biopsy forceps) the most common cause. The presence of a vascular lesion may be contributory, and bleeding diatheses, uremia, or a platelet count less than 50,000 per cm3 may predispose to bleeding.

Management of bleeding includes putting the patient in the lateral decubitus position with the bleeding side dependent. Instillation of ice-cold saline through the bronchoscope may be helpful. Wedging of the bronchoscope into the bleeding segment or use of endobronchial balloon tamponade should also be considered.

If these techniques are unsuccessful, bronchial artery embolization can be performed. Intubation using a 8.0 or larger endotracheal tube with intubation in the non-bleeding mainstem bronchus to allow preservation of the lung and use of an endobronchial blocker in the affected side can be helpful. The use of a double-lumen endotracheal tube is often cumbersome and may be problematic to place and maintain in the desired position; therefore would not be routinely recommended. Rarely, endobronchial instillation of sinoacrylate glue or oxidized, regenerated mesh has been used.

Hypoxemia may occur because of respiratory depression or the presence of obstructive sleep apnea. Suctioning during the procedure removes oxygen from the environment, and endobronchial insertion of the bronchoscope increases airflow obstruction, so supplemental oxygen should be provided through a nasal cannula or oxygen mask. Reversal of sedation may also be helpful. Finally, intubation and mechanical ventilation may be necessary.

Pneumothorax may be detected during routine fluoroscopy, post procedure chest radiograph, or thoracic ultrasound and may require insertion of a chest tube.

Pneumonia and fever may occur following the procedure.

Proper disinfection of the bronchoscope is extremely important in preventing nosocomial transmission of tuberculosis and nontuberculous mycobacterial infections and outbreaks of other notable infections, including those that are due to the Pseudomonas species. High-level bronchoscope disinfection is achieved using 2% glutaraldehyde, and sterilization may be achieved using ethylene oxide-based protocols.

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