Therapeutic Bronchoscopy




Introduction and Historical Background


Gustav Killian performed the first rigid bronchoscopy in 1897 to extract a piece of a pork bone from the right main bronchus. This innovation resulted in a dramatic decrease in the mortality from aspiration pneumonia. In 1966, the flexible bronchoscope was introduced into clinical practice by Shigeto Ikeda. Currently, the majority of pulmonologists are trained in flexible bronchoscopy (FB), whereas only a minority have been trained in rigid bronchoscopy. With the advent of formalized fellowship training programs in interventional pulmonology, training in rigid bronchoscopy is making a comeback and is an extremely valuable instrument in the management of central airway obstruction ( ). Whereas FB remains invaluable for the diagnosis of lung masses, parenchymal disease, and mediastinal/hilar adenopathy, the rigid bronchoscope offers the ability to provide an airway allowing oxygenation and ventilation, as well as the passage of large-bore suction catheters and a variety of tools that can aid in the destruction and excision of tumor. Additionally, silicone stents can be placed only via the rigid bronchoscope, thus allowing the physician to place the “best” stent in a selected patient as opposed to being limited to stents that can be placed solely via FB.




Therapeutic Bronchoscopy


Central airway obstruction, from both malignant and nonmalignant causes ( Table 23-1 ), is associated with significant morbidity and mortality and often presents a great challenge to physicians. It is estimated that 20% to 30% of patients with lung cancer will develop complications associated with airway obstruction, and the incidence of nonmalignant causes such as postintubation/posttracheostomy stenosis is likely to increase due to the increasing use of artificial airways in an ever-aging population.



Table 23-1

Causes of Central Airway Obstruction










Nonmalignant Malignant



  • Vascular




    • Sling




  • Cartilage




    • Relapsing polychondritis




  • Lymphadenopathy




    • Infectious (e.g., histoplasmosis, tuberculosis)



    • Sarcoidosis




  • Granulation tissue associated with:




    • Artificial airways



    • Airway stents



    • Aspirated foreign bodies



    • Surgical anastomosis




  • Inflammatory lesions




    • Granulomatosis with polyangiitis (Wegener granulomatosis)



    • Amyloidosis



    • Papillomatosis




  • Tracheobronchomalacia



  • Other:




    • Goiter



    • Secretions/blood clot





  • Primary airway tumors




    • Bronchogenic



    • Mucoepidermoid



    • Adenoid cystic



    • Carcinoid




  • Tumors metastatic to the airway




    • Bronchogenic



    • Renal cell



    • Breast



    • Melanoma



    • Thyroid



    • Colon



    • Esophageal carcinoma




  • Lymphadenopathy from any malignancy



  • Mediastinal tumors




    • Thyroid



    • Thymus



    • Germ cell



    • Lymphoma




It should be noted that designing large randomized trials to investigate comparative efficacy is extremely difficult in patients with central airway obstruction. Limitations include selecting patients with comparable disease and comorbidities, as well as the fact that many of these patients present in respiratory distress. Double blinding is also clearly impossible. Therefore the literature supporting therapeutic bronchoscopy is primarily based on large case series and retrospective analyses. That being said, the impact of therapeutic bronchoscopy on quality and length of life is impressive. Therapeutic bronchoscopy has also been associated with immediate reductions in the level of care required for patients with acute respiratory failure from central airway obstruction.


Training in advanced diagnostic and therapeutic bronchoscopy tends to be limited and is more common in centers that have dedicated interventional pulmonology training programs. Over the last several years, dedicated training in interventional pulmonology has become more popular, with 26 dedicated programs currently available in the United States ( www.aabronchology.org ) and the development of standardized curricula and in-service examinations. The first board examination for IP was administered in 2013.


Even with the recent increase in training in rigid bronchoscopy, the flexible bronchoscope remains an essential tool in therapeutic bronchoscopy. It is used in almost every rigid bronchoscopic procedure and, when rigid bronchoscopy is not available, can also be used as the only bronchoscope for foreign body removal, tumor excision/tumor destruction, and balloon dilation. There are several therapeutic techniques, each with its own associated risks and benefits, advantages and disadvantages ( Table 23-2 ). Because comparative data are lacking, the technique of choice often depends on equipment availability and the bronchoscopist’s expertise. Two of the most important considerations in the care of patients with central airway obstruction is assessing the stability of the patient for the planned procedure and having a realistic understanding of the local resources and skill set. Clearly, all efforts should be made to ensure that a patient with a relatively stable airway does not develop an unstable airway during the procedure because these patients can deteriorate quickly. These patients are often best cared for in a multidisciplinary approach in “centers of excellence” that routinely evaluate and manage such problems.



Table 23-2

Advantages and Disadvantages of Therapeutic Modalities


























































Modality Time to Achieve Results Advantages Disadvantages Cautions
Electrocautery Immediate Inexpensive
Multiple accessories
Often need to couple with mechanical débridement Need to deactivate pacemaker/AICD
Keep F io 2 < 0.4
Argon plasma coagulation Immediate Inexpensive
Can treat at an angle to electrode
Risk for gas embolization with higher flow rates
Often need to couple with mechanical débridement
Need to deactivate pacemaker/AICD
Depth of penetration 2-3 mm
Keep F io 2 < 0.4
Laser Immediate Extensive data supporting its use Need laser safety precautions Depth of penetration up to 10 mm
Keep F io 2 < 0.4
Stent Immediate Only bronchoscopic modality for extrinsic compression All stents have associated complications of granulation tissue formation, infection, and migration Metallic stents should be used with caution in patients with nonmalignant disease
Microdébrider Immediate Can use in high-F io 2 environments May need additional tools to provide hemostasis Cannot reach distal airways
Cryotherapy 48-72 hr Normal airway is cryoresistant
Can use in high-F io 2 environments
Delayed maximal effect, requiring “cleanout” bronchoscopy Cryoadhesion can remove organic foreign bodies
Photodynamic therapy 48-72 hr Can destroy submucosal tumor
Can use in high-F io 2 environments
Delayed maximal effect, requiring “cleanout” bronchoscopy
Systemic photosensitivity
Need laser safety precautions
Swelling of tumor can cause obstruction
Brachytherapy Delayed: days—weeks Can destroy submucosal tumor Coordination with radiation oncology Radiation bronchitis
Risk for erosion into vessels
Swelling of tumor can cause obstruction

AICD, automatic internal cardiac defibrillator.




Evaluation and Management of Central Airway Obstruction


Foreign Body Removal


Indications


Foreign body aspiration is one of the most common indications for therapeutic bronchoscopy. There is a bimodal incidence of airway aspiration, peaking in children 1 to 2 years old and in adults older than 70. Risk factors for aspiration in adults include alcohol intoxication, sedative and hypnotic drug use, poor dentition, senility, seizure, trauma, swallowing impairment, parkinsonism, and general anesthesia. In adults, foreign bodies are most commonly found in the right-sided airways but, in children, are found equally in the left and right owing to the equal size and angulation of the main bronchi. Because a history of aspiration is obtained in less than 50% of patients, and visible foreign bodies can be identified on chest radiography in less than 10% of cases, a high index of suspicion is required.


Contraindications, Procedure, Results, and Complications


All contraindications that apply to routine FB also apply to the removal of a foreign body. Lack of experience and lack of availability of all necessary endobronchial accessories are the more important considerations. Removal of a foreign body using FB should be attempted only by or under the supervision of an expert bronchoscopist. The removal of foreign bodies can be performed successfully with either the flexible or rigid bronchoscope. Flexible bronchoscopy is successful in 86% to 91% of cases, whereas rigid bronchoscopy is successful in 99.9%. If available, rigid bronchoscopy should be used in all cases of acute respiratory distress caused by foreign body aspiration given the near 100% success rate and the speed at which the procedure can be performed. The benefits of FB include its widespread availability and its lack of a requirement for general anesthesia.


Foreign body removal using FB is carried out in stages: first, dislodging the foreign body; then, grasping or securing the object; and finally, removing it along with the flexible bronchoscope as a single unit. A variety of ancillary accessories (forceps, grasping claws, snares, baskets, and magnets) are available for foreign body extraction ( Fig. 23-1 ). A cryoprobe passed through the flexible bronchoscope can be especially useful for the removal of blood clots, mucous plugs, and organic material, because the extreme cold can cause immediate and strong adherence (“cryoadherence“) to the biologic materials. Once the object is grasped and secured, care must be taken to avoid losing it in the subglottic area or at the level of the vocal cords. If necessary, the patient can also be asked to cough to expel the foreign body once it has been brought into the mid-upper trachea.




Figure 23-1


A, Examples of foreign body retrieval tools: rat tooth forceps, basket forceps, tripod forceps, five-prong forceps. B, Schematic representation of the use of a balloon catheter for dislodging a foreign body by a retrograde pull.

( B, Courtesy Dr. Eric Folch.)


Serious complications can accompany removal of a foreign body, including central airway obstruction, hypoxemia, bronchospasm, and bleeding. Objects can also migrate, and their fragments can impact in distal airways.


Electrocautery


Endobronchial electrocautery is the application of heat produced by high-frequency electrical current to treat tumor tissue. It involves the use of special accessories such as blunt probes, hot forceps, knives, and snares introduced through a bronchoscope. The probe functions as an active electrode that focuses heat at the point of contact, leading to tissue coagulation or vaporization. The electrical current can also cut or combine cutting with coagulation. The degree of tissue destruction depends on the power used, duration of contact, surface area of contact, and water content of the tissue. Use of the snare device is especially suited to the removal of a pedunculated airway lesion because cauterization of the stalk can allow removal of the majority of the tumor for pathologic review ( ).


To avoid endobronchial ignition, the fractional concen­tration of oxygen in inspired gas (F io 2 ) should be kept below 0.4. Insulated bronchoscopes, compatible with electrocautery, are used to prevent leakage of electrical current, avoiding burns or electrical shock to the patient and the bronchoscopist.


Indications and Contraindications


Electrocautery is used for either coagulation or vaporization of malignant or nonmalignant disease within the airways and has been shown to be potentially curative in patients with carcinoma in situ. Coagulation is achieved by gently touching the tumor tissue and applying 1- to 2-second bursts of 20- to 40-W energy until blanching or destruction of the mucosa becomes apparent. Additional contact time can result in vaporization of the tissue as desired. The tumor area should be kept free of blood or mucus by continuous suctioning, or the electrical current will be dissipated through these liquids. The coagulated tissue can then be removed using biopsy forceps or suction. The use of electrocautery is contraindicated in patients with pacemakers and/or defibrillators to avoid electrical interference with these devices.


Results and Complications


Electrocautery has been used effectively and safely as an ablative modality in both malignant and nonmalignant airway obstruction. In several studies, electrocautery has been shown to achieve luminal patency and symptomatic improvement at rates similar to laser (light amplification by stimulated emission of radiation) and other ablative airway modalities. Moreover, electrocautery is a cost-effective bronchoscopic intervention due to the low cost of the machine and the reusable nature of its accessories. In a selected group of patients with small, polypoid endobronchial lesions, Coulter and Mehta showed that electrocautery had a high success rate (89%) under local anesthesia, thereby eliminating the need for the more costly laser therapy. Complications are rare in experienced hands: the most common ones are bleeding (2% to 5%), endobronchial fire in a high-F io 2 environment, and electrical shock to the operator should the cautery probe touch an ungrounded bronchoscope.


Argon Plasma Coagulation


Argon plasma coagulation (APC) is a noncontact form of electrocautery that uses ionized argon gas (plasma) to conduct electrical current from the probe to the tissue. Because positively charged argon gas flows toward the negatively charged tissue, treatment can be directed in an axial or tangential fashion ( Fig. 23-2A ). As the tissue becomes desiccated, it offers more resistance to the electrical current, limiting its penetration to approximately 2 to 3 mm. APC probes can be passed via a rigid or flexible bronchoscope.




Figure 23-2


A, Schematic presentation of argon plasma coagulation. Arrow shows the tungsten carbide electrode. Positively charged argon gas automatically flows radially to the negatively charged bleeding tissue. B, Damage to the tip of the bronchoscope caused during argon plasma coagulation by having the catheter too close to the tip of the bronchoscope during activation. Note the charred tip along with the frayed rubber sheath.

( A, Courtesy Dr. Eric Folch.)


Indications and Contraindications


APC is frequently used for palliation of malignant airway obstruction as part of multimodality therapy, including mechanical débridement; mechanical débridement is needed to remove the cauterized tissue because, unlike laser, APC and other forms of electrocautery do not vaporize tissue. APC is also extremely useful for control of bleeding in the central airways and has been used for the treatment of excess granulation tissue (including stent-related granuloma), postinfectious airway stenosis, and endobronchial papillomatosis ( ). The most important advantages of this technique are the ability to treat lesions at sharp angles from the tip of the electrode, to treat lesions in close proximity to airway stents, and to achieve superior hemostasis. Its major limitation is the depth of penetration of less than 3 mm; however, this also may reduce the risk for airway perforation. Its only absolute contraindication is the presence of a pacemaker or implantable defibrillator susceptible to electrical interference. As with electrocautery and laser use in the airway, APC requires that the F io 2 be < 0.4.


Results and Complications


In properly selected cases, APC provides symptomatic relief in almost 90% of patients. It is also portable, less expensive than laser, and typically available in most operating rooms (though bronchoscopic fibers may need to be purchased). Potential complications include gas embolization, airway fire, postprocedure stenosis, and injury to deeper structures or to the flexible bronchoscope (see Fig. 23-2B ). The observed mortality and overall complication rates are 0.4% and 3.7% of cases, respectively.


Laser Photoresection


Laser light has three unique characteristics—monochromaticity, coherence, and collimation—that permit controlled delivery of a well-defined energy. Laser light causes thermal, photodynamic, and electromagnetic changes in living tissue. Laser energy can cut, coagulate, or vaporize endobronchial lesions in a predictable manner, depending on the wavelength used. Although many types of laser systems exist, the neodymium:yttrium-aluminum-garnet (Nd:YAG) and neodymium:yttrium-aluminum-perovskite (Nd:YAP) lasers are most commonly used in the airways because of their ability to coagulate and vaporize tissue, with a depth of penetration of 5 to 10 mm. Though the carbon dioxide laser provides minimal hemostasis, it is extremely precise (depth of penetration of <1 mm). Such precision can permit fine procedures such as those needed to incise weblike stenoses or to remove granulation tissue surrounding airway stents.


Indications


The main indications for laser photoresection (LPR) are relief of central airway obstruction from exophytic obstructive neoplasms and from tracheal stenosis ( ). An ideal lesion for the LPR is an endobronchial tumor that arises from a single wall of a central airway and has a visible distal lumen, with a duration of lung collapse of less than 4 to 6 weeks. LPR can be performed using either a rigid or flexible bronchoscope. The end results and the complication rates are similar with both types of instruments. The selection of the scope mainly depends upon personal preference, availability of the instruments, and training. Bronchoscopists proficient in rigid bronchoscopy prefer to use the rigid scope because of the ease of mechanical debulking and superior suction capabilities.


Contraindications


Lesions not amenable to LPR are extrinsic or submucosal, primarily involving lobar or segmental bronchi, and those for which the operator is unable to identify a patent airway distal to the obstruction. As with other forms of heat therapy, laser is contraindicated in patients with a high oxygen requirement.


Results and Complications


LPR can restore airway patency with immediate symptomatic improvement in 93% of cases ( Fig. 23-3 ). It can be combined with other techniques such as APC and stent placement to achieve full patency of major airways. This technique palliates symptoms of cough, dyspnea, and hemoptysis along with documented benefits in radiographic, spirometric, and quality of life parameters. Studies have shown a small survival benefit when emergent LPR is compared with emergent radiotherapy. LPR is associated with the following complications (range, 0% to 2.2%): exsanguination (2%), endobronchial ignition, pneumothorax or barotrauma, bronchopleural or bronchoesophageal fistula, and hypoxemia. Extensive knowledge of the anatomy of the tracheobronchial tree is mandatory before performing the procedure. Accumulation of blood and secretions can lead to rapid desaturation. Tracheobronchial tree perforation can be fatal owing to the close proximity of the great vessels. While performing the procedure, one must take precautions to avoid airway fires, activating the laser only when the F io 2 is < 0.4. Laser safety precautions for the bronchoscopist and operating room personnel are also required.














Figure 23-3


Multimodality palliative therapy for a patient with a malignant lesion obstructing the right main-stem bronchus.

A, Pretreatment. B, Laser photoresection (note the laser fiber). C, Argon plasma coagulation (note the blue argon plasma coagulation catheter). D, After mechanical débride­ment. E, Balloon dilation. A silicone balloon is fully inflated in the right main-stem bronchus location. F, Stent placement. Note the self-expanding metallic stent in place.

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Jul 21, 2019 | Posted by in CARDIOLOGY | Comments Off on Therapeutic Bronchoscopy
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