State of the Art

State of the Art* : Interventional Pulmonology Momen M. Wahidi, Felix J. F. Herth and Armin Ernst Chest 2007;131;261-274 DOI 10.1378/chest.06-0975 The online version of this article, along with updated information and services can be found online on the World Wide Web at: http://chestjournal.chestpubs.org/content/131/1/261.full.html

Chest is the official journal of the American College of Chest Physicians. It has been published monthly since 1935. Copyright2007by the American College of Chest Physicians, 3300 Dundee Road, Northbrook, IL 60062. All rights reserved. No part of this article or PDF may be reproduced or distributed without the prior written permission of the copyright holder. (http://chestjournal.chestpubs.org/site/misc/reprints.xhtml) ISSN:0012-3692

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CHEST Recent Advances in Chest Medicine State of the Art* Interventional Pulmonology Momen M. Wahidi, MD, FCCP; Felix J. F. Herth, MD, FCCP; and Armin Ernst, MD, FCCP

Interventional pulmonology (IP) provides comprehensive care to patients with structural airway disorders and pleural diseases. A growing armamentarium of diagnostic and therapeutic tools has expanded the interventional pulmonologist’s ability to care for pulmonary patients with complex abnormalities, often in concert and close collaboration with physicians in other specialties, such as thoracic surgery. Innovative technologies promise to have an impact on diseases and clinical entities not traditionally treated by invasive pulmonary interventions, such as asthma, COPD, and the solitary pulmonary nodule. Training, credentialing, reimbursement, and scientific validation remain key necessities for the continued growth of IP, and require a concerted effort by chest physicians and their professional organizations. (CHEST 2007; 131:261–274) Key words: airways; bronchoscopy; interventional pulmonology; pleural disease; procedures Abbreviations: AFB ⫽ autofluorescence bronchoscopy; CAO ⫽ central airway obstruction; EBUS ⫽ endobronchial ultrasound; IP ⫽ interventional pulmonology; OCT ⫽ optical coherence tomography; PT ⫽ percutaneous dilatational tracheostomy; RB ⫽ rigid bronchoscopy; ST ⫽ surgical tracheostomy; US ⫽ ultrasound

nterventional pulmonology (IP) is an evolving I field within pulmonary medicine that focuses on providing consultative and procedural services to patients with malignant and nonmalignant airway disorders and pleural diseases. The emergence of this discipline was fueled by the surge in technology geared toward lung health, and by the need to maintain procedural competency and expertise in an ever-expanding specialty of pulmonary and critical care medicine. IP encompasses the following three main areas in pulmonary medicine: malignant and nonmalignant *From the Department of Interventional Pulmonology (Dr. Wahidi), Division of Pulmonary and Critical Care Medicine, Duke University Medical Center, Durham, NC; the Department of Pulmonary and Critical Care Medicine (Dr. Herth), Thoraxklinik Heidelberg, Heidelberg, Germany; and the Department of Interventional Pulmonology (Dr. Ernst), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA. Dr. Wahidi or his employer has received unrestricted grants for CME activities or research from Pentax, Denver Biomedical, and Olympus. He serves as a principal investigator on studies for endoscopic lung volume reduction and asthma treatment. Dr. Ernst or his employer has received unrestricted education grants for CME or research activities from Alveolus, Boston Scientific, Bryan, Cook, Denver Biomedical, Olympus, Storz, and Superdimension. He has served or serves as a principal investigator for studies on autofluorescense, endobronchial ultrasound, endoscopic lung volume reduction, and asthma treatment. Dr. Herth www.chestjournal.org

airway disorders; pleural diseases; and artificial airways. Additional activities may be included depending on the practice environment of the individual physician. The requisite skills range from simple thoracic ultrasound (US) to complex diagnostic endobronchial US (EBUS) and resection of large airway tumors (Table 1). With many innovations looming on the horizon, IP is extending to other lung diseases with therapies such as endoscopic lung volume reduction for emphysema and bronchial thermoplasty for asthma. In this review, we will

or his employer has received unrestricted education grants for CME or research activities from Alveolus, Boston Scientific, Bryan, Cook, Olympus, Storz, Wolf, and Superdimension. He has served or serves as a principal investigator for studies on autofluorescence, endobronchial ultrasound, and endoscopic lung volume reduction. Manuscript received April 11, 2006; revision accepted September 23, 2006. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal. org/misc/reprints.shtml). Correspondence to: Armin Ernst, MD, FCCP, Chief, Interventional Pulmonology, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave, Boston, MA 02215; e-mail: [email protected] DOI: 10.1378/chest.06-0975 CHEST / 131 / 1 / JANUARY, 2007

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Table 1—Procedures Commonly Offered by IP Flexible Bronchoscopy Diagnostic Endobronchial biopsy Transbronchial lung biopsy Transbronchial needle aspiration CT scan-guided bronchoscopy Endobronchial US AFB Therapeutic Balloon dilatation Endobronchial heat treatment Laser Argon plasma coagulation Electrocautery Photodynamic therapy Endobronchial cryotherapy Endobronchial brachytherapy Placement of metallic stents

RB

Balloon and rigid dilatation Percutaneous tracheostomy Mechanical debulking Minitracheostomy Endobronchial heat treatment Placement of transtracheal oxygen Laser catheter Argon plasma coagulation Electrocautery Photodynamic therapy Endobronchial cryotherapy Endobronchial brachytherapy Placement of metallic and silicone stents Placement of dynamic and Y-stents Placement of Montgomery T-tubes

summarize the current state of IP, emerging technologies, and future directions. Spectrum of IP Therapeutic Bronchoscopy Therapeutic bronchoscopy was the nidus for the growth of the IP field. The introduction of laser technology into the tracheobronchial tree and the advent of airway stents in the early 1990s sparked an interest among pulmonologists to gain more experience in the diagnosis and management of airway disorders, and caused a resurgence of rigid bronchoscopy (RB). The main indication for therapeutic bronchoscopy is the presence of airway disorders resulting in central airway obstruction (CAO) [ie, trachea, mainstem bronchi, and bronchus intermedius] where the relief of blockage will have the greatest symptomatic benefits.1 The etiologies of CAO include malignant airway disorders (eg, primary bronchogenic carcinoma and metastatic malignancy to the bronchi) and nonmalignant airway disorders (eg, sarcoidosis, amyloidosis, relapsing polychondritis, infectious complications of tuberculosis, histoplasmosis or coccidioidomycosis, complications of lung transplantation, and sequelae from the introduction of artificial airways). The airway compromise may remain asymptomatic until a critical airway diameter (ie, 5 to 8 mm) is reached or a new event (eg, infection, bleeding, or mucus plugging) exacerbates the underlying stenosis. The most common symptoms include dyspnea and cough; hemoptysis may be prominent in patients with malignancies, while infectious symptoms surface when postobstructive pneumonia develops. The 262

Artificial Airways

Pleural Procedures Thoracic US Thoracentesis and pleural manometry Tube thoracostomy Placement of tunneled pleural catheters Medical pleuroscopy with pleural biopsies and pleurodesis

diagnosis of CAO depends on a thorough history and physical examination (with findings such as ipsilateral wheezing, stridor, or localized crackles), imaging studies (eg, chest radiograph and chest CT scan), and diagnostic bronchoscopy.2 Advances in bronchoscopic tools and techniques have provided interventional pulmonologists with a wide array of therapeutic options that can be used individually or in combination to match the needs of all patients. RB has seen a resurgence in the last 2 decades3 (Fig 1). After being the only tool to access the airway for almost an entire century, RB faded with the introduction of flexible bronchoscopy in the

Figure 1. The curves depict the increasing number of rigid bronchoscopies (green) performed in an interventional pulmonary practice (Beth Israel Deaconess Medical Center) over several years. The increase in the number of bronchoscopies is mirrored by the general increase in flexible bronchoscopic interventional procedures (red) performed over the same period of time. OR ⫽ operating room; PSPU ⫽ pulmonary special procedures unit. Recent Advances in Chest Medicine

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late 1960s. The renewed interest stemmed from the recognition of the advantages of RB, such as the ability to ventilate the patient while intervening in the airways, the capability of using large-suction catheters to aspirate blood or debris, and the utility of the barrel of the rigid bronchoscope in “coring out” tumor tissue and dilating stenoses. RB is ideal for massive hemoptysis, tight airway stenosis, and a moderate-to-large tumor tissue burden in the airway. Flexible bronchoscopy in these instances is not optimal due to the small size of its lens and working channel, and the possibility of converting stable airways in marginal patients into a life-threatening respiratory emergency. Therefore, flexible bronchoscopy should be utilized only for these indications after an airway is secured with endotracheal intubation. Dilatation of airway stenoses can be achieved with controlled insertion of the barrel of the rigid bronchoscope, the sequential introduction of serially enlarging semi-rigid (Jackson) dilators, or balloon dilatation.4,5 The latter is considered the preferred method given its perceived gentle dilatation and minimal trauma to the airways.

Tissue removal is a main objective in the relief of airway obstruction. The abnormal tissue can be caused by tumor growth, inflammatory process, or necrotic debris. Mechanical debridement is accomplished by coring out the tissue with the barrel of the rigid bronchoscope or by grasping large pieces with rigid forceps. A new instrument is the so-called therapeutic flexible bronchoscope, which has a large working channel (3.2 mm) and can accommodate large flexible forceps, making it feasible to remove mediumsized endobronchial tissue growths during flexible bronchoscopy procedures in selected patients. During RB, a variety of flexible bronchoscopes are routinely used to access angulated or distal airways and to facilitate the debridement process in these locations. Tumor destruction can also be accomplished with a variety of endobronchial tools including heat therapy (eg, laser therapy, electrocautery, argon plasma coagulation), photodynamic therapy, cryotherapy, or radiotherapy (brachytherapy)6 –15 [Table 262–74]. Although some forms of heat therapy (ie, laser therapy and electrocautery) can be used to directly

Table 2—Comparison of Currently Available Bronchoscopic Ablative Therapies

Modality Nd:YAG laser

Mechanism

Effect

Thermal energy produced by laser light Electrocautery Thermal energy produced by an electrical current Argon plasma coagulation

Photodynamic therapy

Brachytherapy

Cryotherapy

Coagulation and vaporization of tissue Coagulation of tissue but more superficial effect than laser Thermal energy Superficial produced by the coagulation of interaction between tissue argon gas and an electrical current Injection of a Delayed destruction photosensitizer of tissue (24–48 h) followed by the destruction of presensitized tumor cells through illumination with nonthermal laser Direct delivery of Delayed and in-depth radiation therapy destruction of into the airway tissue Destruction of tissue by alternating cycles of freezing to extreme cold temperatures and thawing

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Delayed destruction of tissue (1–2 wk)

Advantages Excellent debulking

Disadvantages

Restoration of Airway Lumen, % of Patients

Relief of Symptoms, % of Patients

Expensive; 83–93%9,10,62,63 63–94%10,62 cumbersome setup

Excellent safety Contact mode profile; multiple requiring frequent instrument designs; cleaning of probe inexpensive No undesired deep Ineffective for intissue effects depth tissue coagulation or debulking

88–89%64–66

Relatively long-lasting effects

Expensive; need for multiple bronchoscopies; skin photosensitivity lasting up to 6 wk

46–67%68,69

100%68,69

Long-lasting effect; synergistic with external beam radiation Good tool for retrieval of foreign objects and removal of large mucus plugs or clots

Higher incidence of complications, particularly hemorrhage Not suitable for debulking in acute airway obstruction; need for multiple bronchoscopies

78–85%70–72

69–90%70–72

77–79%13,73,74

70–93%13,73,74

91%67

70–97%64–66

100% relief of hemoptysis8,67

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vaporize tumor tissue, they are often used to coagulate tissue prior to mechanical debridement, in a fashion known as heat-assisted mechanical debulking (Fig 2). Increasingly, electrocautery and argon plasma coagulation are replacing laser therapy as the method of choice for coagulation and vaporization in the airways due to their lower cost, less cumbersome setup, easier use, and more favorable safety profile. Airway stenting is the primary treatment for airway obstruction caused by extrinsic compression. Airway stents come in the following two varieties: metallic and silicone. Metallic stents with partial silicone covers are also available. Silicone stents are cheaper and easily removed; however, they have a higher incidence of migration and require RB for placement16 (Fig 3). Metallic stents can be placed via flexible bronchoscopy or RB, with or without fluoroscopy. Growth of the bronchial mucosa over the metallic wires leads to endothelialization of the stent, and is the likely explanation for the lower migration rate and the

decreased interference with the mucociliary clearance of secretions17 (Fig 4). While metallic stents function exceedingly well in airways afflicted by invasive cancer, they have not faired as well in airways afflicted by benign diseases because of their long-term complications, including obstructive granulation tissue, stent fracture, and difficult and perilous removal. This has prompted the US Food and Drug Administration to issue a warning in July 2005 advising physicians against the placement of metallic stents in patients with benign tracheal diseases except as a last resort (http:// www.fda.gov/cdrh/safety/072905-tracheal.html). When managing benign airway disorders, close collaboration with a surgeon who is experienced in the reconstruction of complex airway abnormalities is crucial to achieve the best results for the patient. With the availability of effective local therapy for the airway, the paradigm of primary treatment in patients with malignant airway obstruction is shifting from external beam radiation to therapeutic bron-

Figure 2. Granulation tissue is visible at the proximal end of a tracheal stent (top left). The tissue is coagulated with the help of argon plasma. The ignited arc working in a noncontact mode is seen (top right). The necrotic tissue (bottom left) is debrided mechanically with the help of large forceps (bottom right). 264

Recent Advances in Chest Medicine

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Figure 3. Top, A: a proximal view of a silicone stent within the right mainstem bronchus. Bottom, B: a distal view of a silicone stent within the bronchus intermedius.

choscopy. External beam radiation was the treatment of choice for patients with CAO, but its effects were often delayed and unreliable. The success rate for reestablishing the aeration of atelectatic lung portions has ranged from 21 to 23%.18,19 If IP capabilities are available, first-line endoscopic interventions should now be strongly considered due to more immediate results and a favorable safety profile. Radiation therapy can then often be performed in a stable patient with an improved performance status to consolidate the effect of endoscopic therapy. The body of evidence supporting the effectiveness www.chestjournal.org

Figure 4. Top, A: squamous cell carcinoma with near complete occlusion of the left mainstem bronchus. Bottom, B: left mainstem bronchus after mechanical resection of the tumor tissue and placement of a metallic stent

of therapeutic bronchoscopy, while growing, is still limited. The data have come predominantly from retrospective studies with very few comparative or randomized clinical trials. The data for ablative therapy is summarized in Table 1. Similar to ablative therapy, airway stenting achieves symptomatic relief in the majority of patients (metal stents, 82 to 97%17,20 –22; silicone stents, 85 to 95%16,23). The impact on survival has been more difficult to elucidate due to the uncontrolled nature and small size of most studies. Clearly, more research is CHEST / 131 / 1 / JANUARY, 2007

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needed to address questions pertaining to the comparison of the effects of various therapeutic modalities, the role of combined therapy, and maximizing benefit while reducing risk. Diagnostic Bronchoscopy The following two US Food and Drug Administration-approved innovations in diagnostic bronchoscopy are available to the interventional pulmonologist: autofluorescence bronchoscopy (AFB) and EBUS. Both modalities provide the following information that is beyond the vision of conventional white-light bronchoscopy: premalignant or early malignant mucosal transformation with AFB; and structural characteristics of the airway wall and adjacent tissue with EBUS. It is arguable that both technologies can be performed by noninterventional pulmonologists, but the steep learning curve and the high cost of equipment make a dedicated practice of IP the ideal venue. The autofluorescence bronchoscope emits a specific wavelength of light, collects the tissue-reflected light, and projects it onto a screen, with green color representing a normal autofluorescence and redbrown color signaling reduced autofluorescence. The latter is seen in premalignant or early malignant lesions due to the increased thickness of the epithelium or tumor neovascularization24 (Fig 5). The targets of AFB are squamous cell neoplasms arising in the central airways. Numerous studies25–27 have shown the superiority of AFB over white-light bronchoscopy in the detection of cancerous lesions; however, an impact on survival has not been elucidated, and, therefore, AFB is not yet recommended as a screening tool for lung cancer. Additionally, endobronchial carcinoma in situ seems overall to be an uncommon event (especially in countries with a rising prevalence of peripheral adenocarcinoma). Most identified abnormalities are of a metaplastic or dysplastic nature, and the value of intervention is unproven in these circumstances.28,29 It is important to remember that most AFB is based on fiberoptic technology. When comparing AFB images to white-light images obtained by modern video endoscopes (especially when equipped with contrast enhancement or high-definition features), it is unclear whether a significant advantage remains. A newer generation of video AFB is awaiting proper evaluation. EBUS utilizes a miniature probe with radial scanning capabilities that, after being coupled with the airway wall by a water-filled balloon, can visualize the layers of the bronchial mucosa, and reliably differentiates neighboring tumor masses, lymph nodes, and vascular structures. Information on the 266

Figure 5. A patient with a small endobronchial carcinoma in situ. The white-light endoscopy (top, A) shows small raised lesions; they are much more clearly visible with the help of AFB (bottom, B).

surrounding mucosa aids in distinguishing adjacent tumor invasion from mere external compression, as well as determining the depth of an endobronchial neoplastic growth, which ultimately influences the utility of surgical resection or endobronchial treatment in an early-stage cancerous lesion.30,31 Many interventional pulmonologists now consider an EBUS examination a necessary step in the evaluation of suspected carcinoma in situ lesions to assess the likelihood of endoscopic treatment success. Recent Advances in Chest Medicine

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One of the greatest benefits of EBUS is the real-time guidance of transbronchial needle aspiration of mediastinal lymph nodes. A new dedicated EBUS bronchoscope is now available and is equipped with a built-in US probe that is capable of curvilinear scanning, which produces a sectorial image of the surrounding lymph nodes and allows real-time sampling (Fig 6). A number of prospective studies32–34 have documented the high sensitivity (85 to 95.7%), high specificity (100%), and high accuracy (89 to 97%) of EBUS-transbronchial needle aspiration in the diagnosis of enlarged mediastinal lymph nodes. A randomized clinical trial35 showed a higher yield for EBUS-guided lymph node sampling vs that for standard aspiration in all locations except the subcarinal region (84% vs 58%, respectively). Furthermore, a 2005 study36 demonstrated the high yield of combined US-guided transbronchial and transesophageal sampling of mediastinal lymph nodes. A diagnosis was established in 94% of 160 patients with enlarged lymph nodes located in one or more of eight mediastinal lymph node stations, which is a yield that is comparable to mediastinoscopy with the advantages of performing the procedure under moderate sedation and accessing nodes beyond the reach of the mediastinoscope (ie, posterior carina, hilar, paraesophageal, and pulmonary ligament lymph nodes, and in some cases the adrenal lymph nodes). In this arena, advanced diagnostic endoscopy may reshape the current algorithm in lung cancer staging; it is reasonable to predict that combined endobronchial and esophageal US endoscopy may replace mediastinoscopy as a primary staging procedure in

Figure 6. Image of a transbronchial needle puncture of a small lymph node in the 10R position. The needle is guided by EBUS through a dedicated EBUS endoscope. A Doppler function clearly shows the neighboring vessel. www.chestjournal.org

many patients. Trials that will further outline the role of endoscopy are currently being planned. Pleural Interventions Pleural diseases represent a common problem encountered by pulmonologists in their daily practice. However, surveys37 have shown that fewer than two thirds of pulmonary physicians perform pleural procedures as simple as chest tube insertion. This has led to a practice pattern in which pleural procedures are directed toward interventional radiologists and thoracic surgeons. As pulmonology is uniquely suited to take care of patients with pleural disorders, IP took an interest in pleural disease and sought to empower physicians in the field to handle pleural pathologies in a comprehensive manner, starting from an evaluation with US-guided thoracentesis or tube thoracostomy and ending with definitive management using pleurodesis via medical pleuroscopy. Mastering thoracic US is an important skill for interventional pulmonologists. US is used as a complimentary tool to further assess pleural abnormalities (eg, volume and loculation of pleural effusions, pleural masses, and pleural thickening), to mark the best insertion sites for needles and catheters, and to confirm tube placement or assess complications following pleural procedures. Although data are conflicting and randomized controlled trials are lacking, several studies38,39 have shown a decreased rate of complications when thoracentesis is guided by US. Besides the placement of large-bore chest tubes, the interventional pulmonologist possesses skills in the placement of small-bore pleural catheters (dubbed as pigtail catheters) and long-term indwelling pleural catheters. The former is a less-invasive method of draining the pleural cavity with a smaller tube (8F to 14F), resulting in minimal pain, an invisible scar, and effective fluid drainage. Talc pleurodesis has been accomplished using these tubes with a success rate comparable to those of larger chest tubes; however, their use in patients with empyema or hemothorax may not result in optimal drainage due to tube clogging.40 Tunneled pleural catheters are used on an outpatient basis for the intermittent drainage of malignant pleural fluid. They are as effective as chemical pleurodesis in relieving patients’ dyspnea and can lead to spontaneous, albeit often delayed, pleurodesis in up to 46% of patients.41 Medical pleuroscopy is an evaluation of the pleural space that is performed by the interventional pulmonologist as an alternative to closed pleural biopsy and video-assisted thoracic surgery.42 The procedure is performed with a conventional rigid or a semi-rigid CHEST / 131 / 1 / JANUARY, 2007

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pleuroscope (similar in design to a bronchoscope). The evaluation proceeds with the insertion of the pleuroscope into the pleural space through one or two incisions with the patient under moderate sedation. This tool enables the operator to inspect the pleural layers, drain pleural fluid, perform targeted biopsies of the parietal pleura, and insufflate talc for chemical pleurodesis (Fig 7). Medical pleuroscopy has proven to be safe and effective, and far superior to closed pleural biopsy in establishing a diagnosis of a pleural pathology.43 Video-assisted thoracic surgery, performed by thoracic surgeons in the operating room under general anesthesia with doublelumen intubation and collapse of the targeted lung, remains the “gold standard” for the evaluation and management of a complex pleural space and for the sampling of lung tissue. Artificial Airways Surgical tracheostomy (ST) is one of the oldest surgical procedure and was the “gold standard” until Ciaglia and colleagues44 introduced the percutaneous route in 1985. Percutaneous dilatational tracheostomy (PT) has since become a popular procedure that is performed in ICUs around the world by interventional pulmonologists, intensivists, otolaryngologists, and surgeons. The indications for PT are identical to those for ST and consist of the establishment of airway access for long-term mechanical ventilation, the need for a

conduit for pulmonary toilet, and the relief of upper airway obstruction. PT employs the modified Seldinger technique by introducing sequential dilators through the skin into the trachea to create a tract for the tracheostomy tube. Many operators use bronchoscopy for real-time guidance to ensure the correct placement of the wire and dilators. The rate of complications with PT is low and is comparable to that with ST, as shown by multiple randomized controlled trials.45 Postoperative complications, particularly bleeding and infection, have been shown to be lower with PT, likely due to the reduced tissue trauma and the snug fit of the tracheostomy tube in the cutaneous-tracheal tract. Other advantages of PT over ST are cost reduction (related to the avoidance of operating room costs) and the elimination of the higher risk that may be involved in the transport of critically ill patients to the operating room.46 The interventional pulmonologist is ideally suited to perform PT due to their ability to handle late postoperative complications such as tracheal stenosis, tracheomalacia, and tracheoesophageal fistula. Surgical resection is the main treatment for a limited tracheal lesion, but for patients with complex long lesions or poor medical conditions, bronchoscopic interventions, such as balloon dilatation, laser incisions, or placement of silicone or Montgomery Ttube stents, can provide patients with symptomatic relief and a superior quality of life.47,48 Other artificial airway procedures offered by IP include the placement of transtracheal oxygen catheter in patients with chronic pulmonary diseases requiring high concentrations of oxygen and the insertion of a minitracheostomy in patients with neuromuscular diseases who are in need of easy access to the airways to facilitate the suctioning of respiratory secretions.49 New Developments and Concepts in Evaluation New innovations are continually fueling the growth of IP; while some are adopted from other fields and are tailored to pulmonary applications, others represent new pioneering concepts. Therapeutic Developments

Figure 7. Nodules seen on the diaphragmatic pleura during medical pleuroscopy in a patient who presented with a right pleural effusion. The biopsy specimen showed adenocarcinoma cells that were consistent with an ovarian origin. 268

The microdebrider, a surgical tool routinely used by otolaryngologists and orthopedic surgeons, may also have a therapeutic role in the central airways. It is a powered instrument with a rotating blade inside a hollow metal tube that is connected to suction. When it comes in contact with tissue, it is capable of cutting and disposing of it in an efficient manner. In a study of 23 patients with benign and malignant Recent Advances in Chest Medicine

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tracheal conditions, the microdebrider was able to rapidly clear all obstructing lesions and keep a blood-free field with no procedure-related complications.50 Radiofrequency ablation is a thermal therapy that is traditionally applied percutaneously to treat primary or secondary malignancies of the lung. An interest in using this modality bronchoscopically has surfaced in the following three areas: its potential for use as an adjunct therapy in the removal of metallic stents by means of thermal destruction of granulation tissue51; its role in ablative treatment for pulmonary nodules and masses; and its possible therapeutic role in asthma. The latter application has caught the attention of many physicians, given the broad health implications in a common disease like asthma in which a fraction of patients exhibit poor control with medical management alone. The hypothesis centers around the significant contribution of airway smooth muscles to the airway narrowing that is seen during asthma exacerbations and the prospect of decreasing airway hyperresponsiveness by reducing the smooth muscle mass with controlled low-energy radiofrequency ablation in the airways (Alair Bronchial Thermoplasty; Asthmatx; Mountain View, CA). Two preliminary studies52,53 have demonstrated the safety and effectiveness of this treatment in patients with mild-tomoderate asthma with significant reduction in airway responsiveness to methacholine challenge, and improvement in peak flows and number of symptomfree days. A randomized controlled trial is currently underway. Another promising application of therapeutic bronchoscopy in a common disease is bronchoscopic lung volume reduction in patients with emphysema. The National Emphysema Treatment Trial54 has shed some light on the benefits of surgical lung volume reduction while exposing the high mortality in patients with severely reduced pulmonary function. By the placement of one-way valves in the upper lobe bronchi of patients with upper lobepredominant emphysema, upper lobe collapse can potentially be achieved, replicating the benefits of surgical lung volume reduction in a less invasive manner55,56 (Fig 8). A large randomized study using one-way valves (the Endobronchial Valve for Emphysema Palliation Trial) has been completed, and efficacy as well as safety results should be available within 1 to 2 years. Multiple other approaches to endoscopic lung volume reduction for heterogeneous emphysema are under investigation. For patients with homogeneous emphysema, endoscopic extraanatomic airway bypass procedures are being evaluated. www.chestjournal.org

Figure 8. View of endobronchial one-way valves placed into the airways of a patient with heterogeneous emphysema.

Diagnostic Developments One of the more revolutionary developments in the care of pulmonary patients in the last decade has come from the field of radiology with the advent of multidetector helical CT scanners, enabling an accurate and expanded understanding of central airway disorders.57 These new scanners are capable of acquiring a single data set of the entire thorax during one breathhold. Additionally, they have greatly enhanced the reformation of axial images into twodimensional and three-dimensional (virtual bronchoscopy) images (Fig 9). The benefits of such advanced images include an accurate assessment of the extent and length of the airway lesion, an evaluation of the patency of the airway distal to a stenotic area, an understanding of the complex relationship of the airway abnormality to adjacent mediastinal structures, preprocedure planning for the optimal intervention during therapeutic bronchoscopy, and a noninvasive follow-up of treated airway lesions. Navigational bronchoscopy by electromagnetic guidance (superDimension; Plymouth, MN) is a groundbreaking concept in the diagnosis of peripheral lung lesions. The patient is placed over an electromagnetic board and a microsensor probe is inserted through the working channel of the bronchoscope into the airways. Reference anatomic landmarks, such as the main and secondary carinae, as well as the target lesion are identified on a preacquired digitized chest CT scan and are loaded into the system. The same landmarks are then identified by the probe bronchoscopically, registered in the system, and aligned with data from the chest CT scan. The sensor probe can now be directed in real time to the target lesion, and histologic sampling of CHEST / 131 / 1 / JANUARY, 2007

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improvement in the technology and larger multicenter studies are needed to propel electromagnetic guidance to the forefront of the diagnostic and therapeutic algorithm for solitary pulmonary nodules. The enhancement of bronchoscopic image quality is a tireless mission of many researchers in academic centers and the bronchoscopy industry. A new generation of high-resolution bronchoscopes has made their way into use with ongoing studies attempting to define their diagnostic role. Narrow band imaging is a new bronchoscopic system equipped with filters that illuminates the target tissue at narrower red/green/blue bands of the light spectrum with delineation of the details of the microvascular network59 (Fig 11). Characterization of the vascular pattern of the bronchial epithelial surface promises to advance the understanding of angiogenesis in the early phases of carcinogenesis of lung tissue and the diagnosis of premalignant lesions. Optical coherence tomography (OCT) is another evolving technology that brings the capability of a pathologist’s microscope into the flexible bronchoscope. OCT is similar to US in the fact that both technologies collect backscattered signals from various structures and construct them into images; however, since OCT detects light waves rather than sound waves, the images are much clearer and have an exceptional spatial resolution. When compared to hematoxylin-eosin-stained histologic samples of animal and excised human tracheas, OCT images compared favorably and displayed with precision microstructures such as the epithelium, lamina propria, glands, and cartilage.60,61 An attractive future clinical application of OCT would be the detection and follow-up of submucosal in situ histologic changes without the need to obtain a biopsy.

Training and Certification Figure 9. Axial CT scan image of a patient with a high-grade tracheal obstruction due to adenoid cystic carcinoma (top, A). The three-dimensional reconstruction (bottom, B) gives a much better understanding of the extent of the lesion, and allows for improved procedural and surgical planning.

tissue is conducted through an extended working channel (Fig 10). Moreover, localized treatment such as radiofrequency ablation may be delivered directly to a malignant lesion in selected patients. A preliminary study58 has shown a diagnostic yield of 69% in 29 patients with lesions ranging in size from 12 to 106 mm in diameter and a mean distance to the pleura of 19.6 mm. The overall performance of this technology, however, is still inconsistent. Further 270

IP is constantly growing and integrating new technologies. Acquiring the various skills and maintaining competence is a challenging undertaking. Current venues for training consist of dedicated 1-year IP fellowships, extended sabbaticals in IP centers, and 1- to 3-day condensed courses in selected procedures that are offered throughout the world. There is an intense debate over whether a dedicated additional year of training is required or advanced skills can be obtained during the traditional 3-year fellowship training in pulmonary and critical care medicine. The argument is strongest for dedicated fellowship training. To master a procedural skill, the operator should not only perform a sufficient number of procedures but also should Recent Advances in Chest Medicine

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Figure 10. Typical images of an electromagnetically guided (superDimension) transbronchial lung biopsy. The parenchymal lesion is visible in sagittal, coronal, and axial views. The forward view in the lower right-hand corner gives the “bulls-eye” image when the targeted lesion is reached.

evaluate a large number of patients with a variety of medical conditions and learn, in the process, how to judiciously select optimal candidates for a specific procedure, when to seek alternative therapies, and how to deal with complications. Of equal impor-

tance, an operator should have access to all available tools and technologies so the best treatment can be offered to the patient, not just whatever is on hand locally. Therefore, it is clear that optimal training can only be acquired through dedicated extended learning periods in centers of excellence that provide state-of-the-art care to a high volume of patients. Challenges and Future Directions

Figure 11. Narrow band image of an endobronchial severe dysplasia. Observe the clearly visible microvascular abnormalities. www.chestjournal.org

IP has quickly gained recognition and drawn interest from young trainees, industry, and hospital administrators. The allure is in the “instant gratification” associated with immediate procedural success, the introduction and use of new technologies and treatments, and the sense of empowerment felt with the ability to perform a series of therapeutic interventions by a single physician to the benefit of the patient. However, the reality does not mirror the perceived image, and there are numerous problems facing IP. First, as a young field, IP is confronted by skepticism and may experience territorial battles with other disciplines. This may create a less than collaborative environment during the preliminary phase of establishing an IP practice. Second, an exclusive practice of IP is currently not financially viable outside the realm of high-volume CHEST / 131 / 1 / JANUARY, 2007

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multidisciplinary airway centers in academic centers due to the low professional reimbursement. The current payment schema does not take into consideration the effort and risk put into such complex procedures as RB and the removal of large airway tumors. While the professional reimbursement for coronary artery stent placement is ⬎ $900, the payment for an airway stent insertion is in the range of $230 to $280 (https://catalog.ama-assn.org/Catalog/ cpt/cpt_search.jsp). Third, the present lack of regulation in the validation of training and the verification of competency is problematic. Although individual pulmonologists may be able to do any combination of IP procedures, ideally, the designation of “interventional pulmonologist” is reserved for a pulmonologist who has obtained formal training and has gained experience that spans the entire spectrum of IP skills. To move forward, the IP community has to address these concerns in a cohesive and open-minded manner. The territorial battles are easily remedied by highlighting the multidisciplinary nature of IP and its positive impact on other specialties. The financial concerns need to be addressed through representatives from professional pulmonary societies. The accreditation of IP training programs by the Accreditation Council for Graduate Medical Education and the establishment of an IP board examination or added certification are key steps to ensure the proper acquisition of IP skills and the protection of patients. But, most importantly, IP has the responsibility of practicing evidence-based medicine. It is incumbent on interventional pulmonologists to conduct clinical trials to prove the benefits of their interventions and to study their limitations. Research efforts should address not only improvements in quality of life but also the detection of early disease and the prolongation of survival.

Summary IP focuses on the diagnosis and treatment of malignant and nonmalignant airway and pleural disorders. A variety of new scopes, debulking modalities, and technological innovations have energized the field, and have extended its reach beyond the traditional limits of pulmonary medicine. The future growth of IP will depend on overcoming key issues impeding its progress through the regulation of training and credentialing, petitioning for fair financial reimbursement, and the conduct of rigorous scientific research. 272

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Recent Advances in Chest Medicine

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State of the Art* : Interventional Pulmonology Momen M. Wahidi, Felix J. F. Herth and Armin Ernst Chest 2007;131; 261-274 DOI 10.1378/chest.06-0975 This information is current as of June 15, 2012 Updated Information & Services Updated Information and services can be found at: http://chestjournal.chestpubs.org/content/131/1/261.full.html References This article cites 44 articles, 24 of which can be accessed free at: http://chestjournal.chestpubs.org/content/131/1/261.full.html#ref-list-1 Cited Bys This article has been cited by 6 HighWire-hosted articles: http://chestjournal.chestpubs.org/content/131/1/261.full.html#related-urls Permissions & Licensing Information about reproducing this article in parts (figures, tables) or in its entirety can be found online at: http://www.chestpubs.org/site/misc/reprints.xhtml Reprints Information about ordering reprints can be found online: http://www.chestpubs.org/site/misc/reprints.xhtml Citation Alerts Receive free e-mail alerts when new articles cite this article. To sign up, select the "Services" link to the right of the online article. Images in PowerPoint format Figures that appear in CHEST articles can be downloaded for teaching purposes in PowerPoint slide format. See any online figure for directions.

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