Tracheobronchial stenosis can occur as a result of a variety of congenital and acquired disorders (Table 1).1-9 It can manifest with a variety of symptoms, including recurrent infection, difficulty mobilizing secretions, wheeze, dyspnea, stridor, or overt respiratory failure.
Techniques for promptly alleviating central airway obstruction involve surgical and endoscopic approaches. Surgical techniques include tracheostomy to bypass obstructed regions or definitive tracheo- or bronchoplasty to remove a stenotic segment of the airway.10 Frequently, the overall prognosis of the patient or the comorbid medical conditions make the risk of open surgical repair prohibitive. In these settings, one may choose from among a variety of available endoscopic techniques, including bougie dilatation, balloon bronchoplasty, stent placement, laser photoresection, electrocautery, cryotherapy, and brachytherapy.11 The majority of these procedures can be performed with either a flexible or a rigid bronchoscope. The flexible bronchoscope offers the advantage of reaching areas of the bronchial tree outside the reach of the rigid instrument. Flexible bronchoscopy can generally be performed using conscious sedation, minimizing the risks of general anesthesia and hastening the recovery time. The rigid bronchoscope provides better control of the airway, allows simultaneous ventilation of the patient, and can itself be used to dilate proximal stenoses.12
Each of the endoscopic techniques mentioned has associated risks. Stents can become displaced causing airway compromise or can become obstructed by secretions, ingrowth of granulation tissue, or tumor. Metallic stents also may fracture or become deformed as a result of metal fatigue. Laser photoresection risks perforation of the airway lumen, hemorrhage, or airway ignition, especially in the presence of high inspired oxygen concentration, a silicone stent, or endotracheal tube. Electrocautery also runs the risk of significant hemorrhage. Cryotherapy generally mandates a second procedure within several days of the first to remove necrotic debris whose presence can threaten airway patency. Brachytherapy provides relief, which is slower in onset, and the use of radiation risks additional mucosal injury.13
Balloon bronchoplasty (BB) has been used in the setting of both malignant and nonmalignant airway obstruction, either as the sole therapy or as an adjunct to several of the previously mentioned endoscopic techniques.8,13,14 The relatively simple nature of this procedure and its low incidence of complications likely portend widespread use in the future. This review explores the published literature on the use of BB in the management of central airway obstruction.
Before performing BB, it is critical to carefully examine imaging studies to determine the length of the stenosis, the patency of the airway distal to the stenosis, and its proximity to airway branch points and vascular structures. It is fruitless to dilate proximal airways when distal segments are also obstructed and not amenable to the therapy. The roentgenographic features of the stenosis will also help guide selection of a balloon with an appropriate length and diameter. The latter is based on the size of the normal airway lumen proximal to the area of obstruction. In case of a stenosis of the right or left main bronchus too close to the carina, the diameter of the contralateral normal main bronchus is used to determine the balloon size.
A thorough inspection of the airways is then performed, and the location and length (when possible) of the stenosis are determined. The balloons designed for endobronchial dilation are made up of silicone and require high inflation pressures (CRE pulmonary balloon dilatation catheter; Boston Scientific, Natick, MA). A specially designed bronchoplasty balloon can be expanded to 3 different diameters corresponding to 3 different inflation pressures and allow incremental dilation when necessary. To deliver appropriate and sustained inflation pressure without causing the balloon rupture, a calibrated high-pressure syringe with a “3-way lock” design is required to carry out the procedure (Fig. 1).
Depending on the diameter of the working channel of the flexible bronchoscope and that of the balloon catheter, we place the latter directly through the bronchoscope with the aid of a water-based lubricant and position it across the area of stenosis, as described by Mayse et al.15 It is essential to extend the entire balloon out of the working channel of the flexible bronchoscope to prevent any damage to the scope during balloon inflation. An alternative to this method is to use a guidewire and a modified Seldinger technique to place the balloon under fluoroscopy.11 Placement of radiopaque skin markers depicting the extent of the stenosis, under fluoroscopy, is required before the insertion of the guidewire (Fig. 2). It is important to position the catheter so that approximately 0.5 cm of the balloon is visible proximal to the stenosis. If the balloon is placed too proximally or too distally, it will tend to slide out of the stenotic region in the respective direction upon inflation (Fig. 3). Once proper balloon position is confirmed endoscopically, the balloon is inflated using a “pressure syringe” (Fig. 4). We usually perform 2 to 3 inflations for 30 seconds at the appropriate atmospheric pressures designated by the manufacturer. We use saline for balloon dilation when the procedure is performed under direct vision or water-soluble contrast medium at a 1:3 dilution when the procedure is performed under fluoroscopy. Contrast material is diluted to reduce its viscosity and minimize lung injury in the event of inadvertent balloon rupture.
The balloon must be completely deflated before withdrawal from the bronchoscope to minimize the risk of lacerating the working channel. If the residual fluid in the balloon hinders removal through the bronchoscope, the bronchoscope and balloon can be withdrawn together. This allows cutting off of the balloon catheter, which is extending from the distal end of the flexible bronchoscope, and then safe removal of the proximal end of the catheter.
In settings where it is difficult to pass the balloon through the lumen of the stenosis, we frequently attempt gentle dilation with a Fogarty embolectomy catheter. These catheters differ from the bronchoplasty catheter in the fact that the balloon is made of latex and is inflated with air at low inflation pressures. The Fogarty catheter is passed through the area of stenosis, and the balloon is inflated distal to the stenosis. The latter is then withdrawn through the area of stenosis while inflated, providing gentle dilation of the stenotic segment to facilitate insertion of a bronchoplasty balloon catheter or other instrument through the stenosis. Although it shares obvious similarities, this procedure is distinct from balloon bronchoplasty because the latex elastic balloon easily deforms and cannot withstand the inflation pressures typically used to disrupt a fibrotic region of stenosis.
Bronchoscopy is repeated to evaluate the result, to determine need for further dilation or additional therapy such as stent or electrocautery, and to evaluate for complications such as airway tear,16 rupture,17 or hemorrhage.
A number of benign diseases can result in airway stenosis that behaves in a life-threatening fashion. Although the prognosis depends on the underlying etiology, nonmalignant causes of stenosis tend to have a more favorable prognosis than malignant ones. This carries importance in regard to selecting the most appropriate endobronchial therapy. Given the complications of granulation tissue ingrowth and strut fractures, the decision to place metallic stents for nonmalignant disease should be weighed carefully. The literature on the use of balloon bronchoplasty in benign diseases is limited to small case series (Table 2), a number of which used BB in addition to other techniques. Ferretti et al reported a series of 19 patients with stenosis of at least 50% in main or lobar bronchi.3 The etiologies included Wegener's granulomatosis, radiation therapy, postsurgical (lung transplant or sleeve lobectomy), and trauma. Thirteen of 19 patients underwent successful balloon dilatation. Of these, 7 developed restenosis within 30 days, which was successfully treated in 3 with repeated procedures. In all, 9 patients (47%) improved with BB alone, for a mean follow-up period of 21.6 months. Sheski and Mathur reported the use of balloon bronchoplasty on 14 patients with benign airway stenosis resulting from lung transplantation, sleeve resection, radiation therapy, and fibrosing mediastinitis. Ten (71%) achieved long-term success requiring only 1 session for up to 72 months of follow up.11
Balloon bronchoplasty has also been described in the treatment of granulomatous airway disease from sarcoidosis and tuberculosis. Fouty et al reported a series of 6 patients with sarcoidosis with multifocal airway stenosis and referable symptoms. All were treated successfully using a Fogarty embolectomy catheter.18 Four of the 6 patients required more than 1 procedure, but all have experienced improvement of symptoms. These results are comparable to those obtained by previous authors who noted long-term benefit of bougie and balloon dilation in patients with sarcoidosis.19,20 Lee et al described their management of 19 patients with left main bronchus occlusion resulting from tuberculosis,20 15 of which underwent BB, whereas the remainder received metallic Z stents as a result of long segmental stenosis and total atelectasis of the left lung. Complications of BB were limited to fever in 8 and mild hemoptysis in 6. Of the 15 patients treated with BB, 11 (73%) had immediate improvement in dyspnea. Three of the 4 patients treated with stents had complications, including strut fracture (2) and granulation tissue causing luminal obstruction (1). Two of these patients eventually required left pneumonectomy. These results suggest that BB should serve as a first-line therapy for airway obstruction resulting from tuberculosis.20
Balloon bronchoplasty in children was first described by Cohen et al, who successfully used the technique to dilate an anastomotic stricture in a 4½-month-old girl who had undergone surgical resection of the distal trachea and proximal right main bronchus as a result of congenital stenosis.21 Hebra et al reported 15-year experience with 37 children treated with BB and other adjunctive therapies, including electrocautery, stent placement, and local injection of steroids. A total of 158 dilations were performed, with 54% of the children experiencing long-term improvement (defined as 2 months by the authors).22 Half of the patients with a tracheostomy were successfully decannulated posttherapy. They noted complications in 7% of procedures, including tracheitis in 2, atelectasis in 3, tracheal laceration in 2 (1 of whom required operative repair and subsequently died), and 1 case each of hypercarbia and pneumomediastinum. Their experience suggests that BB may carry more risk in the pediatric population. Jaffe reported a series of 6 children with tracheal or bronchial stenosis who underwent a total of 23 balloon dilations. Four of the 6 patients improved with the procedure, although multiple repeat dilations were performed in an incremental fashion.23 All successful procedures were notable for the presence of a fluoroscopically visible indentation on initial balloon inflation (Fig. 2), which disappeared during the procedure.23
An additional advantage of balloon bronchoplasty is that it can avoid excessive mucosal trauma unlike that produced by laser photoresection or the rotating insertion of a rigid bronchoscope or a bougie.24 The mucosal damage resulting from these techniques can lead to excessive fibrosis and resultant restenosis. A bronchoplasty balloon exerts only radial force on the airway without the longitudinal shearing seen with other mechanical dilation techniques. Tremblay et al described a mucosal-sparing technique for use in short circumferential stenoses not involving the cartilage where an electrocautery knife was used to make 3 radial incisions in the stenotic region followed by gentle balloon dilation.25 A similar procedure using an Nd:YAG laser followed by gentle balloon dilation (not BB) had previously been reported by Mehta et al, suggesting that lesions less than 1 cm in length responded best to this technique.24
The results of the use of BB for patients with nonmalignant tracheobronchial stenosis from a variety of causes suggest that it is safe and frequently provides long-term benefit. It seems reasonable to consider balloon bronchoplasty as a first-line therapy for tracheobronchial stenosis in the absence of acutely life-threatening stenosis, reserving more aggressive measures for those who fail to improve or develop frequent recurrence of their stenosis.9 Complications are rare, but those that have been reported include tracheal laceration, hypercarbia, tracheitis, fever, atelectasis, hemoptysis, and pneumomediastinum. Use of bronchoplasty in combination with electrocautery, laser therapy, intralesional steroid, or mitomycin-c26 may result in less mucosal damage and a better long-term result (Fig. 5A, B).
Malignant Airway Stenosis
Balloon bronchoplasty is generally not used as the sole therapy in cases of malignant airway obstruction as a result of the high likelihood of tumor regrowth and restenosis. Laser photoresection, electrocautery, cryotherapy, brachytherapy, photodynamic therapy, and the insertion of silicone-covered metallic stents are alternatives with a higher expected rate of success. Hautmann et al reported their series of 78 patients who underwent 126 BB procedures for malignant airway obstruction.8 BB was chosen when lesions were not amenable to stents as a result of location of the lesion, when laser therapy or cryotherapy were considered inappropriate as a result of the presence of intrinsic compression, when the risk of bronchial rupture was felt to be high, to dilate previously placed stents, or to facilitate brachytherapy or stent placement. A total of 29 patients underwent 69 balloon bronchoplasties as the sole procedure.8 The majority of these patients had stage III or IV bronchogenic carcinoma. Seventy-one percent of the procedures demonstrated immediate bronchoscopic improvement. Only 43% of these procedures, however, were associated with improvement that lasted greater than 7 days. BB achieved higher rates of luminal patency when used to dilate previously placed stents (86% immediate, 52% at 7 days), to dilate the airway to place a new stent (94% immediate success), or to permit insertion of a brachytherapy catheter (85% success). The procedures were associated with improvement in postobstructive sequelae with resolution of 11 of 12 postobstructive pneumonias, 2 of 2 lung abscesses, and 5 of 8 atelectatic regions. Despite these radiographic improvements, dyspnea improved in only 12 of the 32 patients in whom BB was considered successful.
Complications may be more common when using BB for malignant airway obstruction than its counterpart. In 1 case series dealing with malignant indications, BB was associated with 1 fatality in which a tumor was encasing a pulmonary artery branch. The procedure resulted in massive hemoptysis and asphyxia resulting from laceration of the vessel. Minor bleeding occurred in 41 patients and bronchospasm and hypoxemia each in 2.8
The use of BB in the treatment of malignant airway stenosis has a much more limited role than in benign disease, but can be considered an option if the airways are not amenable to stenting or in regions where other alternatives are not an option. It remains as a useful adjunct while placing stents and delivering brachytherapy.27
Balloon bronchoplasty can be performed safely using a flexible bronchoscope with or without fluoroscopy. Although uncommon, possible complications include bronchospasm, airway laceration, hemorrhage, pneumomediastinum, atelectasis, or pneumothorax. Available data suggest that BB has a high success rate and low complication rates in airway stenosis as a result of benign processes, although repeat procedures are often necessary. BB should be considered a first-line therapy in nonmalignant tracheobronchial stenosis, either alone or as an adjunct with electrocautery or laser therapy to reduce mucosal trauma. BB is less successful in the setting of malignant airway stenosis, and its primary role in this setting is to facilitate performance of more efficacious procedures. It may be used in patients whose stenosis occurs in a region that makes alternative therapies problematic.
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