Tracheobronchial obstruction or tracheoesophageal fistula is a potentially life-threatening condition that usually necessitates immediate interventions for securing airway patency. Most causes of central airway obstruction or airway-esophageal fistula in adults are secondary to malignant conditions including lung cancer, esophageal cancer, metastatic malignancy, lymphoma, and others.1 The placement of airway stents is an effective method of establishing luminal patency in patients with malignant central airway obstruction and restoring luminal integrity in those with tracheoesophageal fistula.2 When the disease involves the lower trachea, carina or the proximal bronchial lumen, insertion of a Y-shaped airway stent becomes necessary.
The traditional method in these situations has been the placement of Y-shaped silicone stents (Orlowski, Hood, Harell, Dumon, and others), the most common being the Dumon Y stent.3 The insertion of silicone Y stents not only requires rigid bronchoscopy and general anesthesia, but also demands a high level of technical expertise that is not readily available at all centers. Moreover, the rigid bronchoscope needs to be placed beyond the obstruction, near the tracheal carina for successful stent placement. This is not only difficult in many of the patients but may also increase the risk of complications secondary to additional procedures that are required to create an adequate airway lumen.4 To circumvent these difficulties, utilization of self-expanding metallic Y stents has been described.1,4–8 Herein, we describe our multicenter experience with the deployment of self-expanding airway metallic Y stents in the management of patients with malignant airway obstruction or fistulization near the tracheal carina.
PATIENTS AND METHODS
This is a retrospective analysis of data collected between August 2013 and August 2015 at 6 different centers across India (Apollo Hospitals, Bengaluru; Kovai Medical Center, Coimbatore; Jaipur Golden Hospital, and Rajiv Gandhi Cancer Institute and Research Center, New Delhi; Department of Pulmonary Medicine and Sleep Disorders, All India Institute of Medical Sciences, New Delhi; and Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh). The study protocol was approved by the Ethics Review Committee of all the participating centers, and a written informed procedural consent was obtained from all the study participants.
The bronchoscopy databases of each participating center were searched for records of airway stent procedures. Consecutive subjects who underwent placement of self-expanding metallic Y stents were included in the study. The following information was extracted from the database: demographic details, clinical diagnosis, presence of respiratory failure (defined as a PaO2<60 mm Hg or a PaCO2>45 mm Hg), indication for the placement of Y stent, site and degree of airway obstruction, presence of tracheoesophageal fistula, the type of (rigid or flexible) bronchoscope used for stent deployment, success of stent placement, and procedure-related and stent-related complications. The subjects were contacted at 3 months after stent placement to ascertain their clinical status.
After a thorough clinical assessment, all subjects underwent preanesthesia evaluation and laboratory investigations including arterial blood gas analysis, complete blood count, clotting profile, serum electrolytes, liver and renal function tests, chest radiograph, and computed tomography of the chest. Flexible bronchoscopy was performed for airway assessment before Y stent placement, wherever feasible. The severity of obstruction was assessed by passing the flexible bronchoscope through the area of obstruction and estimating the lumen size in comparison with the outer diameter of the respective bronchoscope.9 The degree of luminal obstruction was graded as: grade 1, <50%; grade 2, 50% to 74%; grade 3, 75% to 89%; grade 4, 90% to 100%.10 The size of the stent was decided on the basis of the airway measurements performed on computed tomography and flexible bronchoscopy.
Y Stent Placement
All the subjects received a self-expanding metallic Y stent (Micro-Tech Y stent; Micro-Tech; Nanjing, China, or Ottomed Y stent; Mitra & Co., New Delhi, India) with a tracheal limb of 16 to 18 mm diameter and 4 to 6 cm length, and bronchial limbs of 12 to 14 mm diameter (length for the left and right main bronchi being 2.5 and 1.5 cm, respectively). The metallic stent is made up of a nitinol mesh with a thin inner silicone membrane covering. The distal 5 mm of the right limb is uncovered so as to prevent closure of the right upper lobe, if the stent is inadvertently oversized. The stent comes loaded within an introducer sheath (outer diameter 9 mm), and is deployed in 3 steps. The stent assembly is first placed above the carina. The initial retraction of the introducer sheath releases the bronchial limbs. The limbs are color coded (yellow for right and black for left) and are bound by threads that traverse the stent assembly. When the threads are pulled back, the bronchial limbs are deployed from proximal to distal. Further retraction of the introducer sheath of the stent assembly releases the tracheal limb (Fig. 1).
The stent was deployed either with the rigid or the flexible bronchoscope. With the flexible bronchoscope, the Y stent was placed using the Seldinger technique under moderate sedation without the use of an artificial airway. A super stiff (0.035 inch) guidewire was placed in each main bronchus. The bronchial limbs of the Y stent were then loaded on to the guidewires taking care that the guidewires do not cross over. Next, the entire delivery system was advanced to the level of the tracheal carina. The bronchial limbs were then released by initial retraction of the introducer sheath. The stent assembly was further advanced such that the bronchial limbs of the stents were in their respective positions. The placement of the bronchial limbs was confirmed either with fluoroscopy or with an ultrathin (2.8 mm) flexible bronchoscope. Subsequently, the bronchial limbs were deployed by pulling the retaining threads. The tracheal limb of the Y stent was deployed by further withdrawing the introducer sheath, thus completely releasing the stent. For placement using the rigid bronchoscope, the procedure was performed under general anesthesia. The trachea was intubated with a large lumen rigid bronchoscope (internal diameter, 14 mm). For Micro-Tech stents, initial placement of guidewires was performed with the flexible bronchoscope inserted through the barrel of the rigid bronchoscope. For Ottomed stents, the stent assembly was directly introduced through the rigid barrel without the need for guidewires. The stents were deployed using the aforementioned technique. Real-time visualization was achieved using the rigid optical telescope inserted alongside the stent assembly through the rigid barrel.
Data are presented in a descriptive manner as mean with SD (or 95% confidence intervals) or number with percentage.
During the study period, placement of 38 metallic Y stents (23 Ottomed, 15 Micro-Tech) was attempted. The study population included 25 (65.8%) men with a mean (SD) age of 54.8 (10.5) years. The most common underlying disease necessitating the procedure was carcinoma of the esophagus (25, 65.8%) (Table 1). The most common indication (30 subjects, 78.9%) for stent placement was central airway obstruction (Table 1). The site of obstruction was located at the tracheal carina alone in 10 (33.3%) subjects, whereas it was at the level of the carina and the main bronchi in 20 (66.7%) individuals. The degree of airway obstruction was grade 3 to 4 in 24 of the 30 (80%) subjects with central airway obstruction. Respiratory failure was encountered in 17 (44.7%) subjects at presentation. The Y stent was deployed using the rigid (with or without the flexible) bronchoscope in 32 subjects, whereas in 6 subjects the procedure was performed exclusively with the flexible bronchoscope (Table 2). Fluoroscopic assistance was used in 17 (44.7%) subjects.
The stent was successfully deployed in 37 of the 38 (97.4%) subjects (Fig. 2). In 1 patient during flexible bronchoscopic stent deployment, there was injury to the bronchial mucosa with moderate bleeding while placing the guidewire in the left main bronchus. Subsequently, the bronchoscope could not be renegotiated to clear the distal segments. After several attempts the procedure had to be abandoned. In 4 other subjects while deploying the stent using the Seldinger technique (2 each with rigid and flexible bronchoscopic placement), there was criss-crossing of guidewires and the guidewires had to be reinserted. Subsequently, the stents were placed successfully.
The mean duration for deploying the Y stent was 38 minutes (Supplemental Video 1, Supplemental Digital Content 1, http://links.lww.com/LBR/A126), and was not significantly different between rigid and flexible bronchoscopic placement. There was significant improvement in the patients’ symptoms after the procedure. In fact, in all subjects with respiratory failure in whom the stent was successfully placed, there was substantial improvement in symptoms immediately following the procedure, and subsequent cessation of the requirement for supplemental oxygen. The subjects were followed up for a mean duration of 12.2 weeks. The most common stent-related complication was failure to effectively clear the airway secretions with subsequent inspissation in the postprocedure period, which necessitated bronchoscopic toileting in 12 subjects (Table 2). Eight subjects developed granulation tissue at the edges of the stent. In 2 of these subjects, ablation of the granulation tissue was performed with electrocautery. In 2 subjects the stent was removed, one due to stent fracture and in another patient with mucoepidermoid carcinoma (Supplemental Video 2, Supplemental Digital Content 2, http://links.lww.com/LBR/A127). On follow-up at 12 weeks, 18 patients had died due to progression of the underlying disease.
The present study describes our multicenter experience with placement of self-expanding metallic Y stents for the palliation of symptoms in selected patients with malignant airway obstruction or airway-esophageal fistula near the tracheal carina. To the best of our knowledge, this is the second largest series reported till date. The Y stent resulted in immediate improvement in symptoms, and thus effective palliation. A majority of the procedures in this study were performed under general anesthesia using the rigid bronchoscope. There were few procedure-related complications. In patients with airway obstruction involving the lower trachea with or without airway-esophageal fistula, the luminal patency of the airway cannot be ensured even with the combined use of tracheal and bronchial stents, and usually requires placement of a bifurcation silicone Y stent.11 An alternate option in these patients is the self-expanding metallic Y stent (Table 3).1,4,7,12–15
The initial attempt at improvising a bifurcation stent was described by Hauck et al16 in 2003. The procedure involved 2 uncovered (18 mm×6 cm) self-expanding tracheal stents. After stenting of the lower trachea and left main bronchus using a single tracheal metallic stent, an opening (1.5 cm size) in the stent was created at the site of the orifice of the right main bronchus through which the second tracheal stent was introduced to stent the right main bronchus. Subsequently in 2007, Yang et al4 reported the description of the first custom-made, single-unit, single nitinol wire woven self-expanding metallic Y stent. Since then, increasing utilization of metallic Y stents from several manufacturers including Micro-Tech, ECO-Y, Leufen, and others has been reported (Table 3). Most of these studies have reported the use of Y stents in malignant tracheobronchial obstruction or airway-esophageal fistula, similar to our study. Rigid bronchoscopy performed under general anesthesia was the most commonly utilized technique, as was the case in the current study. However, flexible bronchoscopic insertion8,17 and nonbronchoscopic fluoroscopy-guided insertion (1 study) have also been described.14 In 3 large studies describing the deployment of metallic Y stents,1,7,13 lung cancer was the most common indication, whereas esophageal cancer was the most frequent malignancy in our study. The difference in the etiologies is likely due to the inclusion of a large number of subjects with malignant airway-esophageal fistula in the current study, which is most frequently caused by esophageal cancer.18 In contrast to the present study, all the 3 large series have deployed Y stent using guidewires and universally used fluoroscopy during the procedure.1,7,13
In this study, we describe our initial experience of a locally manufactured (Ottomed) self-expanding metallic Y stent. In contrast to other metallic Y stents (Table 3), the stent does not require placement of guidewires with deployment using the rigid bronchoscope, as the bronchial limbs are stiffer and once pushed out of the introducer sheath separate at an angle almost equaling the angle of the tracheal carina (Fig. 3). The placement of 2 guidewires may be associated with technical difficulties. In our study despite adequate precautions, there was criss-crossing of guidewires in 4 patients, and the guidewires had to be reinserted. The stent is also cost-effective (about 500 US dollars), and can be customized according to the size of the tracheobronchial tree by the manufacturer. In situations wherein there is a unilateral bronchial compromise along with lower tracheal involvement, insertion of a single hinged or angled J stent is also an option.
The placement of a bifurcation stent is relatively safe (Table 3) and complications are uncommon as observed in the present study. Apart from a single instance of stent fracture, excess airway secretions and granulation tissue formation at the stent edges were the only significant complications encountered in our study. A significant proportion of patients in our study had expired by the 12-week follow-up. The causes of death were attributable to the underlying disease such as lung cancer and esophageal cancer, other than airway compromise. The increase in the life expectancy of the patients cannot be discerned from this study as there was no control group. However, several of the study participants presented with respiratory failure due to central airway obstruction, a situation where death is imminent in a few hours to days. Thus, the placement of the stents not only increased the longevity but also provided effective palliation from respiratory distress.
The self-expanding metallic Y stent is an alternate option to the silicone Y stent. The metallic stent is compressed and loaded within a thinner deployment catheter (8 to 9 mm), enabling insertion using the flexible bronchoscope. For metallic Y stent deployment with the rigid bronchoscope, the barrel can be positioned far above the obstruction and only the stent assembly and the optical telescope needs to be negotiated beyond the obstruction. The metallic Y stent with its metallic meshwork and a fine silicone covering also is more pliant and has a uniform radial expansile force leading to better approximation to the airway wall. This may theoretically result in lesser risk of leaks and thus better outcomes in patients with tracheoesophageal fistula, although there is no evidence to support this conjecture. The closer conformity to the shape of the tracheobronchial tree due to the radial expansile force also offers a clear advantage in areas where the airway anatomy is irregular. Further, the lesser thickness of the metallic stent leads to greater luminal patency. These features possibly allow better clearance of secretions.19 Further, the placement of the stent does not usually require balloon dilatation to open up the tracheal or bronchial limbs, which may occasionally be required with a silicone stent.11 In addition, the self-expanding metallic stents are easily deployed in situations where there is significant bronchial narrowing despite balloon dilatation, which hinders the opening up of the bronchial limb of the silicone Y stent.
Although metallic Y stents can be placed using the flexible bronchoscope, we propose rigid bronchoscopy as the ideal modality for inserting the metallic Y stent, especially in those with extensive tumor infiltration or those with significant luminal compromise or bleeding. There are several disadvantages of flexible bronchoscopic placement of the Y stent. Rapid and fatal airway loss can occur in case of any procedural complication during flexible bronchoscopic interventions near the carina, particularly in those with involvement of bilateral proximal bronchi. Rigid bronchoscopy allows ventilation of the patient during the procedure and easy suctioning of any procedural airway bleeding,20 which is not possible with the flexible bronchoscope. Although flexible bronchoscopy allows the procedure to be performed under moderate sedation, it entails a risk of loss of airway during the procedure. In case of an incorrect placement of the stent, the stent cannot be easily retrieved using the flexible bronchoscope and might have fatal outcomes in patients who have significant airway obstruction. Further, in our experience, the flexible bronchoscopic placement of metallic Y stent is fairly uncomfortable for the patient.
Finally, as with other metallic stents, the airway metallic Y stents are only indicated for palliation in patients with malignant central airway obstruction or malignant airway-esophageal fistula. Even in those with malignant etiologies, a silicone Y stent is preferred if the expected survival is >6 months as in those with lymphoma and others. In patients with benign causes where Y stent is indicated, the modality of choice should be surgery with silicone Y stent used only as a bridge to surgery.
In conclusion, our multicenter experience with placement of self-expanding metallic Y stents demonstrates that the insertion of the Y stents is safe and provides excellent palliation of airway obstruction or airway fistulization near the tracheal carina.
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self-expanding metallic stent; Y stent; tracheoesophageal fistula; central airway obstruction; bifurcation stent; lung cancer; cancer esophagus; airway stent; tracheobronchial stent
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