Tracheal stenosis is a frequent complication of tracheostomy

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1 Endotracheal Balloon Dilatation and Stent Implantation in Benign Stenoses Bernd Schmidt, MD, Heidi Olze, MD, Adrian C. Borges, MD, Matthias John, MD, Uta Liebers, MD, Oliver Kaschke, MD, Konrad Haake, MD, and Christian Witt, MD Division of Pneumology, Departments of Internal Medicine I and Otorhinolaryngology, Medical School (Charité) of the Humboldt-University of Berlin, Berlin, Germany Background. Tracheal reconstruction is the treatment of choice in nontumorous tracheal stenoses, but recurrences and concomitant medical conditions limit this approach. We investigated the outcome after balloon dilatation and silicone stent implantation. Methods. Forty-two patients with inoperable tracheal stenoses underwent balloon dilatation and afterward silicone stent implantation. Patients were divided into two groups, in group A 24 patients received tracheal stents as a temporary treatment. In group B, definitive stenting was done in 18 patients with severe concomitant medical conditions that did not allow for stent removal. Results. Immediate results were satisfactory in all patients. In group A, stents could be removed in 12 patients after a mean interval of 20 months. Restenting was not required during the following 18.9 months. Twelve patients are still waiting for stent removal after a mean follow-up of 20 months. In group B, mean follow-up is now 48.4 months. Complications included retained secretions, dislocation, and granuloma formation. Conclusions. Stenting after balloon dilatation is safe and effective in benign tracheal stenoses. After temporary use, stents can be removed when local and general conditions permit. In all other patients, stenting proved beneficial for 5 years as more definitive treatment. (Ann Thorac Surg 2001;71:1630 4) 2001 by The Society of Thoracic Surgeons Tracheal stenosis is a frequent complication of tracheostomy and prolonged endotracheal intubation (up to 67%). It is believed to be mainly secondary to shrinking of the cartilagineous structures. Concentric tracheal stenoses comprising 20% or more of the airway lumen were seen in 16% [1, 2]. Segmental tracheal resection with end-to-end anastomosis is the preferred treatment for benign stenoses [3, 4]. Gutter s procedure and submucosal scar resection are done in selected patients [5, 6]. Alloplastic tracheal prostheses, homologous grafts, and investigations in the field of tissue engineering are experimental [7, 8]. The major risks after operation are recurrence of stenosis and difficulties at the site of the anastomosis [3]. The surgical approach is also limited by concomitant medical conditions, operability, and difficult local situations (eg, after several attempts of tracheal reconstruction). Altogether bronchoscopic intervention may be a complementary therapeutic strategy. Montgomery [9] presented the first tracheal-t-stent in 1965, which is still used by ear, nose, and throat surgeons in selected patients [10]. Since 1990, the silicone stent from Dumon [12] has become the most implanted [11]. The Y-shaped Dynamic stent with steel arcs imitating the cartilagineous structure is sometimes required in stenoses and instabilities of the distal trachea [13]. The latest development is that of a thin-walled Accepted for publication Nov 18, Address reprint requests to Dr Witt, Division of Pneumology, Department of Internal Medicine I, Medical School (Charité) of Humboldt University of Berlin, Schumannstr 20/21, D Berlin, Germany. self-expanding polyester stent with silicone covering [14]. The implantation of silicone stents is done under general anesthesia using a rigid bronchoscope, as described elsewhere [12]. Self-expandable metallic stents (Wall-, Ultraflex-Nitinol-stents; Wallstent, Schneider, Bürlach, Switzerland; Ultraflex, Boston Scientific, Watertown, MA) might be an interesting alternative in tracheal stenoses, but need further evaluation [15, 16]. In general, stent implantation should be divided into temporary and definitive stent implantation. The former is done in the expectation of curing stenotic lesions and stabilization of tracheomalacia. It can be a bridging strategy before surgical intervention and, by definition, for a limited time. The feasibility of temporary stenting has been demonstrated [17 19]. Definitive stent implantation is done in patients with severe comorbidity or in case of longer malacia. The immediate improvement of lung function, dyspnea, blood gases, and ventilation after stent implantation has been shown [18, 20, 21]. Longterm results have been reported in single patients [17, 22, 23]. At present, there is still no answer to the question how long stents should be left in place in benign tracheal stenoses. Dumon initially recommended 6 to 12 months, other investigators recommend a longer period of 18 months [17]. Randomized comparative study designs cannot be performed due to ethical reasons. Only the report of experiences in large patient groups can contribute to answer the questions and improve treatment strategies. Therefore, we report the outcome of long-term 2001 by The Society of Thoracic Surgeons /01/$20.00 Published by Elsevier Science Inc PII S (01)

2 Ann Thorac Surg SCHMIDT ET AL 2001;71: STENTING IN BENIGN TRACHAEL STENOSES 1631 definitive and temporary stenting after balloon dilatation in benign tracheal stenoses. Material and Methods Between 1994 and 1998, 42 consecutive patients (12 women) aged between 23 and 95 years (mean age, 60 years) were treated with endoscopic stent implantation for nontumorous tracheal stenoses and were included in this study. The indications for tracheal stent implantation were fibrous stenotic strictures (n 21), predominantly malacic stenoses (n 18), and combined stenoses (n 3). Underlying causes were long-term intubation (n 33), tracheostomy (n 6), and goiter with airway compromise (n 3). Airway diameter was less than 50% of normal in all patients. The selection for intervention was based on symptoms (dypnea, stridor) and findings (airway lumen, retained secretions, oxygen saturation, and others). Computed tomograms and lung function tests were done on several patients, but did not significantly influence the therapeutic strategy. Length of the stenoses was between 15 and 110 mm (mean, 25 mm). Every case was extensively discussed with experienced general and ear, nose, and throat surgeons. Indication for surgical treatment of the tracheal stenoses had to be denied before stent placement, except for 2 patients with goiter in whom the underlying cause was operated. Patients were divided into two groups before stent implantation. In group A, stent implantation was done with the intention of temporary treatment. This included patients with malacia of the tracheal wall and complicated tracheal stenoses. Five of these patients had recurrent stenoses after tracheal resection and reconstruction. Two patients with severe goiter received stents to secure airway lumen perioperatively. Decisive criteria for stent removal in this group were absence of inflammation in the tracheal mucosa, stabilization of the wall at the ends of the stents, loosening of the device when carefully touched with endoscopic forceps, and stent dislocation without significant remaining stenosis (airway lumen, 60%). In group B, stent implantation was used as a definitive palliation. Patients with concomitant medical conditions that did not allow for any further invasive procedure or operation, or patients who had undergone several operations without success or had experienced recurrent complications were included in this group. We used Dumon silicone stents (Novatech, France) in all patients of this study. Stent diameter was 14 to 18 mm and stent length between 40 and 110 mm. Implantation The implantation of stents was performed under general anesthesia and jet ventilation using a rigid bronchoscope. The stent was inserted according to the procedure described by Dumon [12]. Balloon dilatation has been performed in all patients before stent implantation using Maxforce TTS balloons (Boston Scientific, Watertown, MA) with a diameter of 15 to 18 mm (maximum pressure, 5 atm). Adjustment of the stent within the trachea was Fig 1. (A) Tracheal stenosis after long-term intubation. (B) Recanalization of the benign tracheal stenosis with a silicone stent (Dumon). done with endoscopic forceps and a dilatation balloon. Flexible bronchoscopic controls were routinely performed 24 hours, 1 and 4 weeks, and 6 months after stent implantation. In long-term stenting bronchoscopy was done annually. The long-term outcome in both groups was analyzed. Results Balloon dilatation and subsequent Dumon stent implantation has been done in 42 patients. Immediate results were technically satisfactory in all patients. It was possible to place the device into the stenotic area (Fig 1). One patient died 22 months after stent placement from unrelated causes.

3 1632 SCHMIDT ET AL Ann Thorac Surg STENTING IN BENIGN TRACHAEL STENOSES 2001;71: Table 1. Group A: Patients Treated With the Intention of Temporary Stenting Patient No. Age (yr)/sex Cause Stent in Place (months) Follow-up After Removal (months) 1 55/f Intubation /m Intubation /m Intubation /m Goiter /m Tracheostomy 18 a /m Intubation 13 a /m Intubation /m Intubation /f Goiter /m Intubation /f Tracheostomy 18 a /m Intubation /m Intubation 9 in 14 37/f Tracheostomy 18 in 15 30/m Intubation 21 in 16 61/m Intubation 11 in 17 27/f Intubation 24 in 18 67/m Intubation 22 in 19 63/m Tracheostomy 23 in 20 65/m Intubation 30 in 21 26/m Intubation 23 in 22 60/f Tracheostomy 2 in 23 71/m Intubation 32 in 24 75/f Intubation 22 in a Stent dislocation, no important remaining stenosis after removal. f female; in stent not yet removed; m male. Group A Twenty-four of 42 patients were treated with the intention of temporary stenting and were included in group A (Table 1). In 12 patients stents could be successfully removed after a mean period of 20 months (range, 1 to 51 months). During the mean follow-up of 18.9 months (range, 1 to 58 months), no significant recurrence of tracheal stenosis was observed (Fig 2). No stent reimplantation was necessary. Only 1 patient required tracheostomy when being admitted to hospital with myocardial infarction. Analyzing this group we can distinguish two different types of temporary stenting. In 2 patients with airway compromise due to severe goiter in whom thyroidectomy was performed, stents remained in place for only 1 month to secure the tracheal lumen in the pre- and perioperative periods. In all other patients stent removal was done when mucosal inflammation diminished and when the stent loosened and the remaining stenosis of the airway was not important. In 3 patients of group A, loosening of the stents led to dislocation between 13 and 18 months after implantation. The remaining stenoses did not require restenting. Stent removal was generally attempted between 1 and 2 years after stent implantation. In 12 patients stents are still in situ after a mean interval of 20 months waiting removal. Fig 2. Five months after removal of the stent. Group B Definitive stenting was performed in 18 of 42 patients. Nine of these patients were not amenable to operation because of advanced age and severe comorbidity. In 7 patients severe alteration of the anatomic structures after recurrent operations did not permit any further surgical intervention. Two patients of advanced age (80 and 95 years) refused consent for tracheal resection and therefore, were treated with stent implantation. These conditions gave reason for the decision to perform stenting as definitive long-term palliation. Mean follow-up in these patients is 48.4 months (range, 36 to 61 months). Stent tolerance was good or excellent in all patients. Only 2 patients required replacement of the stents with longer devices when the trachea collapsed at the distal end of the stent. Annual controls were done to verify stent position and remove secretions within the stent. Complications Complications included important granuloma formation in 2 patients (5%), which were successfully treated with neodymium:yttrium-aluminum-garnet laser in contact technique. Retained secretions that aggravated dypnea necessitating bronchoscopy appeared in 13 patients (31%). Two patients needed stent replacement after dislocation of the device. Removal and replacement was done without major difficulties. Emergency tracheostomy was not necessary. Comment Operation is the established treatment of choice in benign tracheal stenoses. However, in a percentage of patients tracheal reconstruction or other surgical interventions do not yield success or cannot be performed because of concomitant disease. Advances in endoscopic techniques, biocompatible materials, and the development of suitable tracheobronchial stents have made

4 Ann Thorac Surg SCHMIDT ET AL 2001;71: STENTING IN BENIGN TRACHAEL STENOSES 1633 Fig 3. Temporary (Group A) and definitive (Group B) stenting in 42 patients with benign tracheal stenoses. stenting an interesting alternative to operation in the past years. In patients who are not amenable to an operation it represents the only strategy to avoid a tracheostomy and its complications. The use of Montgomery T-tubes should be restricted to selected patients because of the need for a tracheostomy. In the treatment of postintubation or post-tracheostomy complications they are of limited value. Metallic stents have been used but may cause difficulties because of the presence of inflammation [24, 25]. The Dumon stent has become the device of choice in this situation. Newly designed stent types such as Polyflex (polyester with silicon covering; Rüsch, Kernen, Germany), Ultraflex stents (self-expandable metallic stent with or without silicone covering, Boston Scientific), or Wallstents may have advantages over the Dumon device (Novatech). They need further clinical evaluation before being recommended. The relatively high number of patients with inoperable or recurrent benign stenoses that are included in our study is because many patients with complicated courses of disease are referred to our institution from other teaching hospitals. We performed balloon dilatation before stenting to dilate fibrous strictures or fibrous components of combined stenoses. This made implantation of relatively large stents possible and the implantation procedure easier. One might speculate that the risk of stent dislocation can thereby be reduced. The balloon dilatation also causes mucosal lesions and induces scar formation that might help to stabilize the tracheal wall. It was performed also in predominantly malacic stenoses. The device we used for this purpose (Maxforce TTS-Balloon, Boston Scientific, Watertown, MA) proved to be very useful. In our experience the rigid bronchoscope causes more damage to the mucosal surface as it exerts more shear forces. We did not see any important bleeding or tracheal rupture after balloon dilatation. The immediate effect of stent implantation has already been well documented [18, 20, 21] and can be clinically confirmed. Our long-term results show that tracheal silicone stents can be left in situ for 5 years and more with very few complications. This emphasizes that stenting can be a valuable definite treatment in patients with several previous unsuccessful attempts at tracheal recontruction. Long-term stenting must be accompanied by intensive stent maintenance and inhalation therapy. Regular bronchoscopic controls and, if necessary, removal of incrustations are warranted. As for temporary stenting periods of 12 [12] or 18 [17] months have been recommended. We believe that patients with nontumorous tracheal stenoses form a heterogeneous group. In some cases preoperative and perioperative stenting for 1 month can be sufficient, whereas in other patients mucosal inflammation persists for 24 months. In general, a period of 12 to 24 months seems reasonable, but regular controls and reevaluations are warranted to define the right time for stent removal. As we did not encounter severe difficulties when removing and reinserting stents, we believe it is safe to remove the stent when inflammation has diminished and severe malacia absent while remainig ready to reinsert a new device if required. Complications after stent implantation were retained secretions, granuloma formation, and stent dislocation. Retained secretions were relatively common early on in patients (overall 31%). When we intensified our inhalation regimen (three to five times per day, with saline or mucolytic agents) and suggestions for home care we could reduce this complication decisively. The formation of granulomata proximally or distally to the stent appeared in 5% of patients, which is comparable with the results of other researchers [17]. We successfully removed these granulations with neodymium:yttriumaluminum-garnet laser. This approach remains controversial as the use of the neodymium:yttrium-aluminumgarnet laser is generally contraindicated in patients with silicone stents. The silicone and metallic devices can be seriously damaged by the laser beam [26]. When the laser is used in contact technique with a bare fiber the local control over the effect of the laser beam is improved. We believe it is safe to use the laser in this situation when the alternative is removal and replacement of the stent. This strategy is based on clinical experience and requires further systematic investigations. Stent dislocation has to be analyzed in detail. Only 2 of our patients required stent replacement after dislocation. Stents were not replaced when the stenosis remaining after dislocation was not important. These patients underwent regulary bronchoscopic controls and did not require another stent during follow-up. Comparing these findings with other groups who report stent replacement in more than 17.5% [17, 27], it is arguable whether stent reimplantation is necessary in every case of dislocation. The relatively low number of stent migrations might also be due to the fact that the stenoses were dilated before stenting and the largest possible stents were used. In conclusion, stent implantation after balloon dilatation is a safe and effective therapy in benign tracheal stenoses. After temporary stenting, stents can be removed when local and general conditions permit. In all other patients definitive long-term stenting proved ben-

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