Airway stenting

Most reports of metallic stenting in the airways in patients with esophageal cancer are limited to case reports. The largest series of esophagorespiratory fistulas treated by airway stenting was recently reported by Sabharwal et al. (2000). Six patients... 

Contraindications to the placement of central airway stents are curable malignant tumors. Due to the difficulty in removing metallic stents, these should not be placed in patients with a curable disease. Metallic stents that have been incorporated into the mucosa are extremely difficult to retrieve at endoscopy and surgery. However, in emergency situations with hyperacute airway compression and the need for rapid restoration of adequate pulmonary ventilation, temporary placement of a (preferably) plastic stent may be indicated. 

The most important morphological examination prior to insertion of an airway stent is a spiral computed tomography (CT) of the major airways. A CT enables a delineation of the airway obstruction. It further demonstrates the length of stenosis, grade of obstruction, and allows calibrated measurements of the smallest diameter of the obstruction. CT can also differentiate a mucosal obstruction from a submucosal cause of obstruction, and further extra-tracheal or exo-bronchial disease responsible for airway comprise. Another advantage of CT is the possibility to assess the relation of the underlying cause of obstruction to other crucial mediastinal and/or pulmonary structures (e.g., major vessels, esophagus, heart, lymph nodes). 

Colreavy MP, Keogh 1, Hone S, Lacy PD, Gaffney RJ, Walsh MA (2000) Nitinol stents their value in tracheobronchial obstruction. Clin Otolarynology 25 233-239 Colt HG, Dumon JF (1995) Airway stents. Present and future. 

Colt HG, Meric B, Dumon JF (1992) Double stents for carcinoma of the esophagus invading the tracheo-bronchial tree. Gastrointest Endosc 38 485-489 Dasgupta A, Dolmatch BL, Abi-Saleh WJ, Mathur PN, Mehta AC (1998) Self-expandable metallic airway stent insertion employing flexible bronchoscopy. Chest 114 106-109 Dumon JF (1990) A dedicated tracheobronchial stent. Chest 97 328-332... 

Furman RH, Backer CL, Dunham ME et al. (1999) The use of balloon-expandable metallic stents in the treatment of pediatric tracheomalacia and bronchomalacia. Arch Otolaryngol Head Neck Surg 125 203-207 Freitag L, Bicker R, Linz B et al. (1994) Theoretical and experimental basis for the development of a dynamic airway stent. Eur Resp J 7 2038-2045... 

Mehta AC, Dasgupta A (1999) Airway stents. Clin Chest Med 20 139-151... 

Wood DE (2001) Airway stenting. Chest Surg Clin N Am 11 841-860... 

Wang, J., Boutin, K.G., Abdulhadi, O., Personnat, L.D., Shazly, T., Langer, R., Channick, C.L., Borenstein, J.T., 2013. FuUy biodegradable airway stents using amino alcohol-based poly(ester amide) elastomers. Advanced Healthcare Materials 2,1329-1336. 

Localized disease refractory to medical therapy or associated with compromise of organ function [e.g., tracheal or bronchostenosis (50-52), mass lesions encroaching the orbit or optic chiasm (44)] may require percutaneous or surgical management or intralesional CS therapy (3,50,52). For tracheobronchial WG, treatment modalities include CO2 or Nd YAG laser, dilatation, intratracheal CS injections, placement of Silastic airway stents, tracheostomy, laryngeal-tracheal reconstmction, and partial tracheal resection (3,50,51,53,215-218). Silastic stents may provide sustained relief of symptoms in some patients, but are associated with... 

Sondrup C, Liu Y, Shu X Z, Prestwich G D and Smith M E (2006), Cross-linked hyaluronan-coated stents in the prevention of airway stenosis , Otolaryngol Head... 

Covered metallic stents provide effective treatment for malignant flstulas and perforations. The clinical success rates are very high and most patients derive relief from symptoms of aspiration or debilitating thoracic sepsis. Patients with recurrent flstulas or leaks may be treated by additional overlapping stents in most cases. Metallic stents placed in the airways may be useful for some patients with a dilated esophagus, very high fistulas, or airway obstruction due to local invasion by esophageal tumors. 

Patients should be able to cooperate during the procedure. Some patients with severely symptomatic SVCOS may have difficulties in lying flat on the examination table. In these circumstances, the procedure should be undertaken under general anesthesia. A minority of patients will present with simultaneous tracheobronchial narrowing, due to malignant mediastinal compression. Stenting of the airways should precede management of the caval obstruction in such patients. 

Recent technological advances in the last two decades have led to the development of self-expanding or expandable metallic mesh stents. These stents represent the latest technology for the treatment of malignant and benign airway obstructions. A stent can be described as a tubular prosthesis that maintains luminal patency and a predefined luminal diameter of a tubular structure by opposing radial forces to extrinsic or intramural compressive forces. Thus, a stent provides internal support for luminal patency. 

Recent developments of plastic stents have aimed to improve the resistance of plastic stents to external compression forces. Therefore, metal has been incorporated into the plastic material of the stent. One of the latest developments is the dynamic bifurcation stent made of silicone (Freitag et al. 1994). This Dynamic stent (Riisch, Kernen, Germany) is reinforced with horseshoe-shaped steel struts. A posteriorly located flexible membrane allows dynamic compression of the stent during coughing, whereas the steel struts prevent airway compression from external forces. Theoretically, this stent mimics the mechanical dynamics of the normal trachea. The distal end is a Y shape which rides on the carina to prevent distal migration. 

Another development to prevent stent dislocation is the Reynders stent (Reynders Medical Supply, Lennik, Belgium), which is a screw-thread plastic prosthesis. The stent clicks into the tracheal cartilage rings, thus providing better airway-wall adherence. It also has a greater rigidity than sificone stents (Noppen et al. 1996,1999). 

Another special indication for placement of a plastic or a covered metallic stent are actively bleeding tumors, which can not be managed surgically or by endoscopic measures. A self-expanding covered stent can compress the tumor, relieve the airway obstruction, and simultaneously stop the bleeding due to compression (see Fig. 12.1). 

Another contraindication for the placement of a covered stent is the crossing of a major airway... 

Appropriate assessment of the location of the tracheal or bronchial obstruction is mandatory to choose the correct stent and to allow proper placement. In the case of a proximal tracheal lesion the distance to the vocal cord has to be assessed and measured. In the case of a distal tracheal lesion the relation to the Carina has to be defined in order to assess whether a single tracheal stent or an additional unilateral or bilateral bronchial stent is required to achieve sufficient luminal diameter in the central airways. In the case of bronchial obstruction, the relation to lobar bronchial orifices has to be analyzed. 

The repositioning or removal of metallic stents is very difficult once they are fully deployed. An exemption from this rule is the above-mentioned newly developed retrievable stent from Korea (Song et al. 1999). Repositioning of a deployed stent can be achieved with the use of a forceps. The stent can be grasped at the proximal or distal margin and can be pushed or pulled into the desired position. In case of only partial coverage of the obstruction, placement of an additional stent is reasonable. If a stent has to be removed, it is best done immediately after placement. If the stent has been in place for a couple of weeks, it will be embedded and partially covered in the mucosal layer of the airways (especially in case of a non-covered open mesh stent). Removal at that stage always causes injury to the airway epithelium. 

After stent insertion, a final completion bronchoscopy with the use of the flexible endoscope should be done to check appropriate stent position, determine patency of bronchial ostia, rule out complications (e.g., bleeding, airway disruption, mucus impaction) and ascertain proper attachment of the proximal and distal stent ends to the tracheobronchial mucosa (see Fig. 12.If). 

George and colleagues (1992) treated nine patients with malignant central airway obstruction due to tracheal (n=3) or main bronchial ( =6) stenosis with Gianturco stents. All patients suffered from severe dyspnea or asphyxia (four were emergency treatments). All patients had dramatic and rapid reUef of their symptoms after stent insertion. Two patients with intraluminal tumor growth required additional endobronchial measures to control local tumor progression. Patients survived between 3 weeks and 8 months after the intervention. Causes of death were cachexia or pneumonia. 

Tan et al. (1996) reported on seven patients with unresectable cancer comprising the large airways, where they placed Wallstents in the trachea ( =3) and bronchi (n=ll). Patients showed improvement of their dyspnea after stent insertion. One patient died immediately after the procedure from cardiac arrest. The remaining patients died after a survival of up to 10 months. 

Dasgupta and colleagues (1998) treated 20 patients with neoplastic tracheobronchial strictures with uncovered Wallstents. Stents were successfully deployed in all patients and airway patency was restored. Four patients were successfully weaned after stent insertion, five were receiving mechanical ventilatory assistance, while the remaining died from unrelated causes while receiving mechanical ventilatory assistance. No deaths occurred from stent failure or stent related complications. 

A large series of 100 Ultraflex stent insertions in 96 patients comes from two experienced airway centers (Herth et al. 2001). In all, 79 stents were placed for malignant incurable central airway diseases, the remaining indications were benign conditions. Of the 96 patients, 90 had high-grade stenoses. Stents... 

A recent study reported on the placement of 28 Ultraflex stents in 25 patients with respiratory distress due to inoperable airway obstruction (Madden et al. 2002). In this trial, 21 tracheal and seven bronchial stents were placed. The vast majority of patients received covered stents (n=21), the minority uncovered stents (n=7). Of the 25 patients, 20 reported symptomatic improvement after stent implantation. The follow-up period ranged from 3 days to 27 months. Late complications included sputum retention and infection in four patients, halitosis in one patient, and granulation tissue formation in another patient. 

The group of Colt et al. (1992) were the first to report double stents for carcinoma of the esophagus invading the tracheobronchial tree. Ten patients with severe dyspnea at rest due to airway obstruction ( =5) or esophagorespiratory fistulas (n=5) had tracheal (n=5) or bronchial (n=5) stents placed additionally to the esophageal stent. The tracheobronchial stents were Dumon silicone stents. The fistulas were sealed in all cases. The mean survival time was 121 days (range, 12-350 days). 

Bolliger CT, Heitz M, Hauser R, Probst R, Perruchoud AP (1996) An airway Wallstent for the treatment of tracheobronchial malignancies. Thorax 51 1127-1129 Bolliger CT, Wyser C, Wu X et al. (1999) Evaluation of a new self-expandable silicone stent in an experimental tracheal stenosis. Chest 115 496-501... 

Carrasco CH, Nesbitt JC, Charsangavej C, Ryan B, Walsh GL, Yasumori K, Lawrence DD, Wallace S (1994) Management of tracheal and bronchial stenoses with the Gianturco stent. Ann Thorac Surg 58 1012-1016 Cavaliere S, Venuta F, Foccoli P et al. (1996) Endoscopic treatment of malignant airway obstructions in 2,008 patients. Chest 110 1536-1542... 

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