Tracheal stents

The possibility of an ease tuning of the composition of the multilayers allows the building of materials with good bio-compatibility with cells and tissues. This allows the preparation of different coating for biomedical devices, such as stents, tracheal prostheses, artificial vessels and many other applications [232]. 

Siloxane-containing devices have also been used as contact lenses, tracheostomy vents, tracheal stents, antireflux cuffs, extracorporeal dialysis, ureteral stents, tibial cups, synovial fluids, toe joints, testes penile prosthesis, gluteal pads, hip implants, pacemakers, intra-aortic balloon pumps, heart valves, eustachian tubes, wrist joints, ear frames, finger joints, and in the construction of brain membranes. Almost all the siloxane polymers are based on various polydimethylsiloxanes. 

Patients who develop tracheal obstruction as a result of local invasion of an esophageal tumor, or after placement of a metallic stent in the esophagus. 

Tracheal stents are usually effective in the treatment of patients with the above indications. Covered stents should be used, although patients with tracheal... 

Nicholson DA (1998) Tracheal and oesophgeal stenting for carcinoma of the upper esophagus invading the tracheobronchial tree. Clin Rad 53 760-763 Novak Z, Coldwell DM, Mitchell RD, et al. (1999) Percutaneous transgastric placement of esophageal stents. JVIR 10 428-430... 

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). 

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). 

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 first report on the oldest metal stent used in the tracheobronchial system was pubUshed by Wallace et al. in 1986 (Wallace et al. 1986). Since then, several studies on the use of this stent type have been pub-hshed and the stent became one of the most frequently applied metal stents in tracheobronchial mahgnancy. Wallace and colleagues initially reported on two cancer patients. Gianturco stents were placed in one to dilate a postoperative bronchial stenosis that caused pneumonia, and in the second to support a tracheal graft that collapsed with respiration. Stents were successfully placed and the patients symptoms improved (Wallace et al. 1986). 

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. 

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. 

Song and co-workers (1999) placed their self-developed potentially retrievable covered metallic stent in eight patients with tracheobronchial malignant obstructions (esophageal cancer, n=4 lung cancer, n=2 tracheal cancer, n=l gastric cancer, n=l). Stents were successfully placed in all patients but one. In this case a hinged stent (combined tracheal and bronchial stent) was placed too caudal so... 

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). 

In the initial paper on the self-expanding polyester stent covered with a thin layer of sificone (Polyflex stent), the authors reported treatment of flve esophagorespiratory fistulas with placement of this stent into the trachea (Wassermann et al. 1997). Three patients had a tracheal stent only two patients had additional previously placed esophageal stents. The Polyflex stent sealed the flstula initially in all flve cases, but this success was only transient. Symptoms recurred in four patients after a median of 1 month and required placement of additional tracheal stents. All patients had deceased after a mean survival of 6.6 months (range, 2-11 months). 

Madden and coworkers (2002) reported in their series of placement of an Ultraflex self-expanding stent out of a total of 25 patients one patient, who presented with an esophagotracheal flstula due to advanced esophageal cancer. A previously placed esophageal stent had migrated through the tracheal wall. A covered stent was placed in the trachea and sealed off the fistula immediately. The patient was alive 9 months after tracheal stent placement without signs of further respiratory infection. 

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... 

Montgomery W (1965) T-tube tracheal stent. Arch Otolaryngol 82 320-321... 

Nomori H, Horio H, Imazu Y, Suemasu K (2000) Double stenting for esophageal and tracheobronchial stenoses. Ann Thorac Surg 70 1803 1807 Noppen M, Dhase J, Meysman M et al. (1996) A new screw-thread tracheal endoprosthesis. J Bronchol 3 22-26 Noppen M, Meysman M, Claes I et al. (1999) Screw-thread vs Dumon endoprosthesis in the management of tracheal stenosis. Chest 115 532-535... 

Experimental and clinical tracheal repair or anastomosis began in the late 19th century. A few examples of limited tracheal resection and primary anastomosis were cited in the first half of the 20th century [12]. Fmther experimental investigation on potential extent of tracheal resection and primary anastomosis without prosthesis greatly widened these possibilities. Approximately one-half of the adult trachea can be removed and primary reanastomosis performed [99—102], so most tracheal lesions can now be resected and primary anastomosed safely. But resection has several limitations in adult patients, only one-half the tracheal length can be successfully treated and only one-third in pediatric patients [7]. These patients are now treated with palliative techniques such as subpotent laser treatments and stents or T-tubes [14]. 

The various tracheal substitutes and techniques of reconstmction were analyzed by GriUo [12], who classified them in five categories foreign materials (silicone tubes [103,104], coated stents, metallic [104,105], and other solid prostheses [106]), nonvi-able tissues, autogenous tissues, TE, and tracheal transplantation. 

M. Weinberg, J. Sandbank, Y. Flumenblit, B. Klin, I. Vinogtad, Tracheal reaction to three different intraluminal stents in an animal model of tracheomalacia, J. Lapatoendosc. Adv. Surg. Tech. A 15 (3) (June 2005) 333-337. 

Figure 8.3 Tracheal stent of silicone after a relatively short time of implantation ...

Figure 8.4 Interface between a tracheal stent and Incrustations (see Fig. 8.3) ...

Tracheal prosthesis (tracheal stent) of silicone rubber [11] ... 

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... 

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