Role of the Gianturco expandable metal stent in the management of tracheobronchial obstruction

Tracheobronchial stents: an expanding prospect

The first dedicated tracheobronchial silicone stent was designed by the French pulmonologist Jean-Paul Dumon. The most common indications for stenting are to minimise extrinsic airway compression from mass effect, maintain airway patency due to intrinsic obstruction or treat significant nonmalignant airway narrowing or fistulae. Silicone stents require rigid bronchoscopy for insertion; however, they are more readily repositioned and removed compared with metallic stents. Metallic stents demonstrate luminal narrowing when loads are applied to their ends, therefore stents should either be reinforced at the ends or exceed the area of stenosis by a minimum of 5 mm. Nitinol, a nickel-titanium metal alloy, is currently the preferred material used for airway stents. Airway stenting provides effective palliation for patients with severe symptomatic obstruction. Drug-eluting and three-dimensional printing of airway stents present promising solutions to the challenges of the physical and anatomical constraints of the tracheobronchial tree. Biodegradable stents could also be a solution for the treatment of nonmalignant airway obstruction.

Applications and challenges of using 3D printed implants for the treatment of birth defects

Pediatric implants are a special subclass of a vast number of clinically used medical implants, uniquely designed to address the needs of young patients who are at the onset of their developmental growth stage. Given the vulnerability of the implant receiver, it is crucial that the implants manufactured for small children with birth-associated defects be given careful considerations and great attention to design detail to avoid postoperative complications. In this review, we focus on the most common types of medical implants manufactured for the treatment of birth defects originating from both genetic and environmental causes. Particular emphasis is devoted toward identifying the implant material of choice and manufacturing approaches for the fabrication of pediatric prostheses. Along this line, the emerging role of 3D printing to enable customized implants for infants with congenital disorders is presented, as well as the possible complications associated with prosthetic-related infections that is prevalent in using artificial implants for the treatment of birth malformations.

Fluoroscopic-guided balloon dilatation and stenting in tracheal stenosis with metallic self-expandable stents and long-term follow-up results

The purpose of this study was to assess the safety and long-term efficacy of self-expandable stents in the treatment of benign tracheal stenosis. Nine patients (seven men) with tracheal stenosis (including one with fistula) of varied cause were treated by fluoroscopically guided balloon dilatation and stenting with self-expandable metallic stents. The procedure was carried out under topical spray in eight patients and under general anaesthesia in one patient. The patients were followed up for a period ranging between 13 and 60 months. In eight of the nine patients, satisfactory positioning of the stent was achieved at the first instance, with immediate relief of dyspnoea. One patient with innominate artery aneurysm died 16 days after the procedure because of renal failure. At 1 month of follow up, six out of eight (75%) of our live patients were without any respiratory embarrassment. This dyspnoea-free result reached almost 90% by the end of 1 year especially so in the fibrous strictures. Four out of the eight live patients (50%) had cough for 2 months and two (25%) had mild blood-tinged sputum treated by inhalation and mucolytic agents. Secondary intervention was required in one patient at 1 month because of recurrent symptoms. The patient with tracheo-oesophageal fistula required surgical intervention because of fracture of the stent. Fluoroscopically guided balloon dilatation and stenting of the tracheal stenosis is an effective non-surgical therapy resulting in cure of fibrous strictures and palliation in cases of malignancy.

Main bronchial reconstruction with sparing of pulmonary parenchyma for benign diseases

Main bronchial reconstruction is anatomically suitable for benign main bronchial stenosis. But, it has been hardly recommended for operative mortality and morbidity. This study was aimed at providing validity and the proper clinical information of bronchoplasty for benign main bronchial stenosis by reviewing the results we obtained over the last ten years for main bronchial reconstruction operations. We retrospectively reviewed admission and office records. Twenty eight consecutive patients who underwent main bronchoplasty were included. Enrolled patients underwent main bronchial reconstruction for benign disease (tuberculosis in 21, trauma in 4, endobronchial mass in 3). Concomitant procedures with main stem bronchoplasty were performed in 19 patients. There were no incidences of postoperative mortality and significant morbidity. There were 2 cases of retained secretions, and these problems were resolved by bronchoscopy or intubation. All of the patients are still alive without obstructive airway problem. Bronchoplasty should be considered as one of the primary treatment modalities, if it is anatomically feasible.

Outcomes of Tracheobronchial Stent Placement for Benign Disease

PURPOSE

To retrospectively determine long-term outcomes in patients who have undergone tracheobronchial stent placement for benign diseases.

MATERIALS AND METHODS

Institutional Review Board approval was obtained for this retrospective HIPAA-compliant study, with waiver of informed consent. Forty patients (22 female, 18 male; mean age, 52.0 years) who were treated with metallic airway stents for benign stenosis were identified from an interventional radiology database. Causes of airway stenosis included transplant stricture (n = 13), tracheal tube injury (n = 10), inflammation (n = 6), tracheobronchomalacia (n = 4), infection (n = 3), and extrinsic compression (n = 4). Follow-up, which ranged from 6 to 2473 days, was performed by means of chart review for deceased patients and by means of clinical visit or telephone interview for surviving patients. Survival, primary patency, and assisted patency were estimated by using the Kaplan-Meier product limits method.

RESULTS

Initial technical success was achieved in all cases. Symptomatic improvement was present in 39 of 40 cases. At review, 15 patients were alive and had clinical improvement, 18 had died of comorbid causes, one had died of uncertain causes, three had undergone subsequent airway surgery, two had undergone airway stent retrieval, and one was lost to follow-up. Survival at 1, 2, 3, 4, 5, and 6 years was 79%, 76%, 51%, 47%, 38%, and 23%, respectively. Loss of primary patency was most rapid during the 1st year. With repeat intervention, assisted patency was 90% at 6.8 years.

CONCLUSION

Attrition of tracheobronchial stent patency is most rapid during the 1st year, and a high rate of long-term patency can be achieved with secondary interventions. Metallic airway stents are well-tolerated and useful adjuncts for management of select benign tracheobronchial stenoses.

Tracheomalacia and Tracheobronchomalacia in Children and Adults

Tracheomalacia and tracheobronchomalacia are disorders that are encountered in both pediatric and adult medicine. Despite increasing recognition of these disease processes, there remains some uncertainty regarding their identification, causes, and treatment. This article is intended to be a comprehensive review of both the adult and pediatric forms of the diseases, and includes sections on the historical aspects of the disorders, and their classification, associated conditions, histopathology, and natural history. We also review the various modalities that are used for diagnosis as well as the state of the art of treatment, including airway stent placement and surgical intervention.

Influence of a dexamethasone-eluting covered stent on tissue reaction: an experimental study in a canine bronchial model

This study was designed to evaluate the feasibility and efficacy of a dexamethasone (DXM)-eluting, covered, self-expanding metallic stent to reduce tissue reaction following stent placement in a canine bronchial model. We placed a DXM-eluting, polyurethane-covered, self-expanding metallic stent (drug stent, DS) and a polyurethane-covered, self-expanding metallic stent (control stent, CS) alternately in each left main bronchus and left lower lobe bronchus in 12 dogs. The stents were 20 mm in diameter and length when fully expanded. The dose of DXM was approximately 36.7 mg in each DS, but was absent in the CS. The dogs were euthanased 1 week (n=4), 2 weeks (n=4) or 4 weeks (n=4) after stent placement. Histologic findings, such as epithelial erosion/ulcer or granulation tissue thickness, were obtained from the mid-portion of the bronchus, where the stent had been placed, and evaluated between DS and CS. There were no procedure-related complications or malpositioning of any of the bronchial stents. Stent migration was detected in one dog just before euthanasia 1 week following stent placement. Stent patency was maintained until euthanasia in all dogs. Epithelial erosion/ulcer (%) was significantly less in the DS (mean+/-standard deviation, 46.88+/-23.75) than in the CS (73.75+/-14.08) (P=0.026) for all time-points. There was a decrease in epithelial erosion/ulcer as the follow-up period increased in both DS and CS. The granulation tissue thickness (mm) was less in DS (2.63+/-2.05) than in CS (3.49+/-2.95), although the difference was not significant (P=0.751) for all time-points. There was a tendency toward an increase in granulation tissue thickness and chronic lymphocytic infiltration as the follow-up period increased in both DS and CS. In conclusion, DXM-eluting, covered, self-expanding metallic stent seems to be effective in reducing tissue reaction secondary to stent placement in a canine bronchial model.

Malignant tracheobronchial strictures: palliation with covered retrievable expandable nitinol stent

PURPOSE

To evaluate the safety and clinical effectiveness of a covered retrievable expandable nitinol stent for the treatment of malignant tracheobronchial stricture and/or esophagorespiratory fistula (ERF).

MATERIALS AND METHODS

With fluoroscopic guidance, stents were placed in 35 symptomatic patients with malignant tracheobronchial stricture and/or ERF in most cases caused by lung or esophageal cancer. The site of stricture was most commonly at the trachea or left main bronchus. If there were complications, the stent was removed with a retrieval set. Nine patients had combined symptomatic ERF.

RESULTS

A total of 47 tracheobronchial stents were placed and were technically successful and well-tolerated in all patients. Improvement of dyspnea was achieved in 92% of the patients (24 of 26 patients). Associated ERF in nine patients was effectively treated with tracheobronchial stent placement with or without esophageal stent placement. Stent migration, tumor overgrowth, symptomatic sputum retention, and hemoptysis occurred in 17% (6/35), 6% (2/35), 20% (7/35), and 17% (6/35) of patients, respectively. There were no documented cases of tumor ingrowth. Stent removal was performed easily in five patients when stent migration (n = 2), severe pain (n = 1), tumor overgrowth (n = 1), or persistent gastrobronchial fistula (n = 1) developed. All patients died 2 days to 26 weeks (mean, 9.62 weeks) after stent placement because of disease progression (n = 18), pneumonia (n = 9), hemoptysis (n = 5), or unknown cause (n = 3).

CONCLUSION

Use of a covered retrievable expandable nitinol stent is a safe and effective method for relieving dyspnea. This procedure contributed to improved quality of life for patients with malignant tracheobronchial stricture and/or ERF. Stent retrievability was useful in resolving stent-related complications.

A case of relapsing polychondritis involving placement of an expandable metallic stent

Relapsing polychondritis is a relatively uncommon disease characterized by recurrence of progressive inflammation of cartilaginous structures. Laryngotracheal involvement occurs in 50-70% of cases, and occasionally results in acute airway obstruction. We reported a case of relapsing polychondritis with severe tracheal stenosis that was treated by the placement of two expandable metallic stents. A 58-year-old man was hospitalized with fever and breathing difficulties. A tracheostomy was performed and a silicone T-tube was placed. A diagnosis of relapsing polychondritis was made based on the biopsy from auricular and tracheal cartilages. Two expandable metallic stents were placed in the trachea to bilateral main bronchus. This dilated the airway lumen and resulted in the dyspnea disappearing completely. However, 18 months later a sudden massive hemorrhage occurred through the tracheostoma, and he died of respiratory failure. Autopsy showed a tracheoinnominate artery fistula. We discuss the management of relapsing polychondritis with severe tracheal stenosis.

Cellular composition of stent-penetrating tissue

BACKGROUND

A surprisingly low number (< 20%) of relevant (> 75%) restenoses occur in exophytic lesions after treatment with uncovered metal stents. The goal of this study was to investigate whether radial stent forces can exert localized influence on tumor growth.

PATIENTS AND METHODS

In 17 patients, intraluminal tumor tissue was histologically investigated before and 1 week after stent implantation. The amount of intact tumor cells (ITCs) was compared to necrotic and nontumor cells. The result in patency was proved by fiberoptic bronchoscopy.

RESULTS

Initially, stenoses in all patients were > 75%. Before stent implantation, biopsy samples in seven patients showed > 67% ITCs, and five patients had 34 to 67% ITCs. Five patients had 1 to 33% ITCs, and no patients had 0% ITCs. One week after stent implantation, the cellular aspect of the biopsy samples had changed significantly (p < 0.03): two patients had > 67% ITCs, one patient had 34 to 67% ITCs, and seven patients had 1 to 33% ITCs. Seven patients had no ITCs at all. Endoscopically, patency increased significantly (prestent, 10 +/- 14.1%; poststent, 90.6 +/- 14.3% [mean +/- SD]; p < 0.0001).

CONCLUSION

Pressure exerted by the stent on adjacent tumor tissue may cause a profound reduction in the amount of ITCs, most probably caused by radial and shear stress forces that compromise blood supply and nutrients of the tumor stroma.

Benign tracheobronchial stenoses: long-term clinical experience with balloon dilation

PURPOSE

To assess the safety and long-term efficacy of balloon dilation in the treatment of benign tracheobronchial stenosis.

MATERIALS AND METHODS

Balloon dilation was performed under fluoroscopic guidance in 59 consecutive patients with benign tracheobronchial stenosis. Most patients had tuberculosis (48 of 59, 81%). Two to three serial balloon insufflations were performed for 5-180 seconds (mean, 85 sec) with inflation pressures as high as 16 atm with use of 6-20-mm-diameter balloon catheters. Patients with clinical evidence of restenosis underwent repeat balloon dilation. Patients were followed for 12-42 months (mean, 32 mo).

RESULTS

A total of 101 balloon dilation sessions were performed in 59 patients, with a range of one to four sessions per patient (mean, 1.7 sessions). Initial symptomatic improvement was achieved in 49 (83%) of the 59 patients; however, during the follow-up period, 39 (80%) of the 49 patients experienced recurrence of their symptoms. The primary patency rates at 3, 6, 9, 12, 18, 24, and 32 months were 92%, 60%, 45%, 24%, 20%, 20%, and 20%, respectively. The secondary patency rates at 3, 6, 9, 12, 18, 24, and 32 months were 92%, 87%, 75%, 43%, 43%, 43%, and 43%, respectively. Procedure-related major complications of deep mucosal laceration (n = 2) and bronchospasm (n = 1) occurred in three patients, but they experienced no subsequent problems.

CONCLUSION

Although the recurrence rate is high during the long-term follow-up period, balloon dilation seems to be a safe primary treatment modality for benign tracheobronchial stenoses and has an acceptable secondary patency rate.

Benign tracheobronchial stenoses: changes in short-term and long-term pulmonary function testing after expandable metallic stent placement

PURPOSE

To determine the short- and long-term improvement in airflow dynamics in patients undergoing tracheobronchial stent placement for benign airway stenoses.

METHODS

Twenty-two patients underwent 34 tracheal and/or bronchial stent placement procedures for benign airway stenoses and had the results of pulmonary function tests available. Stent placement indications included bronchomalacia after lung transplantation (n = 11), postintubation stenoses (n = 6), relapsing polychondritis (n = 2), and 1 each of tracheomalacia, tracheal compression, and histoplasmosis. Six patients underwent more than one stent placement procedure (range: 2-7 procedures). The mean forced expiratory volume in one second (FEV(1) ), forced expiratory flow rate in the midportion of the forced vital capacity curve (FEF(25-75) ), forced vital capacity, and peak flow (PF) rate obtained before stent placement were compared with those immediately after stent placement and with those measurements most remote from stent placement using the paired two-tailed test.

RESULTS

All patients reported improved respiratory function immediately after stent placement. The mean FEV(1), FEF(25-75), and PF rate improved significantly (p < 0.001, p = 0.002, and p = 0.009, respectively) after stent placement. On long-term follow-up averaging 15 months after stent placement, these parameters declined despite patients' subjective sense of improvement. Segregating the population into transplant and nontransplant airway stenosis etiologies, however, FEF(25-75) and PF rate remained significantly improved (p = 0.045, p = 0.027, respectively), over the long term for the latter. FEV increased after subsequent stent placements for patients receiving multiple stents.

CONCLUSION

Stent placement for benign tracheobronchial stenoses provides significant immediate improvement in airflow dynamics. Long-term improvement in airflow obstruction may be expected, and additional stent placements may further improve pulmonary function.

Outcome for malignant tracheobronchial stenoses in esophageal cancer

OBJECTIVE

Optimal tracheobronchial stenosis treatment in esophageal cancer remains a clinical challenge.

METHODS

Subjects were 26 patients with tracheobronchial stenosis due to esophageal cancer treated by modalities such as expandable metallic stent emplacement, laser therapy, radiotherapy, and/or chemotherapy. We assessed patient outcome and modality efficacy, and determined prognostic factors for survival using multivariate analysis.

RESULTS

Of the 26, 16 (61%) had improved respiration after treatment. Average posttreatment survival was 140 days (10-1550 days). Multivariate analysis indicated that a Karnofsky performance score of > or = 70% was the most significant prognostic factor, with chemotherapy and laser therapy also significant factors.

CONCLUSIONS

Although individual modalities were effective in ameliorating respiratory symptoms, patients with good performance status survived the longest. After a tracheobronchial stenosis diagnosis in esophageal cancer patients, chemotherapy and laser therapy are recommended if the patient is in good general condition.

Covered retrievable tracheobronchial hinged stent: an experimental study in dogs

PURPOSE

To evaluate the safety and technical feasibility of the use of a covered retrievable tracheobronchial hinged stent and investigate the histopathologic airway changes after placement and removal of the stent in dogs.

MATERIALS AND METHODS

The experimental stent was composed of tracheal and bronchial stents that were connected together at their ends. Each stent was woven from a single thread of 0.2-mm-diameter nitinol wire filament in a tubular configuration and covered with polyurethane solution by a dipping method. Drawstrings were attached at the upper end of the tracheal stent for stent removal. Under fluoroscopic guidance, 20 stents were placed at the lower trachea and left main bronchus in 20 dogs and were electively removed 4 weeks (n = 10) or 8 weeks (n = 10) after placement. Ten dogs were killed just after stent removal and the remaining 10 were killed 2 weeks after stent removal.

RESULT

Stents were successfully placed in all dogs. Pneumonia was observed in three dogs. Stent migration occurred in seven dogs (35%). Except for two cases of stent expectoration, 18 stents were easily removed within a few minutes. There was considerable granulation tissue proliferation and inflammatory reaction in the airways of the dogs that were killed just after stent removal. The pathologic changes of the airways returned to almost-normal conditions 2 weeks after stent removal.

CONCLUSION

Placement and removal of a covered retrievable tracheobronchial hinged stent seems to be feasible, and histopathologic changes of the airway related to the stents returned to normal 2 weeks after stent removal.

Stenting of the tracheobronchial tree

Endoscopic treatment of endobronchial obstructions is becoming increasingly important. Tracheobronchial stents often are needed in the treatment of obstructions from submucosal or extrabronchial lesions. Tube stents have been available since the early 1960s but are underused because their insertion requires the use of a rigid bronchoscope. With the recent development of metallic stents, interventional radiologists increasingly are involved in the treatment of tracheobronchial obstructions. Metallic stents, easily placed with flexible bronchoscopy, are growing in popularity. All available tracheobronchial stents have been shown in various clinical series to be able to achieve immediate resolution of respiratory symptoms from various tracheobronchial obstructions. A stent's performance, however, should not be based solely on short-term response. Presently, there is no ideal stent because none is free of complications and none are able to consistently maintain life-long patency. Gianturco stents are associated with serious major complications (bronchial perforations and strut fractures) and are no longer recommended for use in the tracheobronchial tree. The Palmaz stent has also fallen into disfavor, because a strong external force, such as a vigorous cough, can recompress it. The Strecker stent can only be used in smaller airways, but may be useful in the accurate stenting of short segment stenoses because it does not foreshorten on deployment. The Wallstent and Ultraflex are our present metallic stents of choice. Both are easy to deploy, available in covered forms, exert adequate radial force, remain relatively stable in position, and have good longitudinal flexibility for use in tortuous airways. Disadvantages include excessive granulation tissue formation and difficulty of removal once the stent has been epithelialized. Metallic stents should be chosen very carefully for use in benign lesions with ongoing active local inflammation or when temporary stenting is needed. In the absence of an ideal stent, technologic advancements will continue. Potential developments include removable metallic stents, biodegradable stents, and chemically and radioactively coated stents. Unquestionably, the expanding stent market will drive scientific research toward the development of the ideal stent. Clearly, physicians need to be ready to assess these technologic advancements.

Tracheobronchial strictures: treatment with a polyurethane-covered retrievable expandable nitinol stent--initial experience

A polyurethane-covered retrievable expandable stent was placed in 13 patients with tracheobronchial strictures. In four patients with benign strictures, the stent was removed with use of a retrieval hook 2-6 months after placement. After stent removal, three of the four patients did not need further treatment. The retrievable stent warrants further investigation in the treatment of tracheobronchial strictures.

Tracheobronchial metal stents: effects of covering a bronchial ostium in pigs

RATIONALE AND OBJECTIVES

The purpose of this study was to examine the effects of placing a metal stent across a bronchial orifice.

MATERIALS AND METHODS

Nine pigs were used as test subjects, because the right upper lobe bronchus comes directly off the trachea in these animals. One of three types of metal stents was placed into the trachea of each pig and covered the orifice of the right upper lobe bronchus. Follow-up studies were performed at 1 and 3 months to evaluate the right upper lobe for signs of bronchial obstruction, infection, and atelectasis. The animals were sacrificed at 3 months to study the histopathologic changes of the trachea and lungs.

RESULTS

Two upper lobe bronchi remained patent; seven were obstructed by granulation tissue or plugs of mucus and inflammatory cells. Right upper lobe infiltration and atelectasis were seen in eight animals. Interestingly, radiographic opacities were also common in other lung segments. There was a tendency toward fewer and less extensive lung opacities at 3 months compared with that at 1 month. At histopathologic examination, areas of both acute and chronic pneumonia were found in the right upper lobe of all animals. The segment of trachea covered by the stent was lined with a thin layer of granulation tissue containing neutrophils, monocytes, and lymphocytes. The stent luminal surface was covered with columnar, cuboidal, and stratified squamous epithelium. Tracheal stenosis was seen in three animals because of excessive granulation tissue in two and a collapsed stent in one.

CONCLUSION

Placement of metal stents in pig trachea covering the orifice of the right upper lobe bronchus resulted in retention of secretions and secondary infection in the right upper lobe and other distant lung segments.

Efficacy and complications of the Gianturco-Z tracheobronchial stent for malignant airway stenosis

PURPOSE

To describe our experience using the Gianturco Z-stent (G-Z stent) for the management of malignant tracheobronchial stenosis, with special reference to complications.

METHODS

Thirty-six stents were used in 22 patients with 28 lesions. Thirteen patients were grade 5 according to the Hugh-Jones classification. The technical success rates, follow-up results, and complications were reviewed on the basis of the patients' charts and radiographs.

RESULTS

All stents were successfully placed in the ideal position without procedure-related complications. After the procedure, respiratory status improved in 95% (21/22) of patients, and performance status improved in 77% (17/22). Mean survival after stent placement was 15 weeks. Four patients suffered from increased thick secretions requiring multiple suctioning and aspiration by bronchoscopy. One of these patients died from asphyxiation 2 weeks after placement. Stent disruption and/or migration was observed in six patients. Of these six, four experienced life-threatening hemoptysis; all four had received aggressive anticancer treatment.

CONCLUSION

G-Z stents are useful for palliation of malignant tracheobronchial obstruction. However, complications of stent strut fracture and migration give cause for concern.

Interventional radiology and the use of metal stents in nonvascular clinical practice: a systematic overview

PURPOSE

The intent of this systematic overview was to describe the clinical role of metal stents in nonvascular health care interventions and the level of evidence supporting their use.

MATERIALS AND METHODS

Structured searches of Medline were conducted and limited to original peer-reviewed articles published in English.

RESULTS

Clinical practice involving metal stents was reported in more than 109 clinical series involving 4,753 patients. Stents were placed mainly for palliation of malignant biliary, esophageal, and airway obstruction in patients who were untreatable or had surgically unresectable lesions. Assessment of these interventions has so far centered on safety and technical success. Efficacy, quality of life, and costing factors were not routinely reported. Randomized trial evidence was available but limited; six randomized trials involving metal stents have been reported. Three trials involved biliary malignant obstruction, and all three reported metal stent (132 patients) palliation to be superior to plastic stent palliation (136 patients) based on longer patency and lower reintervention costs. Safety and complication differences between stents, however, were inconsistent across trials. In three trials involving esophageal malignant obstruction, metal stent (82 patients) palliation was reported to be superior to plastic stent (41 patients), based on lower complication and reintervention rates, and superior to laser therapy (18 patients), based on better dysphagia relief.

CONCLUSION

Use of metal stents has been reported for obstructed ducts and passageways of most body systems. There is, however, limited controlled trial evidence confirming the advantages of their use over plastic stents or other forms of treatment.

Pulmonary function improves after expandable metal stent placement for benign airway obstruction

STUDY OBJECTIVE

To determine whether expandable metal stent placement for benign airway lesions improves pulmonary function.

DESIGN

Case series.

SETTING

University medical center.

PATIENTS

Nine patients who underwent balloon-mediated expandable metal stent deployment for airway obstruction due to benign etiologies.

RESULTS

All nine patients had expandable stents deployed for benign airway lesions using fiberoptic bronchoscopy and fluoroscopic guidance. Pulmonary function improved after stent placement. The mean FVC increased by 388 mL (95% confidence interval [CI], 30 to 740 mL), the mean peak expiratory flow (PEF) increased by 1,288 mL (95% CI, 730 to 1,840 mL), the mean FEV1 increased by 550 mL (95% CI, 240 to 860 mL), and the mean forced expiratory flow between 25% and 50% of vital capacity (FEF25-75%) increased by 600 mL (95% CI, 110 to 1,090 mL). Corresponding relative measurements included increases in FVC (12%), PEF (95%), FEV1 (38%), and FEF25-75% (87%). The complete characterization of a benign airway obstruction generally required a multimodal approach.

CONCLUSIONS

Expandable metal stent placement appears to be an effective therapy for benign airway obstruction.

Stenting therapy for stenosing airway disease

Stenosing airway disease is classified as intraluminal obstruction, extrinsic compression, and malacia by the anatomical site of the lesion. Stenting therapy is indicated for symptomatic relief of life-threatening dyspnea caused by the last two types. Airway stents are made with metal mesh and/or silicone rubber, and currently more than 20 kinds of stent are available. The metal stent (e.g. Gianturco stent, Wallstent) is easy to insert, may not need general anesthesia, and has wider internal lumen. Because it is very hard to reposition or remove, it is mainly used in malignant airway obstruction. Among many kinds of silicone stent, the Dumon stent is most widely used for benign and malignant airway stenoses, but general anesthesia and rigid bronchoscopy are needed for insertion. It can be removed when the stenosing airway disease subsides completely. In many clinical studies, most patients (85-90%) improved immediately after stenting, and procedure-related mortality is low (< 3%) in experienced centers. Stent displacement, mucus impaction, and granulation tissue formation are potential complications. Stenting is one of many effective therapeutic modalities for stenosing central airway disease. Careful patient selection, experiences, and continuous development of new technology will bring better results.

Open surgery for removal of a failing Gianturco stent with reversed sleeve resection of the right middle and lower lobes

Although the use of a metallic stent in the treatment of benign tracheobronchial stenosis has been reported as a useful and safe technique, the incorporation of wire stents into the airway may be irreversible and is associated with problems. The authors' experience in a patient with incorrectly positioned metallic stent in the right main bronchus, which was successfully treated with bronchial sleeve resection, is presented.

The use of expandable metallic stents for acute tracheal stenosis in the growing lamb

PURPOSE

Expandable metallic stents (Palmaz stents) have been used in the treatment of tracheobronchial obstruction in children and adults. The authors investigated their utility in the management of acute airway stenosis in a growing animal model.

METHODS

A model for tracheal stenosis was developed in young lambs (mean age, 4 weeks; mean weight, 8.6 kg). Via an anterior tracheotomy, a circumferential mucosal injury to the trachea was produced with electrocautery in 31 lambs. In the control group (n = 10) no further intervention was used. In the treatment groups, either serial balloon dilatation of the stricture was performed (n = 6), or expandable metallic stents were inserted across the stricture (n = 15). All animals were monitored daily for signs of respiratory distress. Body weights, fluoroscopic airway measurements and rigid bronchoscopy were performed at least weekly.

RESULTS

The average weekly rate of airway growth was 8.2% +/- 5.5% of the tracheal cross-sectional area (CSA). All animals displayed severe stenosis (mean, 90.2% +/- 7.5% of CSA) within 13.1 +/- 4 days after the injury. All animals in the control group had severe respiratory distress, weight loss and died within 14.6 +/- 2.8 days after injury. Serial balloon dilatation of the stricture alone failed to relieve symptoms in all six animals in this group, who died within 20 +/- 1 days after the injury, despite two to three dilatations each. With placement of expandable metallic stents, only 3 of 15 lambs died (two of pneumonia, one of iatrogenic perforation). The remaining 12 remained symptom-free and gained weight during a 2-month follow-up period. However, fluoroscopic examination showed partial collapse of the stents in all of these animals (mean, 44.7% +/- 21.6% of CSA) requiring an average of 2 +/- 0.7 bronchoscopic dilatations. Pathological evaluation showed more pronounced granulation tissue in the stented animals.

CONCLUSIONS

The authors conclude that expandable metallic stents provide an effective tool in the management of acute tracheal stenosis. However, airway growth, tissue reaction, and the mechanical properties of the stent require close monitoring and stent adjustment.

Experience of expandable metallic stents for central airway obstruction

The aim of this study was to investigate retrospectively the efficacy of expandable metallic stents (EMSs) for severe respiratory distress in patients with central airway obstruction. Twenty patients with central airway obstructions were treated with an EMS. An intraluminal stricture was present in 15 and an extraluminal stricture in 5 patients. Of the 15 patients with intraluminal stenosis, 11 exhibited symptomatic improvement. All 11 patients had tumor infiltration occupying less than 50% of the endoluminal diameter. The other four patients with intraluminal stenosis had tumor infiltration occupying > 50% of the endoluminal diameter and demonstrated no improvement. All five patients with extraluminal stenosis were improved. EMS is useful for an extraluminal stricture in the central airway and the effect of EMS for intraluminal stenosis is related to the degree of infiltration and of tumor progression itself.

Implantation of Accuflex and Strecker stents in malignant bronchial stenoses by flexible bronchoscopy

Silicone and metal stents are available for the treatment of malignant bronchial stenoses. This project sought to compare the self-expanding nitinol Accuflex stent (Boston Scientific Corp; Watertown, Mass) with the passively expandable tantalum Strecker stent (Boston Scientific Corp; Watertown, Mass), both implanted by flexible bronchoscopy under local anesthesia and sedation. In 51 patients with malignant bronchial stenosis, 14 nitinol and 51 tantalum stents were used and stenoses of 75 to 100% were treated. The intervention was successful in all but one patient; a mean patency of 93% was achieved. In the follow-up period, the probability of survival was significantly lower in patients with total bronchus occlusion than in patients with stenotic alterations (44 vs 109 days; p<0.05). In 10 patients, lung function analysis after stent implantation revealed a significant increase in PaO2 (65 vs 71 mm Hg; p<0.01), inspiratory vital capacity (2.5 vs 2.7 L; p<0.05), and FEV1 (1.8 vs 2.0 L; p<0.05). Mucus retention was the main (39%) adverse factor in the early phase after stent implantation, whereas tumor penetration became the most frequent problem (67%) in the later phase. Recanalizing interventions were necessary in 18% of the cases in which tumor penetration occurred. Stent distortion occurred in 12 patients with Strecker and in none with Accuflex stents. In comparison to the Strecker stent, the self-expanding Accuflex stent is preferable owing to its excellent flexibility and faster delivery system. Both types of stents could be sufficiently deployed within the lesion and allowed for highly precise positioning. Furthermore, no general anesthesia was required. The fiberbronchoscopic mode of implantation under sedation is very efficient even for tumor patients with severe impairment of their physical and respiratory condition.

Covered gianturco stents for malignant biliary obstruction: preliminary clinical evaluation

PURPOSE

To evaluate the effectiveness of covered Gianturco stents in patients with malignant biliary obstruction.

MATERIALS AND METHODS

Three types of partially polyurethane-covered stents were implanted in 19 patients with malignant biliary obstruction located distal to the hilar confluence. A transhepatic approach was employed in all but one patient, in whom the stent was placed through a T-tube tract.

RESULTS

Stent placement was possible in all patients. In 15 patients, the implanted stents were expanded to a mean of 81% of their original diameter. In the remaining four patients, the stents expanded to less than 40% of the original diameter, and balloon dilation and additional bare stent placement were required. All patients except one, who had impairment of liver function due to multiple liver metastases, showed relief of jaundice after stent placement. At follow-up, which ranged from 5 to 57 weeks (mean, 24.7 weeks), one stent (5%) was occluded after 26 weeks due to tumor growth above the upper stent edge, and required secondary intervention. Complications in three patients included stent migration in one (5%) and cholangitis in two (11%).

CONCLUSION

Preliminary results suggest that placement of covered Gianturco stents is feasible, the complication rate is acceptable, and short-term patency appears promising.

Migration of Gianturco expandable metallic stents in the upper trachea

Endotracheal expandable metallic stents have been shown to be useful in treating malignant tracheobronchial stenosis. We report two cases of early stent migration in the upper trachea after what appeared to be a successful stent placement. We conclude that care should be taken when placing Gianturco stents across short, extrinsic, stenotic lesions with smooth mucosa located in the upper trachea because they have a tendency to migrate.

Partially covered Gianturco stent for tracheobronchial stricture caused by intraluminal tumor

Partially covered Gianturco stents were used successfully in two patients to treat tracheobronchial strictures caused by intraluminal tumor growth. The stents were accurately placed without complications. The covered portion of the stent compressed the tumor, and prevented tumor ingrowth until the patients' deaths. This stent seems to act as effective palliation for tracheobronchial stricture caused by intraluminal tumor.

Effect of conventional mechanical ventilation and jet ventilation on airway pressure in dogs and plastic models with tracheal stenosis

OBJECTIVE

To evaluate the effect of jet ventilation on tracheal stenosis in dogs and plastic models.

DESIGN

Prospective, randomized trial in dogs, and multitrial tests in tracheal stenosis models.

SETTING

Animal laboratory in a university setting.

INTERVENTIONS

Tracheal stenosis was surgically created around the middle of the trachea. Conventional mechanical ventilation and jet ventilation were compared at the same value of Paco2 in dogs and at the same tidal volume in tracheal stenosis models.

SUBJECTS

Twelve mongrel dogs and four types of plastic models with combinations of short or long stenosis and fluid or nonfluid stenosis.

MEASUREMENTS AND MAIN RESULTS

Canine Studies. Mean peak peak airway pressure values at the distal and proximal portion of the stenosis, and the end-expiratory pressure at the distal portion of the stenosis, were significantly higher during conventional mechanical ventilation than during jet ventilation. The mean values of arterial pressure, pulmonary arterial pressure, central venous pressure, and cardiac output did not change significantly between conventional mechanical ventilation and jet ventilation, except for the pulmonary artery occlusion pressure valve. Plastic Mold Studies. peak airway pressure and end-expiratory airway pressure at the poststenotic trachea during jet ventilation with the model lung were significantly lower than during conventional mechanical ventilation. The difference in peak airway pressure, and end-expiratory airway pressure values between jet ventilation and conventional mechanical ventilation increased more in short stenosis and nonfluid stenosis.

CONCLUSIONS

The jet flow that struck the portion of the stenosed wall reversed direction, even during early expiration. Therefore, the expiration during jet ventilation was facilitated more by the reversed flow than by the expiration during conventional mechanical ventilation. This reversed flow may provide lower end-expiratory airway pressure at the poststenotic portion with jet ventilation than with conventional mechanical ventilation. We conclude that jet ventilation was a useful method of ventilation in cases with tracheal stenosis, especially nonfluid and short stenosis.

Wire stent for tracheomalacia in a five-year-old girl

A wire stent was used successfully to treat life-threatening tracheomalacia in a 5-year-old girl. Wire stents placed bronchoscopically are nonobstructing and have the potential for balloon expansion to accommodate growth.

Metallic endoprostheses for malignant tracheobronchial obstruction: initial experience

PURPOSE

To assess the efficacy of the Wallstent endoprosthesis in malignant tracheobronchial obstruction.

METHODS

Seven patients with irresectable carcinoma of the bronchus were treated with nine Wallstent endoprostheses. The procedures were performed under endoscopic and fluoroscopic guidance. Wallstent endoprostheses ranging from 8-16 mm in diameter and 26-49 mm in length were deployed after balloon dilatation of the strictures.

RESULTS

All stents were successfully deployed in the desired positions. There was one procedural complication and one procedure related death. Three patients showed significant improvement in respiratory status after stenting. At a mean follow-up of 5.1 months, there has been no stent migration, fracture, or collapse. One patient had proximal tumor overgrowth that was treated with additional stent insertion. One patient died after a bout of massive hemoptysis 3 months poststenting and it was difficult to tell whether this was related to the endoprosthesis.

CONCLUSION

The use of the Wallstent endoprosthesis in malignant tracheobronchial obstruction is technically feasible.

Endoscopic management of acute respiratory failure related to tracheobronchial malignancies

Endobronchial treatment has an expanding role in the treatment of tracheobronchial tumors. Most patients are treated in this way for the palliation of dyspnea caused by a tumor located in a major airway. In cases where immediate relief is required, prompt control is better achieved by the neodymium-YAG laser or by stents. These two modalities and their indications and limitations in the endoscopic management of acute respiratory failure related to tracheobronchial malignancies are discussed.

Gianturco-Rösch Z stents in tracheobronchial stenoses

PURPOSE

To evaluate expandable metallic Gianturco-Rösch Z (GRZ) stents for treatment of benign and malignant tracheobronchial stenoses.

PATIENTS AND METHODS

Six patients, ages 45-73 years, were treated for severe dyspnea with placement of GRZ stents. Three patients had benign tracheal lesions (one tracheomalacia, two postoperative) and received uncovered GRZ stents. Three patients had malignant stenoses at the level of the carina; one received an uncovered stent and the other two received silicone-covered GRZ stents.

RESULTS

Two patients with benign lesions responded well to stent placement. One was asymptomatic for a year and then was lost to follow-up; the other improved substantially but died of end-stage lung disease 5 months after stent placement. A third patient with a benign high tracheal lesion did poorly; symptoms recurred secondary to inferior migration of a stent, which was removed surgically at 4 months. All patients with malignant lesions improved symptomatically after stent placement and remained without significant dyspnea until death (from 1 to 6 months).

CONCLUSION

Expandable GRZ stents are promising devices for treatment of benign lesions and offer effective palliation of malignant tracheobronchial stenoses.

Management of tracheal and bronchial stenoses with the Gianturco stent

Thirty-six cancer patients with symptomatic tracheobronchial stenoses received Gianturco tracheobronchial stents over a 9-year period. Symptoms improved in 28 patients (78%). The overall median survival was 1 month 3 weeks (range, 4 days to 35 months). The median survival for patients who showed improvement after receiving stents was 3 months compared with 1 week for those who did not respond. Complications were minimal. The Gianturco stent may palliate symptoms of tracheobronchial compression in selected cancer patients.