Ultraflex stents for the management of airway complications in lung transplant recipients

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.

Interventional pulmonology techniques in lung transplantation

Lung transplantation is a key therapeutic option for several end-stage lung diseases. Interventional pulmonology techniques, mostly bronchoscopy, play a key role throughout the whole path of lung transplantation, from donor evaluation to diagnosis and management of post-transplant complications. We carried out a non-systematic, narrative literature review aimed at describing the main indications, contraindications, performance characteristics and safety profile of interventional pulmonology techniques in the context of lung transplantation. We highlighted the role of bronchoscopy during donor evaluation and described the debated role of surveillance bronchoscopy (with bronchoalveolar lavage and transbronchial biopsy) to detect early rejection, infections and airways complications. The conventional (transbronchial forceps biopsy) and the new techniques (i.e. cryobiopsy, biopsy molecular assessment, probe-based confocal laser endomicroscopy) can detect and grade rejection. Several endoscopic techniques (e.g. balloon dilations, stent placement, ablative techniques) are employed in the management of airways complications (ischemia and necrosis, dehiscence, stenosis and malacia). First line pleural interventions (i.e. thoracentesis, chest tube insertion, indwelling pleural catheters) may be useful in the context of early and late pleural complications occurring after lung transplantation. High quality studies are advocated to define endoscopic standard protocols and thus help improving long-term prognostic outcomes of lung transplant recipients.

Interventional Bronchoscopy

For over 150 years, bronchoscopy, especially flexible bronchoscopy, has been a mainstay for airway inspection, the diagnosis of airway lesions, therapeutic aspiration of airway secretions, and transbronchial biopsy to diagnose parenchymal lung disorders. Its utility for the diagnosis of peripheral pulmonary nodules and therapeutic treatments besides aspiration of airway secretions, however, has been limited. Challenges to the wider use of flexible bronchoscopy have included difficulty in navigating to the lung periphery, the avoidance of vasculature structures when performing diagnostic biopsies, and the ability to biopsy a lesion under direct visualization. The last 10-15 years have seen major advances in thoracic imaging, navigational platforms to direct the bronchoscopist to lung lesions, and the ability to visualize lesions during biopsy. Moreover, multiple new techniques have either become recently available or are currently being investigated to treat a broad range of airway and lung parenchymal diseases, such as asthma, emphysema, and chronic bronchitis, or to alleviate recurrent exacerbations. New bronchoscopic therapies are also being investigated to not only diagnose, but possibly treat, malignant peripheral lung nodules. As a result, flexible bronchoscopy is now able to provide a new and expanding armamentarium of diagnostic and therapeutic tools to treat patients with a variety of lung diseases. This State-of-the-Art review succinctly reviews these techniques and provides clinicians an organized approach to their role in the diagnosis and treatment of a range of lung diseases.

Airway stenting: Technological advancements and its role in interventional pulmonology

AS offers rapid and sustained relief of symptoms in most patients treated for malignant or benign CAO and can also be curative in itself in cases of benign tracheobronchial stenosis. In the past 30 years, this field has seen significant progress, from the misuse of vascular non-covered metallic stents to the development of silicone airway stents with an increasingly large panel of shapes and of hybrid, partially or fully covered, SEMS customized to the airways. This study aims to offer an overview on: (i) the respective advantages and drawbacks of these two main categories of devices; (ii) the main indications for AS and the rationale behind the choice of stent in each situation; and (iii) the main promises borne from the progress made in the field in the past few years, including the development of drug-eluting, biodegradable or patient-specific customized AS.

Fully Covered Metallic Stents for the Treatment of Benign Airway Stenosis

Introduction. We herein report our experience with new fully covered self-expanding metallic stents in the setting of inoperable recurrent benign tracheobronchial stenosis. Methods. Between May 2010 and July 2014, 21 Micro-Tech® FC-SEMS (Nanjing Co., Republic of Korea) were placed in our hospital in 16 patients for inoperable, recurrent (after dilatation), and symptomatic benign airway stenosis. Their medical files were retrospectively reviewed in December 2014, with focus on stent's tolerance and durability data. Results. Twenty-one stents were inserted: 13 for posttransplant left main bronchus anastomotic stricture, seven for postintubation tracheal stenosis, and one for postlobectomy anastomotic stricture. Positioning was easy for all of them. Stents were in place for a mean duration of 282 days. The most common complications were granulation tissue development (35%), migration (30%), and sputum retention (15%). Fifty-five % of the stents (11/20) had to be removed because of various complications, without difficulty for all of them. None of the patients had life-threatening complications. Conclusion. Micro-Tech FC-SEMS were easy to position and to remove. While the rate of complications requiring stent removal was significant, no life-threatening complication occurred. Further studies are needed to better define their efficacy and safety in the treatment of benign airway disease.

Current readings: the role of stenting in tracheobronchial disease

Airway stents have gained acceptance for palliation or treatment of tracheobronchial pathologies or both since the second half of the 20th century. However, minimal advances have been made in the last 3 decades with regard to innovations in stent technology. Following a health alert issued by the Food and Drug Administration in 2005, silicone stents are now mainly used for benign pathologies whereas self-expanding metal stents are reserved for use with malignant airway obstruction. In this article, we review 5 articles published between 2010 and 2013 addressing the roles of stents in the management of malignant, benign, and post-lung-transplantation-related tracheobronchial narrowing. We identified what were the largest or most clinically relevant series in each case, but with the understanding that all are retrospective reviews with patient selection bias.

The use of self-expandable metallic stents in the airways in the adult population

The airway stents restore patency in the face of luminal compromise from intrinsic and/or extrinsic pathologies. Luminal compromise beyond 50% often leads to debilitating symptoms such as dyspnea. Silicone stents remain the most commonly placed stents worldwide and have been the "gold standard" for the treatment of benign and malignant airway stenoses over the past 20 years. Nevertheless, silicone stents are not the ideal stents in all situations. Metallic stents can serve better in some selected conditions. Unlike silicone stents, there are large and increasing varieties of metallic stents available on the market. The lack of prospective or comparative studies between various types of metallic stents makes the choice difficult and expert-opinion based. International guidelines are sorely lacking in this area.

Interventional techniques in the management of airway complications following lung transplantation

The last four decades have seen tremendous advances in the field of pulmonary transplantation. Vast improvements in the areas of surgical transplantation techniques, immunosuppressive agents, and postoperative care have all contributed to improved survival of patients. Advances in noninvasive imaging and bronchoscopy have allowed the pulmonary transplant team to intervene early in patients presenting with airway complications, often using minimally invasive procedures such as endobronchial balloon dilation or stent placement, or both. Stent technology itself has also improved and stents may sometimes be customized for treatment of short airway lesions or to optimize continued airflow through the sides of stents by creating openings using balloons or bronchoscopically directed laser. Preliminary work with brachytherapy may be decreasing the need for secondary reinterventions. The authors present an overview of some of these conventional and novel approaches to the treatment of airway complications after lung transplantation.

Managing obstruction of the central airways

Lung cancer is the most common cause of cancer death in Australia, Europe and the USA. Up to 20-30% of these cancers eventually affect the central airways and result in reduced quality of life, dyspnoea, haemoptysis, post-obstructive pneumonia and ultimately death. Non-malignant processes may also lead to central airway obstruction and can have similar symptoms. With the development of newer technologies, the last 20 years have seen the emergence of the field of interventional pulmonology to deal specifically with the diagnosis and management of thoracic malignancy, including obstruction of the central airways. This review discusses the pathology, pre-procedure work-up and management options for obstructing central airway lesions. Several treatment modalities exist for dealing with endobronchial pathology with local availability and expertise guiding choice of treatment. While the literature lacks large, multicentre, randomized studies defining the optimal management strategy for a given problem, there is growing evidence from numerous case studies of improved physiology, of quality of life and possibly of survival with modern interventional techniques.

Update on lung transplantation for emphysema

Lung transplantation in the modern era remains an evolving field and a viable option for patients suffering from end-stage emphysema. Recent modifications for recipient prioritization has resulted in a modest decrease in the number of patients with emphysema receiving transplants. More time will be required to determine what impact, if any, these modifications will have on the overall survival of patients with end-stage emphysema. Ongoing research will address persistent issues with lung transplantation, most notably, primary graft dysfunction and chronic BOS.

Update on lung transplantation

Lung transplantation is a suitable treatment to improve the quality of life and the prognosis of patients with various end-stage pulmonary diseases. There is a shortage of organs and the number of patients on waiting list is exceeding the number of transplants per year approximately two-fold in most countries. Strategies to increase the donor pool are therefore crucial. The long-term prognosis after lung transplantation is not yet as good as for other transplantation procedures and special complications should be taken into account. Aside from infections chronic organ dysfunction is the main cause of death and the most important prognosis limiting factor. Other typical problems are rejection, bronchus complications, and primary transplant dysfunction. However, the results of large centers show promising improvements in recent years.

Do airway metallic stents for benign lesions confer too costly a benefit?

Background

The use of self-expanding metallic stents (SEMAS) in the treatment benign airway obstruction is controversial.

Methods

To evaluate the safety and efficacy of SEMAS for this indication, we conducted a 10-year retrospective review at our tertiary medical centre.

Results

Using flexible bronchoscopy, 82 SEMAS (67% Ultraflex, 33% Wallstent) were placed in 35 patients with inoperable lesions, many with significant medical comorbidities (88%). 68% of stents were tracheal, and 83% of patients showed immediate symptomatic improvement. Reversible complications developed in 9% of patients within 24 hrs of stent placement. Late complications (>24 hrs) occurred in 77% of patients, of which 37% were clinically significant or required an interventional procedure. These were mainly due to stent migration (12.2%), fracture (19.5%), or obstructive granulomas (24.4%). The overall granuloma rate of 57% was higher at tracheal sites (59%) than bronchial ones (34%), but not significantly different between Ultraflex and Wallstents. Nevertheless, Wallstents were associated with higher rates of bleeding (5% vs. 30%, p = 0.005) and migration (7% vs. 26%, p = 0.026). Of 10 SEMAS removed using flexible bronchoscopy, only one was associated with incomplete removal of fractured stent wire. Median survival was 3.6 ± 2.7 years.

Conclusion

Ill patients with inoperable lesions may be considered for treatment with SEMAS.

Airway stents in children

Airway obstruction in children is a rare, but difficult clinical problem, with no clear agreement on optimal therapeutic approach. Stenting of the airway has been used successfully in adults, and is an attractive alternative in children. Fundamental differences of pediatric compared to adult use include the benign nature of most stenoses, the narrow and soft airways of children, the required long-term tolerance and adaptation to growth. These differences may significantly alter the therapeutic balance, calling into question the precise role stents play in the treatment of airway obstruction in children. Stent placement can be technically demanding but is not exceedingly difficult. Experience is necessary to select the proper size and type of stent. Metal stents usually achieve airway patency and clinical improvement in the majority of cases, while this is less frequently the case with silicone stents. Some complications such as granulation and secretion retention seem to occur in most children after stent implantation. Unfortunately, severe complications including death have been reported in a significant proportion of children. Stent related mortality can be estimated at 12.9% from published data, but these include complication centered reports. The initial euphoria for airway stents in children has largely abated and most authors agree that they should only be employed in circumstances with no good alternatives. It is crucial that all surgical and medical alternatives are considered and the decision to place a stent is not made because other options are overlooked or not available locally. Stent use in a palliative setting has also been reported and is probably reasonable. Stents will only allow limited adaptation for the growth of pediatric airways by balloon dilatation. All metal stents should be considered as potentially permanent, and removal sometimes may only be possible through a surgical and sometimes risky approach.

Endobronchial stent placement for the management of airway complications after lung transplantation

PURPOSE

To retrospectively evaluate the efficacy and complications of endobronchial stent placement for the management of airway complications following lung transplant.

MATERIALS AND METHODS

From 1992 to 2003, tracheobronchial stenting was performed on 25 lung transplant recipients (16 male and 9 female; mean age 51.6 years; range 21-65 years). A total of 27 lesions were treated and 27 stents were deployed (nine bronchomalacia, 12 bronchial stenosis, three bronchial stenosis and bronchomalacia both and three anastomotic dehiscence). The clinical and bronchoscopic follow-up ranged from 1 month to 69 months.

RESULTS

The technical success was 100%. Eighty-four percent of patients had immediate relief in dyspnea. The overall complication rate following stent placement was 0.049 per patient per month (23 complications/471 patient months). Stent migration and granulation tissue formation were the most frequent complications. The mean percentage change in FEV-1 was significantly greater than zero at 1 month and 6 months (P<.05) post-stent placement. The mean percentage change in FEV-1 was marginally greater than zero at 12 months (P=.07).The mean percentage change in FVC was marginally greater than zero at 1 month and 6 months (P=.08) post-stent. It was not significantly greater than zero at 12 months (P=1.00).

CONCLUSION

Tracheobronchial stent placement provides effective palliation of postoperative airway complications in lung transplant with morbidity that can be managed effectively by available treatment options. Airway stenting may be used as a primary management option for airway complications after lung transplantation as a large number of patients are not suitable candidates for repeat surgery.

Surgical therapies for pulmonary arterial hypertension

Surgical therapies for the treatment of pulmonary arterial hypertension typically are reserved for patients who are deemed to be refractory to medical therapy and have evidence of progressive right-sided heart failure. Atrial septostomy, a primarily palliative procedure, may stave off hemodynamic collapse from right-sided heart failure long enough to permit a more definitive surgical treatment such as lung or combined heart-lung transplantation. This article discusses indications for and results of atrial septostomy and lung and heart-lung transplantation in patients who have pulmonary arterial hypertension.

Bronchoscopic balloon dilatation in the management of bronchial stenosis following lung transplantation

BACKGROUND

Bronchial stenosis (BS) is currently found in 7-15% of lung transplantation (LT) recipients. Current treatment strategies have included Nd:Yag laser, cryotherapy, bougie dilatation and stent placement. Bronchoscopic balloon dilatation has been used as alternative treatment in a few cases with controversial results. This is a study to prospectively assess the efficacy of bronchoscopic balloon dilatation as a first step in the management of post-LT BS.

METHODS

From January 1995 to December 2002, bronchoscopic balloon dilatation was evaluated as first therapeutic option in all consecutive LT patients with BS. Symptoms, pulmonary function tests, airway diameter and use of other therapeutic techniques were evaluated.

RESULTS

A total of 10 out of 284 anastomed airways (3.5%) in 9 out of 152 LT patients were included in the study and follow-up lasted from 6 to 81 months. Dilatation of all but one BS met with initial success: increase of both luminal dimensions and forced vital capacity (P=0.01), and relief of symptoms. Bronchoscopic balloon dilatation long-term follow-up showed effective results in 5 out of 10 (50%) bronchial stenoses, after an average of 4 bronchoscopic balloon dilatation procedures (range 1-8). No severe complications were observed. Stent placement was required in the other 5 bronchial stenoses.

CONCLUSIONS

Bronchoscopic balloon dilatation is a safe method that should be considered as first therapeutic treatment of post-LT BS. Its use avoids the need for stent placement in up to 50% of cases.

[Endoscopic treatment of central airway stenosis: five years' experience]

OBJECTIVE

To describe our experience with interventional bronchoscopy in the treatment of central airway stenosis.

PATIENTS AND METHODS

We reviewed patient records and bronchoscopic findings. Clinical data, findings from computed tomography, techniques performed, complications, and results were recorded.

RESULTS

One-hundred and thirty-six patients (90 males and 46 females) were treated. The mean (SD) age was 57 (7) years (range, 3-81). A total of 320 therapeutic interventions were performed: 145 laser treatments, 33 balloon or mechanical dilatations, 26 electrocauterizations, and 116 stent insertions. Pathogenesis varied: in 64 (47%) patients, the stenosis was caused by a tumor (48 were bronchopulmonary and 16 nonpulmonary); in 72 (53%) patients, stenosis was secondary to a nontumor-related process, of which the most common was prolonged intubation (42% of these cases). Central airway patency was achieved in 92% (59/64) of the tumor-related stenoses and 96% (69/72) of those unrelated to tumors. Improvement in dyspnea was observed in 96% of all patients. Two deaths (due to hemoptysis and to acute myocardial infarction) occurred in the first week, for a 1.4% mortality rate. The most common complications were stent migration (8%; 9/116 cases) and the formation of granulomas (9%; 11/116).

CONCLUSIONS

Interventional bronchoscopy is an effective technique to resolve life-threatening obstructions of the central airways. Dyspnea improves immediately and there is no significant morbidity or mortality.

Utilização de endoprótese metálica no tratamento de estenose brônquica após transplante pulmonar

As complicações decorrentes da anastomose brônquica nos transplantes pulmonares, embora tenham diminuído ao longo do tempo, ainda figuram como um dos principais fatores de morbi-mortalidade nesses pacientes. As formas de tratamento dessas complicações incluem dilatação por balão, fotocoagulação por laser, endopróteses de silicone e metálicas, e reoperação. Relata-se o caso de um paciente que apresentou estenose brônquica após transplante pulmonar unilateral esquerdo, cujo tratamento foi realizado com endoprótese metálica auto-expansível de nitinol (Ultraflex®). Embora seja um caso pioneiro no Brasil, a boa resposta clínica, concordante com os dados da literatura, sugere que esse tratamento seja uma boa alternativa nesses casos.

Cutaneous carbon dioxide monitoring in adults

PURPOSE OF REVIEW

Arterial blood gas analysis is the 'gold standard' method to measure the arterial partial pressure of carbon dioxide (PaCO2). However, arterial sampling including arterial catheterization is invasive and expensive. Cutaneous carbon dioxide tension (PcCO2) measurement is used as a noninvasive surrogate measure of PaCO2, which is used to either estimate PaCO2 or determine trend changes in the measurement. There has been considerable progress in the technical aspects of PcCO2 monitoring in the last few years. In this article, we evaluate recent developments and the renewed interest in the subject of PcCO2 monitoring in adults and discuss the technical aspects, clinical applications and the future outlook for this technique in the clinical setting.

RECENT FINDINGS

With evolution in technology, PcCO2 monitoring is now less cumbersome than before. Combined PcCO2 measurement and pulse oximetry is now possible with a single earlobe sensor.

SUMMARY

The clinical settings in which PcCO2 monitoring can be applied include patient monitoring during and after anaesthesia, patients receiving noninvasive ventilation, post extubation, endoscopy under sedation, the sleep laboratory and the lung function laboratory. Although there is an overlap of the clinical indications when both PcCO2 and end-tidal carbon dioxide monitoring may be used, it is our opinion that both these methods have independent indications and are sometimes also complementary to each other in patient care.