Stenting at the Flow-limiting Segment in Tracheobronchial Stenosis due to Lung Cancer

Y Reverse: Modified technique in challenging airway management

INTRODUCTION

Self-expanding Y-metal stents (SEMS) are best suited lesions with involvement of the carina and proximal main bronchi; however, Y-stents can be difficult to place. These difficulties guided us to develop a modification of the classic technique that addresses some of the challenges during positioning. We present the Y reverse technique for Y stent insertion using a combination of rigid and flexible bronchoscopy.

MATERIALS AND METHODS

This retrospective study included 15 consecutive patients, suffering from tracheal-carina-lower main bronchi complex, hospitalized at the Thoracic Surgery Unit of the Vanvitelli University of Naples between October 2021 and October 2023.

INCLUSION CRITERIA

patients in which the length of the stenosis of the right bronchi was greater than that of the left bronchi, advanced oncological conditions, severe respiratory failure; exclusion criteria: Karnofsky scale with <40 points. All patients were admitted to the hospital and treated with Y-stent insertion using the modified technique Y reverse.

RESULTS

The comparison between the group undergoing the Y reverse technique with the group undergoing the traditional positioning of the Y prosthesis has shown an improvement in respiratory function; prolongation of the mean survival time; improvement in SpO2 in spontaneous breathing; reduction mean time procedure. p < 0.05 was considered as statistically significant.

CONCLUSION

Y Reverse is a safe and effective procedure that provides rapid symptom relief in individuals who have critical central airway obstruction near the distal portion of the trachea, carina, and main right and left bronchi.

World Association for Bronchology and Interventional Pulmonology (WABIP) guidelines on airway stenting for malignant central airway obstruction

Malignant Central Airway Obstruction (MCAO) encompasses significant and symptomatic narrowing of the central airways that can occur due to primary lung cancer or metastatic disease. Therapeutic bronchoscopy is associated with high technical success and symptomatic relief and includes a wide range of airway interventions including airway stents. Published literature suggests that stenting practices vary significantly across the world primarily due to lack of guidance. This document aims to address this knowledge gap by addressing relevant questions related to airway stenting in MCAO. An international group of 17 experts from 17 institutions across 11 countries with experience in using airway stenting for MCAO was convened as part of this guideline statement through the World Association for Bronchology and Interventional Pulmonology (WABIP). We performed a literature and internet search for reports addressing six clinically relevant questions. This guideline statement, consisting of recommendations addressing these six PICO questions, was formulated by a systematic and rigorous process involving the evaluation of published evidence, augmented with expert experience when necessary. Panel members participated in the development of the final recommendations using the modified Delphi technique.

Tissue accumulation of microplastics and potential health risks in human

Microplastics have become ubiquitous throughout the environment. Humans constantly ingest and inhale microplastics, increasing concerns about the health risks of microplastic exposure. However, limited data impedes a full understanding of the internal exposure to microplastics. Herein, to evaluate microplastic exposure via the respiratory and digestive systems, we used laser direct infrared spectroscopy to identify microplastics >20 μm in size in different human tissues. Consequently, 20-100 μm microplastics were concentrated in all tissues, with polyvinyl chloride (PVC) being the dominant polymer. The highest abundance of microplastics was detected in lung tissue with an average of 14.19 ± 14.57 particles/g, followed by that in the small intestine, large intestine, and tonsil (9.45 ± 13.13, 7.91 ± 7.00, and 6.03 ± 7.37 particles/g, respectively). The abundance of microplastics was also significantly greater in females than in males (p < 0.05). Despite significant diversity, our estimation showed that the lungs accumulated the highest amounts of microplastic. Moreover, PVC particles may cause potential health risks because of their high polymer hazard index and maximal risk level. This study provides evidence regarding the occurrence of microplastics in humans and empirical data to support assessments of the health risks posed by microplastics.

Malignant Airway Obstruction and Endobronchial Stent Placement: A Systematic Review on the Efficacy and Safety

The systematic review aims to evaluate the efficacy and safety of endobronchial stent placement for malignant airway obstruction.  A comprehensive search was conducted across multiple databases to identify relevant studies. Cohort studies, randomized controlled trials, and case-control studies examining the outcomes of endobronchial stent placement in patients with malignant airway obstruction were included. Data on pre-treatment evaluation, such as pulmonary function testing, dyspnea severity scoring systems, arterial blood gas parameters, imaging, and degree of obstruction, were also collected. Primary outcomes of interest included post-procedure stenosis, pulmonary function testing evaluation, blood gas parameters, and survival outcomes. Secondary outcomes encompassed improvements in clinical status, dyspnea grade, and procedure-related complications. A total of 27 studies met the inclusion criteria and were included in the systematic review. The included studies demonstrated promising outcomes of endobronchial stent placement in managing malignant airway obstruction. Post-procedure airway diameters, pulmonary function testing, and blood gas parameters improved significantly. Survival outcomes varied among studies. Furthermore, endobronchial stent placement was associated with improvements in clinical status and dyspnea grade. Procedure-related complications ranged from pain, hemoptysis and mucus plugging to stent obstruction, migration and pneumothorax.  This systematic review suggests that endobronchial stent placement is an effective and safe intervention for managing malignant airway obstruction. It offers significant improvements in post-procedure stenosis, pulmonary function testing, blood gas parameters, and clinical outcomes. However, further studies with larger sample sizes and standardized reporting are warranted to better evaluate the long-term efficacy and safety of endobronchial stent placement for malignant airway obstruction.

Evidence of Microplastics in Bronchoalveolar Lavage Fluid among Never-Smokers: A Prospective Case Series

Microplastics (MPs) are abundant in air, but evidence of their deposition in the respiratory tract is limited. We conducted a prospective case series to investigate the deposition of microplastics in bronchoalveolar lavage fluid (BALF) and determine the internal dose of MPs via inhalation. Eighteen never-smokers aged 32-74 years who underwent fiberoptic bronchoscopy with BALF were recruited from Zhuhai, China. Control samples were obtained by performing the same procedure using isotonic saline instead of BALF. Laser direct infrared spectroscopy combined with scanning electron microscopy detected the presence and characteristics of MPs and quantitatively analyzed the microplastic in BALF and control samples. Concentrations of total and specific MPs in BALF and control samples were compared using the Wilcox test. Thirteen types of MPs were observed in 18 BALF samples. Polyethylene (PE, 86.1%) was the most abundant in BALF, followed by poly(ethylene terephthalate) (PET, 7.5%) and polypropylene (PP, 1.9%). Compared with the control samples, BALF had significantly higher concentrations of PE (median [IQR] of BALF: 0.38 [8.05] N/g), PET (0.26 [0.54] N/g), polyurethane (0.16 [0.24] N/g), PP (0.16 [0.11] N/g), and total MPs (0.91 [6.58] N/g). The presence of MPs in BALF provides novel evidence that MPs penetrate deep into the respiratory tract.

Placing covered self-expanding metal stents by suspension laryngoscope in benign tracheal stenosis

BACKGROUND

Tracheobronchial stent placement for malignant airway strictures has been proved to improve respiratory function, but experience for benign tracheobronchial stenoses is limited. The purpose of our study is to investigate the efficacy of covered expandable metallic stents, inserted through a suspension laryngoscope, treating tracheal stenosis following intubation or tracheostomy.

METHODS

From 2010 to 2018, 67 adult patients with the benign tracheal stenosis, underwent stent placement, using a suspension laryngoscope. According to the date of stent placement and stent caliber, these patients have been subdivided into two groups: Group 1 (from 2010 to 2013, stent caliber ranging from 16 to 20 mm) and Group 2 (from 2014 to 2018, stent caliber ranging from 18 to 22 mm). Complications, related reinterventions, and long-term prognosis were retrospectively evaluated.

RESULTS

Primary successful stent placement was achieved and symptoms were improved in all patients. Complications occurred in 27 (40.3%) cases. Among these, there were 14 (20.9%) cases with stent migration, 10 (14.93%) with granulation tissue formation and 3 (4.48%) with pneumonia. Stent migration in Group 1 was nearly 30% higher than that in Group 2 (P = 0.002). Five of the 8 patients who had placement of 16 mm stents had stent migration, more often than with 20 mm stents (P = 0.002). Ten patients' trachea had slight narrowing but without any symptoms. Six patients still had granulation tissue but without any growth at least two-year follow-up (2 patients whose stents were removed more than 1 year after placement). Even without tracheal narrowing and granulation tissue, 5 patients felt persistent shortness of breath. 92.5% of the patients reported to be satisfied with significant improvement in symptoms.

CONCLUSIONS

Patients with tracheal obstruction secondary to intubation or tracheostomy can benefit from tracheal stents. Placing 16 mm stents might lead to stent migration more easily than 20 mm stents. Tracheal stents placed by a suspension laryngoscope provide a reasonable alternative to open surgery for patients with benign tracheal stenosis or obstruction.

Detection and diagnosis of large airway collapse: a systematic review

Large airway collapse (LAC) is a frequently encountered clinical problem, caused by tracheobronchomalacia +/− excessive dynamic airway collapse, yet there are currently no universally accepted diagnostic criteria. We systematically reviewed studies reporting a diagnostic approach to LAC in healthy adults and patients, to compare diagnostic modalities and criteria used. Electronic databases were searched for relevant studies between 1989 and 2019. Studies that reported a diagnostic approach using computed tomography (CT), magnetic resonance imaging or flexible fibreoptic bronchoscopy were included. Random effects meta-analyses were performed to estimate the prevalence of LAC in healthy subjects and in patients with chronic obstructive airway diseases. We included 41 studies, describing 10 071 subjects (47% female) with a mean±sd age of 59±9 years. Most studies (n=35) reported CT findings, and only three studies reported bronchoscopic findings. The most reported diagnostic criterion was a ≥50% reduction in tracheal or main bronchi calibre at end-expiration on dynamic expiratory CT. Meta-analyses of relevant studies found that 17% (95% CI: 0–61%) of healthy subjects and 27% (95% CI: 11–46%) of patients with chronic airways disease were classified as having LAC, using this threshold. The most reported approach to diagnose LAC utilises CT diagnostics, and at a threshold used by most clinicians (i.e., ≥50%) may classify a considerable proportion of healthy individuals as being abnormal and having LAC in a quarter of patients with chronic airways disease. Future work should focus on establishing more precise diagnostic criteria for LAC, relating this to relevant physiological and disease sequelae.

CT is mostly used to diagnose LAC, and at a threshold used by most clinicians (i.e. ≥50%) that would classify a large proportion of healthy individuals as being abnormal and LAC in a quarter of patients with chronic airway diseaseshttps://bit.ly/3izAuSk

Contributions of Airway Stent for Long-term Outcome in Patients With Malignant Central Airway Stenosis or Obstruction

BACKGROUND

Although an airway stent is used for malignant central airway stenosis or obstruction, long-term outcomes are unknown. In this study, we retrospectively analyzed the clinical features of patients who required stenting for malignant central airway stenosis or obstruction.

PATIENTS AND METHODS

We retrospectively analyzed clinical data from 116 patients with stenting for central airway stenosis or obstruction who underwent treatment at Toho University Hospital from 1998 to 2018. We evaluated the clinical features, prognoses, and complications for stenting in these patients.

RESULTS

The distribution of the 116 patients was as follows: lung cancer, 53; esophageal cancer, 40; thyroid cancer, 8; and others, 15. Patients with thyroid cancer had a significantly higher rate of complications after stenting than patients with lung cancer (P=0.0062), esophageal cancer (P=0.0029), and others (P=0.0062). Patients with esophageal cancer had a significantly worse prognosis than patients with lung and thyroid cancer. In patients with lung cancer the prognosis was significantly different between patients who underwent additional treatment for lung cancer after stenting and patients with no treatment (P=0.0398), and patients who received chemoradiotherapy for lung cancer after stenting had a significantly better prognosis than patients with no treatment (P=0.0306).

CONCLUSION

Stenting for airway stenosis/obstruction may improve prognosis in patients with lung or thyroid cancer, especially if patients with lung cancer undergo additional treatments after stenting, although airway stenting for patients with esophageal cancer was palliative. New treatment strategies may be necessary for patients with esophageal cancer after stenting to improve prognosis.

Assessment of Extensive Airway Obstruction Using Point-by-Point Lateral Pressure Measurements during Bronchoscopy

BACKGROUND

The positioning of the stent at the flow-limiting segment is crucial for patients with extensive airway obstruction to relieve dyspnea. However, CT and flow-volume curves cannot detect the area of maximal obstruction.

OBJECTIVES

The aim of this study is to physiologically evaluate extensive airway obstruction during interventional bronchoscopy.

METHODS

We prospectively measured point-by-point lateral airway pressure (Plat) at multiple points from the lower lobe bronchus to the upper trachea using a double-lumen catheter in 5 patients. The site of maximal obstruction was evaluated continuously to measure point-by-point Plat at multiple points when the airway catheter was withdrawn from the lower lobe bronchus to the upper trachea.

RESULTS

Remarkable pressure differences occurred at the site of maximal obstruction assessed by point-by-point Plat measurements. After initial stenting in 1 case, migration of the maximal obstruction to a nonstented segment of the weakened airway was seen with extensive stenosis from the trachea to the bronchi. In the second case, in addition to radiological analysis, point-by-point Plat measurements could identify the location of the maximal obstruction which contributed to dyspnea.

CONCLUSIONS

Point-by-point Plat measurement could be used to detect the site of maximal obstruction physiologically. Furthermore, Plat measurement could assess the need for additional procedures in real time in patients with extensive airway obstruction.

Long-term survival of airway silicone stents in patients with central airway stenosis or obstruction due to thoracic malignancy

OBJECTIVES

Silicone airway stents are used to manage central airway stenosis or obstruction, although their impact on long-term survival remains unknown in patients with central airway stenosis or obstruction due to thoracic malignancy. In this study, we retrospectively analyzed the impact of silicone stents on survival.

METHODS

We retrospectively analyzed clinical data of 106 patients with central airway stenosis or obstruction due to thoracic malignancy treated by stenting at Toho University Omori Medical Center between 1998 and 2018.

RESULTS

Patients treated with silicone stents had significantly higher survival rates than patients treated with metallic stents (p = 0.0173). Silicone stents patients also had significantly more additional treatments for thoracic malignancy after stenting than metallic stents patients (p = 0.0007). Notably, significantly more silicone stents patients underwent chemoradiotherapy or radiotherapy (p = 0.0268, p = 0.0300). During multivariate analyses, the additional treatment, including chemoradiotherapy or radiotherapy, was an independent optimal prognostic factor.

CONCLUSIONS

Silicone stents patients had significantly higher survival rates than metallic stents patients. Although stenting for airway stenosis or obstruction due to thoracic malignancy may be mainly palliative, additional treatments after stenting should be considered to improve the prognoses of patients with airway stenosis or obstruction due to thoracic malignancy.

Tracheobronchial stent sizing and deployment practices airway stenting practices around the world: a survey study

Background

Tracheobronchial stents types, uses, techniques for deployment and extraction have practice variations around the world.

Methods

We collected responses by sending an online survey of 8 questions to world interventional bronchology member societies and social media groups.

Results

There were 269 respondents from 47 countries. Europe had 97 respondents from 22 countries. There were 8 respondents from Australia, 7 from Africa (3 countries) and 7 from 4 countries in South America (SA). North America (NA) had 72 respondents from 3 countries. Asia had 78 respondents from 14 countries. For stent placements 15% [41] used fiberoptic bronchoscope (FB) only. Rigid bronchoscopy (RB) was solely utilized by 38% [102]. Forty-six percent [123] used a combination of RB and FB (P value <0.00001). For stent extraction 13% [19] used FB alone, 57% [85] used RB, and 36% [54] used a combination of RB and FB (P value <0.00001). Placement of stents were 50.5% [135] only by direct visualization. Twenty-three percent [61] always used fluoroscopic guidance. Twenty-six-point-five percent [71] used fluoroscopy in certain cases (P value <0.00001). Sixty percent [162] decided stent sizing by measurements of stenotic and non-stenotic areas on radiology. Twelve percent [32] respondents used sizing devices. Sixty-five percent [177] used a ruler and bronchoscope to measure stenotic areas. Thirty-eight percent [104] used visual estimation and experience. Seven percent [19] used serial balloon dilatation size. To prevent clogging of stents, 22% [59] prescribed mucolytics. Seventy-three percent [195] nebulized saline, 26% [70] had Mucomyst Nebulization, 24% [65] Nebulized bronchodilators and other methods 11% [30] were advised. Covered self-expandable metal stents (SEMS) 44% was the commonest type of stent used around the world. Silicone stents 37%, Y stents 15%, uncovered SEMS 12%, Montgomery T tube 5% followed. Polyflex stents 3% and custom-made stents 3% were least used. Biodegradable stents were used by 7.5%, and not used by 92.5%.

Conclusions

Tracheobronchial stent practice norms have slowly evolved, but its practice variations lack uniformity, and have sparse evidence-based studies for its direction.

An Update on Tracheal and Airway Collapse in Dogs

Tracheal and airway collapse (bronchomalacia) are common causes of chronic cough in middle-aged to older dogs in which weakening of cartilage within the respiratory system leads to narrowing of airways, irritation, inflammation, partial to complete airway obstruction, and other secondary effects. Tracheomalacia occurs in small-breed dogs, whereas bronchomalacia can occur in any size dog. Successful treatment involves correct identification of the problem, recognition of concurrent disease processes, and appropriate medical therapy. Surgical intervention and intraluminal stenting are readily available so it is important to understand indications for such procedures.

Pulmonary Perfusion Using Intrabronchial Capnography in Pulmonary Artery Stenosis

Stenting at the flow-limiting segment can improve the ventilation-perfusion ratio in patients with central airway stenosis. However, there is no quantitative examination for assessing the perfusion status during interventional bronchoscopy. Intrabronchial capnography can estimate regional gas exchange by measuring carbon dioxide concentration. We herein report a case of bilateral bronchial stenosis where stenting was able to improve ventilation-perfusion ratio using intrabronchial capnography. A 44-year-old man was admitted to our institution with orthopnea. Chest computed tomography showed an extrinsic compression at the bilateral main bronchus and right pulmonary artery due to a mediastinal mass. After introduction of general anesthesia, arterial oxygen tension suddenly decreased in the supine position. After initial stenting, an increase was seen in ventilation at the right lung; however, a ventilation-perfusion mismatch occurred due to an increase in dead-space ventilation at the right pulmonary artery stenosis. Intrabronchial capnography was an effective modality to confirm the regional perfusion status during interventional bronchoscopy in real time.

Assessment of Bronchial Obstruction Using Lateral Pressure Measurement during Bronchoscopy

BACKGROUND

In patients with bronchial obstruction estimating the location of the maximal obstruction is crucial for guiding interventional bronchoscopy. However, flow-volume curves cannot discriminate between the right and left lungs.

OBJECTIVES

The aim of this study was to physiologically evaluate bronchial obstruction during interventional bronchoscopy.

METHODS

We prospectively measured lateral airway pressure (Plat) at either side of the obstruction using a double-lumen catheter (pressure-pressure [P-P] curve) simultaneously to assess the degree of bronchial obstruction in 22 patients. The shape of the P-P curve was assessed to confirm the site of maximal obstruction.

RESULTS

In the experimental study, Plat was uniform between both bronchi in the normal model. For the unilateral and bilateral obstruction models, a phase shift was only seen for the more obstructed side. In healthy subjects, the angle of the P-P curve was close to 45° and linear in shape. In patients with bronchial obstruction, the angle was much smaller but approached 45° after the bronchoscopic procedure. The degree of bronchial obstruction was significantly correlated with the angle of the P-P curve (r = -0.51, p < 0.01). Dyspnea significantly increased when the airway lumen was obstructed by more than 60% (p < 0.0001), and when the P-P curve appeared loop-shaped (p < 0.01).

CONCLUSIONS

The shape of the P-P curve could be used to detect the site of maximal obstruction for the optimal positioning of the stent and assess the need for additional procedures in real time in patients with bronchial obstruction.

Comparison of Airway Measurements for Tracheobronchial Stenosis Between Stereoscopic Bronchoscope and MD-CT

BACKGROUND

Stereoscopic bronchoscopy is a new diagnostic tool to measure the diameter and cross-sectional area of the airway. The stereoscopic bronchoscope, which operates the same as a standard bronchoscope, utilizes 2 lenses to measure the airway using the principles of triangulation. Furthermore, the stereoscopic bronchoscope has the capability to measure the size of the airway during intervention in real-time, including variable stenosis.

MATERIALS AND METHODS

To prospectively compare preoperative stereoscopic and multidetector computed tomography (MD-CT) images to select the appropriate stent size for airway stenosis. Stereoscopic and MD-CT images were then measured to confirm the correct placement of the stent.

RESULTS

Airway stenting was performed on 21 consecutive patients of whom, 15 were diagnosed with malignant and 6 with benign diseases. In total, 165 measurements were taken (134 healthy; 31 affected). For the diameter, Bland-Altman plots were used to measure data from 165 matched stereoscopic and MD-CT measurement sites (bias, 0.40±2.86 mm SD; percentage error, 33%), 134 healthy sites (bias, 0.554±2.83 mm SD; percentage error, 34%), and 31 affected sites (bias, 1.20±2.67 mm SD; percentage error, 52%). For the cross-sectional area, matched stereoscopic and MD-CT measurements were analyzed for 65 sites (bias, -10.53±92.85 mm SD; percentage error, 89%), 49 healthy sites (bias, -9.88±39.00 mm SD; percentage error, 32%), and 16 affected sites (bias, -13.12±48.81 mm SD; percentage error, 92%).

CONCLUSION

Stereoscopic bronchoscopy was able to accurately measure the size of the airway during intervention, to assist in selecting the appropriate size of the stent.

Airway stenting in patients requiring intubation due to malignant airway stenosis: a 10-year experience

Background

Critically ill patients with severe acute respiratory failure due to malignant airway stenosis often require emergency intubation and mechanical ventilation. Urgent intervention is necessary for the survival of such patients. The aim of this study was to determine the efficacy and outcomes of airway stenting in patients with malignant airway stenosis requiring emergency intubation.

Methods

Patients with malignant airway stenosis who underwent emergency intubation prior to airway stent placement from September 2005 to September 2015 in a single center were retrospectively reviewed. All stenting procedures were performed using both rigid and flexible bronchoscopes under general anesthesia.

Results

Thirty patients with malignant airway stenosis (17 with lung cancer, 6 with esophageal cancer, and 7 with other types of malignancy) who required emergency intubation prior to stenting procedures (silicone stenting in 23 and metallic stenting in 7) were analyzed. Extubation within 48 hours after stenting could be performed in 28 of 30 patients (93%). Of the 21 chemoradiotherapy-naïve patients, 18 (86%) received chemotherapy and/or radiation therapy after stenting. No significant complications occurred during the stenting procedures. The median survival after stenting was 198 days (range, 13-3,009 days).

Conclusions

Airway stenting facilitates extubation in critically ill patients with malignant central airway stenosis. It plays an important role as a bridge to additional tumor-specific therapies, especially in chemoradiotherapy-naïve patients.

Choke point physiology in airway stenting: A case presentation and discussion

BACKGROUND

The point in the airway that allows the smallest maximal flow is known as the "choke point". The tube law describes the velocity of the expired air, which cannot exceed the wave-speed. Flow limitation during forced expiration is affected by the relationship between the transmural pressure (Ptm) and cross-sectional area (A) of the airway. Wave speed is dependent on the stiffness of the airway wall, as well as on the cross-section of the airway itself (dA/dPtm).

METHODS

Airway stenting at the wave-speed, flow-limiting segment (choke point) is assessed by using a catheter, via the working channel of a stereoscopic bronchoscope, to measure the difference between lateral pressure and pleural pressure.

RESULTS

Based on the wave-speed concept of maximal expiratory flow limitation, stenting at the choke point increased the cross-sectional area and supported the weakened airway wall, thus improving expiratory flow limitation and relieving dyspnea.

CONCLUSION

To ensure correct stent positioning and thus optimal functional benefit, it is important to locate the exact position of tracheobronchial stenosis.

[Treatment of malignant central airways obstruction by rigid bronchoscopy]

INTRODUCTION

Endobronchial resection is now the standard treatment for tracheobronchial narrowing due to malignancy. The clinical and functional respiratory improvement has been evaluated previously but only in heterogeneous population.

METHODS

Between February 2009 and February 2011, we conducted a prospective single centre study at the University Hospital of Lille. Twenty-five patients with malignant tracheobronchial stenosis received a clinical and functional respiratory evaluation before and after a rigid bronchoscopy procedure to reduce the obstruction followed where appropriate by placement of an endobronchial stent.

RESULTS

Thirteen patients (52%) had primary lung cancer and in 12 the tumor had another origin. Nineteen patients (76%) received a stent after bronchial unblocking. Clinically, all patients felt an improvement in their dyspnea estimated by the Borg score with a median improvement of -2 points [-1; -4] following the procedure (P<0.001). In 96% the dyspnea visual analogic scale improved by 40 mm [27; 67] (P<0.0001). The FEV1 increased significantly after unblocking by 9% [-3.5; 28.5] (P<0.05). The Rint decreased significantly by -0.19 kPa/L per second [-0.06; -0.023] (P=0.001). Correlations between scales of dyspnea and spirometric values were not significant (P>0.05). The survival rate at 1 year was 29%.

CONCLUSION

Interventional bronchoscopy decreases dyspnea. It modestly improves respiratory function and decreases the Rint. However, lung function and dyspnea scales are not correlated. No spirometry factor can predict clinical dyspnea response but an elevated Borg dyspnea scale might be a good indicator.

Fully covered self-expandable metal stent in tracheobronchial disorders: clinical experience

BACKGROUND

The third-generation fully covered self-expandable metallic stent (SEMS) has been developed to solve the problems of difficult removal and in-stent granuloma formation related to the uncovered or partially covered type. There are few written reports about the performance of this type of stents with early encouraging results.

OBJECTIVES

To report and analyse our experience with the Silmet® stent in the management of malignant and benign tracheobronchial disorders.

METHODS

We retrospectively reviewed medical records of patients who underwent fully covered SEMS Silmet placement at the Interventional Pulmonology Unit, La Maddalena Cancer Center, Palermo, Italy, between May 2010 and August 2013.

RESULTS

Stents were placed in 52 patients with malignant (n = 49) and benign airway obstruction (n = 2) and broncho-oesophageal fistula (n = 1). SEMSs were inserted into the trachea (n = 19), the main bronchi (n = 21) and the peripheral bronchi (n = 31). Besides 1 procedural dislocation, the deployment was successful in all patients with an immediate significant improvement of symptoms (Barthel Index p < 0.001; Medical Research Council score p < 0.001). A radiographic improvement was detected in 48% of patients. The mean follow-up duration was 119 ± 120 days (range 22-549 days). Complications observed were: migration (7.6%), tumour overgrowth (15%), infections (5.7%), granulation tissue formation (3.8%) and mucus plug (3.8%).

CONCLUSIONS

The Silmet stent is effective, safe and simple to implant and remove. We suggest its use in cases of tight stenoses, in the treatment of small- to medium-caliber airways or in cases of tortuous airways.

Left and right lung asynchrony as a physiological indicator for unilateral bronchial obstruction in interventional bronchoscopy

BACKGROUND

In patients with bronchial obstruction, pulmonary function tests may not change significantly after intervention. The airflow asynchrony in both lungs due to unilateral bronchial obstruction may be applicable as a physiological indicator. The airflow asynchrony is reflected by the difference in the left and right lung sound development at tidal breathing.

OBJECTIVES

To investigate the usefulness of left and right lung asynchrony due to unilateral bronchial obstruction as a physiological indicator for interventional bronchoscopy.

METHODS

Fifty cases with central airway obstruction were classified into three groups: tracheal, bronchial and extensive obstruction. The gap index was defined as the absolute value of the average of gaps between the left and right lung sound intensity peaks for a 12-second duration.

RESULTS

Before interventional bronchoscopy, the gap index was significantly higher in the bronchial (p<0.05) and extensive obstruction groups (p<0.05) than in the tracheal group. The gap index in cases with unilateral bronchial obstruction of at least 80% (0.18±0.04 seconds) was significantly higher than in cases with less than 80% obstruction (0.02±0.01 seconds, p<0.05). After intervention for bronchial obstruction, the dyspnea scale (p<0.001) and gap index significantly improved (p<0.05), although no significant improvements were found in spirometric assessments. The responder rates for dyspnea were 79.3% for gap indexes over 0.06 seconds and 55.6% for gap indexes of 0.06 seconds or under.

CONCLUSIONS

Assessment of left and right lung asynchrony in central airway obstruction with bronchial involvement may provide useful physiological information for interventional bronchoscopy.

Contribution of flow-volume curves to the detection of central airway obstruction

OBJECTIVE:

To assess the sensitivity and specificity of flow-volume curves in detecting central airway obstruction (CAO), and to determine whether their quantitative and qualitative criteria are associated with the location, type and degree of obstruction.

METHODS:

Over a four-month period, we consecutively evaluated patients with bronchoscopy indicated. Over a one-week period, all patients underwent clinical evaluation, flow-volume curve, bronchoscopy, and completed a dyspnea scale. Four reviewers, blinded to quantitative and clinical data, and bronchoscopy results, classified the morphology of the curves. A fifth reviewer determined the morphological criteria, as well as the quantitative criteria.

RESULTS:

We studied 82 patients, 36 (44%) of whom had CAO. The sensitivity and specificity of the flow-volume curves in detecting CAO were, respectively, 88.9% and 91.3% (quantitative criteria) and 30.6% and 93.5% (qualitative criteria). The most prevalent quantitative criteria in our sample were FEF50%/FIF50% ≥ 1, in 83% of patients, and FEV1/PEF ≥ 8 mL . L^–1 . min^–1, in 36%, both being associated with the type, location, and degree of obstruction (p < 0.05). There was concordance among the reviewers as to the presence of CAO. There is a relationship between the degree of obstruction and dyspnea.

CONCLUSIONS:

The quantitative criteria should always be calculated for flow-volume curves in order to detect CAO, because of the low sensitivity of the qualitative criteria. Both FEF50%/FIF50% ≥ 1 and FEV1/PEF ≥ 8 mL . L^–1 . min^–1 were associated with the location, type and degree of obstruction.

Bronchoscopic management of malignant airway obstruction

Approximately one-third of patients with lung cancer will develop airway obstruction and many cancers lead to airway obstruction through meta stases. The treatment of malignant airway obstruction is often a multimodality approach and is usually performed for palliation of symptoms in advanced lung cancer. Removal of airway obstruction is associated with improvement in symptoms, quality of life, and lung function. Patient selection should exclude patients with short life expectancy, limited symptoms, and an inability to visualize beyond the obstruction. This review outlines both the immediate and delayed bronchoscopic effect options for the removal of airway obstruction and preservation of airway patency with endobronchial stenting.

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.

New dedicated bifurcated silicone stent placement for stenosis around the primary right carina

BACKGROUND

Silicone stenting has been widely used to palliate respiratory symptoms in patients suffering from airway stenosis. Although many types and shapes of stents have been developed, there is no ideal stent for stenosis around the carina between the bronchus to the right upper lobe and the bronchus intermedius (primary right carina). The purpose of this study was to evaluate the feasibility, efficacy, and safety of a new silicone stent designed for treating airway stenosis around the primary right carina.

METHODS

We recruited 16 patients with suspected stenosis around the primary right carina. Ten of the patients met the inclusion criteria for inserting the study stent. All stenting procedures were performed with a rigid and flexible bronchoscope under general anesthesia.

RESULTS

The study stent could be mounted successfully on the primary right carina in all 10 patients. Five patients underwent stenting using only the new stent, and the other five underwent stenting with it on the primary right carina and a silicone Y stent on the main carina. The dyspnea index improved in eight of the 10 patients, including one who was mechanically ventilated. Early complications developed in three patients (temporary pneumonia in two and retention of secretions in one), and late complications occurred in two patients (granuloma formation in one and hemoptysis in one).

CONCLUSIONS

Stent placement with the new silicone stent designed to fit on the primary right carina is feasible, effective, and acceptably safe.

TRIAL REGISTRY

UMIN-Clinical Trials Registry; No.: UMIN000001776; URL: www.umin.ac.jp/ctr.

Tracheal and airway collapse in dogs

Tracheal and airway collapse (bronchomalacia) are common causes of chronic cough in middle-aged to older dogs where weakening of cartilage within the respiratory system leads to narrowing of airways, coughing, wheezing, and other secondary effects. Successful treatment involves correct identification of the problem, recognition of concurrent problems, and appropriate medical therapy. Surgical and noninvasive treatment options are becoming readily available, and it is important to understand indications for such procedures.

A three-microphone acoustic reflection technique using transmitted acoustic waves in the airway

The acoustic reflection technique noninvasively measures airway cross-sectional area vs. distance functions and uses a wave tube with a constant cross-sectional area to separate incidental and reflected waves introduced into the mouth or nostril. The accuracy of estimated cross-sectional areas gets worse in the deeper distances due to the nature of marching algorithms, i.e., errors of the estimated areas in the closer distances accumulate to those in the further distances. Here we present a new technique of acoustic reflection from measuring transmitted acoustic waves in the airway with three microphones and without employing a wave tube. Using miniaturized microphones mounted on a catheter, we estimated reflection coefficients among the microphones and separated incidental and reflected waves. A model study showed that the estimated cross-sectional area vs. distance function was coincident with the conventional two-microphone method, and it did not change with altered cross-sectional areas at the microphone position, although the estimated cross-sectional areas are relative values to that at the microphone position. The pharyngeal cross-sectional areas including retropalatal and retroglossal regions and the closing site during sleep was visualized in patients with obstructive sleep apnea. The method can be applicable to larger or smaller bronchi to evaluate the airspace and function in these localized airways.

Numerical analysis of airflow alteration in central airways following tracheobronchial stent placement

The computational fluid dynamics method, which provides an estimation of the pressure drop in the airway before and after the stent implantation, is proposed in this study. This method is based on the finite volume model. The pressure field was solved by the Navier-Stokes equations. The proposed methodology was evaluated in seven health people (control group) and in fourteen patients who were assigned in two groups, in which one was tracheal stenosis and the other was bronchial stenosis. The results showed that the pressure drop after tracheal stent implantation became significantly smaller. For bronchial stent implantation cases, the airway resistance improved insignificantly.

Tracheobronchomalacia in children: review of diagnosis and definition

Tracheobronchomalacia is characterised by excessive airway collapsibility due to weakness of airway walls and supporting cartilage. The standard definition requires reduction in cross-sectional area of at least 50% on expiration. However, there is a paucity of information regarding the normal range of central airway collapse among children of varying ages, ethnicities and genders, with and without coexisting pulmonary disease. Consequently, the threshold for pathological collapse is considered somewhat arbitrary. Available methods for assessing the airway dynamically--bronchoscopy, radiography, cine fluoroscopy, bronchography, CT and MR--have issues with reliability, the need for intubation, radiation dose and contrast administration. In addition, there are varying means of eliciting the diagnosis. Forced expiratory manoeuvres have been employed but can exaggerate normal physiological changes. Furthermore, radiographic evidence of tracheal compression does not necessarily translate into physiological or functional significance. Given that the criteria used to make the diagnosis of tracheobronchomalacia are poorly validated, further studies with larger patient samples are required to define the threshold for pathological airway collapse.

Surface layer-preserving photodynamic therapy (SPPDT) in a subcutaneous mouse model of lung cancer

BACKGROUND AND OBJECTIVES

Photodynamic therapy (PDT) may be a less invasive treatment for lung cancer. Our newly developed surface layer-preserving PDT (SPPDT) technique enables us to irradiate deep tumor while preserving the overlying tissue. The aim of this basic study was to verify that the SPPDT technique might be applied to lung cancer.

STUDY DESIGN/MATERIALS AND METHODS

PDT with talaporfin sodium was performed using a pulsed laser with different pulse dose rates (PDRs, 2.5-20.0 mJ/cm(2) /pulse) in a mouse model of subcutaneous tumor. To mimic the tracheal wall structure and a thoracic tumor in the tracheobronchus, we also made a mouse model in which a piece of swine cartilage was placed between the dermis and the tumor, and PDT was carried out 2 weeks after implantation. In both experiments, the tissue samples were collected 48 hours after PDT and evaluated microscopically.

RESULTS

SPPDT using a high-PDR laser damaged the underlying tissue but left the superficial tissue intact in the mouse subcutaneous tumor model. In SPPDT, a higher PDR produced a thicker layer of intact superficial tissue than a lower PDR, while a lower PDR produced a deeper layer of damaged tissue than a higher PDR. SPPDT was also able to preserve the superficial tissue and to damage the tumor tissue beneath the cartilage implant.

CONCLUSION

SPPDT was able to damage tumor beneath the superficial normal tissue layer, which included tracheal cartilage in the mouse model. The thickness control of SPPDT was provided by controlling laser pulse intensity. SPPDT is a new technology, whose future potential is unknown. The initial clinical application of this technology could be endoscopic treatment (e.g., palliative therapy of thoracic malignancies via bronchoscopy).

Update on interventional bronchoscopy for the thoracic radiologist

Interventional bronchoscopy, together with other domains of interventional pulmonology, has experienced tremendous technological advances. Diagnostic applications include endobronchial ultrasound, which enables endoscopists to see through airway walls. White light videobronchoscopy, autofluorescence imaging, and narrow band imaging have enhanced the ability to detect early lung cancer at a preinvasive stage. Electromagnetic navigational bronchoscopy, ultrathin bronchoscopy, and virtual bronchoscopy increase the diagnostic yield of biopsy of small peripheral lung lesions. The options that are currently available for the relief of central airway obstruction are also numerous, with both flexible and rigid bronchoscopic applications. Stents, although dichotomized to silicone and metal, come in various sizes and shapes to suit the requirements of the pathology being treated. Ablative techniques are categorized into those with an immediate effect and those with a delayed effect. Laser, electrocautery, and argon plasma coagulation can immediately relieve obstruction and control hemoptysis, whereas cryosurgery, brachytherapy, and photodynamic therapy have established roles in subacute airway obstruction and in the treatment of early lung cancer. Microdebriders have recently been added to the armamentarium of modalities for mechanical debulking of tumor. Distal airway obstruction has also been targeted with bronchial thermoplasty treatment of refractory asthma and with bronchoscopic lung volume reduction for the management of severe emphysema. This array of new technology has fostered collaborative work with a wide range of other medical specialties to deliver safer, more effective, minimally invasive treatment.

Recent advances in optical coherence tomography for the diagnoses of lung disorders

There have been many advances in the field of diagnostic and therapeutic pulmonary medicine in the past several years, with major progress in the field of imaging. Optical coherence tomography (OCT) is a high-resolution (micron level) imaging modality currently being advanced with the potential to image airway wall structures in real time and at higher resolution than previously possible. OCT has the potential to increase the sensitivity and specificity of biopsies, create 3D images of the airway to guide diagnostics, and may have a future role in diverse areas such as the evaluation and treatment of patients with obstructive sleep apnea, tracheal stenosis, airway remodeling and inhalation injury. OCT has recently been investigated to monitor airway compliance in chronic obstructive pulmonary disease and asthma patients as well as differentiate causes of pulmonary hypertension. In future clinical and research applications, OCT will likely be combined with other endoscopic based modalities such as ultrasound, spectroscopy, confocal, and/or photoacoustic tomography to determine functional and biomolecular properties. This article discusses the current uses of OCT, its potential applications, as it relates to specific pulmonary diseases, and the future directions for OCT.

An outcome analysis of self-expandable metallic stents in central airway obstruction: a cohort study

BACKGROUND

Self-expandable metallic stents (SEMSs) have provided satisfactory management of central airway obstruction. However, the long-term benefits and complications of this management modality in patients with benign and malignant obstructing lesions after SEMS placement are unclear. We performed this cohort study to analyze the outcomes of Ultraflex SEMSs in patients with tracheobronchial diseases.

METHODS

Of 149 patients, 72 with benign and 77 with malignant tracheobronchial disease received 211 SEMSs (benign, 116; malignant, 95) and were retrospectively reviewed in a tertiary hospital.

RESULTS

The baseline characteristics of patients who received SEMS implantation for benign conditions and those who underwent implantation for malignant conditions were significantly different. These characteristics included age (mean, 63.9 vs. 58; p < 0.01), gender (male, 62% vs. 90%; p < 0.0001), smoking (47% vs. 85%; p < 0.0001), forced expiratory volume in 1 second (mean, 0.9 vs. 1.47 L/s; p < 0.0001), follow-up days after SEMS implantation (median; 429 vs. 57; p < 0.0001), and use of covered SEMS (36.2% vs. 94.7%; p < 0.0001). Symptoms improved more after SEMS implantation in patients with benign conditions than in those with malignant conditions (76.7% vs. 51.6%; p < 0.0001). The overall complication rate after SEMS implantation in patients with benign conditions was higher than that in patients with malignancy (42.2% vs. 21.1%; p = 0.001). Successful management of SEMS migration, granulation tissue formation, and SEMS fracture occurred in 100%, 81.25%, and 85% of patients, respectively.

CONCLUSIONS

Patients who received SEMS implantation owing to benign conditions had worse lung function and were older than those who received SEMS for malignancies. There was higher complication rate in patients with benign conditions after a longer follow-up period owing to the nature of the underlying diseases.

Advances in diagnostic bronchoscopy

Diagnostic bronchoscopy has undergone two major paradigm shifts in the last 40 years. First, the advent of flexible bronchoscopy gave chest physicians improved access to the tracheobronchial tree with a rapid learning curve and greater patient comfort compared with rigid bronchoscopy. The second paradigm shift has evolved over the last 5 years with the proliferation of new technologies that have significantly enhanced the diagnostic capabilities of flexible bronchoscopy compared with traditional methods. At the forefront of these new technologies is endobronchial ultrasound. In its various forms, endobronchial ultrasound has improved diagnostic yield for pulmonary masses, nodules, intrathoracic adenopathy, and disease extent, thereby reducing the need for more invasive surgical interventions. Various navigational bronchoscopy systems have become available to increase flexible bronchoscope access to small peripheral pulmonary lesions. Furthermore, various modalities of airway assessment, including optical microscopic imaging technologies, may play significant roles in the diagnosis of a variety of pulmonary diseases in the future. Finally, the combination of new diagnostic bronchoscopy technologies and novel approaches in molecular analysis and biomarker assessment hold promise for enhanced diagnosis and personalized management of many pulmonary disorders. In this review, we provide a contemporary review of diagnostic bronchoscopy developments over the past decade.

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.

Endobronchial ultrasound

The efficacy and technical aspects of endobronchial ultrasound (EBUS) are reviewed because this technology promises to revolutionise bronchoscopy. EBUS extends the endoscopist's view beyond the mucosal surface of the large airways to peri-bronchial structures and peripheral lung lesions. Guided biopsies and real-time transbronchial needle aspirations (TBNA) have been shown to increase the diagnostic yield over conventional bronchoscopic techniques. The technology is available in two forms: radial EBUS probes and linear EBUS-TBNA bronchoscopes. Radial EBUS utilizes higher frequencies and the transducer is inserted via a standard flexible bronchoscope. The higher ultrasound frequencies improve image resolution to <1mm. Radial EBUS is used to assess airway walls, guide TBNA (diagnostic yield: 72-86%) and diagnose peripheral lung lesions (diagnostic yield: 61-80%). Linear EBUS-TBNA transducers are built into dedicated bronchoscopes to produce sector view images and permit real-time TBNA. The pooled sensitivity of real-time EBUS-TBNA in lung cancer is 90% but the false negative rate is 20%. Therefore, EBUS-TBNA is a viable alternative to cervical mediastinoscopy in the diagnosis and staging of mediastinal lymphadenopathy. However, negative results need either further confirmatory testing or adequate clinical follow-up. Complications are rare with either EBUS modality and are usually related to the underlying biopsy procedure rather than the use of ultrasound. Procedure duration is short enough to be incorporated into an outpatient setting and can performed under moderate sedation. Clear training standards are emerging to facilitate credentialing as EBUS is rapidly evolving to become a part of standard diagnostic bronchoscopy.

Factors leading to tracheobronchial self-expandable metallic stent fracture

OBJECTIVE

This retrospective study was to determine factors that contribute to self-expandable metallic stent fracture in patients with tracheobronchial disease.

METHODS

From 2001 to 2006, 139 patients (age, 62.1 +/- 15.4 years; range, 23-87 years) with benign (n = 62) and malignant (n = 77) tracheobronchial disease received 192 Ultraflex (Boston Scientific, Natick, Mass) self-expandable metallic stents (98 in patients with benign disease and 94 in patients with malignant disease).

RESULTS

Seventeen fractured self-expandable metallic stents were found; the incidence was 12.2% (17/139 patients) among patients with tracheobronchial disease. Tortuous airway (odds ratio, 4.06; 95% confidence interval, 1.04-18.34; P = .04) independently predicted self-expandable metallic stent fracture. Most self-expandable metallic stent fractures (64.7%, 11/17) were detected 500 to 1000 days after self-expandable metallic stent implantation. Clinical presentations for patients with fractured self-expandable metallic stents included dyspnea exacerbation (70.6%, 12/17) and cough (23.5%, 4/17).

CONCLUSIONS

Self-expandable metallic stent fracture is not uncommon in patients with tracheobronchial disease. Tortuous airway is an independent predictor for it. Although management of the fractured self-expandable metallic stent in our study was feasible and safe, self-expandable metallic stents should be restricted to a more select population.

[Multidetector CT evaluation of airway metallic stents]

INTRODUCTION

Stenting is accepted in managing patients with inoperable obstruction of the upper airways. The choice of the type as well as the dimensions of stents are crucial as it impacts on the success of the procedure and potential complications which must be diagnosed non-invasively.

STATE OF THE ART

The goal of this review is to present our multidisciplinary experience using multidetector CT as a minimally invasive technique for detecting airway obstructions, for evaluating preoperatively local anatomic conditions useful to determinate the type and size of metallic stents to be used, and following non-invasively the stent in order to detect various complications.

CONCLUSIONS

MDCT acquisition should use thin slices as multiplanar reformations and 3D reconstructions play an essential complementary role to axial images in pre- and post-stent placement settings.

Central Airway Mechanics and Flow Limitation in Acquired Tracheobronchomalacia

BACKGROUND

Acquired tracheobronchomalacia (TBM) can cause central airway collapse in patients with COPD and may worsen airflow obstruction and symptoms. It is usually not known whether central airway malacia contributes to airflow obstruction. This study was undertaken to quantify central airway collapsibility and relate it to expiratory flow limitation in patients with TBM.

METHODS

Eighty patients evaluated for acquired TBM and 4 healthy control subjects were studied with measurements of central airway narrowing derived from bronchoscopic videotapes and simultaneous pressure measurements in the trachea and esophagus. Tracheal narrowing was assessed by a shape index and plotted against the transtracheal pressure to measure collapsibility. Subsequently, airflow and transpulmonary pressure (PL) were measured to identify expiratory flow limitation during quiet breathing and to determine the critical PL required for maximum expiratory flow.

RESULTS

Tracheal collapsibility varied widely among patients. Some had profound tracheal narrowing during quiet breathing, and others showed substantial collapse only during forced exhalation. Of the patients, 15% were not flow limited during quiet breathing, 53% were flow limited throughout exhalation, and 30% were flow limited only during the latter part of the exhalation. Patients with flow limitation at rest showed greater tracheal narrowing than those without (p = 0.009), but the severity of expiratory flow limitation was not closely related to tracheal collapsibility. Twenty-three patients were flow limited during quiet exhalation at PLs that did not cause central airway collapse.

CONCLUSIONS

In TBM, central airway collapse is not closely related to airflow obstruction, and expiratory flow limitation at rest often occurs in peripheral airways without central airway collapse.