Respiratory infections increase the risk of granulation tissue formation following airway stenting in patients with malignant airway obstruction

Evaluating the interaction of a tracheobronchial stent in an ovine in-vivo model

Tracheobronchial stents are used to restore patency to stenosed airways. However, these devices are associated with many complications such as stent migration, granulation tissue formation, mucous plugging and stent strut fracture. Of these, granulation tissue formation is the complication that most frequently requires costly secondary interventions. In this study a biomechanical lung modelling framework recently developed by the authors to capture the lung in-vivo stress state under physiological loading is employed in conjunction with ovine pre-clinical stenting results and device experimental data to evaluate the effect of stent interaction on granulation tissue formation. Stenting is simulated using a validated model of a prototype covered laser-cut tracheobronchial stent in a semi-specific biomechanical lung model, and physiological loading is performed. Two computational methods are then used to predict possible granulation tissue formation: the standard method which utilises the increase in maximum principal stress change, and a newly proposed method which compares the change in contact pressure over a respiratory cycle. These computational predictions of granulation tissue formation are then compared to pre-clinical stenting observations after a 6-week implantation period. Experimental results of the pre-clinical stent implantation showed signs of granulation tissue formation both proximally and distally, with a greater proximal reaction. The standard method failed to show a correlation with the experimental results. However, the contact change method showed an apparent correlation with granulation tissue formation. These results suggest that this new method could be used as a tool to improve future device designs.

Malignant central airway obstruction

This review comprehensively describes recent advances in the management of malignant central airway obstruction (CAO). Malignant CAO can be a dramatic and devastating manifestation of primary lung cancer or metastatic disease. A variety of diagnostic modalities are available to provide valuable information to plan a therapeutic intervention. Clinical heterogeneity in the presentation of malignant CAO provides opportunities to adapt and utilize endoscopic technology and tools in many ways. Mechanical debulking, thermal tools, cryotherapy and airway stents are methods and instruments used to rapidly restore airway patency. Delayed bronchoscopic methods, such as photodynamic therapy (PDT) and brachytherapy can also be utilized in specific non-emergent situations to establish airway patency. Although data regarding the success and complications of therapeutic interventions are retrospective and characterized by clinical and outcome measure variability, the symptoms of malignant CAO can often be successfully palliated. Assessment of risks and benefits of interventions in each individual patient during the decision-making process forms the critical foundation of the management of malignant CAO.

Temporary Endobronchial Stent as a Bridge to Corrective Surgery For Severe Kyphoscoliosis-associated Central-Airway Extrinsic Compression

Kyphoscoliosis is known to compromise lung function, with the primary mechanism being reduced chest wall compliance with a resultant restrictive pulmonary physiology. Severe scoliosis can also cause extrinsic compression of the central airways, leading to recurrent respiratory infections, lobar atelectasis, and potentially acute respiratory failure. Definitive therapy is corrective surgery of the spine. However, patients with severe scoliosis are at a potentially high risk of perioperative pulmonary complications. To our knowledge, we report the first successful use of retrievable endobronchial stents as a bridge to corrective surgery for kyphoscoliosis-associated complete central-airway extrinsic compression in a patient who was considered as too high risk for surgical correction due to her respiratory status. After surgery, the stents were removed and our patient experienced sustained improvement in pulmonary function and the clinical respiratory status.

Multidetector CT evaluation of airway stents: what the radiologist should know

Airway stents are increasingly used to treat symptomatic patients with obstructive tracheobronchial diseases who are not amenable to surgical resection or who have poor performance status, precluding them from resection. The most common conditions that are treated with tracheobronchial stents are primary lung cancer and metastatic disease. However, stents have also been used to treat patients with airway stenosis related to a variety of benign conditions, such as tracheobronchomalacia, relapsing polychondritis, postintubation tracheal stenosis, postoperative anastomotic stenosis, and granulomatous diseases. Additionally, airway stents can be used as a barrier method in the management of esophagorespiratory fistulas. Many types of stents are available from different manufacturers. Principally, they are classified as silicone; covered and uncovered metal; or hybrid, which are made of silicone and reinforced by metal rings. The advantages and disadvantages of each type of airway stent are carefully considered when choosing the most appropriate stent for each patient. Multidetector computed tomography plays an important role in determining the cause and assessing the location and extent of airway obstruction. Moreover, it is very accurate in its depiction of complications after airway stent placement.

Complications Following Therapeutic Bronchoscopy for Malignant Central Airway Obstruction: Results of the AQuIRE Registry

BACKGROUND

There are significant variations in how therapeutic bronchoscopy for malignant airway obstruction is performed. Relatively few studies have compared how these approaches affect the incidence of complications.

METHODS

We used the American College of Chest Physicians (CHEST) Quality Improvement Registry, Evaluation, and Education (AQuIRE) program registry to conduct a multicenter study of patients undergoing therapeutic bronchoscopy for malignant central airway obstruction. The primary outcome was the incidence of complications. Secondary outcomes were incidence of bleeding, hypoxemia, respiratory failure, adverse events, escalation in level of care, and 30-day mortality.

RESULTS

Fifteen centers performed 1,115 procedures on 947 patients. There were significant differences among centers in the type of anesthesia (moderate vs deep or general anesthesia, P < .001), use of rigid bronchoscopy (P < .001), type of ventilation (jet vs volume cycled, P < .001), and frequency of stent use (P < .001). The overall complication rate was 3.9%, but significant variation was found among centers (range, 0.9%-11.7%; P = .002). Risk factors for complications were urgent and emergent procedures, American Society of Anesthesiologists (ASA) score > 3, redo therapeutic bronchoscopy, and moderate sedation. The 30-day mortality was 14.8%; mortality varied among centers (range, 7.7%-20.2%, P = .02). Risk factors for 30-day mortality included Zubrod score > 1, ASA score > 3, intrinsic or mixed obstruction, and stent placement.

CONCLUSIONS

Use of moderate sedation and stents varies significantly among centers. These factors are associated with increased complications and 30-day mortality, respectively.

Therapeutic bronchoscopy for malignant central airway obstruction: success rates and impact on dyspnea and quality of life

BACKGROUND

There is significant variation between physicians in terms of how they perform therapeutic bronchoscopy, but there are few data on whether these differences impact effectiveness.

METHODS

This was a multicenter registry study of patients undergoing therapeutic bronchoscopy for malignant central airway obstruction. The primary outcome was technical success, defined as reopening the airway lumen to > 50% of normal. Secondary outcomes were dyspnea as measured by the Borg score and health-related quality of life (HRQOL) as measured by the SF-6D.

RESULTS

Fifteen centers performed 1,115 procedures on 947 patients. Technical success was achieved in 93% of procedures. Center success rates ranged from 90% to 98% (P = .02). Endobronchial obstruction and stent placement were associated with success, whereas American Society of Anesthesiology (ASA) score > 3, renal failure, primary lung cancer, left mainstem disease, and tracheoesophageal fistula were associated with failure. Clinically significant improvements in dyspnea occurred in 90 of 187 patients measured (48%). Greater baseline dyspnea was associated with greater improvements in dyspnea, whereas smoking, having multiple cancers, and lobar obstruction were associated with smaller improvements. Clinically significant improvements in HRQOL occurred in 76 of 183 patients measured (42%). Greater baseline dyspnea was associated with greater improvements in HRQOL, and lobar obstruction was associated with smaller improvements.

CONCLUSIONS

Technical success rates were high overall, with the highest success rates associated with stent placement and endobronchial obstruction. Therapeutic bronchoscopy should not be withheld from patients based solely on an assessment of risk, since patients with the most dyspnea and lowest functional status benefitted the most.

Stents are associated with increased risk of respiratory infections in patients undergoing airway interventions for malignant airways disease

BACKGROUND

Long-term complications of therapeutic bronchoscopy include infections and airway restenosis due to tumor. No studies have compared the incidence rates of infection in patients with stents with those without stents. We hypothesized that patients with stents would have a higher incidence of lower respiratory tract infections than would patients without stents.

METHODS

We conducted a retrospective cohort study, covering the period September 2009 to August 2011, of patients who had therapeutic bronchoscopy for malignant airways disease. Outcomes recorded were lower respiratory tract infection and airway restenosis by tumor.

RESULTS

Seventy-two patients had therapeutic bronchoscopy for malignant airways disease. Twenty-four of these patients had one or more stents placed. Twenty-three of the 72 patients (32%) developed lower respiratory tract infections. Stents were associated with an increased risk of infection (hazard ratio [HR], 3.76; 95% CI, 1.57-8.99; P = .003). The incidence rate of lower respiratory tract infection was 0.0057 infections per person-day in patients with stents vs 0.0011 infections per person-day in patients without stents. The incidence rate difference, 0.0046 infections per person-day, was significant (95% CI, 0.0012-0.0081; P = .0002). Restenosis due to tumor overgrowth was associated with more severe obstruction at baseline (obstruction ≥ 50% vs &lt; 50% preprocedure; HR, 13.71; 95% CI, 1.75-107.55; P = .013).

CONCLUSION

Therapeutic bronchoscopy with stent placement is associated with a higher risk of infection than is therapeutic bronchoscopy alone. If ablative techniques reopen the airway and there is a good chance that the tumor may respond to chemotherapy and/or radiation, a strategy of initially holding off on stenting may be warranted.

An instant rare complication: a fractured metallic pyloric stent

Metallic pyloric stenting (also termed as metallic enteral stenting) performed endoscopically, stands as first-line treatment for malignant gastric outlet obstruction. With reported evidence, these self-expandable metallic stents (SEMS) re-enable oral food intake, preventing patients having to face invasive techniques such as surgical gastroenterostomy. We report a patient having received a covered pyloric SEMS insertion following a tumour growth causing stenosis in the gastric antropyloric region. After 3 weeks, the patient presented with a fracture of the pyloric SEMS, a rare complication, resulting in a second pyloric SEMS insertion.