Bacteria and granulation tissue associated with Montgomery T-tubes

Global predictors of tracheostomy-related pressure injury in the COVID-19 era: A study of secondary data

OBJECTIVES

To determine the incidence and risk factors of tracheostomy-related pressure injuries (TRPI) and examine the COVID-19 pandemic's impact on TRPI incidence.

DESIGN

Secondary analysis of Global Tracheostomy Collaborative database and a multi-center hospital system's electronic medical records.

SETTING

27 hospitals, primarily in the United States, United Kingdom, and Australasia.

PATIENTS

6,400 adults and 2,405 pediatric patients hospitalized with tracheostomy between 1 January 2019 and 31 December 2021.

MEASUREMENT

TRPI as a binary outcome, reported as odds ratios.

RESULTS

TRPI incidence was 4.69 % in adults and 5.65 % in children. For adults, associated risks were female sex (OR: 0.64), severe obesity (OR: 2.62), ICU admission (OR: 2.05), cuffed tracheostomy (OR: 1.49), fenestrated tracheostomy (OR: 15.37), percutaneous insertion (OR: 2.03) and COVID-19 infection (OR: 1.66). For children, associated risks were diabetes mellitus (OR: 4.31) and ICU admission (OR: 2.68). TRPI odds increased rapidly in the first 60 days of stay. Age was positively associated with TRPI in adults (OR: 1.014) and children (OR: 1.060). Black patients had higher TRPI incidence than white patients; no moderating effects of race were found. Hospital cluster effects (adults ICC: 0.227; children ICC: 0.138) indicated unmeasured hospital-level factors played a significant role.

CONCLUSIONS

Increasing age and length of stay up to 60 days are TRPI risk factors. Other risks for adults were female sex, severe obesity, cuffed/fenestrated tracheostomy, percutaneous insertion, and COVID-19; for children, diabetes mellitus and FlexTend devices were risks. Admission during the COVID-19 pandemic had contrasting effects for adults and children. Additional research is needed on unmeasured hospital-level factors.

IMPLICATIONS FOR CLINICAL PRACTICE

These findings can guide targeted interventions to reduce TRPI incidence and inform tracheostomy care during public health crises. Hospital benchmarking of tracheostomy-related pressure injuries is needed.

Synergistic effects of silver nanoparticles and cisplatin in combating inflammation and hyperplasia of airway stents

Anti-inflammatory and antihyperplasia activities are essential requirements for the successful use of airway stents. In this work, silver nanoparticles (AgNPs) and cisplatin (DDP) were combined in a synergistic modification strategy to improve the surface function of airway stents. Using polycaprolactone (PCL) as a drug carrier, a dual-functional PCL-AgNPs-DDP fiber film-coated airway stent was fabricated by electrospinning. The physicochemical and biological properties of the obtained fiber films were examined. The ATR-FTIR, XPS, SEM-EDS and TEM results suggested that AgNPs and DDP could be successfully immobilized onto the airway stent surface. The drug release and surface degradation results revealed that AgNPs and DDP can undergo sustained release from films for 30 d, and the weight loss was approximately 50% after 35 d. In addition, the dual-functional fiber film suppressed human embryonic lung fibroblast growth and exhibited excellent antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. Furthermore, the effectiveness of the dual-functional fiber film-coated airway stent was evaluated by application to the trachea of New Zealand rabbits. The in vivo results indicated that PCL-AgNPs-DDP fiber film-coated airway stent can significantly inhibit granulation tissue formation and collagen deposition, reduced the expression of IL-8, TNF-α, IL-1α, PCNA, α-SMA and CD68, and ultimately achieved anti-inflammatory and antihyperplasia effects. Hence, this study provides a dual-functional surface-coated airway stent to address the clinical complications associated with respiratory tract inflammation and granulation tissue hyperplasia, thus inhibiting tracheal stenosis.

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This study provides a dual-functional PCL-AgNPs-DDP nanofiber film-coated airway stent.

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The airway stent processes antibacterial activity and suppress CCC-HPF-1 growth.

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The stent inhibits tracheal stenosis by antiinflammatory and antihyperplasia treatment.

Antibacterial and antihyperplasia polylactic acid/silver nanoparticles nanofiber membrane-coated airway stent for tracheal stenosis

Antibacterial and antihyperplasia airway stents are highly desirable for tracheal stenosis. Herein, a series of polylactic acid (PLA) and silver nanoparticles (AgNPs) nanofiber membranes (PLA, PLA-4 %AgNPs and PLA-6 % AgNPs) were prepared by electrospinning. The physicochemical and biological properties of the resultant nanofiber membranes were examined. The SEM and drug release results indicated that the AgNPs were successfully introduced into PLA, and could be sustained to be released from membranes. The membranes showed antibacterial activity against S. aureus and P. aeruginosa, and cytocompatibility towards CCC-HPF-1 and NHBE cells. Furthermore, the membranes were used to cover a self-expandable metallic stent for use in the treatment of rabbit tracheal stenosis. The in vivo results revealed that the membranes, especially the AgNPs-coated airway stent could suppress tracheal stenosis by reducing inflammation and collagen deposition. Additionally, the study further confirmed that the inhibition of bacterial content in the trachea could be positively correlated with the reduction in tracheal granulation tissue hyperplasia. Conclusively, the PLA/AgNPs nanofiber membrane-coated airway stent has practical value for patients with clinical tracheal stenosis.

Airway granulation response to lung-implantable medical devices: a concise overview

Increasing numbers of endoscopically implantable devices are implanted in the airways, such as airway stents, one-way valves and coils, to treat both malignant and benign diseases. They significantly improve patient outcomes, but their long-term effectiveness and sustainability is hampered by the reaction of the formation of granulation tissue. Factors including procedural-related tissue injury; micro-organism presence; device-related factors, such as the material, design and sizing in relation to the airway; and patient-related factors, including genetic susceptibility, comorbidities and medication use, might all effect the severity of the tissue response and the subsequent degree of granulation tissue formation. However, research into the underlying mechanism and risk factors is scarce and therefore our knowledge is limited. Joint efforts from the scientific community, both pre-clinical and clinical, are needed to gain a deeper understanding and eventually improve the long-term treatment effectiveness of lung-implantable devices.

Medical implantable devices are increasingly used in pulmonary medicine. Complications related to the tissue–device interaction are often present, but our knowledge of the underlying processes is limited.https://bit.ly/2RdWVkG

Revision Bronchoscopy After Endobronchial Valve Treatment for Emphysema: Indications, Findings and Outcomes

Background

Endobronchial valve (EBV) treatment is an effective treatment for patients with severe emphysema. Revision bronchoscopies after endobronchial valve treatment can be essential to prolong the effect of treatment or address long-term complications.

Purpose

To evaluate the indications, endoscopic findings and outcomes of revision bronchoscopies and investigate if any predictors for granulation tissue formation, after EBV treatment, can be identified.

Patients and Methods

Patients who underwent EBV treatment between 2016 and 2019 in our hospital, as routine care, were included. If a patient underwent a revision bronchoscopy, data regarding revision bronchoscopies, including indication, finding, intervention and pulmonary function testing (PFT) after revision bronchoscopy were analysed.

Results

One hundred seventy-nine patients were included of which 41% required at least one revision bronchoscopy. In 43% of the revision bronchoscopy patients, the indication was loss of initial treatment effect. In 53% of the revision bronchoscopy patients, granulation tissue was found to be the underlying cause. Valve replacement(s) were performed in 51% of the revision bronchoscopy cases. Permanent valve removal was required in 13% of all patients. Overall, revision bronchoscopies led to improvements in PFT outcomes for patients experiencing no or a loss of initial treatment effect. No clinically relevant predictors for granulation tissue formation were identified.

Conclusion

Performing a revision bronchoscopy after EBV treatment is a useful procedure leading to an improved treatment effect in most patients. Granulation tissue formation, causing valve dysfunction, is the most common cause of longer term problems.

Silicone Stent Versus Fully Covered Metallic Stent in Malignant Central Airway Stenosis

BACKGROUND

Airway stenting to restore airway patency in cases of malignant central airway obstruction is an effective palliation treatment. Our goal was to compare the efficacy after deployment and complications of a fully covered self-expandable metal stent (SEMS) (Aerstent) and a silicone stent (Dumon).

METHODS

This was a retrospective cohort of 2 similar groups of patients with malignant central airway obstruction treated with stents between August 2012 and July 2017. Complications were assessed bronchoscopically. A competing risk for death analysis was performed to adjust the probability of developing a complication.

RESULTS

Seventy patients (29 with silicone stents and 41 with SEMS) were included. Stent insertion was successful in all cases. Mucus retention was the most frequent complication (75.9% with silicone stents and 84.8% with SEMS; P = .51), followed by granulation tissue (51.7% with silicone stents and 41.3% with SEMS; P = .52) and migration (6.9% with silicone stents and 13.0% with SEMS; P = .47). In the first month, the cumulative incidence of a complication was 36.7% for silicone stents and 41.3% for SEMS and increased to 90.0% and 97.8% after 6 months, respectively (hazard ratio = 1.66; P = .04). A competing risk for death analysis showed an adjusted hazard ratio of 1.41 (P = .49) indicating no differences in overall complications between stents.

CONCLUSIONS

Both stents were equally successful and safe. The incidence of complications increased over time to 90% at 6 months for both stents. The risk of overall complications was higher for SEMS; nevertheless, when mortality was measured in a competitive risk analysis, no differences were found between SEMS and silicone stents.

Bacterial infection before and after stent placement in dogs with tracheal collapse syndrome

Background

Dogs with tracheal stents often have positive airway bacterial cultures. The pathogenicity of these organisms and risk factors for infection have not been investigated.

Objective

Describe bacterial infection in dogs with tracheal collapse before and after tracheal stent placement.

Animals

Fifty‐three client‐owned dogs.

Methods

Retrospective review of medical records of dogs receiving tracheal stents with thoracic radiographs, tracheoscopy, and endotracheal lavage.

Results

There was no difference between the overall prevalence of dogs with positive bacterial cultures before (31/38; 82%) or after stent placement (24/31; 77%) (P = .67). An increased number of geriatric (17/28; 61%) and traditional‐type collapse (TTC) (16/26; 62%) dogs had positive pathogenic airway infections before stent placement, compared to young (8/25; 32%; P = .04) and malformation‐type collapse (MTC) dogs (9/27; 33%; P = .04). After tracheal stent placement, geriatric dogs had a 52% reduction in pathogenic bacteria infection frequency (P = .02) and dogs with TTC had a 56% reduction in pathogenic bacteria infection frequency (P = .01). Significant risk factors for pathogenic infection included a history of pneumonia (OR = 3.6; 95% CI, 0.28‐43.36) and cardiac disease (OR = 1.25; 95% CI, 0.16‐9.92) in geriatric dogs, and hepatomegaly in young dogs (OR = 1.5; 95% CI, 0.12‐19.44).

Conclusions and Clinical Importance

Tracheal stent placement does not increase the overall rate of pathogenic bacterial infection in dogs with tracheal collapse and can decrease the rate of subsequent pathogenic infections in geriatric dogs and dogs with TTC that require tracheal stenting. Airway culture and cytology should be performed in all dogs undergoing tracheal stent placement.

Surgical treatments for post-intubation laryngotracheal stenosis in patients with central nervous system injuries

Post-intubation laryngotracheal stenosis is a complication commonly encountered in patients with central nervous system (CNS) injuries, often preventing decannulation. To date, no data is available in the literature focusing on this issue. Our objective was to describe surgical treatments for laryngotracheal stenosis and discuss factors associated with successful decannulation in this group of patients.Medical records of patients with CNS injury who received tracheal surgeries at our institution between 2009 and 2016 were retrospectively collected and analyzed.Data on 124 surgeries in 62 patients with CNS injury were collected. The total complication rate was 20.9% with no surgical mortality. The decannulation success rate was 85.5%. Argon laser surgeries (48), diode laser surgeries (22), tracheal resection and reconstructions (R&R) (9), and tracheal T-tube placements (67) were performed. The average times from the first bronchoscopy check up to surgery and surgery to decannulation were 0.7 and 8.2 months, accordingly. The mean post-decannulation follow-up time was 13.5 months. A shift from the use of rigid bronchoscopy in the initial surgeries to laryngeal mask in the latter surgeries yielded an average decrease of 3 days in hospital length of stay (LOS). A change from initial rigid bronchoscopic core out procedures and argon laser to interventional flexible bronchoscopic resections with diode laser also decreased LOS significantly.Surgical treatments for patients with CNS injury and laryngotracheal stenosis can be safely performed with low mortality, acceptable complications, and a high decannulation success rate. The majority of patients with laryngotracheal stenosis can be managed with laser endoscopic surgeries, though tracheal R&R might still be required in selected cases. The use of laryngeal mask to secure the airway and diode laser in the intra-luminal resections improved the surgical outcome and was therefore recommended for these patients suffering from post-intubation laryngotracheal stenosis.

Structured care to improve outcomes in primary single stage laryngotracheal reconstruction

PURPOSE

To examine single stage laryngotracheal reconstruction (SSLTR) care to reduce complication and failure rate.

METHODS

Forty-five patients that underwent primary SSLTR were examined retrospectively. All had pre-operative direct laryngoscopy and bronchoscopy, esophagoscopy with biopsy and MRSA screening. Pre-operative subglottic stenosis (SGS) grade and associated comorbidities were recorded. Intraoperative graft location and type was documented. Hospital course and results were evaluated and compared to cited literature.

RESULTS

The median age at reconstruction was 2 years (0-15 years). 42.2% were male. 66.7% had gastroesophageal disease and 24.4% a MRSA history. Grade 2 SGS was noted pre-operatively in 37.8% and grade 3 or 4 in 57.7% of patients. Post-surgical hospital course was examined. 77.8% of patients were extubated on planned date. 95.6% of patients had operation specific successful decannulation. Graft type and variations of graft placement as well as MRSA and GERD status didn't affect procedure success rate. Active GERD was related to failure of extubation on planned day (p = 0.02). An abnormal pre-operative swallowing examination was associated with higher complication rates (p = 0.03).

CONCLUSION

Utilizing a more structured approach to SSLTR work-up and addressing potential SSLTR pitfalls may result in higher operation specific decannulation rates. Pre-operative GERD and swallowing dysfunction were associated with higher rates of adverse events.

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.

Effect of repeated tracheostomy tube reprocessing on biofilm formation

Objectives/Hypothesis

To determine the effect of repeated reprocessing of pediatric tracheostomy tubes (TTs) on biofilm formation.

Study Design

In vitro microbiological study.

Methods

Pediatric, uncuffed, polyvinyl chloride (PVC) TTs from two different manufacturers (Tracoe Mini and Shiley) were reprocessed mechanically with household detergent and soaked in sodium hypochlorite (bleach). Two TTs of each brand were reprocessed 0 (control), 10, or 20 times. Twenty 2‐mm coupons were then obtained from each TT, immersed in human mucus, and cultured with either Staphylococcus aureus or Pseudomonas aeruginosa. Biofilm formation was evaluated with bacterial counts.

Results

Bacterial counts of S. aureus for both brands were significantly higher on the TTs that were reprocessed 20 times compared to those that were not reprocessed (Tracoe: P = .040, Shiley: P  <  .0001) or those that were reprocessed 10 times (Tracoe: P = .022, Shiley: P = .0002). There was no difference between controls and TTs reprocessed 10 times (Tracoe: P = .76, Shiley: P = .24). P. aeuruginosa counts were not significantly different among the varying numbers of reprocessing cycles for either Tracoe or Shiley TTs (P = .08 and P = .97, respectively).

Conclusions

Repeated reprocessing of PVC TTs with detergent and bleach paradoxically promotes S. aureus biofilm development, possibly due to degradation of the tube surface that facilitates bacterial attachment. Further investigation is needed to determine the optimal technique and limits of reprocessing TTs in clinical practice.

Level of Evidence

NA Laryngoscope, 126:996–999, 2016

Bacterial biofilms and increased bacterial counts are associated with airway stenosis

OBJECTIVES

Most airway stenoses are acquired secondary to the use of prolonged endotracheal intubation. Antibiotics have been shown to decrease local inflammation and granulation tissue formation in the trachea. However, antibiotic therapy is not 100% effective in preventing or treating granulation tissue formation. Development of bacterial biofilms may explain this finding. This study evaluates the difference between tracheal stenotic segments and normal trachea in terms of (1) presence of bacterial biofilms, (2) quantitative bacterial counts, and (3) inflammatory markers.

STUDY DESIGN

Cross-sectional study.

SETTING

Tertiary care academic medical center.

SUBJECTS

A total of 12 patients were included in the study. Tissue from stenotic segments from 6 patients with airway stenosis undergoing open airway procedures were compared with tracheal tissue from 6 patients without airway stenosis undergoing tracheostomy.

METHODS

Scanning electron microscopy for biofilm detection, quantitative polymerase chain reaction for quantitative analysis of bacterial count, and immunohistochemistry were performed for inflammatory markers transforming growth factor β1 (TGF-β1) and SMAD3.

RESULTS

Compared with the patients without airway stenosis, patients in the airway stenosis group showed presence of bacterial biofilms, a significantly higher expression of 16S rRNA gene copies per microgram of tissue (187.5 vs 7.33, P = .01), and higher expression of TGF-β1 (91% vs 8%, P < .001) and SMAD3 (83.5% vs 17.8%, P < .001).

CONCLUSION

Bacterial biofilms, increased bacterial counts, and higher expression of TGF-β1 and SMAD3 are associated with airway stenosis.

Successful tracheal replacement in humans using autologous tissues: an 8-year experience

BACKGROUND

Fifty years of surgical research using synthetic materials and heterologous tissues failed to find a good, durable replacement for the trachea. We investigated autologous tracheal substitution (ATS) without synthetic material or immunosuppression.

METHODS

For ATS, we used a single-stage operation to construct a tube from a forearm free fasciocutaneous flap vascularized by radial vessels that was reanastomosed to internal mammary vessels and reinforced by rib cartilages interposed transversally in the subcutaneous tissue. Tracheal resections 7 to 12 cm long (mean, 11 cm) were done to treat 8 primary tracheal neoplasms, including 5 adenoid cystic carcinomas (ACC) and 3 squamous cell carcinomas (SCC); 3 secondary tracheal neoplasms, including 1 thyroid carcinomas and 2 lymphomas; and 1 postintubation tracheal destruction after a long history of stenting. Transitory tracheotomy was associated to the absence of mucociliary clearance.

RESULTS

ATS has been performed in 12 patients since 2004, with additional resections in 4 patients, comprising 1 carinal resection alone, 1 associated with lobectomy, and 2 pharyngolaryngectomies. All patients were extubated on postoperative day 1. Eight patients are alive at a mean of 36 months (range, 2 to 94 months) postoperatively, with no respiratory distress. The 2 patients with ATS and carinal resections died of pulmonary infection. No airway collapse has been detected by endoscopy, dynamic computed tomography scan, or spirometry. Two patients still have a tracheotomy because the procedure was performed too low at the level of the proximal anastomosis. One patient with a chronic severe respiratory insufficiency recently required a distal, short stent.

CONCLUSIONS

ATS is a good, durable, tracheal substitution that resists respiratory pressure variations because of transverse rigidity, without any immunosuppression.

Autologous tracheal replacement: from research to clinical practice

BACKGROUND

Despite numerous attempts, synthetic materials and heterologous tissues failed to replace durably the trachea. Autologous tracheal substitution (ATS) without synthetic material or immunosuppression was investigated to replace extended tracheal defect. We present our experience regards to this innovative challenge.

METHOD

After a previous research study, we developed a novel reconstruction technique for extended tracheal defects on animals. Through a single stage operation, a tube from a forearm free fascio-cutaneous flap vascularized by radial vessels is re-anastomosed to cervical vessels. This flap is reinforced by rib cartilages interposed transversally in the subcutaneous tissue. It provides also a reliable ATS. Twelve patients benefits from an extended tracheal resections, 7-12 centimeter (mean 11 cm) long. Indications were eight Primary tracheal Neoplasms (including 5 adenoid cystic carcinoma [ACC] and 3 squamous cell carcinoma [SCC]), three secondary tracheal neoplasms (including 1 thyroid carcinoma and 2 lymphoma) and one post-intubation tracheal destruction after long history of stenting. Daily bronchoscopy and transitory tracheotomy was associated due to absence of mucociliary clearance.

RESULTS

The research work leads to present the first described animal model for tracheal resection and replacement with an autologous conduit. It was constructed from costal cartilages and a pediculed cervical skin flap. From 2004 to 2012, 12 patients have had ATS with associated resections in four cases. All patients were extubated on the first postoperative days; eight patients are alive at 2 to 94 months (mean=36) postoperatively, with no respiratory distress. The two patients with ATS after resection extended to the carina died due to pulmonary infection. No airway collapse has been detectable, either by endoscopy, dynamic CT scan or spirometry. Two patients still have a tracheotomy because performed too low at the level of the proximal anastomosis. One patient with a chronic severe respiratory insufficiency required recently a distal and short stent.

CONCLUSION

ATS is actually a good, durable tracheal substitute that can resist respiratory pressure variations because of their transverse rigidity without any immunosuppression. The limits of this technique are probably, chronic respiratory insufficiency and cartilage calcifications. Research to develop a method for lining the neo-trachea with ciliated respiratory epithelium is needed.

Tracheal wall thickening is associated with the granulation tissue formation around silicone stents in patients with post-tuberculosis tracheal stenosis

PURPOSE

Tracheal restenosis due to excessive granulation tissue around a silicone stent requires repeated bronchoscopic interventions in patients with post-tuberculosis tracheal stenosis (PTTS). The current study was conducted to identify the risk factors for granulation tissue formation after silicone stenting in PTTS patients.

MATERIALS AND METHODS

A retrospective study was conducted between January 1998 and December 2010. Forty-two PTTS patients with silicone stenting were selected. Clinical and radiological variables were retrospectively collected and analyzed.

RESULTS

Tracheal restenosis due to granulation tissue formation were found in 20 patients (47.6%), and repeated bronchoscopic interventions were conducted. In multivariate analysis, tracheal wall thickness, measured on axial computed tomography scan, was independently associated with granulation tissue formation after silicone stenting. Furthermore, the degree of tracheal wall thickness was well correlated with the degree of granulation tissue formation.

CONCLUSION

Tracheal wall thickening was associated with granulation tissue formation around silicone stents in patients with post-tuberculosis tracheal stenosis.

Regenerative medicine for the respiratory system: distant future or tomorrow's treatment?

Regenerative medicine (RM) is a new field of biomedical science that focuses on the regeneration of tissues and organs and the restoration of organ function. Although regeneration of organ systems such as bone, cartilage, and heart has attracted intense scientific research over recent decades, RM research regarding the respiratory system, including the trachea, the lung proper, and the diaphragm, has lagged behind. However, the last 5 years have witnessed novel approaches and initial clinical applications of tissue-engineered constructs to restore organ structure and function. In this regard, this article briefly addresses the basics of RM and introduces the key elements necessary for tissue regeneration, including (stem) cells, biomaterials, and extracellular matrices. In addition, the current status of the (clinical) application of RM to the respiratory system is discussed, and bottlenecks and recent approaches are identified. For the trachea, several initial clinical studies have been reported and have used various combinations of cells and scaffolds. Although promising, the methods used in these studies require optimization and standardization. For the lung proper, only (stem) cell-based approaches have been probed clinically, but it is becoming apparent that combinations of cells and scaffolds are required to successfully restore the lung's architecture and function. In the case of the diaphragm, clinical applications have focused on the use of decellularized scaffolds, but novel scaffolds, with or without cells, are clearly needed for true regeneration of diaphragmatic tissue. We conclude that respiratory treatment with RM will not be realized tomorrow, but its future looks promising.

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

BACKGROUND

The most serious complications of airway stenting are long term, including infection and granulation tissue formation. However, to our knowledge, no studies have quantified the incidence rate of long-term complications for different stents.

METHODS

To compare the incidence of complications of different airway stents, we conducted a retrospective cohort study of all patients at our institution who had airway stenting for malignant airway obstruction from January 2005 to August 2010. Patients were excluded if more than one type of stent was in place at the same time. Complications recorded were lower respiratory tract infections, stent migration, granulation tissue, mucus plugging requiring intervention, tumor overgrowth, and stent fracture.

RESULTS

One hundred seventy-two patients with 195 stent procedures were included. Aero stents were associated with an increased risk of infection (hazard ratio [HR] = 1.98; 95% CI, 1.03-3.81; P = .041). Dumon silicone tube stents had an increased risk of migration (HR = 3.52; 95% CI, 1.41-8.82; P = .007). Silicone stents (HR = 3.32; 95% CI, 1.59-6.93; P = .001) and lower respiratory tract infections (HR = 5.69; 95% CI, 2.60-12.42; P < .001) increased the risk of granulation tissue. Lower respiratory tract infections were associated with decreased survival (HR = 1.57; 95% CI, 1.11-2.21; P = .011).

CONCLUSIONS

Significant differences exist among airway stents in terms of infection, migration, and granulation tissue formation. These complications, in turn, are associated with significant morbidity and mortality. Granulation tissue formation develops because of repetitive motion trauma and infection.

Granulation formation following tracheal stenosis stenting: influence of stent position

OBJECTIVES/HYPOTHESIS

To determine whether stent-to-vocal fold distance influences morbidity following stent placement for tracheal stenosis.

METHODS

Fifty-five stent procedures (46 Montgomery T-tube [Boston Medical Products, Westborough, MA] and 9 Dumon stents [Novatech, Grasse, France]) were performed in 40 patients enrolled in this study.

RESULTS

The most common complication of stenting for tracheal stenosis was granulation (23 procedures, 41.82%). Of 43 procedures where the stent upper edge was located at or below the vocal folds, granulation occurred in 21 procedures (48.84%). Of 12 procedures where the stent edge was located above the vocal fold, granulation occurred in two procedures, or 16.67% (odds ratio = 4.773, P = .0458, chi(2) test). Among patients in whom the stent edge was located at or below the vocal folds, the granulation complication rate was higher in those with a stent-to-vocal fold distance of <10 mm. Multivariate analysis revealed that the stent-to-vocal fold distance independently predicted granulation formation; an inverse correlation was identified between stent-to-vocal fold distance and granulation severity (n = 43, r = -.501, P = .0006; Spearman ranking test). Receiver operating characteristic curve analysis further demonstrated that a stent-to-vocal fold distance cutoff value between 9.5 and 11 mm had the best accuracy in predicting granulation formation.

CONCLUSIONS

A stent-to-vocal fold distance of 10 mm was found to be a critical distance for discriminating granulation formation. Optimal stent-to-vocal fold distance should routinely be evaluated before stent placement.

Penicillium species as a rare isolate in tracheal granulation tissue: a case series

Introduction

Granulation tissue formation is a major problem complicating the treatment of upper airway stenosis. We present two cases of recurrent tracheal granulation tissue colonisation by Penicillium species in patients undergoing laryngotracheal reconstructive surgery for post-intubation tracheal stenosis. We believe that although most Penicillium species do not cause invasive disease they can be a contributory factor to the occurrence of upper airway stenosis.

Case presentation

A microbiological and mycological study of tracheal granulation tissue in two patients with recurrent laryngotracheal stenosis was carried out. Penicillium species was seen microscopically and cultured from tracheal granulation tissue. Neither patient grew any bacteria known to be associated with airway granulation tissue formation. Amphotericin B, itraconazole, flucytosine voriconazole and caspofungin were highly active against both isolates.

Conclusion

A search for a fungal cause should form part of the investigation for recurrent tracheal granulation tissue during laryngotracheal reconstruction.

Prevalence of genes encoding for members of the staphylococcal leukotoxin family among clinical isolates of Staphylococcus aureus

Well-characterized Staphylococcus aureus nasal and blood isolates (N = 429) were tested by polymerase chain reaction for the prevalence of genes that encode leukocidal toxins. The leukotoxin genes lukE+lukD were found at high prevalence, significantly more so in blood (82%) than in nasal isolates (60.5%). Although almost all isolates were positive for the gamma-hemolysin gene, none was positive for lukM. Genes encoding Panton-Valentine leukocidin (PVL) components were very rare in either nasal or blood isolates. The lukE+lukD-negative isolates were significantly more likely to be positive for the staphylococcal enterotoxin gene combination seg/sei (89.5%) and the toxic shock syndrome toxin-1 gene (39.3%) than lukE+lukD-positive isolates (41.7% and 12.7%, respectively). The lukE+lukD-negative isolates were also more likely to show positivity for the accessory gene regulatory locus agr III, but less likely to be positive for the agr II locus. The co-possession of different virulence factors and their probable synergy should receive more attention in order to better understand their role in pathogenicity.