Customized self-expanding bare metal Y stents in the treatment of malignant carinal stenosis: a retrospective analysis.

BACKGROUND: Self-expanding Y metal stent insertion is a safe and effective palliative method for malignant lesions involving the lower trachea, tracheal carina, and the main-stem bronchi. However, the length and degree of airway stenosis in different patients tend to vary, which leads to a call for a customized Y stent that could achieve a better treatment effect. METHODS: This retrospective analysis included patients who received customized self-expanding bare metallic Y stents for malignant carinal stenosis at Beijing Tiantan Hospital, Capital Medical University between January 2007 and June 2020. CT scans and initial bronchoscopy were performed to provide reliable data for stent selection and size customization. Data on technical success, clinical success, and follow-up were analyzed. RESULTS: A total of 36 patients (26 males and 10 females; median age, 61 years; age range, 30-83 years) were enrolled. Technical success was 97.2% (35/36), while clinical success was 97.2% (35/36). There was no procedure-related mortality. Out of 35 patients, 4 (11.4%) had stent-associated complications that did not affect the procedure of stent insertion. Re-stenosis of the stent due to tumor progression was the main mid- and long-term stent-related complication (65% and 57.1%, respectively), followed by stent fractures (5% and 14.3%, respectively). CONCLUSIONS: The current study described the design and insertion of customized self-expanding bare metal Y-stents and demonstrated the feasibility of their use for maintaining tracheal and main-stem bronchus patency in malignant carinal stenosis. This approach could be used as a bridging method before commencing adjuvant therapy and final palliative therapy for the relief of symptoms.

Application of Micro-Tech stents in malignant carinal stenosis.

Malignant carinal stenosis is a disease process that is not always suitable for treatment with a Y-shaped stent. When one of the main bronchi is completely obstructed and cannot be recanalized, or its distal lung tissue has lost function, inserting a Y-shaped stent is infeasible. In this complex condition, a cone-shaped stent is selected to maintain the patency of the trachea and the other main bronchus. The efficacy of the bare cone-shaped Micro-Tech stent to treat malignant carinal stenosis was evaluated in the current study. The medical records of 47 patients with malignant carinal stenosis who underwent Micro-Tech stent placement between January 2004 and October 2017 in Beijing Tian Tan Hospital (Beijing, China) were analyzed retrospectively. A total of 47 bare Micro-Tech stents (28 Y-shaped and 19 cone-shaped) were successfully inserted in the patients. Following stent placement, immediate satisfactory results were achieved in all patients, especially an improvement of dyspnea (100%), cough (81.1%) and stridor (100%). The Karnofsky scores were significantly increased (P<0.001), and the American Thoracic Society Dyspnea Index values were significantly decreased (P<0.001). Following a median of 88 days, initial bronchoscopic interventions were performed for tumor overgrowth (84.6%), stent fracture (7.7%) and granulation tissue (7.7%). Restenting was performed in two patients due to tumor progression (n=1) and stent fracture (n=1). Removal of a Y-shaped stent was attempted in one patient, but failed, as the stent had become partly embedded in the airway mucosa. In conclusion, cone-shaped Micro-Tech stent placement maintained tracheal-unilateral main bronchus patency and benefitted patients with malignant carinal stenosis in whom Y-shaped stents were not suitable for insertion.

Comparison of clinical features and stent placement outcomes between airway stenosis caused by primary pulmonary malignancies and that caused by primary non-pulmonary malignancies.

BACKGROUND: Primary pulmonary malignancies (PPMs) and non-pulmonary malignancies (PNPMs) may result in airway stenosis requiring stenting. This study aimed to compare and evaluate the clinical features and stent placement outcomes of airway stenosis caused by PPMs and PNPMs. METHODS: A total of 141 patients with malignant airway stenosis who underwent Micro-Tech stent placements between January 2004 and October 2017 at Department of Respiratory Medicine, Beijing Tian Tan Hospital, Capital Medical University were divided into PPM (n = 100) and PNPM groups (n = 41). Patients' clinical features and stent placement outcomes were collected and analyzed. Chi-square test was used to compare the categorical variables, while independent- or paired-sample t test was used to compare the continuous variables. RESULTS: There were no significant differences in age, sex, treatment history, respiratory symptoms, and incidence of obstructive pneumonia between groups. Multiple airway involvement (63.0% vs. 31.7%; χ = 11.459, P = 0.001) and atelectasis (17.0% vs. 2.4%; χ = 5.536, P = 0.019) were more common in the PPM group, while extraluminal obstruction (24.4% vs. 6.0%; χ = 8.033, P = 0.005) was more common in the PNPM group. Before stenting, the American Thoracic Society Dyspnea Index (ADI) and Karnofsky Performance Scale (KPS) scores showed no significant differences between groups (all P > 0.05). After stenting, a satisfactory rate of symptom improvement was achieved in both groups (98.0% and 100.0% in the PPM and PNPM groups, respectively; χ = 0.016, P = 0.898); ADI and KPS scores, which showed no significant differences between groups (all P > 0.05), were significantly improved in each group (all P < 0.001). Complications after stenting could be effectively managed using bronchoscopic procedures. CONCLUSIONS: Among cases of malignant airway stenosis requiring stenting, those caused by PPM are more likely to involve multiple airways and are associated with atelectasis, while those caused by PNPM are more likely to cause extraluminal obstruction. Micro-Tech stent placement has the same immediate effect in terms of improvement in respiratory symptoms and performance status for both malignant airway stenosis caused by PPM and that caused by PNPM.

Scarring Airway Stenosis in Chinese Adults: Characteristics and Interventional Bronchoscopy Treatment.

BACKGROUND: Scarring airway stenosis is commonly seen in China as compared to other developed countries, due to the high prevalence of tuberculosis. Nowadays, interventional bronchoscopy treatment has been widely used to treat this disease in China. This study demonstrated the characteristics of scarring airway stenosis in Chinese adults and retrospectively evaluated the efficacy of interventional bronchoscopy treatment of this disease. METHODS: Patients with scarring airway stenosis from 18 tertiary hospitals were enrolled between January 2013 and June 2016. The causes, site, and length of scarring airway stenosis were analyzed, and the efficacy of the interventional bronchoscopy treatment was evaluated. RESULTS: The final study cohort consisted of 392 patients. Endotracheobronchial tuberculosis (EBTB) was the most common cause of scarring airway stenosis (305/392, 77.8%) in Chinese adults with a high rate of incidence in young women. The left main bronchus was most susceptible to EBTB, and most posttuberculosis airway scarring stenosis length was 1.1-2.0 cm. The average clinical success rate of interventional bronchoscopy treatment for scarring airway stenosis in Chinese patients is 60.5%. The stent was inserted in 8.7% scarring airway stenosis in China. CONCLUSIONS: Scarring airway stenosis exhibits specific characteristics in Chinese patients. Interventional bronchoscopy is a useful and safe treatment method for the disease.

Interventional Bronchoscopic Therapy in Adult Patients with Tracheobronchial Mucoepidermoid Carcinoma.

BACKGROUND: Tracheobronchial mucoepidermoid carcinoma (MEC) is a rare airway tumor in adults for which surgery is considered a first-line treatment. However, some patients already lost the best opportunity of a surgical intervention when diagnoses are confirmed, and surgery causes considerable trauma resulting in partial loss of pulmonary function. Moreover, the tumor is resistant to radiotherapy and chemotherapy. These factors make the treatment of tracheobronchial MEC challenging. This study aimed to evaluate the safety and efficacy of interventional bronchoscopic therapy in adult patients with tracheobronchial MEC. METHODS: We retrospectively analyzed the clinical manifestations, bronchoscopic interventions, complications, and outcomes of 11 adult patients with tracheobronchial MEC. Paired t-test was used to analyze the parameters of the American Thoracic Society Dyspnea Index and the Karnofsky Score before and after the first interventional bronchoscopic therapy. RESULTS: All tumors occurred in the main bronchus and were easily visualized by bronchoscopy. After interventional bronchoscopic therapy, the symptoms of all patients showed significant improvement. The American Thoracic Society Dyspnea Index decreased from 1.91 ± 1.22 to 0.27 ± 0.47 (t = 6.708, P < 0.001) and the Karnofsky Score increased from 78.18 ± 16.62 to 95.46 ± 8.20 (t = -5.190, P < 0.001). Bronchoscopic intervention did not result in serious complications or mortality. During the follow-up period between 3 and 96 months after the first therapy, the following results were noted: (1) among the eight patients with low-grade tracheobronchial MEC, only one patient had a relapse and agreed to surgical treatment; (2) among the three patients with high-grade tracheobronchial MEC, one patient required repeated bronchoscopic interventions, one patient died of pulmonary infection, and one patient died of systemic failure owing to tumor metastasis. CONCLUSIONS: Interventional bronchoscopic therapy, as an alternative treatment, shows promise in some adult patients with low-grade tracheobronchial MEC confined to the bronchus. However, for adult patients with high-grade tracheobronchial MEC, early diagnosis and surgical treatment are still strongly recommended.

Paclitaxel Drug-eluting Tracheal Stent Could Reduce Granulation Tissue Formation in a Canine Model.

BACKGROUND: Currently available silicone and metallic stents for tracheal stenosis are associated with many problems. Granulation proliferation is one of the main complications. The present study aimed to evaluate the efficacy of paclitaxel drug-eluting tracheal stent in reducing granulation tissue formation in a canine model, as well as the pharmacokinetic features and safety profiles of the coated drug. METHODS: Eight beagles were randomly divided into a control group (bare-metal stent group, n = 4) and an experimental group (paclitaxel-eluting stent group, n = 4). The observation period was 5 months. One beagle in both groups was sacrificed at the end of the 1st and 3rd months, respectively. The last two beagles in both groups were sacrificed at the end of 5th month. The proliferation of granulation tissue and changes in tracheal mucosa were compared between the two groups. Blood routine and liver and kidney function were monitored to evaluate the safety of the paclitaxel-eluting stent. The elution method and high-performance liquid chromatography were used to characterize the rate of in vivo release of paclitaxel from the stent. RESULTS: Compared with the control group, the proliferation of granulation tissue in the experimental group was significantly reduced. The drug release of paclitaxel-eluting stent was the fastest in the 1st month after implantation (up to 70.9%). Then, the release slowed down gradually. By the 5th month, the release reached up to 98.5%. During the observation period, a high concentration of the drug in the trachea (in the stented and adjacent unstented areas) and lung tissue was not noted, and the blood test showed no side effect. CONCLUSIONS: The paclitaxel-eluting stent could safely reduce the granulation tissue formation after stent implantation in vivo, suggesting that the paclitaxel-eluting tracheal stent might be considered for potential use in humans in the future.

Nonstent Combination Interventional Therapy for Treatment of Benign Cicatricial Airway Stenosis.

BACKGROUND: Benign cicatricial airway stenosis (BCAS) is a life-threatening disease. While there are numerous therapies, all have their defects, and stenosis can easily become recurrent. This study aimed to investigate the efficacy and complications of nonstent combination interventional therapy (NSCIT) when used for the treatment of BCAS of different causes and types. METHODS: This study enrolled a cohort of patients with BCAS resulting from tuberculosis, intubation, tracheotomy, and other origins. The patients were assigned to three groups determined by their type of stenosis: Web-like stenosis, granulation stenosis, and complex stenosis, and all patients received NSCIT. The efficacy and complications of treatment in each group of patients were observed. The Chi-square test, one-factor analysis of variance (ANOVA), and the paired t -test were used to analyze different parameters. RESULTS: The 10 patients with web-like stenosis and six patients with granulation stenosis exhibited durable remission rates of 100%. Among 41 patients with complex stenosis, 36 cases (88%) experienced remission and 29 cases (71%) experienced durable remission. When five patients with airway collapse were eliminated from the analysis, the overall remission rate was 97%. The average treatment durations for patients with web-like stenosis, granulation stenosis, and complex stenosis were 101, 21, and 110 days, respectively, and the average number of treatments was five, two, and five, respectively. CONCLUSIONS: NSCIT demonstrated good therapeutic efficacy and was associated with few complications. However, this approach was ineffective for treating patients with airway collapse or malacia.

[A method for the primary culture of fibroblasts isolated from human airway granulation tissues].

OBJECTIVE: To establish a feasible method to culture primary fibroblasts isolated from human airway granulation tissues, and therefore to provide experimental data for the investigation of the pathogenesis of benign airway stenosis. METHODS: The granulation tissues were collected from 6 patients during routine bronchoscopy at our department of Beijing Tiantan Hospital from April to June 2011. Primary fibroblasts were obtained by culturing the explanted tissues. Cell growth was observed under inverted microscope. RESULTS: All of these 6 primary cultures were successful. Fibroblast-like cells were observed to migrate from the tissue pieces 3 d after inoculation. After 9-11 d of culture, cells reached to 90% confluence and could be sub-cultured. After passage, the cells were still in a typical elongated spindle-shape and grew well. The cells could be sub-cultured further when they formed a monolayer. CONCLUSION: Explant culture is a reliable method for culturing primary fibroblasts from human airway granulation tissues.

Inhibitory effect of mitomycin C on proliferation of primary cultured fibroblasts from human airway granulation tissues.

BACKGROUND: Airway granulation tissue and scar formation pose a challenge because of the high incidence of recurrence after treatment. As an emerging treatment modality, topical application of mitomycin C has potential value in delaying the recurrence of airway obstruction. Several animal and clinical studies have already proven its feasibility and efficacy. However, the ideal dosage has still not been determined. OBJECTIVES: To establish a novel method for culturing primary fibroblasts isolated from human airway granulation tissue, and to investigate the dose-effect of mitomycin C on the fibroblast proliferation in vitro, so as to provide an experimental reference for clinical practitioners. METHODS: Granulation tissues were collected during the routine bronchoscopy at our department. The primary fibroblasts were obtained by culturing the explanted tissues. The cells were treated with different concentrations of mitomycin C (0.1, 0.2, 0.4, 0.8 and 1.6 mg/ml) for 5 min followed by additional 48-hour culture before an MTT assay was performed to measure cell viability. RESULTS: MTT assay showed that mitomycin C reduced cell viability at all tested concentrations. The inhibitory ratios were 10.26, 26.77, 32.88, 64.91 and 80.45% for cells treated with mitomycin C at 0.1, 0.2, 0.4, 0.8 and 1.6 mg/ml, respectively. CONCLUSIONS: Explant culture is a reliable method for culturing primary fibroblasts from human airway granulation tissue, and mitomycin C can inhibit proliferation of the fibroblasts in vitro.

[The influence of mitomycin C and paclitaxel on the proliferation and apoptosis of human pulmonary fibroblast].

OBJECTIVE: To observe the inhibitory effect and potential mechanism of mitomycin C and paclitaxel on the proliferation of Human Pulmonary Fibroblast in vitro. So as to providing an experimental reference for the design of drug eluting airway stents. METHODS: Cell viability was measured by MTT assay after different concentrations of mitomycin C or paclitaxel varying from 10(-1)1 mol/L to 10(-4) mol/L had been applied to the fibroblasts for 24, 48 or 72 h, respectively. Cell apoptosis was assessed by flow cytometry using dual staining with annexin V-FITC and propidium iodide 48 h after administering mitomycin C or paclitaxel at a concentration of 5×10(-6), 10(-5), 5×10(-5), 10(-4), 2×10(-4) mol/L, respectively. And the morphological character of cell apoptosis was observed by Hoechst 33342 fluorescent staining. RESULTS: The results of MTT revealed that cell proliferation were inhibited by mitomycin C and paclitaxel at all concentrations and exposure times. Among them, the inhibitory effect of mitomycin C were weak when the concentrations were between 10(-1)1 mol/L to 10(-8) mol/L. And within this context, the inhibitory ratio didn't correspond to the elevation of the concentration or the prolongation of the exposure times.However, when the concentration were between 10(-7) mol/L to 10(-4) mol/L, the inhibitory ratio rise progressively as the elevation of the concentration at all exposure times. The inhibitory ratio were 53.52%, 60.23%, 89.81% and 96.47% respectively when cells were treated by 10(-7), 10(-6), 10(-5) mol/L and 10(-4) mol/L mitomycin C for 72 h. An apparent "threshold dose effect" was observed in the paclitaxel treated groups.It's worth noting that the inhibitory ratio was only 48.22% when the cells had already been treated by 10(-5) mol/L paclitaxel for 72 h.However, when the concentration had reached 10(-4) mol/L, the inhibitory ratio sharply climbed to 93.38% even the cells had only been treated for 24 h. And the inhibitory ratio continued to rise as time prolonged. The results of cell apoptosis were consistent with MTT.When a significant inhibitory effect were detected by MTT, remarkable cell apoptosis could be observed by flow cytometry, and typical apoptotic cell could be identified by Hoechst 33342 fluorescent staining. CONCLUSIONS: A certain concentration of mitomycin C or paclitaxel can inhibit Human Pulmonary Fibroblast proliferation in vitro. Both of these two drugs have potential value for the preparation of drug eluting airway stents. In order to ensure the inhibitory effect, the eluting concentration of mitomycin C and paclitaxel should not be less than 10(-7) mol/L and 10(-5) mol/L. But the eluting concentration of these two drugs should not exceed 10(-4) mol/L when both of the inhibitory ratio of these two drugs were higher than 95%.On this basis, elevating the drug concentration has little significance for improving the inhibitory effect, but increase the risk of systemic toxicity. Inducing cell apoptosis is one of the potential mechanisms of mitomycin C and paclitaxel in inhibiting cell proliferation.

[Effect of topical application with mitomycin C in the management of benign cicatricial airway stenosis].

OBJECTIVE: To assess the efficacy and safety of topical application of mitomycin-C in the management of benign cicatricial airway stenosis (BCAS), and to discuss the feasibility of catheter drip to achieve the topical application of mitomycin-C. METHODS: Twenty patients with BCAS were divided into control group and experimental group (topical application of mitomycin-C). Patients in control group were treated only with interventional bronchoscopy which including balloon dilation, argon plasma coagulation/electrotomy, cryotherapy, stent placement and so on, while patients in experimental group were treated with interventional bronchoscopy adjuncted with topical application of mitomycin-C (0.4 mg/ml). According to the length of airway lesion, the dosage was 1 ml/cm. Topical application of mitomycin-C was achieved by catheter drip. Photographs were taken at the place above the proximal end of airway stenosis and a software called Digimizer was used to measure the cross sectional area of stenosed airway. A 3-month follow-up was done to observe the safety and curative effect of topical application mitomycin-C in airway. RESULTS: Ten patients (3 male and 7 female) ranging in age from 20 to 71 years [mean (36 ± 17) years] enrolled in control group and 10 patients (5 male and 5 female) ranging in age from 20 to 74 years [mean (42 ± 18) years] enrolled in experimental group. The average airway cross-sectional areas before and after treatment of 2 groups were (22 ± 13) mm(2), (23 ± 11) mm(2) (control group) and (20 ± 8) mm(2), (34 ± 12) mm(2) (experimental group), respectively. The average increased airway cross-sectional areas of experimental group and control group before and after treatment were (15 ± 13) mm(2) and (1 ± 10) mm(2) respectively, which had statistical differences. The average times of treatment during 3 months were (2.8 ± 1.5) in control group vs (1.8 ± 0.9) in experimental group which had statistical differences. The 3-month effective rate was 90% of experimental group vs 40% of control group, and the symptom improvement rate was 80% of experimental group vs 30% of control group. There were significant differences in outcomes between two groups. No drug-related complications occurred in experimental group during the follow-up period. CONCLUSIONS: Mitomycin-C is an effective adjuvant treatment method in the management of BCAS. Topical application of mitomycin-C in airway is safety. Catheter drip to achieve the topical application of mitomycin-C in airway is a convenient, economical and effective method.

[A pilot study on interventional bronchoscopy in the management of airway stenosis with benign hyperplasia].

OBJECTIVE: To evaluate the efficacy of different interventional bronchoscopic techniques for the management of benign cicatricial hyperplasia airway stenosis, and to study the factors associated with the treatment effects. METHODS: From December 2004 to December 2009, 36 patients with cicatricial airway stenosis were admitted to our department. An investigation was made to analyze the effects by different interventional bronchoscopic treatments. The most suitable treatment modality for cicatricial airway stenosis was explored and described. RESULTS: For the 36 patients, the disease was cured in 9, improved in 10, not improved in 12, and failure in 5. The cure rate, effective rate and ineffective rate were 25%, 53% and 47%, respectively. Further analysis showed that the effective rate was 8% and 82% respectively for the electrical coagulation therapy and the balloon dilation combined with needle electrical knife and/or cryotherapy. Restenosis extension after operation occurred in 67% of the cases by electrical coagulation therapy, but only 12% of cases by the balloon dilation combined with needle electrical knife and/or cryotherapy. CONCLUSIONS: Our experience demonstrated that for the treatment of airway cicatricial stenosis, electrical coagulation might induce and worsen serious airway restenosis resulting in failure of treatment. On the other hand, balloon dilation combined with needle electrical knife and/or cryotherapy might be a relative safe and effective therapy for airway cicatricial stenosis.

[Interventional bronchoscopy with the use of mechanical ventilation by larynx mask or tracheal intubation under general anesthesia].

OBJECTIVE: To explore and evaluate the technique of performing interventional bronchoscopy by using mechanical ventilation with larynx mask or tracheal intubation under general anesthesia. METHODS: From July 2009 to January 2010, 29 patients received interventional bronchoscopy by using mechanical ventilation with larynx mask or tracheal intubation under general anesthesia. Airway pressure and tidal volume before and after bronchoscope insertion, arterial blood gas analysis during interventional bronchoscopy, complications and operation time were recorded. The factors influencing ventilation effects were evaluated. RESULTS: All the patients' condition were kept stable during interventional bronchoscopy and no severe complications occurred. Tidal volume was reduced by 27.1%, while peak airway pressure, plateau pressure and mean airway pressure were increased by 63.1%, 43.7% and 32.4% following insertion of the bronchoscope respectively. Patients using tracheal intubation had their peak pressure increased by 79.3%, which was higher than that of patients using larynx mask (55.3%). CONCLUSIONS: Interventional bronchoscopy by using mechanical ventilation with larynx mask or tracheal intubation under general anesthesia was safe and reliable. Although peak airway pressure increased following insertion of bronchoscope, the mean airway pressure was maintained in a low level. When performing interventional bronchoscopy during mechanical ventilation, the inside diameter of larynx mask and tracheal intubation should be as large as possible to minimize airway pressure and auto-PEEP.

[The effects of a domestically made jet ventilator in dogs during interventional procedures by rigid bronchoscopy under general anesthesia].

OBJECTIVE: To observe the effects of a domestically made jet ventilator in dogs during interventional procedures by rigid bronchoscopy under general anesthesia. METHODS: Ten healthy mongrel dogs were inserted with a rigid bronchoscope under general anesthesia, and the dogs underwent 3 different ventilation conditions randomly: spontaneous breathing alone (group A), and normal frequency jet ventilation with spontaneous breathing (group B), normal frequency jet ventilation without spontaneous breathing (group C). When the interventional procedure lasted 30 min, 60 min, 90 min, 120 min, blood gas analysis was performed. Arterial blood gas analysis under different driving pressures (0.20 mPa, 0.25 mPa, 0.30 mPa) was compared when dogs underwent normal frequency jet ventilation without spontaneous breathing. Oxygen concentrations at the proximal end and the distal end of the rigid bronchoscope were measured out-of-body, when high pressure oxygen (FiO(2) 100%) was used to drive the normal frequency jet ventilation. RESULTS: After the operation, PaCO(2) increased all the groups. In group C, PaCO(2) increased and pH decreased remarkably as compared with group A and group B (P < 0.01). In group C, PaO(2) decreased after the operation: compared with group A and group B, the difference being significant (P < 0.05). The ventilation effects of the jet ventilator was closely related with its driving pressure, and higher driving pressure improved the dog's oxygenation and the discharge of carbon dioxide. Under high pressure oxygen (FiO(2) 100%), oxygen concentration in the distal end of the rigid bronchoscope was lower than 50% whether (the driving pressures and I:E) was adjusted or not (P > 0.05). The oxygen concentration at the distal end of the rigid bronchoscope was increased a little (but below 50%) when jet needle tip inserted superficially or deeply into the adapter, but the oxygen was lower than 40% at most situation when it was in the midrange (3 - 6 centimeters in the adapter). CONCLUSIONS: This domestically made jet ventilator could not provide enough effective ventilation during interventional procedures with rigid bronchoscopy under general anesthesia because hypoxemia and hypercapnia occurred when the operation time was prolonged. The PaO(2) and PaCO(2) of the dogs were better when spontaneous breathing was maintained during the procedure. The ventilation effects of the jet ventilator was closely related with its driving pressure. The oxygen concentration at the distal end of the rigid bronchoscope was lower than 40% in most situation when it was in the midrange (3 - 6 centimeters in the adapter) under high pressure oxygen (FiO(2) 100%). There was no significant change in the oxygen concentration with adjustment of the driving pressure or the I:E ratio of the jet ventilator.

Effect of three interventional bronchoscopic methods on tracheal stenosis and the formation of granulation tissues in dogs.

BACKGROUND: Therapeutic approaches for tracheal stenosis caused by the formation of exuberant granulation tissues usually include electrocautery, mechanical dilation, laser therapy, argon plasma coagulation (APC), cryotherapy and stent placement. However, restenosis after stent insertion remains a significant limitation. We examined the efficacy of three different approaches, including induction of mechanical lesions, APC performed with different powers or durations and cryotherapy, to identify the method that limited the formation of granulation tissue. METHODS: Twelve specially bred research mongrel dogs were divided into three groups. In group 1 (four dogs) mild (procedure 1; two dogs) or moderate (procedure 2; two dogs) damage was induced mechanically. Group 2 (six dogs) received APC at different powers or durations (procedure 3: 30 W, 1 cm/s; procedure 4: 30 W, 2 cm/s; procedure 5: 25 W, 3 cm/s). Group 3 (two dogs) received cryotherapy (procedure 6: two freeze-thaw cycles of 30 seconds). Uncovered self-expandable metallic stents were inserted in all dogs to maintain a continuous stimulus to the trachea mucosa. Dogs were monitored for 4 weeks and the relationship between granulation tissue proliferation and method used was analyzed. RESULTS: In group 1, granulation tissue growth increased with more severe mechanical damage. The growth of granulation tissue in group 2 was more pronounced than in group 1, and both dogs in procedure 3 died because of severe stenosis. In this group, the formation of granulation tissue decreased with decreasing power and duration. In group 3, no obvious granulation tissue was found at week 4. CONCLUSIONS: Lesions and stimuli from a foreign body (the stent) are two important factors that lead to overgrowth of granulation tissue. Thermal lesions, such as APC, seem to induce greater granulation tissue growth and cartilage damage compared with mechanical and cryotherapy lesions. Cryotherapy in combination with mechanical dilation may be a safe and effective treatment method for managing tracheal stenosis caused by the formation of granulation tissue.

[The inhibition effect of paclitaxel on the proliferation of human pulmonary fibroblasts].

OBJECTIVE: To observe the influence of paclitaxel on the proliferation of human pulmonary fibroblast (HPF), and therefore to explore the possible effect on granulation tissue formation in-stent restenosis after airway stent. METHODS: The HPFS were divided into 3 groups: 24 h group, 48 h group and 72 h group, and there were 3 different dosage groups in each time group. MTT assay was used for detecting cell proliferation. RESULTS: The inhibition ratio of 4.5 microg/ml group, 13.5 microg/ml group and 45 microg/ml group were 43.7%, 58.8% and 68.1% after 24 hours; 75.5%, 77.7%, 91.9% after 48 hours; 95.1%, 97.1%, 97.0% after 72 hours. CONCLUSIONS: Paclitaxel inhibited the proliferation of HPF, and the inhibition ratio has partly relation with time and dosage.

[Evaluation of domestically made recalled nitinol alloy stent implantation for severe airway stenosis].

OBJECTIVE: it is more difficult and carries more risks to place airway stent under local anaesthesia for the patient with severe airway stenosis. The technique and method of domestically made recalled nitinol alloy stent implantation for severe airway stenosis was explored and evaluated. METHODS: by using bronchoscopy via larynx mask, trachea intubation, or rigid bronchoscope under general anaesthesia and mechanical ventilation, stents are placed in the airway of patients with severe airway stenosis for which had been difficult to performed under local anaesthesia. RESULTS: according to the various tracheobronchial lesions of patients, 42 stents were successfully placed in 40 patients, via larynx mask 23 cases, trachea intubation 11 cases, and rigid bronchoscope 6 cases under general anaesthesia and mechanical ventilation. No complications happened. The recalled nitinol alloy stents were placed in trachea 27 cases (membrane covered stent 9 cases), left primary bronchus 8 cases, right primary bronchus to medial segment 2 cases, trachea to left primary bronchus (wedge shaped stent) 5 cases respectively. The airway pressure decreased to normal level and other ventilator parameters also recovered after stents were placed. In most patients, the dyspnea index was improved immediately and the scores decreased from grades IV-V to grades 0-II, with higher scores indicating worse dyspnea. CONCLUSION: for patients with severe airway stenosis, it is safer, effective and more comfortable to place the stent via larynx mask, trachea intubation, or rigid bronchoscope under general anaesthesia and mechanical ventilation compared to local anaesthesia and is worth spread and popularization in the future.