The study subjects were 29 patients underwent the rigid bronchoscopy from November 2007 to February 2011 in St. Paul's Hospital, The Catholic University of Korea. With 7~47 month follow-up period, retrospective review was performed on clinical symptoms and treatment methods. St. Paul's Hospital has started the rigid bronchoscopy since November 2007, and this study passed deliberation of the Clinical Ethics Committee of St. Paul's Hospital (PIRB-00094_3-006).

Clinical manifestation, simple chest X-ray, chest-computed tomography (CT), and a flexible bronchoscope were used for examination of airway lesions. All of the patients received rigid bronchoscopy under general anesthesia induced with injection of propofol. The intervention was performed by a single doctor. After inserting a rigid bronchoscope (Hopkins; Karl Storz, Tuttlingen, Germany), the lesion was examined by a flexible bronchoscope (EVIS BF 1T240 & 1T260; Olympus, Tokyo, Japan). Depending on the type of lesions, electrocautery (electrosurgical unit [PSD-20], coagulation electrode [CD-6C-1], electrosurgical snare [SD-7C-1], electrosurgical knife [KD-31C-1]; Olympus), balloon catheter (8~15 mm controlled radial expansion balloon; Boston Scientific, Natick, MA, USA), and other surgical devices were used to remove or dilate the lesions. Silicone stents were inserted in case needed. After the intervention, the site was examined using a flexible bronchoscope.

By examining clinical manifestation of a patient, simple chest X-ray, pulmonary function test, and a flexible bronchoscope, treatment effects and progression were verified. After the intervention, follow-up of each patient by flexible bronchoscopy was scheduled individually. Through flexible bronchoscopy, changes on interventional site, migration of stents, formation of granulation tissue, recurrent stenosis were examined. In addition, patients were treated through rigid or flexible bronchoscopy in case needed. In some cases, additional approaches were used in treatment such as a surgery.

Pulmonary function test of subjects before and after the insertion of silicone stents were compared by applying paired t-test. For statistical analysis, SPSS version 17.0 (SPSS Inc., Chicago, IL, USA) program was used and statistically significant difference was thought to be present when the p-value is less than 0.05.

The study subjects were 29 composed of 18 males and 11 females. The median age was 59 (age range, 20~78 years). The most common causal diseases for performing rigid bronchoscopy were tracheal stenosis after endotracheal intubation, obstructive fibrinous tracheal pseudomembrane, and benign tracheal stenosis secondary to burn inhalation injury (n=20). Other causal diseases were airway obstruction by malignant tumor (n=6), tracheal stenosis due to tuberculosis and foreign body within the trachea (Table 1).

Among 18 cases of tracheal stenosis caused by endotracheal intubation and inhalation burn, silicone stents were inserted in 16 cases and T-tube insertion was performed in a case for treatment (Figures 1, 2). In a case, insertion of a rigid bronchoscope was impossible since hyperextension of the neck was not secured in anatomical position. Among 16 cases of tracheal stenosis caused by endotracheal intubation, 8 cases underwent tracheostomy including T-tube before stent insertion. In a case, tracheal end-to-end anastomosis was performed but tracheal stenosis reoccurred. In the rest of 7 other cases, silicone stent insertion was implemented as an initial treatment. In two cases of obstructive fibrinous tracheal pseudomembrane, tracheal stenosis was alleviated by completely removing pseudomembrane using a rigid bronchoscope and a forcep. In 6 cases of malignant tumor, tumors were removed by performing snare and mechanical polypectomy using electrocautry through a rigid bronchoscope. In two cases, additional silicone stents were inserted on tracheal stenosis lesions after the removal of tumors. Moreover, in the other two cases of tracheal stenosis due to tuberculosis, balloon dilation and electrocautry was performed. Removal was conducted in a case of foreign body within the trachea (Figure 3).

The average follow-up period was 27 months in the case of tracheal stenosis resulted from endotracheal intubation (range, 11~41 months); 23 months in inhalation burn cases (range, 22~24 months); 34 months in obstructive fibrinous tracheal pseudomembrane cases (range, 21~47 months); 15 months in the case of tracheal stenosis caused by malignant tumors (range, 7~30 months); 34 months in tracheal stenosis due to tuberculosis (range, 22~46 months); and 28 months in the case of foreign body within the trachea.

Sixteen cases of tracheal stenosis caused by endotracheal intubation and inhalation burn were treated by stent insertion. In 13 out of 16 cases, inserted silicone stents were maintained. In two cases of recurrent stenosis caused by repeated formation of granuloma and deteriorating breathing patterns, T-tube was inserted after eliminating stents. In one of the above cases, a patient was completely recovered from tracheal stenosis by conducting tracheal end-to-end anastomosis after eliminating stents when general physical condition was alleviated.

To confirm the clinical effectiveness among patients who underwent silicone stents insertion, pulmonary function of 12 subjects were significantly improved when the pulmonary function test was performed on them before and after the intervention (Table 2). Pulmonary function test was performed less than one month and between 1~3 months after intervention for 4 patients each. In between 3~6 months and over a year period were 1 and 3 patients, respectively.

In all of the cases of tracheal stenosis resulted from malignant tumors, airway obstruction was immediately improved after the intervention through a rigid bronchoscope. Therefore, additional anti-cancer treatments were able to be performed after the elimination of tumors. In one of two cases where silicone stents were inserted after tumor resection, the lesion was alleviated after the additional radiotherapy was implemented. For that reason, stents were removed. In one of cases, radiotherapy was performed on squamous cell carcinoma of pulmonary parenchyma, the primary lesion, with maintaining stents. During follow-up period, two subjects died. In a case where a mass of lung cancer, which induced obstructive pneumonia, within the trachea was removed. The subject underwent anti-cancer treatments after pneumonia was relieved. However, the patient died due to the progress of lung carcinoma 23 months after the intervention. In the other case, tumors within the trachea and main bronchus were improved after the intervention. Although the radiotherapy was able to be carried on, the subject died due to advancement of the cancer 11 months after the intervention.

In two cases of tracheal stenosis induced by tuberculosis within the trachea, the lesion was relieved with just balloon dilation and electrocautery only. Clinical manifestations such as difficulty in breathing were immediately improved. In the case of foreign body within trachea, repeatedly occurring pneumonia was alleviated after the foreign body was removed.

Regarding complications, 9 cases were the formation of granulation tissue related to stents; 3 cases were migration of stents; and 2 cases were infections at the stitched area for fixing stents. There was each case in mucous retention, tracheal burn injury, and severe bleeding, respectively (Table 3). In 3 cases of the stent migration, the position was adjusted. In the case of infected stitches, only one case was relieved simply with antibiotics only. In another case, the subject was treated with antibiotics and reinsertion of stents after removal of existing stents. In case of the mucous retention, diagnosis and mucus removal was performed through a flexible bronchoscope. In case of the severe bleeding occurred during tumor resection, the subject showed hypoxia temporarily. However, the patient stabilized by hemostasis after the removal of tumor mass.