Ninety covered tracheal stents were inserted in TF group and 76 tracheal stents were implanted in TS group. 81.2% of patients with tracheal fistulas were caused by malignancy disease in TF group, 82.1% of patients with tracheal stenosis were caused by benign primary disease in TS group. The success rate of stent removal was 98.9% (89/90) in TF group. Only one patient underwent bronchoscopic removal for the retained stent pieces after failure in fluoroscopic removal. In TS group, 74 of 76 tracheal stents were successfully removed, only 2 stents retained, with a technical success rate of 97.4% (74/76). The mean procedure time of stent implantation or removal was similar between two groups. Tumor invasion or tumor operation was the main causes for tracheal fistula, and tracheotomy or trachea cannula was the main causes for tracheal stenosis (p < 0.0001, Table 1).
Indications for stent removal and interval
Following to doctors’ advices, 47 stents (52.2%) and 40 stents (52.6%) were routinely removed for tracheal fistula and tracheal stenosis, respectively. Stent migration and stent intolerance were the main indications for early stent removal in both groups. Excessive granulation tissue increased as time interval increased, with a mean interval of 142.1±25.9 days for tracheal fistula and 89.9±15.0 day for tracheal stenosis, which was the most common indications for later stent removal. Interestingly, tracheal stents were routinely removed after 107.8±9.8 days and 85.4±6.7 days in TF group and TS group, respectively (Table 2). These two time points are consistent, suggesting that the stent should be removed about 3 months after implantation to reduce the incidence of restenosis. Six bare stents were emergency implanted in TS group for sever tracheal stenosis, of which, 3 stents were removed and replaced by covered stents, with a mean duration of 8.7±3.2 days, and 1 stent was replaced by tracheal T tube.
The technical success rate of stent removal was 98.9% and 97.4% for tracheal fistula and tracheal stenosis, respectively. In TF group, 75 stents were removed in one piece; stent fracture and retained stent pieces was found in 14 and 1 stent. In TS group, 74 tracheal stents were successfully removed from, 5 stents showed strut fracture. Of which, 2 stents retained, and the 3 retained stent pieces were successfully removed by endoscopy; the remained 71 stents were removed in one piece (Table 3).
Recurrence of fistula or stenosis requiring stenting was the most comment complications in both groups. Two patients showed severe dyspne in each group and were endotracheal intubation and mechanical ventilation. Symptoms were relieved and the endotracheal tube was removed within 4 hours. Massive hemoptysis occurred in 2 cases during stent removal in TF group. One patient died of asphyxia caused by blood clogging, and bleeding ceased in the other patient after administration of pituitrin. Two patients died perioperatively in TS group, resulting in a clinical success rate of 94.7% (72/76). One patient with tracheal stenosis after resection of esophageal carcinoma died of massive hemoptysis 3 days after stent removal. The other patient died of respiratory failure 2 days after the second stent insertion.
Second stenting after removal
Eight stents were replaced immediately and 5 stents were replaced 5 to 9 days after removal in TF group. Replacements included Y-type tracheal stents (n=5), L-type tracheal stents (n=3), Y-shaped single-plugged stents (n=2), straight tracheal stents (n=2) and 1 combination of a large and a small Y-type tracheal stent. One patient required stenting due to proximal re-obstruction of the stent after removal of a straight tracheal stent, and the same size of straight tracheal stent was implanted immediately. In TS group, 20 tracheal stents (15 straight tracheal stents and 5 Y type tracheal stents) were implanted again after removal for replacement of bare stents (n=3), or due to restenosis (n=9), migration (n=3), inadequate expansion (n=3), and intolerance (n=2).
All patients were followed up except for perioperative deaths. Five patients (6.0%) lost in TF group and 4 lost (6.2%) in TS group during follow up. Thirty-three patients were cured and 20 patients were improved in TF group. In TS group, 29 patients were cured and 20 patients were improved; six patients underwent tracheotomy and tracheal T tube implantation after stent removal. Twenty-four patients died in TF group, tumor progression was the most common cause of death. Besides, one died of respiratory failure due to asphyxia, and 2 patients died of massive hemoptysis and hematemesis (Table 4). The 0.5-, 3-, 6-year survival rates were 90.3%, 59.6%, and 36.1% for TF group, and 80.4%, 75.7%, 75.7% for TS group (Figure 3).