The result of our study suggested that placement of the modified silicone stent under rigid bronchoscopy could be an effective and safe option for refractory BPF. This is the first study with the largest sample size which explores the efficacy and safety of the modified silicone stent for BPF treatment.
The BPF is still a severe and even fatal complication. The good prognosis of BPF depends on early diagnosis and proper management. Early recognition is a challenging for BPF due to its insidious presentation[13]. At present, the main diagnostic techniques are CT and bronchoscopy. The chest CT is a common and useful technique that can detect peripheral BPF, optimize planning of management and facilitate the follow-up[14]. Bronchoscopy is able to evaluate and locate the stump simultaneously. In addition, bronchoscopic treatment is also a valuable treatment strategy for BPF[15].
The management of BPF is categorized into two strategies: supportive and definitive treatments. The supportive strategy, such as drainage of thoracic cavity and ventilation, is the initial treatment to avoid aspiration pneumonia and treat presented empyema. The definitive strategy is to close the fistula, several techniques ranging from surgery to endoscopy can be carried out. Although some fistulas may resolve spontaneously or with appropriate supportive management, the definitive managements are required in vast majority of fistulas[16]. Surgery remains the cornerstone, which included open window thoracostomy, completion pneumonectomy, thoracoplasty, suture closure with a vascularized pedicle of omentum or muscle. Although high success rate of surgical management of BPF has been reported, the risk of recurrence is also high[1]. Besides, most patients with BPF are too debilitated to receive second surgery. Compared to surgical management, the endoscopic closure has the advantages of lower cost, less invasive, and wider scope of application. Therefore, bronchoscopic interventions might consider to be the alternative to surgery in some condition[17]. Ravindra et al[18] subdivided the bronchoscopic management into two categories: the sealant and occlusive devices. The reported sealants mainly included: collagen matrix plugs[19], collagen screw plugs[20], different bio-glues[21, 22], and synthetic hydrogel[23]. The utility of these materials was restricted to small BPFs (< 3 mm in size). The other strategy is occlusive devices, mainly included: stents and their modifications, Amplatzar™ devices[24, 25], endobronchial valves (EBVs)[26], and the endobronchial Watanabe spigot (EWS)[27]. However, many of these are expensive or not routinely available in developing countries. Therefore, the use of stent is relatively more prevalent and has been proven to be effective[8, 28–30]. It can occlude the segment(s) or lobar bronchus associated with BPF, which allows parenchymal rest and promotes distal healing.
Recently, the use of various type of stents for fistula closure have been reported anecdotally. Most of these studies were comprised of small series with limited evidence, while Han et al. (15) reported the use of a new customized covered metallic stent in a large population (n = 148). Despite the high success rate, it is notable that the special stent was customized from the manufacturer. The time-consuming process limited its use in emergency situation. Besides, their study reported one manufacturing defect (a 1 mm hole in the stent bullet) and eight stent damage. It suggested that the rupture of membrane and the damage of metal components are common and adverse drawback for covered metallic stent. The silicone stent shows merits of durability and easy removability. Moreover, the smooth inner surface may facilitate the clearance of airway secretions and the Y-shape structure and studs outside the stent have been designed to prevent the stent from migration. The biggest weakness of silicone stent is the poor adaptability. However, the shortcoming can be overcome by modifying the stent manually. We modified the stent on site to obtain the individual stent without waiting.
There remain some disadvantages for the modified silicone stent. First, a stent acts as a foreign body, which would irritate proliferation of granulations and induce infection. Hence, it is suggested to be removed when the fistula was cured. However, there is no consensus on the optimal time to remove the stent. Second, the displacement could be potentially life-threatening, although it happened rarely. Third, it must be deployed under rigid bronchoscopy, which require specialized equipment and well-trained team.
From the above, the successful management of BPF depend on multiple factors. It can be summarized as the appropriately selection of candidates, securely blocking the direct fistulous tract, sustainable eliminating of all inflammatory effusion and precisely administration of appropriate antibiotics. No treatment or device has been shown to be superior to the others. The optimal treatment is the individualized management.
limitations of our study listed as follow: it was a retrospective study with small sample size, making it difficult to perform survival analysis. We cannot compare the different therapeutic options in bronchial fistula treatment, since the BPF is a rare disease that always reported as solitary cases and the condition of candidates varies in different therapeutic options.