Traumatic Complete Occlusion of the Left Main Bronchus Managed by Temporary Placement of a Covered Self-Expandable Metallic Stent: A Case Report

Introduction

Blunt tracheobronchial injuries occur in only 0.8% to 5% of patients with blunt chest trauma [1]. Symptoms are often initially subtle despite the traumatic event [2]. If a patient’s symptoms fail to improve after placement of a closed thoracic drainage device – or if there is persistent air leakage, pneumothorax, mediastinal emphysema, or subcutaneous emphysema – blunt tracheobronchial injury should be suspected [2,3]. In such cases, radiographic examination is recommended. Fibrobronchoscopy is the gold standard for the diagnosis of blunt tracheobronchial injury [3] because it allows comprehensive assessment of the extent of injury and the integrity of the remaining bronchus [2]. Computed tomography (CT) or other radiographic imaging may reveal clinically significant disruption of the bronchial tree or signs of atelectasis. Treatment options for bronchial injuries vary according to the classification framework of Cardillo et al [4,5], in conjunction with radiographic and fibrobronchoscopic findings, patient respiratory status, presence of respiratory failure, need for tracheal intubation, and improvement in respiratory function after intubation. Management may include conservative treatment in mild cases, surgery in severe cases, and stent placement in selected severe cases. Bronchial stenosis or even complete obstruction is mainly attributable to granulation tissue proliferation, either in the late stage of bronchial injury or after airway reconstruction surgery [6].

Stents used in clinical practice mainly include silicone stents and metallic stents. A covered self-expandable metallic stent (CSEMS) is a tubular prosthesis composed of a metallic alloy framework and an impermeable covering membrane. The prosthesis features a self-expanding design that facilitates placement, while its covered structure helps maintain airway integrity. CSEMSs were initially studied in the context of malignant central airway obstruction. Some authors [7,8] have suggested that CSEMSs can be effective in selected patients with benign airway stenosis, including cases of recurrent stenosis after 1-stage anastomosis for airway resection, recurrent narrowing requiring repeated dilation or granulation tissue and/or laser resection, complex airway stenosis, and airway malacia. However, it should primarily be considered a temporary therapy due to the high rate of long-term complications during follow-up (eg, infection, stent migration, stent fracture, airway perforation, and fistula formation). Bronchoscopic interventions offer distinct advantages relative to open surgical approaches, including reduced procedural trauma due to transluminal access through a natural orifice, lower perioperative complication rates, and superior preservation of baseline pulmonary function. These characteristics make this modality particularly advantageous in high-risk surgical candidates with compromised physiological reserve. Nevertheless, reported cases regarding the application of stents in traumatic bronchial obstruction remain scarce [9].

Clinicians at our institution recently treated a patient with bronchial rupture and lobar atelectasis using bronchoscopic placement of a CSEMS. This report describes a case of traumatic complete occlusion of the left main bronchus and left lobar atelectasis, which was managed by temporary placement of a CSEMS under fiberoptic bronchoscopic guidance.

Case Report

A 37-year-old man presented to an external institution with chest discomfort and dyspnea after compression injury caused by a heavy object. The patient had no clinically significant family history of respiratory, cardiovascular, or genetic disorders. Initial CT assessment revealed bilateral pneumothorax and multiple rib fractures. Conservative management, comprising tube thoracostomy and thoracic binder application, led to radiographic resolution of the pneumothorax; however, subsequent CT demonstrated newly developed atelectasis of the left lung. Two weeks post-injury, the patient was transferred to our hospital for further management due to persistent dyspnea. Physical examination revealed preserved thoracic symmetry without intercostal retractions. Reduced breath sounds were auscultated over the left hemithorax; no adventitious sounds were noted. Digital radiography (DR) and thoracic CT demonstrated substantial left-sided pleural effusion and complete left lung atelectasis (Figure 1A, 1B). Bronchoscopic examination (Video 1) revealed complete occlusion of the left main bronchial lumen by a substantial amount of necrotic tissue, viscous secretions, and hyperplastic granulation tissue (Figure 1C). These findings supported a definitive diagnosis of post-traumatic complete occlusion of the left main bronchus. Faced with this challenge, a multidisciplinary team devised a staged interventional strategy. Guidewire traversal of the obstructed segment, as well as sequential balloon dilation combined with targeted cryoablation of hyperplastic granulation tissue, resulted in partial luminal restoration of the occluded left main bronchus (Video 1). Post-interventional bronchoscopy (Video 1), using a 4-mm outer-diameter scope, confirmed successful navigation through the stenotic zone, with patency of the bronchial orifices in left upper and left lower lobes (Figure 1D, 1E). DR on post-interventional day 1 demonstrated persistent lobar atelectasis; bronchoscopic reassessment (Video 2) showed rapid re-occlusion of the left main bronchus due to regrowth of granulation tissue (Figure 1F). The team re-evaluated the situation and concluded that the previous achievement of transient recanalization indicated preserved functional potential of the distal airways and lung parenchyma. Furthermore, the absence of mature fibrotic stenosis at the obstruction site was confirmed, suggesting that lung re-expansion might be feasible with sustained mechanical support to suppress granulation tissue hyperplasia. Consequently, the team prioritized a trial of temporary covered stent placement, aiming to create a period of stability for airway healing and lung re-expansion. Surgical bronchial reconstruction was reserved as a fallback option.

Two weeks after admission to our hospital, the patient underwent endobronchial stent placement under general anesthesia with fibrobronchoscopic guidance. During the procedure (Video 3), the left main bronchus was obstructed by a considerable amount of mucus, secretions, and granulation tissue. Balloon dilation was subsequently performed, followed by placement of a 12×30-mm CSEMS (M00564770; Boston Scientific Corporation, Marlborough, MA, USA) to maintain luminal patency (Figure 2A). After stent deployment, secretions were observed protruding from upper and lower lobes of the left lung (Video 4). These secretions were cleared to expose the bronchial openings of the 2 lobes (Figure 2A). On the day after the operation, radiologic examinations, including DR and CT, revealed considerable pleural effusion accompanied by atelectasis; however, this represented improvement compared with the preprocedural condition. Additionally, minor left-sided pneumothorax was identified (Figure 2B, 2C). This pneumothorax was considered potentially related to lung re-expansion or airway manipulation, and it was managed conservatively with close monitoring. On the following day, fibrobronchoscopy demonstrated that the stent was correctly positioned, and bacterial culture of bronchoalveolar lavage fluid showed unremarkable findings. The patient’s condition improved, without evidence of infection or other complications, and he was discharged 2 days later.

Following stent implantation, the patient entered a planned period of lung re-expansion and observation. At 2.5 months after initial admission to our hospital, DR revealed complete resolution of pleural effusion and pneumothorax, accompanied by disappearance of pulmonary atelectasis (Figure 3A). Given that the goal of lung re-expansion had been achieved, and to avoid potential long-term complications associated with indwelling stents, the patient was readmitted 3.5 months after initial admission for stent removal. Physical examination revealed normal breath sounds in the left lung. The stent was removed the following day under bronchoscopic guidance and general anesthesia (Video 5). Intraoperative evaluation confirmed proper stent positioning, and the device was removed without complications (Figure 3B, 3C). CT imaging performed on the first postoperative day demonstrated satisfactory pulmonary expansion without clinically significant bronchial collapse (Figure 3D). Direct comparison between the initial chest CT, which showed complete left lung atelectasis, and the follow-up CT after stent removal, which confirmed full lung re-expansion, objectively demonstrated successful reversal of the pulmonary collapse. Laboratory tests revealed no abnormalities, and the patient experienced no complications. He was discharged 3 days after readmission.

Recent follow-up outcomes have been satisfactory. Follow-up DR at 7 and 9 months after initial admission showed unremarkable findings (Figure 4A, 4B). Final fiberoptic bronchoscopy (Video 6), performed 9 months after initial admission, revealed mild narrowing of the distal left main bronchus with smooth mucosal surfaces and the absence of hemorrhage or neovascularization (Figure 4C). Other bronchial lumens remained patent with regular mucosal contours, and no strictures or neoplastic lesions were detected (Figure 4D). These findings indicate that the airway injury has entered a stable phase of healing.

Discussion

In the present case, the patient underwent 2 hospitalizations and 3 outpatient follow-ups during the 9-month treatment cycle from stent implantation to post-removal evaluation (Figure 5). It is encouraging that the patient’s clinical recovery was accompanied by self-reported improvement in quality of life, without residual symptoms during the 9-month follow-up period. This case provides insights into the management of complex post-traumatic bronchial stenosis, including criteria for selecting temporary stent implantation, the rationale for choosing a CSEMS, factors contributing to a successful outcome, and ongoing challenges that merit consideration.

Stent implantation strategies are fundamentally guided by the obstruction etiology and therapeutic goal, as illustrated by comparison with similar cases. A comparable case was reported by Li et al [10], in which lung atelectasis had been caused by progressive tumor compression. A self-expandable metallic stent was deployed as a permanent palliative implant to provide durable symptomatic relief for an irreversible condition, and the patient has been followed for more than 2 years. Roh et al [9] reported a similar case of post-traumatic bronchial obstruction; however, post-traumatic fibrotic stenosis had developed, representing a more fixed structural airway state. Consequently, long-term placement of a silicone stent was required to provide durable support. In the present case, atelectasis resulted from post-traumatic granulation tissue. The lesion was presumed to be more reversible than mature fibrosis, prompting the use of a temporary stent strategy. The stent was maintained for only 3 months to support the airway during a critical healing phase, followed by successful removal. These comparisons highlight the core criterion for temporary stent implantation: a benign lesion causing lung atelectasis with credible potential for resolution. This potential must be sufficient to permit future stent removal while avoiding long-term risks associated with permanent implantation.

A stent exerts mechanical force that inhibits scar tissue formation and provides support in areas of structural weakness due to cartilage loss, thereby facilitating healing at the site of injury. Ideally, a stent should allow epithelial healing while preventing bacterial contamination. These goals can be achieved by preserving mucociliary clearance and avoiding excessive pressure that could impair capillary circulation. Metallic stents are associated with a high prevalence of granulation tissue obstruction and are generally unsuitable for removal after long-term placement [4]. Silicone stents are also associated with complications, including interference with normal mucociliary clearance, retention of secretions, and infection [4]. Furthermore, these stents are unable to conform to the complex configuration of the bronchi. Stent migration, misalignment, and granulation tissue proliferation have been identified as potential complications. Therapeutic use of CSEMSs has been highlighted due to their relative advantages and lower risk of complications [4].

Based on retrospective analysis of the procedure in this case, the successful therapeutic outcome may be attributed to the following factors:

However, several challenges and limitations warrant consideration:

Conclusions

Our patient presented with traumatic complete occlusion of the left main bronchus and lobar atelectasis after blunt chest trauma. Initial recanalization with balloon dilation and cryoablation achieved only transient patency due to rapid granulation tissue regrowth. Based on multidisciplinary team recommendations, minimally invasive bronchoscopic intervention – temporary placement of a CSEMS – was performed. Symptoms and radiographic findings substantially improved after stent placement. Successful stent removal was achieved after 3 months, confirming airway patency and sustained lung re-expansion. Six months after removal, follow-up bronchoscopy indicated stable airway healing with mild stenosis. Based on this case, temporary CSEMS placement appears to be a viable and effective therapeutic strategy for managing traumatic bronchial occlusion with granulation tissue and may serve as an alternative to major surgery in selected patients.