Bronchoscopic management of persistent air leaks

Elliot Ho, Joslyn Vo, Ajay Wagh, Douglas Kyle Hogarth

Contributions: (I) Conception and design: All authors; (II) Administrative support: All authors; (III) Provision of study materials or patients: None; (IV) Collection and assembly of data: None; (V) Data analysis and interpretation: None; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

【Abstract】 Air leaks can occur as a complication of thoracic surgery, bronchoscopic procedures, or from barotrauma due to mechanical ventilation. Persistent air leaks defined as air leaks that last longer than 5–7 days are often associated with prolonged hospital stay, higher rates of intensive care unit admission, and a significant source of morbidity and mortality. Surgical repair of persistent air leaks via thoracotomy or videoassisted thorascopic surgery generally has excellent success. However, for patients with severe hypoxemia, poor functional status, or significant comorbidities, surgical repair may not be feasible. The use of bronchoscopic interventions such as the delivery of coils, covered airway stents, endobronchial valves, biological sealants, and other devices to safely and effectively manage persistent air leaks has been widely reported in recent years. Bronchoscopic intervention of persistent air leak has a reported success rate of closure ranging from 30–80% depending on the underlying disease, location, and size of the pleural fistula. It is an excellent option for patients with persistent air leak who are critically ill and are poor surgical candidates. Advantages of using endobronchial devices include quick recovery time, relatively low risk, reduction in hospital stay, and the potential for immediate symptom relief. Here, we review the data regarding the use of bronchoscopic techniques in the management of persistent air leak.

【Key words】 bronchoscopy; persistent air leak; endobronchial valve; pneumothorax

Introduction

Air leaks can occur as a complication of thoracic surgery, bronchoscopic procedures, or from barotrauma due to mechanical ventilation in the setting of infection, malignancy, or chemoradiation (1). Persistent air leaks (PALs) are defined as air leaks that last longer than 5–7 days (2). Although they are not fatal, PAL are often associated with prolonged hospital stay, higher rates of intensive care unit admission, and a significant source of morbidity and mortality (16–72%) (3-6). A main complication of PAL includes loss of pleural space sterility due to direct communication with the airway resulting in empyema. While alveolar-pleural fistulas (APFs) may spontaneously close with supportive care alone, bronchopleural fistulas (BPFs) typically do not and almost always require either surgical or bronchoscopic intervention.

Surgical repair of PALs via thoracotomy or videoassisted thorascopic surgery (VATS) generally has excellent success (80–95%). However, for patients with severe hypoxemia, poor functional status, or significant comorbidities, surgical repair may not be feasible (4,5). In these surgically inoperable patients or those who fail surgical closure, bronchoscopic intervention may provide definitive therapy.

Although established guidelines for bronchoscopic management of patients with PAL do not exist, minimally invasive techniques utilizing bronchoscopic delivery of coils, covered airway stents, endobronchial valves, biological sealants, and other devices have been reported. The mode of bronchoscopic intervention for PAL closure is driven by the size and location of the fistula. Bronchoscopic intervention of persistent air leak has a reported success rate of closure ranging from 30–80% depending on the underlying disease, location, and size of the pleural fistula (7).

Isolation of the air leak

The first step in managing PALs involves evaluating the size and location of the fistula. For BPF, direct visualization via bronchoscopy can help determine the size and location of the fistula, as well as determine which devices can be used to address the fistula bronchoscopically. In the evaluation of APFs, identifying the segment that contains the PAL can be performed bronchoscopically by using sequential balloon occlusion of the segmental airways, evaluating systematically from the proximal to distal airways.

With this method, a simple balloon catheter is inflated

at different levels of the bronchial tree. The mainstem bronchus is first occluded with the balloon catheter to evaluate whether it is possible to stop the air leak. If occlusion of the mainstem bronchus demonstrates a cessation or reduction of the air leak, then each of the lobar bronchi distal to the mainstem bronchus is tested with balloon occlusion to evaluate whether the air leak can be stopped at that level. Once the target lobe is identified, each of the subsequent individual airway segments is tested. This systematic approach allows detection of complex air leaks involving more than one segment and/or more than one lobe (8).

During this process, the pleural drainage device should be arranged in such a way so that it can be easily visualized to assess the air leak during the occlusion of suspected airways. During each occlusion, it is recommended to wait for several respiratory cycles to determine the effect of airway occlusion on the air leak. A reduction or cessation of the air leak during balloon occlusion indicates that the target airway is involved with the air leak (8).

Bronchoscopic management of alveolar pleural fistula

For patients with persistent air leak due to APF, noninvasive approaches such as prolonged chest tube drainage, chemical pleurodesis, or one-way valves attached to chest tubes are attempted. However, prolonged chest tube drainage is associated with increased hospital stay, prolonged discomfort, and risk for potential infection of the pleural space. Chemical pleurodesis is not feasible for patients with trapped lungs or those with significant air leaks that are so brisk such that the visceral and parietal pleural surfaces cannot oppose. One-way valves attached to chest tubes can cause discomfort, can be associated with an increased risk of infection, and may eventually lead to malpositioning or malfunctioning, which can lead to worsening pneumothorax or leakage of pleural fluid. In these patients with PAL due to APF, bronchoscopic procedures involving endobronchial valve placement can be used for definitive treatment (3).

Endobronchial valves

Endobronchial valves were originally developed for bronchoscopic lung volume reduction in patients with emphysema by way of isolating airway segments and inducing atelectasis in the emphysematous lobes of the lung (9). Using this concept of limiting airflow to target lobes and inducing atelectasis, endobronchial valves placed in the airway segments allow for healing of the APF via the resolution of the air leak (10). In a prospective, multicenter study evaluating the bronchoscopic placement of the Spiration?Valve System (SVS) for patients with PAL (n=39), the authors report an 87.5% success rate for air leak resolution when SVS placement was feasible, after a median of 2.5 days (10). Since 2008, the Spiration?Valve System is the first and only FDA approved endobronchial valve for management of post-surgical prolonged air leaks. Clinical series by Gillespieet al.and Travalineet al.demonstrated the safety and efficacy of using endobronchial valves for managing PALs (8,11,12).

Of note, a multicenter study involving patients with severe and refractory air leaks demonstrated the success of using the Zephyr Valve System for managing PALs. The authors showed complete resolution of air leaks in 88% of patients (n=59) who had endobronchial valve placement for PALs. Comparing the data before and after valve placement showed a significantly reduced air leak duration (16.2vs.5.0 days; P＜0.0001), time to chest tube removal (16.2vs.7.3 days; P＜0.0001), and reduced length of hospital stay (16.2vs.9.7 days; P=0.004) (13).

Technical aspects of endobronchial valve placement

Once the air leak is isolated, the next step is to determine the correct size of the EBV to be placed. The Spiration?valve is an umbrella-shaped device of various sizes (5, 6, 7, and 9 mm diameter). A sizing kit that calibrates a balloon catheter is used to measure the airway diameter and determine the valve size for deployment. This is done by advancing the sizing balloon to the airway opening and slowly inflating until the balloon makes circumferential contact with all portions of the airway wall. Once that is achieved, the balloon is advanced and withdrawn gently to ensure no migration occurs distally or proximally within the airway. The degree of balloon inflation corresponds to the valve size used for the target airway (8).

Valve deployment is a multistep process using the EBV deployment catheter. Once the single-use valve is loaded into the catheter, the catheter handle is gently pressed to eliminate the space between the removal rod and stabilization wire. The EBV deployment catheter is then advanced through the bronchoscope until the tip of the catheter is visualized bronchoscopically. The bronchoscope is then directed to the target airway. Once the target airway is visualized, the catheter is advanced distally to the target location, and then pulled proximally to align the valve line with the desired valve placement location. With the bronchoscope in the neutral position, the retractor handle is gently triggered with constant pressure until the EBV is fully deployed into place. Valve deployment is performed in one continuous motion within 1 to 2 seconds. The deployed valve is observed after placement to ensure proper positioning. After valve placement, the air leak chamber of the chest tube collecting system is observed for 4 to 5 ventilatory cycles to evaluate for any changes in the degree of air leak (8).

The patient should be re-evaluated in approximately 6 weeks after valve placement to determine whether EBV removal is feasible. An endotracheal tube should be used during EBV removal in order to protect the vocal cords and other upper airway structures from trauma. EBV can be removed by using cupped or rat-toothed forceps to grasp the removal rod shaft and gently pull proximally until the EBV is dislodged from the airway wall. The bronchoscope, forceps, and EBV are removed en-bloc through the endotracheal tube (8).

Bronchoscopic management of bronchopleural fistula

Although surgical repair of PAL due to BPF has a high rate of success, surgical repair may not be feasible in patients with severe hypoxemia, poor functional status, or significant comorbidities (4,5). For patients with a PAL due to a BPF who are surgically inoperable or fail surgical closure, bronchoscopic intervention may provide definitive therapy.

Coils, covered airway stents, biologic sealants

In those patients with a BPF less than 8 mm in diameter and peripheral, bronchoscopic procedures involving the delivery of coils, biological sealants, or airway stents may be used for definitive treatment (3).

A case series involving the bronchoscopic delivery of expandable polyvinyl alcohol sponge and cyanoacrylate glue showed immediate closure of bronchopleural fistula (4 to 8 mm) in 7 out of 7 patients. No severe complications occurred after the intervention. However, a recurrence of fistula was reported in 2 out of 7 patients due to migration of polyvinyl alcohol sponge, with 1 patient dying two months later due to a complication of recurrent BPF (14). Another case series in India evaluated 25 patients with BPF who were treated bronchoscopically using glues and coils. Twenty-three patients (21 patients underwent Bioglue/cyanoacrylate instillation, 2 patients received coils) demonstrated successful cessation of air leak after bronchoscopic procedure. However, all patients who underwent Bioglue/cyanoacrylate instillation remained symptoms free for only 30–40 days, and re-instillation of biologic sealants had to be repeated. Of the two patients who were treated bronchoscopically with coils, both developed air leaks after one year and required repeat bronchoscopy with instillation of biologic sealants (15). A review of 45 cases of post-surgical BPF (1 to 8 mm) reported their experience of bronchoscopic application of fibrin glue for the management of BPF in 29 patients. The authors reported successful fistula closure in 16 patients who received bronchoscopic application of fibrin glue, with recurrence of BPF seen in two patients (16).

The use of silicone stent placement via rigid bronchoscopy has been reported to successfully manage large post-pneumonectomy BPFs (17,18). Similarly, bronchoscopic deployment of fully covered, selfexpandable metallic stents to manage BPFs has also been reported with high success (19). In a case series of seven patients with large post-pneumonectomy BPFs, fully covered, self-expandable metallic stents deployed via rigid bronchoscopy were used to manage BPFs (6 to 12 mm) with reported immediate success rate of 100%. Stent-related complications involved stent migrations in two cases and stent rupture in one case (20).

Despite their uses for small and peripheral BPFs, biologic glue, sealants, coils, and covered airway stents are not good endoscopic options for large central pleural fistulas that are greater than or equal to 8 mm in diameter. Without a good framework to contain it, glue may spill over into the pleural space or into the contralateral bronchi with large BPFs. Similarly, coils do not anchor well in large central lesions and closure devices such as airway stents and plugs are not large enough to cover a large mainstem bronchi entirely (21). For these reasons, large fistulas typically have poor closure rates with these devices and have a difficult time maintaining occluding materials in place.

Bronchoscopic placement of Amplatzer devices

In those patients with a BPF greater than or equal to 8 mm in diameter and central, bronchoscopic deployment of Amplatzer devices for managing BPFs has been reported. Amplatzer atrial septal occluder devices are originally designed for transcatheter closure of atrial septal defects. It is a self-expandable double-disk device, made of braided nickel-titanium alloy with interwoven polyester fabric mesh. Once deployed, the waist of the device resides inside the defect, while the disks anchor the device on either side of the defect. Bronchoscopic deployment of the Amplatzer septal occluder has been reported to successfully manage large and central BPFs (21,22). Fistula diameter can be estimated by insufflating a ballooned catheter or an endobronchial blocker inside the fistula under bronchoscopic visualization (23).

Similarly, Amplatzer vascular plugs, which are selfexpandable cylindrical occluding device made of nitinol mesh wires which are normally used for transcatheter embolization, can be used for closure of small sinusshaped BPFs. AVP implantation may be suitable for BPFs that originate from the main bronchi and lobar bronchi that are too small for closure by the Amplatzer atrial septal occluder (24).

A review of the literature which included 59 patients who underwent Amplatzer atrial septal occluder for BPF closure demonstrated 91.5% success, with success defined as the absence of symptoms, air leak, or imaging findings of recurrent BPF. Complications due to device deployment was reported as 5.1%, which included empyema, device migration, and broken wire (25). In the same review, which included 17 patients who underwent Amplatzer vascular plugs for closure of smaller BPFs, 94.1% success was demonstrated with the same definitions. There was one reported complication with AVP deployment due to device rotation. Of all the cases reviewed, no mortality was observed during the immediate postoperative period (25).

Conclusions

Bronchoscopic deployment of devices can be used safely and effectively to manage persistent air leaks in the hands of experienced operators. It is an excellent option for those who are critically ill and are poor surgical candidates. Advantages of using endobronchial devices include quick recovery time, relatively low risk, reduction in hospital stay, and the potential for immediate symptom relief. Future work and research is necessary to provide insight into different aspects of PAL management with these devices. It can be directed at evaluating patient selection, peri-procedural care, durability of treatment benefit, long-term management, and determining device utilization. This is important since bronchoscopic management may one day become a first-line option for patients with persistent air leaks.

Acknowledgments

Funding:None.

Footnote

Conflicts of Interest:The authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.3877/cma.j.issn.2095-8773.2021.02.03). Dr. AW has a consulting agreement with Noah Medical, but has not consulted or received any payment as of this date. Dr. DKH reports personal fees from Olympus/Spiration, personal fees from PulmonX, during the conduct of the study; personal fees and other from Auris, personal fees from Ambu, personal fees, non-financial support and other from Body Vision, personal fees and other from Eolo, other from Eon, other from Gravitas, personal fees and other from Noah Medical, personal fees and other from LX-Medical, other from Med-Opsys, other from Monogram Orthopedics, personal fees and other from Preora, other from VIDA, other from Viomics, grants and personal fees from Boston Scientific, personal fees from Johnson and Johnson, personal fees from oncocyte, personal fees from veracyte, personal fees and other from Broncus, grants and personal fees from Gala, personal fees from Heritage Biologics, personal fees from IDbyDNA, personal fees from Level-Ex, personal fees from Medtronic, personal fees from Neurotronic, personal fees from olympus, personal fees from PulmonX, personal fees from Astra-Zeneca, personal fees from Biodesix, personal fees from Genetech, personal fees from Grifols, personal fees from Takeda, personal fees from CSL, personal fees from InhibRX, personal fees and other from Prothea-X, outside the submitted work. Dr. DKH serves as an unpaid editorial board member ofChinese Journal of Thoracic Surgeryfrom Apr 2021 to Mar 2023. Drs. EH and JV have nothing to declare.

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