Use of Endobronchial Valves for the Treatment of Bronchopleural Fistulas after Thermal Ablation of Lung Neoplasms

Management of bronchopleural fistula after microwave ablation of lung tumor: A case report and literature review

Several patients with lung tumors are not eligible for surgical treatment. For those patients, percutaneous lung tumor ablation serves as a minimally invasive alternative to address such tumors. Despite its effectiveness, notable complications associated with this procedure can occur, such as bronchopleural fistula (BPF), which can lead to severe consequences. Therefore, the comprehensive understanding of these complications is of great importance for their safe and efficient management. In the present study, the case of a 73-year-old man with BPF following microwave ablation (MWA) of lung tumor and its clinical management was reported. MWA was performed after the diagnosis of lung cancer. Following ablation, the patient received thoracic drainage and anti-infectious therapy. After verifying the presence of BPF, an endobronchial unidirectional valve (EBV) was implanted into the posterior basal segment bronchus (B10) of the right lower lobe using a bronchoscope. EBV can occlude fistula while allowing drainage of secretions and trapped air. The function contributes to reducing infections around the fistula and promoting healing. The air leakage was stopped five days after EBV implantation and the thoracic drainage tube was then removed. At 86 days after EBV implantation, the pulmonary infection disappeared, while chest computed tomography scan revealed that the pulmonary necrotic cavity was narrowed. EBV implantation may have a higher successful rate compared with other endoscopic treatments for BPF.

Concomitant electromagnetic navigation transbronchial microwave ablation of multiple lung nodules is safe, time-saving, and cost-effective

Objectives

Transbronchial microwave ablation of lung nodules using electromagnetic navigation bronchoscopy is an emerging local therapy for lung oligometastases and multifocal lung cancers as part of a lung-preserving strategy. Concomitant ablation of multiple lung nodules in a single operating session may provide a one-stop solution.

Methods

Between April 2019 and April 2023, 25 patients had 2 or more lung nodules ablated concomitantly in our hybrid operating room. Nodules were proven or highly suspicious of malignancies or metastases. Feasibility and safety were retrospectively reviewed.

Results

A total of 56 nodules in 25 patients received concomitant multi-nodular ablation. The mean age of patients was 60 years, and the reasons for the lung-preserving strategy were multifocal lung cancers (80%) and lung oligometastases (20%). Among those with multifocal disease, 65% had previous major lung resection for lung cancer. Two to 4 nodules were ablated in each session. The mean nodule size was 9.9 mm (range, 5-20 mm), and the mean minimal margin was 5.9 mm. When comparing concomitant nodule ablation with the 103 single-nodule ablations performed in our institute, a mean of 86 minutes of operative time and 131 minutes of anesthetic time were saved. There were no increased complications despite overlapping ablation zones, and the mean hospital stay was 1.23 days. The rate of pneumothorax was 8%, and that of pleural effusion, pain, and fever was 4% respectively.

Conclusions

Concomitant transbronchial microwave ablation of multiple lung nodules is feasible, safe, and associated with reduction in overall anesthetic and operative time. It is an important armamentarium in the contemporary lung-preserving strategy for battling multifocal lung cancers or lung oligometastases.

A Survey of the Thermal Analysis of Implanted Antennas for Wireless Biomedical Devices

Wireless implantable biomedical devices (IBDs) are emerging technologies used to enhance patient treatment and monitoring. The performance of wireless IBDs mainly relies on their antennas. Concerns have emerged regarding the potential of wireless IBDs to unintentionally cause tissue heating, leading to potential harm to surrounding tissue. The previous literature examined temperature estimations and specific absorption rates (SAR) related to IBDs, mainly within the context of thermal therapy applications. Often, these studies consider system parameters such as frequency, input power, and treatment duration without isolating their individual impacts. This paper provides an extensive literature review, focusing on key antenna design parameters affecting heat distribution in IBDs. These parameters encompass antenna design, treatment settings, testing conditions, and thermal modeling. The research highlights that input power has the most significant impact on localized temperature, with operating frequency ranked as the second most influential factor. While emphasizing the importance of understanding tissue heating and optimizing antennas for improved power transfer, these studies also illuminate existing knowledge gaps. Excessive tissue heat can lead to harmful effects such as vaporization, carbonization, and irreversible tissue changes. To ensure patient safety and reduce expenses linked to clinical trials, employing simulation-driven approaches for IBD antenna design and optimization is essential.

Risk of persistent air leaks following percutaneous cryoablation and microwave ablation of peripheral lung tumors

OBJECTIVES

To compare the incidence of persistent air leak (PAL) following cryoablation vs MWA of lung tumors when the ablation zone includes the pleura.

METHODS

This bi-institutional retrospective cohort study evaluated consecutive peripheral lung tumors treated with cryoablation or MWA from 2006 to 2021. PAL was defined as an air leak for more than 24 h after chest tube placement or an enlarging postprocedural pneumothorax requiring chest tube placement. The pleural area included by the ablation zone was quantified on CT using semi-automated segmentation. PAL incidence was compared between ablation modalities and a parsimonious multivariable model was developed to assess the odds of PAL using generalized estimating equations and purposeful selection of predefined covariates. Time-to-local tumor progression (LTP) was compared between ablation modalities using Fine-Gray models, with death as a competing risk.

RESULTS

In total, 260 tumors (mean diameter, 13.1 mm ± 7.4; mean distance to pleura, 3.6 mm ± 5.2) in 116 patients (mean age, 61.1 years ± 15.3; 60 women) and 173 sessions (112 cryoablations, 61 MWA) were included. PAL occurred after 25/173 (15%) sessions. The incidence was significantly lower following cryoablation compared to MWA (10 [9%] vs 15 [25%]; p = .006). The odds of PAL adjusted for the number of treated tumors per session were 67% lower following cryoablation (odds ratio = 0.33 [95% CI, 0.14-0.82]; p = .02) vs MWA. There was no significant difference in time-to-LTP between ablation modalities (p = .36).

CONCLUSIONS

Cryoablation of peripheral lung tumors bears a lower risk of PAL compared to MWA when the ablation zone includes the pleura, without adversely affecting time-to-LTP.

KEY POINTS

• The incidence of persistent air leaks after percutaneous ablation of peripheral lung tumors was lower following cryoablation compared to microwave ablation (9% vs 25%; p = .006). • The mean chest tube dwell time was 54% shorter following cryoablation compared to MWA (p = .04). • Local tumor progression did not differ between lung tumors treated with percutaneous cryoablation compared to microwave ablation (p = .36).

Update on Image-Guided Thermal Lung Ablation: Society Guidelines, Therapeutic Alternatives, and Postablation Imaging Findings

Percutaneous image-guided thermal ablation (IGTA) has been endorsed by multiple societies as a safe and effective lung-preserving treatment for primary lung cancer and metastases involving the lung and chest wall. This article reviews the role of IGTA in the care continuum of patients with thoracic neoplasms and discusses strategies to identify the optimal local therapy considering patient and tumor characteristics. The advantages and disadvantages of percutaneous thermal ablation compared to surgical resection and stereotactic body radiotherapy are summarized. Principles of radiofrequency ablation, microwave ablation, and cryoablation, as well as the emerging use of transbronchial thermal ablation, are described. Specific considerations are presented regarding the role of thermal ablation for early-stage non-small cell lung cancer (NSCLC), multifocal primary NSCLC, pulmonary metastases, salvage of recurrent NSCLC after surgery or radiation, and pain palliation for tumors involving the chest wall. Recent changes to professional society guidelines regarding the role of thermal ablation in the lung, including for treatment of oligometastatic disease, are highlighted. Finally, recommendations are provided for imaging follow-up after thermal ablation of lung tumors, accompanied by examples of expected postoperative findings and patterns of disease recurrence.

Management of bronchopleural fistula with endobronchial valve in hybrid operating room following transbronchial microwave ablation

Transbronchial microwave ablation for the treatment of lung nodules is gaining popularity. In the present case, transbronchial microwave ablation to a right middle lobe lesion was performed under electromagnetic navigation bronchoscopy guidance. It was complicated with pneumothorax and persistent air leak despite chest drainage and chemical pleurodesis. A diagnosis of bronchopleural fistula was reached and an endobronchial valve was implanted to the middle lobe segmental bronchus with almost immediate cessation of air leak. Our case demonstrated that endobronchial valve is safe and effective in managing bronchopleural fistula after transbronchial microwave ablation.

Ex Vivo Performance of a Flexible Microwave Ablation Antenna

OBJECTIVE

In this study, we investigate the performance of a flexible microwave ablation antenna for generating localized ablation zones.

METHODS

We designed a helical dipole antenna to operate at 1.9 GHz in egg white and liver. Semi-rigid prototypes of the antenna were fabricated and used to perform ablation experiments in egg white and perfused liver. Pulsed and continuous-wave power deliveries at different power levels were used. Flexible prototypes of the antenna were fabricated and used to perform ex vivo ablation experiments in perfused liver.

RESULTS

Pulsing was effective in reducing the shaft heating of semi-rigid cables. The antenna was capable of producing substantial ablation zones in perfused liver. Typical diameters (perpendicular to the antenna axis) of generated ablation zones with semi-rigid antennas in egg white and perfused liver were 30 mm and 20 mm, respectively. The flexible antenna had a good impedance match while bent. Average diameter of generated ablation zones by the flexible antenna with 10-W continuous-wave experiments in perfused liver was 26 mm. No significant difference was observed between the performances of semi-rigid and flexible prototypes.

CONCLUSION

The flexible helical dipole antenna is capable of maintaining its good impedance match while bent and can generate substantial ablation zones in presence of perfusion.

SIGNIFICANCE

The proposed flexible antenna is promising for minimally invasive treatment of tumors that are otherwise inaccessible by rigid antennas. One example is lung where a catheter-based deployment of the flexible antenna into the tumor via airways may substantially reduce risks associated with using rigid antennas.

Endobronchial Valves for the Treatment of Bronchopleural Fistula and Pneumothorax Caused by Pulmonary Cryptococcosis in an AIDS Patient

Cryptococcal disease is an opportunistic infection that occurs primarily among people with advanced HIV disease and is an important cause of morbidity and mortality. Spontaneous pneumothorax (SP) is rare in acquired immune deficiency syndrome (AIDS) patients with pulmonary cryptococcosis (PC), but when it occurs, rapid and effective treatment is crucial to the prognosis, with mortality rates varying from 30 to 60%. SP is related to pneumonia mainly due to bacterial infections and pneumocystic jirovecii pneumonia (PJP). However, SP caused by PC is rare. When it occurs, it is often fatal and refractory, which is a challenge both for patients and clinicians. Here, we report a case of SP during the treatment of cryptococcal disease in a patient with AIDS. The pneumothorax remained despite chest tube drainage and evolved into a bronchopleural fistula that was confirmed by the Chartis system. The pneumothorax was significantly resolved following the placement of 2 endobronchial valves (EBVs). The patient tolerated the procedure very well and the pneumothorax gradually resolved. When immunocompromised patients suffer from refractory pneumothorax or prolonged air leaks, EBV implantation may be a feasible and minimally invasive procedure for this vulnerable population.

Cryoablation of Lung Metastases: Review of Recent Literature and Ablation Technique

This article reviews the current indications for image-guided thermal ablation of pulmonary metastatic disease. It also summarizes data regarding the efficacy and complications of lung cryoablation and present techniques for performing lung cryoablation as informed by the recent literature.

Endobronchial one-way valves for treatment of persistent air leaks: a systematic review

Persistent air leak (PAL) is associated with significant morbidity and mortality, prolonged hospitalization and increased health-care costs. It can arise from a number of conditions, including pneumothorax, necrotizing infection, trauma, malignancies, procedural interventions and complications after thoracic surgery. Numerous therapeutic options, including noninvasive and invasive techniques, are available to treat PALs. Recently, endobronchial one-way valves have been used to treat PAL. We conducted a systematic review based on studies retrieved from PubMed, EMbase and Cochrane library. We also did a hand-search in the bibliographies of relevant articles for additional studies. 34 case reports and 10 case series comprising 208 patients were included in our review. Only 4 patients were children, most of the patients were males. The most common underlying disease was COPD, emphysema and cancer. The most remarkable cause was pneumothorax. The upper lobes were the most frequent locations of air leaks. Complete resolution was gained within less than 24 h in majority of patients. Complications were migration or expectoration of valves, moderate oxygen desaturation and infection of related lung. No death related to endobronchial one-way valves implantation has been found. The use of endobronchial one-way valve adds to the armamentarium for non-invasive treatments of challenging PAL, especially those with difficulties of anesthesia, poor condition and high morbidity. Nevertheless, prospective randomized control trials with large sample should be needed to further evaluate the effects and safety of endobronchial one-way valve implantation in the treatment of PAL.

Lung Ablation: Whats New?

Lung cancer had an estimated incidence of 221,200 in 2015, making up 13% of all cancer diagnoses. Tumor ablation is an important treatment option for nonsurgical lung cancer and pulmonary metastatic patients. Radiofrequency ablation has been used for over a decade with newer modalities, microwave ablation, cryoablation, and irreversible electroporation presenting as additional and possibly improved treatment options for patients. This minimally invasive therapy is best for small primary lesions or favorably located metastatic tumors. These technologies can offer palliation and sometimes cure of thoracic malignancies. This article discusses the current available technologies and techniques available for tumor ablation.

Persistent pathways after lung radiofrequency ablation as a risk factor of drain placement

PURPOSE

The risk factors of pneumothorax after lung radiofrequency (RF) ablation are long known. The objective was to demonstrate that the visualisation of an aeric RF path after the needle withdrawal was predictive of pneumothorax occurrence and chest tube placement.

MATERIALS AND METHODS

A total of 70 patients were retrospectively included in this study. For each patient, we determined the pneumothorax risk factors (age, gender, previous surgery, emphysema, lesion size, distance between pleura and lesion), visualisation of a RF track, length and thickness, presence of pneumothorax, volume, chest tube placement, duration of drainage and hospital stay.

RESULTS

Among 70 patients included retrospectively, 26 needed a chest tube placement (37%). Considering the group with path visualisation (37 patients, group A) and the patients without path visualisation (group B), the 2 groups were comparable for pneumothorax risk factors. Considering the patients who needed a chest drain, the visualisation of the path was significatively more important (23 cases, 88.4%) (p< 10^-3) than in the group without (8 patients, 31.8%). Multivariate analyses were significant in the three analyses after adjustments on the risk factors for the occurrence of pneumothorax. Incidence of drains was significantly more (p < 10^-3) important in group A (23 drainages 62%) than in group B (4 drainages or 12%). The length and thickness of the tracks were not predictable of drain placement.

CONCLUSIONS

Besides the well-known risk factors of severe pneumothorax after lung RFA, the simple visualisation of an aeric path just after the RF needle withdrawal is significantly associated with chest tube placement and can be considered as a risk factor as itself.

Clinical experiences with microwave thermal ablation of lung malignancies

Approximately 30% of early stage lung cancer patients are not surgical candidates due to medical co-morbidities, poor cardiopulmonary function and advanced age. These patients are traditionally offered chemotherapy and radiation, which have shown relatively modest improvements in mortality. For over a decade, percutaneous image-guided ablation has emerged as a safe, cost-effective, minimally invasive treatment alternative for patients who would otherwise not qualify for surgery. Although radiofrequency ablation (RFA) is currently the most extensively studied and widely utilised technique in the treatment of lung malignancies, there is a growing body of evidence that microwave ablation (MWA) has several unique benefits over RFA and cryoablation in the lung. This article reviews our institution's clinical experiences in the treatment of lung malignancies with MWA including patient selection, procedural technique, imaging follow-up, treatment outcomes and comparison of ablation techniques.

Use of One-Way Intrabronchial Valves in Air Leak Management After Tube Thoracostomy Drainage

BACKGROUND

A persistent air leak represents significant clinical management problems, potentially affecting morbidity, mortality, and health care costs. In 2008, a unidirectional, intrabronchial valve received humanitarian device exemption for use in managing prolonged air leak after pulmonary resection. Since its introduction, numerous reports exist but no large series describe current utilization or outcomes. Our aim was to report current use of intrabronchial valves for air leaks and review outcome data associated with its utilization.

METHODS

A multicenter, retrospective review of intrabronchial valve utilization from January 2013 to August 2014 was performed at eight centers. Data regarding demographics, valve utilization, and outcomes were analyzed.

RESULTS

We identified 112 patients undergoing evaluation for intrabronchial valve placement, with 67% (75 of 112) undergoing valve implantation. Nearly three quarters of patients underwent valve placement for off-label usage (53 of 75). A total of 195 valves were placed in 75 patients (mean 2.6 per patient; range, 1 to 8) with median time to air leak resolution of 16 days (range, 2 to 156).

CONCLUSIONS

We present the largest, multicenter study of patients undergoing evaluation for intrabronchial valve use for air leak management. Our data suggest the majority of intrabronchial valve placements are occurring for off-label indications. Although the use of intrabronchial valves are a minimally invasive intervention for air leak management, the lack of rigorously designed studies demonstrating efficacy remains concerning. Prospective randomized controlled studies remain warranted.

Pleural puncture that excludes the ablation zone decreases the risk of pneumothorax after percutaneous microwave ablation in porcine lung

PURPOSE

To test the hypothesis that the geometry of probe placement with respect to the pleural puncture site affects the risk of pneumothorax after microwave (MW) ablation in the lung.

MATERIALS AND METHODS

Computed tomography-guided MW ablation of the lung was performed in 8 swine under general anesthesia and mechanical ventilation. The orientation of the 17-gauge probe was either perpendicular (90°) or parallel (< 30°) with respect to the pleural puncture site, and the ablation power was 30 W or 65 W for 5 minutes. After MW ablation, swine were euthanized, and histopathologic changes were assessed. Frequency and factors affecting pneumothorax were evaluated by multivariate analysis.

RESULTS

Among 62 lung MW ablations, 13 (21%) pneumothoraces occurred. No statistically significant difference was noted in the rate of pneumothorax between the perpendicular and the parallel orientations of the probe (31% vs 14%; odds ratio [OR], 2.8; P = .11). The pneumothorax rate was equal for 65-W and 30-W ablation powers (21% and 21%; OR, 1.0; P = .94). Under multivariate analysis, 2 factors were independent positive predictors of pneumothorax: ablation zone inclusive of pleural insertion point (OR, 7.7; P = .02) and time since intubation (hours) (OR, 2.7; P = .02).

CONCLUSIONS

Geometries where the pleural puncture site excluded the ablation zone decreased pneumothorax in swine undergoing MW ablation in the lung. Treatment planning to ensure that the pleural puncture site excludes the subsequent ablation zone may reduce the rate of pneumothorax in patients undergoing MW ablation in the lung.

Endobronchial valves in treatment of persistent air leaks: a systematic review of clinical evidence

Background

Persistent air leak is one of the most common complications of lung diseases and pulmonary resections. Prolonged hospitalization, increased morbidity, and increased overall treatment costs arise from persistent air leaks. The use of endobronchial valves (EBVs) in the management of air leaks is an important alternative, especially for patients who are not candidates for surgical treatment.

Material/Methods

We retrieved the included studies by performing a systematic search in PubMed and Scopus databases. The references of the included studies were also hand-searched.

Results

We retrieved 25 case reports and 3 case series from our literature search. The most common cause of persisting air leaks was spontaneous secondary pneumothorax (12/39, 31%). The left upper lobe (13/39, 33%) and right upper lobe (14/39, 36%) were the most frequent locations of air leaks. Most air leaks treated with EBVs ceased in less than 24 h. Three recurrences of air leak were reported and 2 cases of EBV migration were described. No deaths were reported in correlation with EBVs.

Conclusions

EBVs are a minimally invasive therapeutical option that may be suitable for the treatment of persistent air leaks regardless of the initial cause, especially in high-risk patients. Nevertheless, studies with better methodological quality are essential to standardize this technique and to provide more evidence on EBV safety issues.

Lung cancer ablation: technologies and techniques

The incidence of lung cancers in 2012 is estimated to reach 226,160 new cases, with only a third of patients suitable surgical candidates. Tumor ablation has emerged as an important and efficacious treatment option for nonsurgical lung cancer patients. This localized minimally invasive therapy is best suited for small oligonodular lesions or favorably located metastatic tumors. Radiofrequency ablation has been in use for over a decade, and newer modalities including microwave ablation, cryoablation, and irreversible electroporation have emerged as additional treatment options for patients. Ablation therapies can offer patients and clinicians a repeatable and effective therapy for palliation and, in some cases, cure of thoracic malignancies. This article discusses the available technologies and techniques available for tumor ablation of thoracic malignancies including patient selection, basic aspects of procedure technique, imaging follow-up, treatment outcomes, and comparisons between various therapies.

Endobronchial valves for treatment of bronchopleural fistula in granulomatous polyangitis: a longitudinal case report

Bronchopleural fistula (BPF) is an abnormal communication between the bronchus and the pleural space, commonly occurring after pulmonary resection or due to a spontaneous pneumothorax secondary to an underlying lung disease. We present a case of BPF in the setting of granulomatous polyangitis treated with endobronchial valves (EBV) with a longitudinal follow-up. These 1-way valves allow air and mucus to exit the diseased segment of lung during expiration, but prevent the reentry of air upon inspiration. The targeted segment may undergo atelectasis, achieving nonsurgical lung volume reduction, and allowing the remaining lung to compensate for the loss of volume. The use of these valves has shown to decrease hospitalization, morbidity, and mortality in these patients. In this case, the patient endured a prolonged hospitalization (82 d) and was able to be discharged only 7 days after EBV placement. This facilitated engagement in a pulmonary rehabilitation program, increased physical activity, and ultimately resumption of normal activity for the patient. To our knowledge, this is the first case of EBV used to treat BPF in the setting of underlying granulomatous polyangitis. This underscores the point that in appropriate settings, EBVs can decrease morbidity and mortality, and significantly improve the quality of life.

Ask the Experts: How important is radiofrequency ablation in lung cancer?

Terrance T Healey is the director of Thoracic Radiology at Rhode Island Hospital (RI, USA) and an Assistant Professor of Diagnostic Imaging at the Alpert Medical School of Brown University (RI, USA). Healey received his medical degree from the combined Dartmouth Medical School–Brown Medical School Program in 2003, completed his residency in radiology at Brown University in 2008 and a thoracic radiology fellowship at the Massachusetts General Hospital (MA, USA) in 2009. He joined the faculty staff at Rhode Island Hospital and Brown University in 2009.

Robert C Ward is one of the chief residents within the Department of Diagnostic Imaging at Rhode Island Hospital (RI, USA) and the Alpert Medical School of Brown University (RI, USA). Ward received his medical degree from the George Washington University (Washington, DC, USA) in 2010.

Damian E Dupuy is the director of Tumor Ablation at Rhode Island Hospital (RI, USA) and a Professor of Diagnostic Imaging at The Warren Alpert Medical School of Brown University (RI, USA). Dupuy received his medical degree from the University of Massachusetts Medical School (MA, USA) in 1988 and completed his residency in radiology at The New England Deaconess Hospital (MA, USA) and Harvard Medical School (MA, USA) in 1993. After residency, Dupuy joined the staff at Massachusetts General Hospital (MA, USA) where he worked in the Abdominal Imaging and Bone and Joint Divisions. In 1997, Dupuy joined the Department of Diagnostic Imaging at Rhode Island Hospital and Brown University. Dupuy, a pioneer in the use of image-guided ablation, helped broaden clinical applications to successfully combat cancer involving the kidney, liver, lung, head and neck, adrenal gland and skeleton. Other newer technologies, such as percutaneous microwave ablation, cryoablation and combination therapies using radiofrequency ablation with external radiation or brachytherapy, have been pioneered by Dupuy who has been the principal investigator of two National Cancer Institute-funded multicenter trials. Dupuy has received national awards for research and teaching from the American College of Radiology Imaging Network and the Radiological Society of North America where he is currently the Chair of the Interventional Oncology Symposium featured at the Annual Meeting of the Radiological Society of North America and a Fellow of the American College of Radiology. Dupuy is a member of the Radiological Society of North America, The New England Roentgen Ray Society, The American College of Radiology, Rhode Island Radiological Society and the Society of Interventional Radiology. Dupuy has published over 150 publications and given over 120 invited lectures in the field of radiology and image-guided ablation, both nationally and internationally.