One-way Valve Research Articles

An Imaging and Histological Study on Intrahepatic Microvascular Passage of Contrast Materials in Rat Liver.

Background. Lipiodol has been applied for decades in transarterial chemoembolization to treat liver malignancies, but its intrahepatic pathway through arterioportal shunt (APS) in the liver has not been histologically revealed. This rodent experiment was conducted to provide evidence for the pathway of Lipiodol delivered through the hepatic artery (HA) but found in the portal vein (PV) and to elucidate the observed unidirectional APS. Methods. Thirty rats were divided into 5 groups receiving systemic or local arterial infusion of red-stained iodized oil (RIO) or its hydrosoluble substitute barium sulfate suspension (BSS), or infusion of BSS via the PV, monitored by real-time digital radiography. Histomorphology of serial frozen and paraffin sections was performed and quantified. Results. After HA infusion, RIO and BSS appeared extensively in PV lumens with peribiliary vascular plexus (PVP) identified as the responsible anastomotic channel. After PV infusion, BSS appeared predominantly in the PV and surrounding sinusoids and to a much lesser extent in the PVP and HA (P < 0.001). Fluid mechanics well explains the one-way-valve phenomenon of APS. Conclusions. Intravascularly injected rat livers provide histomorphologic evidences: (1) the PVP exists in between the HA and PV, which is responsible to the APS of Lipiodol; and (2) the intrahepatic vascular inflow appears HA-PVP-PV unidirectional without a physical one-way valve, which can be postulated by the fluid mechanics.

Endobronchial Valves for Endoscopic Lung Volume Reduction: Best Practice Recommendations from Expert Panel on Endoscopic Lung Volume Reduction

Endoscopic lung volume reduction (ELVR) is being adopted as a treatment option for carefully selected patients suffering from severe emphysema. ELVR with the one-way endobronchial Zephyr valves (EBV) has been demonstrated to improve pulmonary function, exercise capacity, and quality of life in patients with both heterogeneous and homogenous emphysema without collateral ventilation. In this “expert best practices” review, we will highlight the practical aspects of this therapy. Key selection criteria for ELVR are hyperinflation with a residual volume >175% of predicted, forced expiratory volume <50% of predicted, and a 6-min walking distance >100 m. Patients with repeated infectious complications, severe bronchiectasis, and those with unstable cardiovascular comorbidities should be excluded from EBV treatment. The procedure may be performed with either conscious sedation or general anesthesia and positive pressure mechanical ventilation using a flexible endotracheal tube or a rigid bronchoscope. Chartis and EBV placement should be performed in 1 procedure when possible. The sequence of valve placement should be orchestrated to avoid obstruction and delivery of subsequent valves. If atelectasis has not occurred by 1 month after procedure, evaluate valve position on CT and consider replacing the valves that are not optimally positioned. Pneumothorax is a common complication and typically occurs in the first 2 days following treatment. A management algorithm for pneumothorax has been previously published. Long-term sequelae from EBV therapy do occur but are easily manageable.

One-Year Follow-Up after Endobronchial Valve Treatment in Patients with Emphysema without Collateral Ventilation Treated in the STELVIO Trial

Background: One-way endobronchial valve (EBV) treatment has shown safety and efficacy at 6 months after treatment in patients with severe emphysema and confirmed absence of interlobar collateral ventilation. Longer follow-up in this subgroup is not available. Objectives: To investigate the efficacy and safety of EBV treatment of the STELVIO cohort at a 1-year follow-up. Methods: Emphysema patients who have been treated with EBV in the STELVIO trial were invited for a voluntary 1-year follow-up visit. Both the original treatment group and the control group who crossed over to treatment have been included. Analyses are performed on the patients who attended the 1-year follow-up visit. Results: Sixty-four patients received EBV treatment. At 1 year, 40 patients (26 female; mean age 59 ± 8 years; FEV₁ 0.86 ± 0.29 L; RV 4.56 ± 1.00 L; 6MWD 367 ± 78 m; and SGRQ 56 ± 13 points) visited the hospital. Significant improvements (p < 0.001) were found for FEV₁ (+17%, 95% CI, 11 to 24), RV (-687 mL, 95% CI, -918 to -456), 6MWD (+61 m, 95% CI, 42 to 80), and SGRQ (-11 points, 95% CI, −17 to −6). Two patients died: 1 after 58 days due to progressive respiratory failure and 1 after 338 days of follow-up due to a myocardial infarction. Seventeen percent of the patients underwent valve replacement and 22% of the initially treated patients had permanent valve removal. In 22% of the patients, pneumothoraces occurred before 6 months, and none occurred between 6 and 12 months. Conclusions: EBV treatment results in clinically relevant benefits at 1 year of follow-up. Maintenance bronchoscopies to achieve this are needed. This study supports the use of EBV treatment in carefully selected patients with severe emphysema without collateral ventilation.

The Heimlich Valve for Pleural Cavity Drainage

Introduction : Traditional chest tube fixation and drainage has been undertaken using standard rigid chest tubes connected to under water seal bottles. These are bulky, cumbersome, expensive, and pose a risk of accidental air suction into the chest. One-way valve systems such as the Heimlich valve are small, portable apparatus that allow regulation of fluid flow and require minimal nursing care other than daily charting. Methods : A retrospective descriptive analysis of all chest drains connected to a Heimlich valve between January 2009 and December 2012. Data on indications, duration of drainage and frequency of complications was collected. Results : Fifty seven chest tubes connected to a Heimlich valve were inserted over the study period. Majority were for pleural effusions. No complications were encountered. Four patients (7%) required thoracotomy. The average duration to removal was 6 days and all patients reported satisfactory comfort and mobility. Conclusion : The Heimlich valve is a feasible and cheap alternative method of chest tube drainage with high rates of success and very low morbidity. We propose their usage in resource-constrained settings. Keywords : Thoracentesis, Heimlich, Thoracostomy

Monitoring the Inhalation Flow Rate of Nebulized Aerosols Using an Ultrasonic Flow Meter: In Vitro Assessment.

The measurement of aerosol flow rates without obscuration of the flow is of particular concern with in vivo lung deposition studies, where precise knowledge of aerosol particle size distributions is a necessary requirement for the development of predictive correlations. This study examines the utility of an ultrasonic flow meter for such measurements and determines if a valved system can be attached to the flow meter for sampling exhaled aerosols. The flow rate across a D-30 flow meter was compared with and without nebulization of 0.9% saline aerosols from a PARI LC Sprint nebulizer. Particle size distributions of the nebulized aerosol before and after adding the D-30 flow meter and duckbill valve were measured using a Spraytec laser diffraction system. Finally, the ability of the Thor D-30 to capture a realistic breathing profile was assessed. The mean ± standard error flow rates measured by the D-30 flow meter with and without nebulization were 10.4 ± 0.1 versus 10.4 ± 0.1 L/min, 66.4 ± 0.1 versus 67.2 ± 0.1 L/min, and 89.9 ± 0.1 versus 91.4 ± 0.1 L/min. The D-30 flow meter did not considerably affect the volumetric median diameter (VMD) of the aerosols, while the VMD reduced slightly by 0.65 μm at 10 L/min and 0.69 μm at 72 L/min upon the inclusion of a duckbill valve. Time-weighted average inhalation flow rates measured by D-30 flow meters placed upstream and downstream of the one-way valve agreed well, 31.9 versus 32.6 L/min, respectively. The D-30 flow meter can be used to accurately measure inhalation flow rates of nebulized aerosols without significantly impacting particle size distributions, and one-way duckbill valves can be used to isolate the inhalation portion of a breathing pattern to facilitate collection of exhaled doses.

Construction of Asymmetrical Hexameric Biomimetic Motors with Continuous Single-Directional Motion by Sequential Coordination.

The significance of bionanomotors in nanotechnology is analogous to mechanical motors in daily life. Here the principle and approach for designing and constructing biomimetic nanomotors with continuous single-directional motion are reported. This bionanomotor is composed of a dodecameric protein channel, a six-pRNA ring, and an ATPase hexamer. Based on recent elucidations of the one-way revolving mechanisms of the phi29 double-stranded DNA (dsDNA) motor, various RNA and protein elements are designed and tested by single-molecule imaging and biochemical assays, with which the motor with active components has been constructed. The motor motion direction is controlled by three operation elements: (1) Asymmetrical ATPase with ATP-interacting domains for alternative DNA binding/pushing regulated by an arginine finger in a sequential action manner. The arginine finger bridges two adjacent ATPase subunits into a non-covalent dimer, resulting in an asymmetrical hexameric complex containing one dimer and four monomers. (2) The dsDNA translocation channel as a one-way valve. (3) The hexameric pRNA ring geared with left-/right-handed loops. Assessments of these constructs reveal that one inactive subunit of pRNA/ATPase is sufficient to completely block motor function (defined as K = 1), implying that these components work sequentially based on the principle of binomial distribution and Yang Hui's triangle.

Abstract PR569

Background & Objectives: Lack’s circuit is a modified co-axial Mapleson A breathing system. Lack-Plus circuit is a modified Lack circuit with additional intraluminal one-way valve. The objective was to compare the Lack-Plus and Lack’s circuit on the minimal fresh gas flow (FGF) requirement with no rebreathing in spontaneously breathing anesthetized adults. Materials & Methods: Twenty-four adult patients with BMI ≤ 30 km/m2, under elective peripheral surgery in supine position with ASA physical status I-II were enrolled. They were allocated into group 1 (LP-L) starting with Lack-Plus then switching to Lack’s circuit or group 2 (L-LP) in reversed pattern. Anesthesia was maintained with 50% N2O/O2 and Desflurane 4 to 6% and fentanyl titration. Starting with the first circuit, all patients were spontaneously breathing with FGF 4 L/min for 10 minutes, and then gradually decreased by 0.5 L/min every five minutes. End-tidal CO2 (ETCO2), inspired minimum CO2 (ImCO2), mean arterial pressure (MAP) and oxygen saturation (SpO2) were recorded until rebreathing (ImCO2 > 0 mmHg) occurred. The anesthesia breathing circuit was then switched to the other and the procedure repeated. Results: The minimal FGF at the point of rebreathing of Lack-Plus and Lack’s circuit were 2.7 ± 0.8 and 3.3 ± 0.5 L/min respectively; P<0.001.Table 1:: FGF, ETCO2, RR, MAP, SpO2 at the point of rebreathing (ImCO2 > 0 mmHg)Conclusion: Lack-Plus circuit can be used safely, effectively, and requires less FGF than Lack’s circuit in spontaneously breathing anaesthetized adults.

Predicting Lung Volume Reduction after Endobronchial Valve Therapy Is Maximized Using a Combination of Diagnostic Tools

Background: Bronchoscopic lung volume reduction using one-way endobronchial valves (EBVs) has been proven to be effective in patients with severe emphysema. However, the selection of patients without collateral ventilation prior to treatment is critical for procedural success. Collateral ventilation can be assessed directly with the Chartis system or indirectly using computed tomography (CT) fissure analysis. Objectives: We retrospectively evaluated the diagnostic value of a combination of the quantitative CT interlobar fissure completeness score (FCS) and Chartis in predicting responders to EBV therapy. Methods: CT data from four prospective studies were pooled and analyzed using semiautomated software to quantify the completeness of interlobar fissures. These FCSs were compared to a reference standard of achieving ≥350 ml of target lobe volume reduction after EBV treatment. Using a receiver operating characteristic curve, optimal thresholds predictive of complete fissures (responders) and incomplete fissures (non-responders) were determined. A subgroup of patients with partially complete fissures was identified, where software had lower accuracy. The complementary value of Chartis was investigated in this group. Results: A fissure was defined as complete (FCS >95%), incomplete (FCS <80%), or partially complete (80% < FCS < 95%). The positive predictive value (PPV) of complete fissures is 88.1%, and the negative predictive value (NPV) is 92.9%, with an overall accuracy of 89.2%. Chartis was utilized in patients with partially complete fissures, with a PPV of 82.3%, an NPV of 84.6%, and an accuracy of 83.3%. Conclusion: Combining diagnostic tools could reduce the burden on patients and the healthcare system while providing clinicians with a better means for patient selection for EBV therapy.

Three-dimensional study of a one-way, flexible magnetorheological elastomer-based micro fluid transport system

This paper presents a three-dimensional study of a controllable flexible magnetically-activated micropump. The tubular micropump employs magnetically induced deformation of magnetorheological elastomer and one-way flexible conical valves for fluid transport. Three-dimensional magneto–fluid–solid interaction analysis is employed to investigate the performance of the system. The effects of key material, geometric, and magnetic parameters on the effectiveness of the system are examined. It is demonstrated that the proposed system can propel the fluid unidirectionally, and the volume of the transported fluid is significantly affected by some of the design parameters.

Invited Commentary

Invited Commentary

Fissure Integrity and Volume Reduction in Emphysema: A Retrospective Study

Background: One-way endobronchial valves (EBVs) relieve symptoms of emphysema, particularly in patients without collateral ventilation between the target and adjacent lobes. Pretreatment knowledge of fissure integrity could serve as an aid in indicating EBV interventions. Objective: This study aimed to investigate the relationship between software-measured lung fissure integrity and clinically relevant lung volume reduction (≥350 ml) in emphysema patients treated with one-way EBVs using a lobar exclusion strategy. Methods: Of 108 patients treated between March 2008 and July 2014, 38 had both baseline and follow-up computed tomography (CT) scans acquired following a specific protocol for quantitative CT analysis and were included in the study (total of 39 treatments, two lungs treated in 1 patient). Outcome measures were fissure integrity measured on baseline CT scans, difference between pre- and postoperative lung volume (considering the lowest measured postoperative volume), and correlation between fissure integrity and volume change. Results: Fissure integrity ≥75% correlated with volume reduction ≥350 ml (Spearman coefficient: -0.65; p < 0.01). The mean and median volume reductions were 1,223.96 ± 907.5 ml and 663 ml, respectively, for lungs with fissure integrity ≥75% (n = 31). The accuracy of fissure integrity ≥75% in predicting a volume reduction was 87.2%. The positive predictive value of fissure integrity ≥75% to predict a volume reduction ≥350 ml was 83.9%, and it was 70% for fissure integrity 75-90% and 90.5% for fissure integrity >90%. Conclusions: A target lobe volume reduction using EBVs is possible with lung fissure integrity ≥75%. For patients with fissure integrity between 75 and 90%, a further evaluation of interlobar ventilation should be performed. A clinically relevant volume reduction following treatment with EBVs is likely with any level of fissure integrity >90%.

31 - A Placebo-Controlled, Randomized Trial of Mesenchymal Stromal Cells Combined with One-Way Endobronchial Valve Therapy in Severe COPD

Rationale: Chronic obstructive pulmonary disease (COPD) is a devastating disease affecting millions worldwide, and therapeutic options are limited. One-way endobronchial valves (EBV) have been used in emphysema patients with dynamic hyperinflation, heterogeneity, and collateral ventilation to reduce lobar volume and improve lung function. However, EBV may increase rates of respiratory infection, COPD exacerbation, and hemoptysis. Mesenchymal stromal cells (MSCs) secrete antibacterial peptides, promote the anti-inflammatory M2 phenotype, and increase phagocytic activity. Thus, we hypothesized that administration of MSCs prior to EBV placement would improve lung function and quality of life in patients with severe heterogeneous COPD.

Sequential Bilateral Bronchoscopic Lung Volume Reduction With One-Way Valves for Heterogeneous Emphysema

Clinical benefits of bronchoscopic lung volume reduction with one-way endobronchial valves have been reported for heterogeneous emphysema after unilateral treatment. We assessed the potential role of contralateral treatment to prolong the benefits obtained with the first procedure. This was a retrospective multicenter study including consecutive patients with heterogeneous emphysema undergoing bronchoscopic valves deployment during the last 4 years. Patients were split into two groups depending on the procedure (unilateral versus bilateral). The intergroup differences were evaluated to assess the viability, effectiveness, and safety of the bilateral procedure. Forty-nine patients were enrolled. Of these, 14 (28%) had a sequential bilateral procedure mainly due to loss of the clinical benefits obtained with the first treatment. A significant improvement of forced expiratory volume in 1 second (p < 0.05), forced vital capacity (p<0.05), residual volume (p < 0.05), 6-minute walking test (p< 0.05), and St. George respiratory questionnaire (p< 0.02) was achieved after the second procedure. These results were maintained during follow-up. There was nosignificant difference regarding the changes of forced expiratory volume in 1 second (p= 0.4), forced vital capacity (p= 0.08), residual volume (p= 0.9), 6-minute walking test (p= 0.3), and St. George respiratory questionnaire (p= 0.1) between the bilateral and unilateral groups. A sequential bilateral approach seems to be a valid strategy to improve respiratory function in patients with bilateral heterogeneous emphysema who have lost the benefits obtained with the first procedure.

Three-step channel conformational changes common to DNA packaging motors of bacterial viruses T3, T4, SPP1, and Phi29

The DNA packaging motor of dsDNA bacterial viruses contains a head-tail connector with a channel for the genome to enter during assembly and to exit during host infection. The DNA packaging motor of bacterial virus phi29 was recently reported to use the “One-way revolving” mechanism for DNA packaging. This raises a question of how dsDNA is ejected during infection if the channel acts as a one-way inward valve. Here we report a three step conformational change of the portal channel that is common among DNA translocation motors of bacterial viruses T3, T4, SPP1, and phi29. The channels of these motors exercise three discrete steps of gating, as revealed by electrophysiological assays. The data suggest that the three step channel conformational changes occur during DNA entry process, resulting in a structural transition in preparation for DNA movement in the reverse direction during ejection.

A proportional assist ventilator to unload respiratory muscles experimentally during exercise in humans.

What is the central question of this study? Can a modern proportional assist ventilator (PAV) function sufficiently well to unload the respiratory muscles during exercise? What is the main finding and its importance? A PAV can be constructed with contemporary hardware and software and be used at all exercise intensities to unload the respiratory muscles by up to 70%. Previously, PAVs have allowed researchers to address many fundamental physiological problems in clinical and healthy populations, but those versions are no longer functional or available. We describe the creation of a PAV that permits researchers to use it as an experimental tool. Manipulation of the normally occurring work of breathing (WOB) during exercise can provide insights into whole-body regulatory mechanisms in clinical patients and healthy subjects. One method to reduce the WOB uses a proportional assist ventilator (PAV). Suitable commercially available units are not capable of being used during heavy exercise. This investigation was undertaken in order to create a PAV and assess the degree to which the WOB could be reduced during exercise. A PAV works by creating a positive mouth pressure (Pm ) during inspiration, which consequently reduces the WOB. Spontaneous breathing patterns can be maintained, and the amplitude of Pm is calculated using the equation of motion and predetermined proportionality constants. We generated positive Pm using a breathing apparatus consisting of rigid tubing, solenoid valves to control the airflow direction and a proportional valve connected to compressed gas. Healthy male and female subjects were able to use the PAV successfully while performing cycling exercise over a range of intensities (50-100% of maximal workload) for different durations (from 30s to 20min) and different protocols (constant versus progressive workload). Inspiratory WOB was reduced up to 90%, while total WOB was reduced by 70%. The greatest reduction in WOB (50-75%) occurred during submaximal exercise, but at maximal ventilations (>180lmin(-1) ) a 50% reduction was still possible. The calculated change in WOB and subsequent reduction in respiratory muscle oxygen consumption resulted in equivalent reductions in whole-body oxygen consumption. With adequate familiarization and practice, our PAV can consistently reduce the WOB across a range of exercise intensities.

The fissure: interlobar collateral ventilation and implications for endoscopic therapy in emphysema.

In patients with severe emphysema, bronchoscopic lung volume reduction using one-way valves is a promising therapeutic option to improve lung function and quality of life. The goal of this treatment is to achieve a complete lobar atelectasis. In a significant proportion of patients, this atelectasis cannot be achieved due to interlobar collateral ventilation. This collateral ventilation is generated through incomplete lobar fissures. Therefore, only patients with complete fissures and no collateral ventilation can be selected for endobronchial therapy with one-way valves.Incomplete fissures are very common and exhibit a great variation in anatomy. The reported prevalence is 17%–85% for the right major fissure, 19%–74% for the left major fissure, and 20%–90% for the minor fissure. There are several methods of measuring or predicting the presence of collateral ventilation, with computed tomography (CT)-fissure analysis and the Chartis measurement being the most important. CT-fissure analysis is an indirect method to measure the completeness of fissures as a surrogate for collateral ventilation. The Chartis system is an endobronchial method to directly measure the presence of collateral ventilation. Both methods have unique value, and the combination of both can accurately predict the treatment response to the bronchoscopic placement of endobronchial valves. This review provides an in-depth view of lung fissure and collateral ventilation to help understand its importance in selecting the appropriate patients for new emphysema treatments and thus avoid useless treatment in unsuitable patients.

Design and Experiment of Rare Earth Giant Magnetostrictive Piston Pump

A new piston pump structure was designed by incorporating a rare earth giant magnetostrictive material as the driving source into the basic working principles of piston pumps. The operational process of the proposed magnetostrictive piston pump was analyzed according to the overall structure design, which includes a magnetostrictive rod, drive coils, pump cavity height, one-way valve and pre-pressure mechanism. Analysis was conducted on both the seal and self-suction capacity of the proposed design. The magnetostrictive piston pump was designed to simplify the structure of a conventional piston pump by requiring fewer moving parts, a small volume, being of light weight, and utilizing a precise controllable flow, among other advantages. An experimental prototype was built and an experimental system was designed to test flow and pressure characteristics. Output flow and pressure curves were obtained to analyze the flow instability when exposed to high currents. Experimental results demonstrate that the magnetostrictive piston pump achieves a maximum output flow of 550.65mL/min when the excitation current frequency is 50Hz, and achieves a maximum output pressure of 0.65MPA when the excitation current frequency is 10Hz.

Speaking valves in tracheostomised ICU patients weaning off mechanical ventilation--do they facilitate lung recruitment?

BackgroundPatients who require positive pressure ventilation through a tracheostomy are unable to phonate due to the inflated tracheostomy cuff. Whilst a speaking valve (SV) can be used on a tracheostomy tube, its use in ventilated ICU patients has been inhibited by concerns regarding potential deleterious effects to recovering lungs. The objective of this study was to assess end expiratory lung impedance (EELI) and standard bedside respiratory parameters before, during and after SV use in tracheostomised patients weaning from mechanical ventilation.MethodsA prospective observational study was conducted in a cardio-thoracic adult ICU. 20 consecutive tracheostomised patients weaning from mechanical ventilation and using a SV were recruited. Electrical Impedance Tomography (EIT) was used to monitor patients’ EELI. Changes in lung impedance and standard bedside respiratory data were analysed pre, during and post SV use.ResultsUse of in-line SVs resulted in significant increase of EELI. This effect grew and was maintained for at least 15 minutes after removal of the SV (p < 0.001). EtCO2 showed a significant drop during SV use (p = 0.01) whilst SpO2 remained unchanged. Respiratory rate (RR (breaths per minute)) decreased whilst the SV was in situ (p <0.001), and heart rate (HR (beats per minute)) was unchanged. All results were similar regardless of the patients’ respiratory requirements at time of recruitment.ConclusionsIn this cohort of critically ill ventilated patients, SVs did not cause derecruitment of the lungs when used in the ventilator weaning period. Deflating the tracheostomy cuff and restoring the airflow via the upper airway with a one-way valve may facilitate lung recruitment during and after SV use, as indicated by increased EELI.Trial registrationAnna-Liisa Sutt, Australian New Zealand Clinical Trials Registry (ANZCTR). ACTRN: ACTRN12615000589583. 4/6/2015.

Another STEP forward in emphysema treatment

Patients with severe chronic obstructive pulmonary disease (COPD) suffer on a daily basis, despite important efforts to support this large patient population with pharmacotherapy. To potentially relieve symptoms, innovative bronchoscopic treatments have been developed in the past decade: the one-way endobronchial valve therapy for patients with severe emphysema and absence of interlobar collateral ventilation;1 the trans-bronchial airway bypass for severe emphysema, relying on the presence of collateral ventilation;2 nitinol coil treatment for a wide range of emphysema phenotypes independent of collateral ventilation;3 parasympathetic lung denervation for patients with COPD who respond well to anticholinergic agents;4 and sclerosing therapies such as crosslink compounds5 and steam,6 both of which target the most diseased parenchymal defects.

Successful treatment of persistent postoperative air leaks following the placement of an endobronchial one-way valve

Treatment of persistent air leaks due to pulmonary resection in pathological conditions of the lung involve a very large spectrum of available methods, from chest drainage and placement of Heimlich valves to surgical repair or pleural decortication. However, in some of these patients surgery may be contraindicated. This report describes an endobronchial approach to the control of marked and prolonged air leaks in four patients using a newly designed one-way airway valve (Pulmonx Corporation; Redwood City, Ca.USA) placed into the segmental bronchus that is the source of air leakage. As the device is a one-way inspiratory airway blocker, it can be used to control persistent air leaks while maintaining the drainage of mucus. This approach potentially provides an effective nonsurgical and minimally invasive alternative addition to the armamentarium of treatments for patients who suffer with persistent post-operative air leaks where other methods have failed or in frail patients who are categorised as a high surgical risk.