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Background and Objective: The RENEW trial demonstrated that bronchoscopic lung volume reduction using endobronchial coils improves quality of life, pulmonary function and exercise performance. In this post hoc analysis of RENEW, we examine the mechanism of action of endobronchial coils that drives improvement in clinical outcomes., Methods: A total of 78 patients from the RENEW coil-treated group who were treated in one or both lobes that were deemed as the most destroyed were included in this retrospective analysis. Expiratory and inspiratory HRCT scans were used to assess lobar volume change from baseline to 12 months post coil treatment in treated and untreated lobes., Results: Reduction in lobar RV in treated lobes was significantly associated with favourable clinical improvement. Independent predictor of the change in RV and FEV 1 was the change in lobar RV reduction in the treated lobes and for change in 6MWD the absence of cardiac disease and the change in SGRQ, while the independent predictor of change in SGRQ was the change in 6MWD., Conclusion: Our results suggest that residual lobar volume reduction in treated lobes measured by QCT is the driving mechanism of action of endobronchial coils leading to positive clinical outcomes. However, the improvement in exercise capacity and quality of life seems to be affected by the presence of cardiac disease., (© 2020 The Authors. Respirology published by John Wiley & Sons Australia, Ltd on behalf of Asian Pacific Society of Respirology.)

Lung volume reduction (LVR) treatment in patients with severe emphysema has been shown to have a positive effect on hyperinflation, expiratory flow, exercise capacity and quality of life. However, the effects on diffusing capacity of the lungs and gas exchange are less clear. In this review, the possible mechanisms by which LVR treatment can affect diffusing capacity of the lung for carbon monoxide ( D LCO ) and arterial gas parameters are discussed, the use of D LCO in LVR treatment is evaluated and other diagnostic techniques reflecting diffusing capacity and regional ventilation ( V ')/perfusion ( Q ') mismatch are considered.A systematic review of the literature was performed for studies reporting on D LCO and arterial blood gas parameters before and after LVR surgery or endoscopic LVR with endobronchial valves (EBV). D LCO after these LVR treatments improved (40 studies, n=1855) and the mean absolute change from baseline in % predicted D LCO was +5.7% (range -4.6% to +29%), with no real change in blood gas parameters. Improvement in V ' inhomogeneity and V '/ Q ' mismatch are plausible explanations for the improvement in D LCO after LVR treatment., Competing Interests: Provenance: Submitted article peer reviewed Conflict of interest: M. van Dijk has nothing to disclose. Conflict of interest: K. Klooster reports other funding from PulmonX Inc., outside the submitted work. Conflict of interest: N.H.T. Ten Hacken has nothing to disclose. Conflict of interest: F. Sciurba has nothing to disclose. Conflict of interest: H.A.M. Kerstjens reports research grants from GSK, Novartis and Boehringer, and fees for consultancies on advisory boards from GSK, Novartis and Boehringer, all paid to his institution, outside the submitted work. Conflict of interest: D-J. Slebos reports grants, personal fees, non-financial support and other funding from PulmonX Inc, during the conduct of the study., (Copyright ©ERS 2020.)

Endoscopic lung volume reduction (ELVR) therapies are gaining prominence as a treatment option with guideline recommendations by COPD GOLD and NICE and the recent FDA approval for endobronchial valves. The transition from an experiment-based therapy only to clinical care comes with new challenges. A significant volume of evidence-based data has been published; all data demonstrate consistent improvements in several aspects of patient outcomes. Patients suffering from severe air trapping and thoracic hyperinflation seem to benefit the most from ELVR. In addition to lung function, baseline assessment should ideally include cardiopulmonary exercise testing, high-resolution computer tomography scan, perfusion scintigraphy, and echocardiography. This expert ELVR statement updates best practice recommendations from 2017 regarding patient selection and utilization of these various techniques for treating patients with advanced emphysema., (© 2019 S. Karger AG, Basel.)

Background: The National Emphysema Treatment Trial studied lung volume reduction surgery (LVRS) for its effects on gas exchange, breathing pattern, and dyspnea during exercise in severe emphysema., Methods: Exercise testing was performed at baseline, and 6, 12, and 24 months. Minute ventilation (Ve), tidal volume (Vt), carbon dioxide output (Vco(2)), dyspnea rating, and workload were recorded at rest, 3 min of unloaded pedaling, and maximum exercise. Pao(2), Paco(2), pH, fraction of expired carbon dioxide, and bicarbonate were also collected in some subjects at these time points and each minute of testing. There were 1,218 patients enrolled in the study (mean [+/- SD] age, 66.6 +/- 6.1 years; mean, 61%; mean FEV(1), 0.77 +/- 0.24 L), with 238 patients participating in this substudy (mean age, 66.1 +/- 6.8 years; mean, 67%; mean FEV(1), 0.78 +/- 0.25 L)., Results: At 6 months, LVRS patients had higher maximum Ve (32.8 vs 29.6 L/min, respectively; p = 0.001), Vco(2), (0.923 vs 0.820 L/min, respectively; p = 0.0003), Vt (1.18 vs 1.07 L, respectively; p = 0.001), heart rate (124 vs 121 beats/min, respectively; p = 0.02), and workload (49.3 vs 45.1 W, respectively; p = 0.04), but less breathlessness (as measured by Borg dyspnea scale score) [4.4 vs 5.2, respectively; p = 0.0001] and exercise ventilatory limitation (49.5% vs 71.9%, respectively; p = 0.001) than medical patients. LVRS patients with upper-lobe emphysema showed a downward shift in Paco(2) vs Vco(2) (p = 0.001). During exercise, LVRS patients breathed slower and deeper at 6 months (p = 0.01) and 12 months (p = 0.006), with reduced dead space at 6 months (p = 0.007) and 24 months (p = 0.006). Twelve months after patients underwent LVRS, dyspnea was less in patients with upper-lobe emphysema (p = 0.001) and non-upper-lobe emphysema (p = 0.007)., Conclusion: During exercise following LVRS, patients with severe emphysema improve carbon dioxide elimination and dead space, breathe slower and deeper, and report less dyspnea.

Rationale: While exercise capacity, expressed as maximal oxygen consumption (VO2max), has been proposed to be the best predictor of postoperative cardiopulmonary complications after surgical resection in lung cancer patients, the literature remains controversial. The purpose of this study was to use the meta-analytic approach to determine if VO2max, expressed as either ml kg(-1) min(-1) or as a percentage of predicted, differed between patients who develop postoperative cardiopulmonary complications versus those that do not., Methods: Studies were retrieved via (1) computerized literature searches, (2) cross referencing from retrieved articles, and (3) expert review of our reference list. Trials were included if they reported preoperative VO2max values (ml kg(-1) min(-1) or percentage of predicted) and had patients in which postoperative cardiopulmonary complications occurred., Results: Fourteen studies representing a total of 955 men and women met our criteria for inclusion. Across all designs and categories, random-effects modeling demonstrated that patients without postoperative pulmonary complications had significantly higher levels of VO2max in ml kg(-1) min(-1) (mean difference=3.0, 95% confidence interval (CI), 1.9-4.0) as well as VO2max as a percentage of predicted (mean difference=8, 95% CI, 3.3-12.8)., Conclusion: After a systematic review of the literature, we found that exercise capacity, expressed as VO2max, is lower in patients that develop clinically relevant complications after curative lung resection. These results are important for the practicing clinician because they answer the literature controversy on the usefulness of measuring preoperative exercise capacity and reinforce the current guidelines on decision making for lung resection.

Background: A study was undertaken to test the hypothesis that patients respond better to lung volume reduction surgery (LVRS) if their emphysema is confluent and predominantly located in the upper lobes., Methods: A density mask analysis was used to identify voxels inflated beyond 10.2 ml gas/g tissue (-910 HU) on preoperative and postoperative CT scans from patients receiving LVRS. These hyperinflated regions were considered to represent emphysematous lesions. A power law analysis was used to determine the relationship between the number (K) and size (A) of the emphysematous lesions in the whole lung and two anatomical regions using the power law equation Y=KA(-D)., Results: The analysis showed a positive correlation between the change in the power law exponent (D) and the change in exercise (Watts) after surgery (r=0.47, p=0.03). There was also a negative correlation between the power law exponent D in the upper region of the lung preoperatively and the change in exercise following surgery (r=-0.60, p<0.05)., Conclusions: These results confirm that patients with large upper lobe lesions respond better to LVRS than patients with small uniformly distributed disease. Power law analysis of lung CT scans provides a quantitative method for determining the extent and location of emphysema within the lungs of patients with COPD.

Computed tomography (CT) has shown that emphysema is more extensive in the inner (core) region than in the outer (rind) region of the lung. It has been suggested that the concentration of emphysematous lesions in the outer rind leads to a better outcome following lung volume reduction surgery (LVRS) because these regions tend to be more surgically accessible. The present study used a recently described, computer-based CT scan analysis to quantify severe emphysema (lung inflation > 10.2 ml gas/g tissue), mild/moderate emphysema (lung inflation = 10.2 to 6.0 ml gas/g tissue), and normal lung tissue (lung inflation < 6.0 ml gas/g tissue) present in the core and rind of the lung in 21 LVRS patients. The results show that the quantification of severe emphysema independently predicts change in maximal exercise response and FEV(1). We conclude that a greater extent of severe emphysema in the rind of the upper lung predicts greater benefit from LVRS because it identifies the lesions most accessible to removal by LVRS.

Study Objective: To determine how the volume and severity of emphysema measured by CT morphometry (CTM) before and after lung volume reduction surgery (LVRS) relates to the functional status of patients after LVRS., Design: A histologically validated CT algorithm was used to quantify the volume and severity of emphysema in 35 patients before and after LVRS: total lung volume (TLV), normal lung volume (< 6.0 mL gas per gram of tissue), volume of mild/moderate emphysema (ME; 6.0 to 10.2 mL gas per gram of tissue), volume of severe emphysema (> 10.2 mL gas per gram of tissue), surface area/volume (SA/V; meters squared per milliliter), and surface area (SA; meters squared). Outcome parameters included maximal cardiopulmonary exercise (CPX) performance in 21 patients and routine pulmonary function in all patients. We hypothesized that baseline CTM parameters predict response to LVRS and that the change in these parameters may offer insight into mechanisms of improvement., Patients and Intervention: Thirty-five patients with severe emphysema who had successful LVRS., Results: The significant decrease in TLV following LVRS was entirely accounted for by a decrease in severe emphysema. The SA/V and the SA both increased significantly following LVRS. The change in maximal CPX in watts following surgery correlated significantly with baseline values of severe emphysema (r = 0.60), which was collinear with TLV, and SA/V. The change in diffusing capacity of the lung for carbon monoxide revealed a significant positive linear relationship with preoperative severe emphysema (r = 0.37) and a negative relationship with ME (r = -0.37). Change in watts revealed a strong relationship with changes in severe emphysema (r = -0.75) and weaker but significant relationships with change in TLV, ME, SA/V, and SA. Other measures of pulmonary function revealed significant albeit less dominant relationships with baseline CTM and change in these indexes., Conclusion: Using CTM, we have identified a close relationship between baseline severe emphysema, or change in severe emphysema, and the improvement in CPX after LVRS. These observations support a potential role of CTM in future clinical trials for predicting responders to LVRS and identifying mechanisms of improvement.

In the past 3 years, lung volume reduction surgery has become the most controversial topic in the clinical management of patients with emphysema. Although literature has added to the understanding of the procedure, many important issues remain unclear. This article emphasizes functional and basic physiologic changes that occur following lung volume reduction surgery in patients with emphysema.

In the 1960s the promise of the Brantigan lung reduction surgery was shattered when it was shown that the improvement in airway conductance drifted back towards the preoperative value over a period of 12 to 18 months. Since then there has been a marked improvement in our understanding of emphysema, its pathology, and techniques for obtaining images of the lung. In addition, reliable automated cardiopulmonary and physiologic testing, advances in critical care medicine, and new pharmacologic agents have improved patient care. Surgical techniques now allow better control of air leaks and access to anatomic regions not previously accessible. The combination of all of the above makes lung reduction surgery worth re-examining as a palliative procedure for severely symptomatic patients. Clearly, it is not a panacea but can in some cases produce dramatic improvements in symptomatology and quality of life. This article presents the available data describing potential mechanisms of improvement and clinical outcomes following lung reduction surgery. It also outlines areas that need further work, such as patient selection and surgical techniques.

Background: Pulmonary function may improve after surgical resection of the most severely affected lung tissue (lung-reduction surgery) in patients with diffuse emphysema. The basic mechanisms responsible for the improvement, however, are not known., Methods: We studied 20 patients with diffuse emphysema before and at least three months after either a unilateral or a bilateral lung-reduction procedure. Clinical benefit was assessed by measurement of the six-minute walking distance and the transitional-dyspnea index, which is a subjective rating of the change from base line in functional impairment and the threshold for effort- and task- dependent dyspnea. Pressure-volume relations in the lungs were measured with static expiratory esophageal-balloon techniques, and right ventricular systolic function was assessed by echocardiography., Results: The patients had significant improvement in the transitional-dyspnea index after surgery (P<0.001). The mean (+/-SD) coefficient of retraction, an indicator of elastic recoil of the lung, improved (from 1.3+/-0.6 cm of water per liter before surgery to 1.8+/-0.8 after, P<0.001). Sixteen patients with increased elastic recoil had a greater increase in the distance walked in six minutes than the other four patients, in whom recoil did not increase (P=0.02). The improved lung recoil led to disproportionate decreases in residual volume as compared with total lung capacity (16 percent vs. 6 percent), but the decreases in both values were significant (P<0.001). Forced expiratory volume in one second increased (from 0.87+/-0.36 to 1.11+/-0.45 liters, P<0.001). End-expiratory esophageal pressure also decreased (P=0.002). These improvements in lung mechanics led to a decrease in arterial partial pressure of carbon dioxide form 42+/-6 to 38+/-5 mm Hg (P=0.006). Furthermore, the fractional change in right ventricular area, an indicator of systolic function, increased from 0.33+/-0.11 to 0.38+/-0.010 (P=0.02)., Conclusions: Lung-reduction surgery can produce increases in the elastic recoil of the lung in patients with diffuse emphysema, leading to short-term improvement in dyspnea and exercise tolerance.

Lung reduction surgery, a procedure that entails removal of portions of the most diseased lung tissue in patients with diffuse emphysema, has been resurrected based on advances in surgical technique, radiographic imaging, and pulmonary physiologic assessment. We outline potential mechanisms for improvement in pulmonary mechanics, gas exchange, pulmonary vascular function, and exercise tolerance following surgery. Available literature is reviewed, and patterns that are beginning to emerge with respect to optimal surgical approach and patient selection criteria are presented. Early results suggest that this procedure offers real hope to our patients; however, long-term follow-up studies will be necessary to define its ultimate utility.

We evaluated the use of a lateral thoracoscopic approach for lung reduction surgery in patients with diffuse emphysema. Sixty-seven patients with a mean age of 61.9 years underwent operation. Operative side was determined by preoperative imaging. The procedures were laser ablation in 10 patients and stapler resection in 57 patients. Ten patients, including six of the 10 patients in the laser-only group had poor outcome (death or hospitalization longer than 30 days), leading us to abandon the laser technique. Of the remaining 57 patients undergoing primary stapled resection, duration of chest tube placement averaged 13 days (range 3 to 53 days) with a mean hospital stay of 17 days (range 6 to 99 days). Seven patients required ventilation for longer than 72 hours, six patients underwent conversion of the procedure to open thoracotomy, four patients acquired arrhythmias, and three patients were treated for empyema. There was one early death (1.7%), from cardiopulmonary failure. Forty patients returned for 3-month evaluation. Significant (p < 0.0001) improvements were seen in forced vital capacity (2.69 L after vs 2.26 L before) and forced expiration volume in 1 second (1.04 L after vs 0.82 L before), with 25 of 40 patients (63%) showing an improvement of more than 20%. Lung volume measures, in particular residual volume, fell significantly. Arterial blood gas analysis revealed that carbon dioxide tension fell significantly in patients with preoperative hypercapnia (carbon dioxide tension > 45 mm Hg, p = 0.018). Six-minute walk test results improved (894 feet after vs 784 feet before, p = 0.002), and symptomatic benefit was confirmed by significant improvement in the dyspnea index. The combination of both hypercapnia and reduced single-breath diffusing capacity for carbon monoxide was significantly more frequent (p = 0.0026) and was 86% specific (5 of 6 patients) in predicting serious postoperative risk. We conclude that the lateral thoracoscopic surgical approach to diffuse emphysema offers significant improvement in pulmonary mechanics and functional impairment. Patients with a combination of hypercapnia and reduced single-breath diffusing capacity for carbon monoxide should not be considered for this procedure because of significant perioperative risk.