Rationale and design of the National Emphysema Treatment Trial (NETT): A prospective randomized trial of lung volume reduction surgery

Efficiency and Reliability of Bronchoscopic Lung Volume Reduction Coil Application in Patients with Severe Emphysema

Objectives

In the past years, surgery has been used for the non-medical treatment of severe emphysema. However, in recent years, bronchoscopic lung volume reduction (LVR) treatment has become more preferred because it is less invasive. Bronchoscopic coil treatment is the most frequently applied technique among these methods. The aim of the investigation was to determine the efficacy and safety of bronchoscopic volume reduction coil treatment for patients with severe emphysema.

Methods

The patients who were performed bronchial volume reduction coil treatment between 2015 and 2017 and were followed in our outpatient clinic were retrospectively examined. They were followed for 1 year at quarterly intervals after the procedure. All the safety and efficacy of the patient's records, including the modified Medical Research Council (MRC) dyspnea score, the St. George's Respiratory Questionnaire (SGRQ) quality of life scale, the 6 min walk distance (6-MWT), pulmonary function tests, and adverse events, were evaluated.

Results

Sixteen patients were included in the study. The mean of the preoperative mMRC clinic dyspnea score was 3.38, the mean of the 3rd month's mMRC score was 2.62 (p=0.007), and the mean of the 12th month's mMRC was 2.37 (p=0.003). The preoperative SGRQ quality of life parameter was 71.95±15.7, the 3rd month was 66.7±16.2 (p=0.007), and the 12th month was 62.9±16.4 (p=0.003). Preoperative mean of 6-MWT was 247.25±112.36 m, 3rd month 264.25±95 m (p=0.148), and 12th month 317±122.9 m (p=0.034). Patients' preoperative residual volume was 5.28±1.96 L, 3rd month 4.52±1.35 L (p=0.023), and 12th month 4.545±1.83 L (p=0.163). Patients' preoperative forced expiratory volume in one second, respectively, was 0.79±0.29 L, 3rd month 0.79±0.3 L (p=0.917), and 12th month 0.86±0.3 L (p=0.756).

Conclusion

It seems that bronchoscopic LVR coil treatment, which is an effective and reliable procedure that reduces shortness of breath rather than respiratory function test parameters and improves the quality of daily life, will become even more widespread.

Comparison of different reference values for lung function: implications of inconsistent use among centers

BACKGROUND

For interpretation of pulmonary function tests (PFTs), reference values based on sex, age, height and ethnicity are needed. In Norway, the European Coal and Steel Community (ECSC) reference values remain widely used, in spite of recommendations to implement the more recent Global Lung Function Initiative (GLI) reference values.

OBJECTIVE

To assess the effects of changing from ECSC to GLI reference values for spirometry, DLCO and static lung volumes, using a clinical cohort of adults with a broad range in age and lung function.

METHODS

PFTs from 577 adults (18-85 years, 45% females) included in recent clinical studies were used to compare ECSC and GLI reference values for FVC, FEV1, DLCO, TLC and RV. Percent predicted and lower limit of normal (LLN) were calculated. Bland-Altman plots were used to assess agreement between GLI and ECSC % predicted values.

RESULTS

In both sexes, GLI % predicted values were lower for FVC and FEV1, and higher for DLCO and RV, compared to ECSC. The disagreement was most pronounced in females, with mean (SD) difference 15 (5) percent points (pp) for DLCO and 17 (9) pp for RV (p < 0.001). With GLI, DLCO was below LLN in 23% of the females, with ECSC in 49% of the females.

CONCLUSIONS

The observed differences between GLI and ECSC reference values are likely to entail significant consequences with respect to criteria for diagnostics and treatment, health care benefits and inclusion in clinical trials. To ensure equity of care, the same reference values should be consistently implemented across centers nationwide.

Critical Analysis of the National Emphysema Treatment Trial Results for Lung-Volume-Reduction Surgery

The National Emphysema Treatment Trial compared medical treatment of severe pulmonary emphysema with lung-volume-reduction surgery in a multiinstitutional randomized prospective fashion. Two decades later, this trial remains one of the key sources of information we have on the treatment of advanced emphysematous lung disease. The trial demonstrated the short- and long-term effectiveness of surgical intervention as well as the need for strict patient selection and preoperative workup. Despite these findings, the key failure of the trial was an inability to convince the medical community of the value of surgical resection in the treatment of advanced emphysema.

Hypercapnia in Advanced Chronic Obstructive Pulmonary Disease: A Secondary Analysis of the National Emphysema Treatment Trial

RATIONALE

Hypercapnia develops in one third of patients with advanced chronic obstructive pulmonary disease (COPD) and is associated with increased morbidity and mortality. Multiple factors in COPD are thought to contribute to the development of hypercapnia including increased carbon dioxide (CO2) production, increased dead space ventilation, and the complex interactions of deranged respiratory system mechanics, inspiratory muscle overload and the ventilatory control center in the brainstem. However, these factors have not previously been systematically analyzed in a large, well-characterized population of severe COPD patients.

METHODS

This is a secondary analysis of the clinical, physiologic and imaging data from the National Emphysema Treatment Trial (NETT). All patients with complete baseline data for the key predictor variables were included. An inclusive list of 32 potential predictor variables were selected a priori based on consensus of the investigators and literature review. Stepwise variable selection yielded 10 statistically significant associations in multivariate regression.

RESULTS

A total of 1419 patients with severe COPD were included in the analysis; mean age 66.4 years (standard deviation 6.3), 38% females, and 422 (29.7%) had baseline hypercapnia. Key variables associated with hypercapnia were low resting partial pressure of oxygen in blood, low minute ventilation (Ve), high volume of exhaled carbon dioxide, low forced expiratory volume in 1 second, high residual volume, lower % emphysema on chest computed tomography, use of oxygen, low ventilatory reserve (high Ve/maximal voluntary ventilation), and not being at high altitude. Low diffusing capacity for carbon monoxide showed a positive association with hypercapnia in univariate analysis but a negative correlation in multivariate analysis. Measures of dyspnea and quality of life did not associate with degree of hypercapnia in multivariable analysis.

CONCLUSION

Hypercapnia in a well-characterized cohort with severe COPD and emphysema is chiefly related to poor lung mechanics, high CO2 production, and a reduced ventilatory capability. Hypercapnia is less impacted by gas exchange abnormalities or the presence of emphysema.

Lung Volume Reduction Surgery for Respiratory Failure in Infants With Bronchopulmonary Dysplasia

Lung volume reduction surgery (LVRS) can be performed in patients with severe emphysematous disease. However, LVRS in pediatric patients has not yet been reported. Here, we report our experience with 2 cases of pediatric LVRS. The first patient was a preterm infant girl with severe bronchopulmonary dysplasia, pulmonary hypertension, and hypothyroidism. The emphysematous portion of the right lung was removed via sternotomy and right hemiclamshell incision. The patient was discharged on full-time home ventilator support for 3 months after the surgery. Since then, her respiratory function has improved continuously. She no longer needs oxygen supplementation or ventilator care. Her T-cannula was removed recently. The second patient was also a preterm infant girl with bronchopulmonary dysplasia. She was born with pulmonary hypertension and multiple congenital anomalies, including an atrial septal defect. Despite receiving the best supportive care, she could not be taken off the mechanical ventilator because of severe hypercapnia. We performed LVRS on the right lung via thoracotomy. She was successfully weaned off the mechanical ventilator 1 month after the surgery. She was discharged without severe complications at 3 months after the operation. At present, she is growing well with the help of intermittent home ventilator support. She can now tolerate an oral diet. Our experience shows that LVRS can be considered as a treatment option for pediatric patients with severe emphysematous lung. It is especially helpful for discontinuing prolonged mechanical ventilator care for patients with respiratory failure.

Lung volume reduction surgery for diffuse emphysema

BACKGROUND

Lung volume reduction surgery (LVRS) performed to treat patients with severe diffuse emphysema was reintroduced in the nineties. Lung volume reduction surgery aims to resect damaged emphysematous lung tissue, thereby increasing elastic properties of the lung. This treatment is hypothesised to improve long-term daily functioning and quality of life, although it may be costly and may be associated with risks of morbidity and mortality. Ten years have passed since the last version of this review was prepared, prompting us to perform an update.

OBJECTIVES

The objective of this review was to gather all available evidence from randomised controlled trials comparing the effectiveness of lung volume reduction surgery (LVRS) versus non-surgical standard therapy in improving health outcomes for patients with severe diffuse emphysema. Secondary objectives included determining which subgroup of patients benefit from LVRS and for which patients LVRS is contraindicated, to establish the postoperative complications of LVRS and its morbidity and mortality, to determine which surgical approaches for LVRS are most effective and to calculate the cost-effectiveness of LVRS.

SEARCH METHODS

We identified RCTs by using the Cochrane Airways Group Chronic Obstructive Pulmonary Disease (COPD) register, in addition to the online clinical trials registers. Searches are current to April 2016.

SELECTION CRITERIA

We included RCTs that studied the safety and efficacy of LVRS in participants with diffuse emphysema. We excluded studies that investigated giant or bullous emphysema.

DATA COLLECTION AND ANALYSIS

Two independent review authors assessed trials for inclusion and extracted data. When possible, we combined data from more than one study in a meta-analysis using RevMan 5 software.

MAIN RESULTS

We identified two new studies (89 participants) in this updated review. A total of 11 studies (1760 participants) met the entry criteria of the review, one of which accounted for 68% of recruited participants. The quality of evidence ranged from low to moderate owing to an unclear risk of bias across many studies, lack of blinding and low participant numbers for some outcomes. Eight of the studies compared LVRS versus standard medical care, one compared two closure techniques (stapling vs laser ablation), one looked at the effect of buttressing the staple line on the effectiveness of LVRS and one compared traditional 'resectional' LVRS with a non-resectional surgical approach. Participants completed a mandatory course of pulmonary rehabilitation/physical training before the procedure commenced. Short-term mortality was higher for LVRS (odds ratio (OR) 6.16, 95% confidence interval (CI) 3.22 to 11.79; 1489 participants; five studies; moderate-quality evidence) than for control, but long-term mortality favoured LVRS (OR 0.76, 95% CI 0.61 to 0.95; 1280 participants; two studies; moderate-quality evidence). Participants identified post hoc as being at high risk of death from surgery were those with particularly impaired lung function, poor diffusing capacity and/or homogenous emphysema. Participants with upper lobe-predominant emphysema and low baseline exercise capacity showed the most favourable outcomes related to mortality, as investigators reported no significant differences in early mortality between participants treated with LVRS and those in the control group (OR 0.87, 95% CI 0.23 to 3.29; 290 participants; one study), as well as significantly lower mortality at the end of follow-up for LVRS compared with control (OR 0.45, 95% CI 0.26 to 0.78; 290 participants; one study). Trials in this review furthermore provided evidence of low to moderate quality showing that improvements in lung function parameters other than forced expiratory volume in one second (FEV1), quality of life and exercise capacity were more likely with LVRS than with usual follow-up. Adverse events were more common with LVRS than with control, specifically the occurrence of (persistent) air leaks, pulmonary morbidity (e.g. pneumonia) and cardiovascular morbidity. Although LVRS leads to an increase in quality-adjusted life-years (QALYs), the procedure is relatively costly overall.

AUTHORS' CONCLUSIONS

Lung volume reduction surgery, an effective treatment for selected patients with severe emphysema, may lead to better health status and lung function outcomes, specifically for patients who have upper lobe-predominant emphysema with low exercise capacity, but the procedure is associated with risks of early mortality and adverse events.

Predicting the Response to Lung Volume Reduction Surgery Using Scintigraphy

This study was conducted to evaluate the use of quantitative scintigraphy with a newly designed marker to assess and predict the efficacy of lung volume reduction surgery in treating emphysema. In a series of 50 patients with severe emphysema who underwent the operation, ventilation/perfusion scintigraphy was performed and 2 markers of area ratio and lung uniformity were measured before and 6 months after surgery. The markers were correlated with the results of pulmonary function tests. The histopathological subtype of emphysema was also determined in the resected specimen and related to improvement in the markers. The markers were closely related to improvement in forced expiratory volume in 1 second, with the highest correlation being the marker lung uniformity measured by perfusion scintigraphy. Improvement in this marker was significantly greater in centrilobular than in panlobular emphysema. This quantitative method of scintigraphy could provide an excellent reflection of surgical efficacy as well as predict the surgical outcome. Additionally, it provides a mechanistic explanation for the differential improvement between the histopathological subtypes of emphysema following surgery.

Chronic obstructive pulmonary disease prognostic score: A new index

BACKGROUND

The evaluation of chronic obstructive pulmonary disease (COPD) has been shifting from spirometry to focus on the patients' overall health. Despite the existence of many COPD prognostic scales, there remains a large gap for improvement, in particular a scale that incorporates the current focus on overall health.

METHODS

We proposed a new prognostic scale (the COPD Prognostic Score) through discussion among the authors based on published studies. Validation was retrospective, using data from the National Emphysema Treatment Trial.

RESULTS

The scores ranged from 0-16, where 16 indicated the poorest prognosis. We assigned 4 points each for forced expiratory volume in one second (%predicted), the modified Medical Research Council dyspnea scale, and age; 2 points for the hemoglobin level; and one point each for decreased activity and respiratory emergency admission in the last two years. The validation cohort included 607 patients and consisted of 388 men (73.9%) and 219 women (36.1%), mean age 67 ± 6 years and an average forced expiratory volume in one second (% predicted) of 27 ± 7%. A one-point increase in the score was associated with increased all-cause death, with a hazard ratio of 1.28 (95%CI: 1.21-1.36. P < 0.001). The areas under the receiver operating characteristic curves for two-year and five-year all-cause death for the new scale were 0.72 and 0.66, respectively. These values were higher than those given by the body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index and age, dyspnea, airway obstruction (ADO) index.

CONCLUSION

The preliminary validation for a new COPD prognostic scale: the COPD Prognostic Score was developed with promising results thus far. Above mentioned 16-point score accurately predicted 2-year and 5-year all-cause mortality among subjects who suffered from severe and very severe COPD.

Maximal Oxygen Uptake--Risk Predictor of NSCLC Resection in Patients With Comorbid Emphysema: Lessons From NETT

We compared VO2 max values from ACCP Guidelines and from NETT's homogenous NULPD surrogate for predicting operative mortalities. Estimated mid and long-term non-cancer related survival in NETT's subset was also obtained. NETT and ACCP Guideline VO2 max values were similar in the "low" and "mid" risk operative mortality categories but NETT's "high" risk subset showed lower mortality (14% vs. 26%). Estimated non-cancer related survival in NETT "low", "mid" and "high" risk VO2 max categories at two and eight years were 100%, 74%, 59% and 48%, 26%, 14%, respectively. The lower predicted risk in NETT's "high- risk" subset raises the possibility of extending indications for potential curative resection in selected patients. The NETT surrogate also provides hitherto unavailable estimate on long-term non-cancer related survival after potential curative resection of NSCLC and suggests that the operation does not shorten eight-year longevity.

Quantification of Improvements in Static and Dynamic Ventilatory Measures Following Lung Volume Reduction Surgery for Severe COPD

Rationale: This study quantitatively measured the effects of lung volume reduction surgery (LVRS) on spirometry, static and dynamic lung and chest wall volume subdivision mechanics, and cardiopulmonary exercise measures. Methods: Patients with severe COPD (mean FEV₁ = 23 ± 6% predicted) undergoing LVRS evaluation were recruited. Spirometry, plethysmography and exercise capacity were obtained within 6 months pre-LVRS and again within 12 months post- LVRS. Ventilatory mechanics were quantified using stationary optoelectronic plethysmography (OEP) during spontaneous tidal breathing and during maximum voluntary ventilation (MVV). Statistical significance was set at P< 0.05. Results:Ten consecutive patients met criteria for LVRS (5 females, 5 males, age: 62±6yrs). Post -LVRS (mean follow up 7 months ± 2 months), the group showed significant improvements in dyspnea scores (pre 4±1 versus post 2 ± 2), peak exercise workload (pre 37± 21 watts versus post 50 ± 27watts ), heart rate (pre 109±19 beats per minutes [bpm] versus post 118±19 bpm), duty cycle (pre 30.8 ± 3.8% versus post 38.0 ± 5.7%), and spirometric measurements (forced expiratory volume in 1 second [FEV₁] pre 23 ± 6% versus post 32 ± 13%, total lung capacity / residual lung volume pre 50 ± 8 versus 50 ± 11) . Six to 12 month changes in OEP measurements were observed in an increased percent contribution of the abdomen compartment during tidal breathing (41.2±6.2% versus 44.3±8.9%, P=0.03) and in percent contribution of the pulmonary ribcage compartment during MVV (34.5±10.3 versus 44.9±11.1%, P=0.02). Significant improvements in dynamic hyperinflation during MVV occurred, demonstrated by decreases rather than increases in end expiratory volume (EEV) in the pulmonary ribcage (pre 207.0 ± 288.2 ml versus post -85.0 ± 255.9 ml) and abdominal ribcage compartments (pre 229.1 ± 182.4 ml versus post -17.0 ± 136.2 ml) during the maneuver. Conclusions: Post-LVRS, patients with severe COPD demonstrate significant favorable changes in ventilatory mechanics, during tidal and maximal voluntary breathing. Future work is necessary to determine if these findings are clinically relevant, and extend to other environments such as exercise.

Evidence suggesting that oral corticosteroids increase mortality in stable chronic obstructive pulmonary disease

BACKGROUND

Oral corticosteroids were used to control stable chronic obstructive pulmonary disease (COPD) decades ago. However, recent guidelines do not recommend long-term oral corticosteroids (LTOC) use for stable COPD patients, partly because it causes side-effects such as respiratory muscle deterioration and immunosuppression. Nonetheless, the impact of LTOC on life prognosis for stable COPD patients has not been clarified.

METHODS

We used the data of patients randomized to non-surgery treatment in the National Emphysema Treatment Trial. Severe and very severe stable COPD patients who were eligible for volume reduction surgery were recruited at 17 clinical centers in the United States and randomized during 1998-2002. Patients were followed-up for at least five years. Hazard ratios for death by LTOC were estimated by three models using Cox proportional hazard analysis and propensity score matching.

RESULTS

The pre-matching cohort comprised 444 patients (prescription of LTOC: 23.0%. Age: 66.6 ± 5.4 year old. Female: 35.6%. Percent predicted forced expiratory volume in one second: 27.0 ± 7.1%. Mortality during follow-up: 67.1%). Hazard ratio using a multiple-variable Cox model in the pre-matching cohort was 1.54 (P = 0.001). Propensity score matching was conducted with 26 parameters (C-statics: 0.73). The propensity-matched cohort comprised of 65 LTOC(+) cases and 195 LTOC(-) cases (prescription of LTOC: 25.0%. Age: 66.5 ± 5.3 year old. Female: 35.4%. Percent predicted forced expiratory volume in one second: 26.1 ± 6.8%. Mortality during follow-up: 71.3%). No parameters differed between cohorts. The hazard ratio using a single-variable Cox model in the propensity-score-matched cohort was 1.50 (P = 0.013). The hazard ratio using a multiple-variable Cox model in the propensity-score-matched cohort was 1.73 (P = 0.001).

CONCLUSIONS

LTOC may increase the mortality of stable severe and very severe COPD patients.

Clinical utility of computed tomographic lung volumes in patients with chronic obstructive pulmonary disease

BACKGROUND

Published data concerning the utility of computed tomography (CT)-based lung volumes are limited to correlation with lung function.

OBJECTIVES

The aim of this study was to evaluate the clinical utility of the CT expiratory-to-inspiratory lung volume ratio (CT Vratio) by assessing the relationship with clinically relevant outcomes.

METHODS

A total of 75 stable chronic obstructive pulmonary disease (COPD) patients having pulmonary function testing and volumetric CT at full inspiration and expiration were retrospectively evaluated. Inspiratory and expiratory CT lung volumes were measured using in-house software. Correlation of the CT Vratio with patient-centered outcomes, including the modified Medical Research Council (MMRC) dyspnea score, the 6-min walk distance (6MWD), the St. George's Respiratory Questionnaire (SGRQ) score, and multidimensional COPD severity indices, such as the BMI, airflow obstruction, dyspnea, and exercise capacity index (BODE) and age, dyspnea, and airflow obstruction (ADO), were analyzed.

RESULTS

The CT Vratio correlated significantly with BMI (r = -0.528, p < 0.001). The CT Vratio was also significantly associated with MMRC dyspnea (r = 0.387, p = 0.001), 6MWD (r = -0.459, p < 0.001), and SGRQ (r = 0.369, p = 0.001) scores. Finally, the CT Vratio had significant correlations with the BODE and ADO multidimensional COPD severity indices (r = 0.605, p < 0.001; r = 0.411, p < 0.001).

CONCLUSION

The CT Vratio had significant correlations with patient-centered outcomes and multidimensional COPD severity indices.

[Alveolar epithelial cell injury as an etiopathogenic factor in pulmonary fibrosis]

Idiopathic pulmonary fibrosis (IPF) is characterized by a progressive accumulation of extracellular matrix and an imbalance between profibrotic and antifibrotic mediators. In the last few years, understanding of the mechanisms of the biology of IPF has increased. One of the most significant discoveries is the finding that alveolar epithelial cell injury plays an important role in the pathogenesis of this disease. In this review, we describe some of the mechanisms involved in alveolar cell injury and their contribution to the development of IPF.

Several clinical interests regarding lung volume reduction surgery for severe emphysema: meta-analysis and systematic review of randomized controlled trials

Objectives

We aim to address several clinical interests regarding lung volume reduction surgery (LVRS) for severe emphysema using meta-analysis and systematic review of randomized controlled trials (RCTs).

Methods

Eight RCTs published from 1999 to 2010 were identified and synthesized to compare the efficacy and safety of LVRS vs conservative medical therapy. One RCT was obtained regarding comparison of median sternotomy (MS) and video-assisted thoracoscopic surgery (VATS). And three RCTs were available evaluating clinical efficacy of using bovine pericardium for buttressing, autologous fibrin sealant and BioGlue, respectively.

Results

Odds ratio (95%CI), expressed as the mortality of group A (the group underwent LVRS) versus group B (conservative medical therapies), was 5.16(2.84, 9.35) in 3 months, 3(0.94, 9.57) in 6 months, 1.05(0.82, 1.33) in 12 months, respectively. On the 3^rd, 6^th and 12^th month, all lung function indices of group A were improved more significantly as compared with group B. PaO2 and PaCO2 on the 6^th and 12^th month showed the same trend. 6MWD of group A on the 6^th month and 12^th month were improved significantly than of group B, despite no difference on the 3^rd month. Quality of life (QOL) of group A was better than of group B in 6 and 12 months. VATS is preferred to MS, due to the earlier recovery and lower cost. And autologous fibrin sealant and BioGlue seems to be the efficacious methods to reduce air leak following LVRS.

Conclusions

LVRS offers the more benefits regarding survival, lung function, gas exchange, exercise capacity and QOL, despite the higher mortality in initial three postoperative months. LVRS, with the optimization of surgical approach and material for reinforcement of the staple lines, should be recommended to patients suffering from severe heterogeneous emphysema.

Lung deflation and oxygen pulse in COPD: results from the NETT randomized trial

BACKGROUND

In COPD patients, hyperinflation impairs cardiac function. We examined whether lung deflation improves oxygen pulse, a surrogate marker of stroke volume.

METHODS

In 129 NETT patients with cardiopulmonary exercise testing (CPET) and arterial blood gases (ABG substudy), hyperinflation was assessed with residual volume to total lung capacity ratio (RV/TLC), and cardiac function with oxygen pulse (O(2) pulse=VO(2)/HR) at baseline and 6 months. Medical and surgical patients were divided into "deflators" and "non-deflators" based on change in RV/TLC from baseline (∆RV/TLC). We defined deflation as the ∆RV/TLC experienced by 75% of surgical patients. We examined changes in O(2) pulse at peak and similar (iso-work) exercise. Findings were validated in 718 patients who underwent CPET without ABGs.

RESULTS

In the ABG substudy, surgical and medical deflators improved their RV/TLC and peak O(2) pulse (median ∆RV/TLC -18.0% vs. -9.3%, p=0.0003; median ∆O(2) pulse 13.6% vs. 1.8%, p=0.12). Surgical deflators also improved iso-work O(2) pulse (0.53 mL/beat, p=0.04 at 20 W). In the validation cohort, surgical deflators experienced a greater improvement in peak O(2) pulse than medical deflators (mean 18.9% vs. 1.1%). In surgical deflators improvements in O(2) pulse at rest and during unloaded pedaling (0.32 mL/beat, p<0.0001 and 0.47 mL/beat, p<0.0001, respectively) corresponded with significant reductions in HR and improvements in VO(2). On multivariate analysis, deflators were 88% more likely than non-deflators to have an improvement in O(2) pulse (OR 1.88, 95% CI 1.30-2.72, p=0.0008).

CONCLUSION

In COPD, decreased hyperinflation through lung volume reduction is associated with improved O(2) pulse.

Lung transplantation and lung volume reduction surgery

Since the publication of the last edition of the Handbook of Physiology, lung transplantation has become widely available, via specialized centers, for a variety of end-stage lung diseases. Lung volume reduction surgery, a procedure for emphysema first conceptualized in the 1950s, electrified the pulmonary medicine community when it was rediscovered in the 1990s. In parallel with their technical and clinical refinement, extensive investigation has explored the unique physiology of these procedures. In the case of lung transplantation, relevant issues include the discrepant mechanical function of the donor lungs and recipient thorax, the effects of surgical denervation, acute and chronic rejection, respiratory, chest wall, and limb muscle function, and response to exercise. For lung volume reduction surgery, there have been new insights into the counterintuitive observation that lung function in severe emphysema can be improved by resecting the most diseased portions of the lungs. For both procedures, insights from physiology have fed back to clinicians to refine patient selection and to scientists to design clinical trials. This section will first provide an overview of the clinical aspects of these procedures, including patient selection, surgical techniques, complications, and outcomes. It then reviews the extensive data on lung and muscle function following transplantation and its complications. Finally, it reviews the insights from the last 15 years on the mechanisms whereby removal of lung from an emphysema patient can improve the function of the lung left behind.

Mechanisms of gas exchange response to lung volume reduction surgery in severe emphysema

Lung volume reduction surgery (LVRS) improves lung function, respiratory symptoms, and exercise tolerance in selected patients with chronic obstructive pulmonary disease, who have heterogeneous emphysema. However, the reported effects of LVRS on gas exchange are variable, even when lung function is improved. To clarify how LVRS affects gas exchange in chronic obstructive pulmonary disease, 23 patients were studied before LVRS, 14 of whom were again studied afterwards. We performed measurements of lung mechanics, pulmonary hemodynamics, and ventilation-perfusion (Va/Q) inequality using the multiple inert-gas elimination technique. LVRS improved arterial Po₂ (Pa(O₂)) by a mean of 6 Torr (P = 0.04), with no significant effect on arterial Pco₂ (Pa(CO₂)), but with great variability in both. Lung mechanical properties improved considerably more than did gas exchange. Post-LVRS Pa(O₂) depended mostly on its pre-LVRS value, whereas improvement in Pa(O(2)) was explained mostly by improved Va/Q inequality, with lesser contributions from both increased ventilation and higher mixed venous Po(2). However, no index of lung mechanical properties correlated with Pa(O₂). Conversely, post-LVRS Pa(CO₂) bore no relationship to its pre-LVRS value, whereas changes in Pa(CO₂) were tightly related (r² = 0.96) to variables, reflecting decrease in static lung hyperinflation (intrinsic positive end-expiratory pressure and residual volume/total lung capacity) and increase in airflow potential (tidal volume and maximal inspiratory pressure), but not to Va/Q distribution changes. Individual gas exchange responses to LVRS vary greatly, but can be explained by changes in combinations of determining variables that are different for oxygen and carbon dioxide.

The minimal important difference of exercise tests in severe COPD

Our aim was to determine the minimal important difference (MID) for 6-min walk distance (6MWD) and maximal cycle exercise capacity (MCEC) in patients with severe chronic obstructive pulmonary disease (COPD). 1,218 patients enrolled in the National Emphysema Treatment Trial completed exercise tests before and after 4-6 weeks of pre-trial rehabilitation, and 6 months after randomisation to surgery or medical care. The St George's Respiratory Questionnaire (domain and total scores) and University of California San Diego Shortness of Breath Questionnaire (total score) served as anchors for anchor-based MID estimates. In order to calculate distribution-based estimates, we used the standard error of measurement, Cohen's effect size and the empirical rule effect size. Anchor-based estimates for the 6MWD were 18.9 m (95% CI 18.1-20.1 m), 24.2 m (95% CI 23.4-25.4 m), 24.6 m (95% CI 23.4-25.7 m) and 26.4 m (95% CI 25.4-27.4 m), which were similar to distribution-based MID estimates of 25.7, 26.8 and 30.6 m. For MCEC, anchor-based estimates for the MID were 2.2 W (95% CI 2.0-2.4 W), 3.2 W (95% CI 3.0-3.4 W), 3.2 W (95% CI 3.0-3.4 W) and 3.3 W (95% CI 3.0-3.5 W), while distribution-based estimates were 5.3 and 5.5 W. We suggest a MID of 26 ± 2 m for 6MWD and 4 ± 1 W for MCEC for patients with severe COPD.

Polymorphisms in surfactant protein-D are associated with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by alveolar destruction and abnormal inflammatory responses to noxious stimuli. Surfactant protein-D (SFTPD) is immunomodulatory and essential to host defense. We hypothesized that polymorphisms in SFTPD could influence the susceptibility to COPD. We genotyped six single-nucleotide polymorphisms (SNPs) in surfactant protein D in 389 patients with COPD in the National Emphysema Treatment Trial (NETT) and 472 smoking control subjects from the Normative Aging Study (NAS). Case-control association analysis was performed using Cochran-Armitage trend tests and multivariate logistic regression. The replication of significant associations was attempted in the Boston Early-Onset COPD Study, the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) Study, and the Bergen Cohort. We also correlated SFTPD genotypes with serum concentrations of surfactant protein-D (SP-D) in the ECLIPSE Study. In the NETT-NAS case-control analysis, four SFTPD SNPs were associated with susceptibility to COPD: rs2245121 (P = 0.01), rs911887 (P = 0.006), rs6413520 (P = 0.004), and rs721917 (P = 0.006). In the family-based analysis of the Boston Early-Onset COPD Study, rs911887 was associated with prebronchodilator and postbronchodilator FEV(1) (P = 0.003 and P = 0.02, respectively). An intronic SNP in SFTPD, rs7078012, was associated with COPD in the ECLIPSE Study and the Bergen Cohort. Multiple SFTPD SNPs were associated with serum SP-D concentrations in the ECLIPSE Study. We demonstrated an association of polymorphisms in SFTPD with COPD in multiple populations. We demonstrated a correlation between SFTPD SNPs and SP-D protein concentrations. The SNPs associated with COPD and SP-D concentrations differed, suggesting distinct genetic influences on susceptibility to COPD and SP-D concentrations.

Pulmonary hypertension and computed tomography measurement of small pulmonary vessels in severe emphysema

RATIONALE

Vascular alteration of small pulmonary vessels is one of the characteristic features of pulmonary hypertension in chronic obstructive pulmonary disease. The in vivo relationship between pulmonary hypertension and morphological alteration of the small pulmonary vessels has not been assessed in patients with severe emphysema.

OBJECTIVES

We evaluated the correlation of total cross-sectional area of small pulmonary vessels (CSA) assessed on computed tomography (CT) scans with the degree of pulmonary hypertension estimated by right heart catheterization.

METHODS

In 79 patients with severe emphysema enrolled in the National Emphysema Treatment Trial (NETT), we measured CSA less than 5 mm(2) (CSA(<5)) and 5 to 10 mm(2) (CSA(5-10)), and calculated the percentage of total CSA for the lung area (%CSA(<5) and %CSA(5-10), respectively). The correlations of %CSA(<5) and %CSA(5-10) with pulmonary arterial mean pressure (Ppa) obtained by right heart catheterization were evaluated. Multiple linear regression analysis using Ppa as the dependent outcome was also performed.

MEASUREMENTS AND MAIN RESULTS

The %CSA(<5) had a significant negative correlation with Ppa (r = -0.512, P < 0.0001), whereas the correlation between %CSA(5-10) and Ppa did not reach statistical significance (r = -0.196, P = 0.083). Multiple linear regression analysis showed that %CSA(<5) and diffusing capacity of carbon monoxide (DL(CO)) % predicted were independent predictors of Ppa (r(2) = 0.541): %CSA (<5) (P < 0.0001), and DL(CO) % predicted (P = 0.022).

CONCLUSIONS

The %CSA(<5) measured on CT images is significantly correlated to Ppa in severe emphysema and can estimate the degree of pulmonary hypertension.

Integration of genomic and genetic approaches implicates IREB2 as a COPD susceptibility gene

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide and is influenced by both genetic determinants and smoking. We identified genomic regions from 56 lung-tissue gene-expression microarrays and used them to select 889 SNPs to be tested for association with COPD. We genotyped SNPs in 389 severe COPD cases from the National Emphysema Treatment Trial and 424 cigarette-smoking controls from the Normative Aging Study. A total of 71 autosomal SNPs demonstrated at least nominal significance with COPD susceptibility (p = 3.4 x 10(-6) to 0.05). These 71 SNPs were evaluated in a family-based study of 127 probands with severe, early-onset COPD and 822 of their family members in the Boston Early-Onset COPD Study. We combined p values from the case-control and family-based analyses, setting p = 5.60 x 10(-5) as a conservative threshold for significance. Three SNPs in the iron regulatory protein 2 (IREB2) gene met this stringent threshold for significance, and four other IREB2 SNPs demonstrated combined p < 0.02. We demonstrated replication of association for these seven IREB2 SNPs (all p values < or = 0.02) in a family-based study of 3117 subjects from the International COPD Genetics Network; combined p values across all cohorts for the main phenotype of interest ranged from 1.6 x 10(-7) to 6.4 x 10(-4). IREB2 protein and mRNA were increased in lung-tissue samples from COPD subjects in comparison to controls. In summary, gene-expression and genetic-association results have implicated IREB2 as a COPD susceptibility gene.

The National Emphysema Treatment Trial: summary and update

Surgery for severe emphysema involves a cohort of patients who are already at risk for increased perioperative morbidity and mortality. Through the careful screening and selection process, improved intraoperative techniques and rigorous attention to postoperative care, the NETT managed to yield acceptable improvements in survival and functional outcomes in this fragile patient cohort and these benefits were sustained over the long-term. Identification of the characteristics associated with a higher risk of death has provided tangible patient selection criteria for the ongoing application of LVRS. Because the NETT was such a large-scale study, the protocols that were developed had to be standardized across several centers. This produced reliable and reproducible standards for evaluation and treatment that can be applied to the surgical treatment of emphysema. When considering these criteria, although individualized patient selection is important, only patients with upper-lobe predominant disease on chest CT and possibly those with non-upper-lobe predominant disease who also have low baseline exercise capacity are appropriate candidates for LVRS. Expectedly, questions remain regarding the exact mechanism whereby the benefits derived from LVRS are obtained. Additionally, the benefit of LVRS in patients with heterogeneous but non-upper-lobe predominant disease remains to be further elucidated. In spite of the limitations of the study, the NETT, through a tremendous coordinated effort, provided valuable outcomes data, answered the pressing questions regarding lung volume reduc-tion surgery that existed at the time, and provided valuable insight into other facets of emphysema physiology and management through direct observation. Based on the NETT findings, in November 2003, CMS published criteria for expanded coverage for LVRS to include non-high-risk patients who demonstrated either upper-lobe predominant emphysema, or non-upper-lobe predominant emphysema and low baseline exercise capacity and who met the screening guidelines.29 This study not only provided data regarding the clinical efficacy of LRVS, but it was instrumental in determining health policy guidelines for the surgical management of emphysema.

Integrating health status and survival data: the palliative effect of lung volume reduction surgery

RATIONALE

In studies that address health-related quality of life (QoL) and survival, subjects who die are usually censored from QoL assessments. This practice tends to inflate the apparent benefits of interventions with a high risk of mortality. Assessing a composite QoL-death outcome is a potential solution to this problem.

OBJECTIVES

To determine the effect of lung volume reduction surgery (LVRS) on a composite endpoint consisting of the occurrence of death or a clinically meaningful decline in QoL defined as an increase of at least eight points in the St. George's Respiratory Questionnaire total score from the National Emphysema Treatment Trial.

METHODS

In patients with chronic obstructive pulmonary disease and emphysema randomized to receive medical treatment (n = 610) or LVRS (n = 608), we analyzed the survival to the composite endpoint, the hazard functions and constructed prediction models of the slope of QoL decline.

MEASUREMENTS AND MAIN RESULTS

The time to the composite endpoint was longer in the LVRS group (2 years) than the medical treatment group (1 year) (P < 0.0001). It was even longer in the subsets of patients undergoing LVRS without a high risk for perioperative death and with upper-lobe-predominant emphysema. The hazard for the composite event significantly favored the LVRS group, although it was most significant in patients with predominantly upper-lobe emphysema. The beneficial impact of LVRS on QoL decline was most significant during the 2 years after LVRS.

CONCLUSIONS

LVRS has a significant effect on the composite QoL-survival endpoint tested, indicating its meaningful palliative role, particularly in patients with upper-lobe-predominant emphysema.

Pulmonary hypertension associated with lung transplantation obliterative bronchiolitis and vascular remodeling of the allograft

Pathologic obliterative bronchiolitis (OB)/Bronchiolitis obliterans syndrome (pathologic OB/BOS) is the major obstacle to long-term survival post-lung transplantation (LT). Our group has demonstrated that pulmonary hypertension (PH) complicates the course of chronic inflammatory lung diseases that have similarities to pathologic OB/BOS and that vascular remodeling of the bronchial circulation occurs during BOS. Consequently, we hypothesized that PH is associated with pathologic OB/BOS and may result from a vasculopathy of the allograft pulmonary circulation. We conducted a single-center, retrospective study and examined the presence of PH and vasculopathy in patients with pathologic OB/BOS. Fifty-two pathologic specimens post-LT were recovered from January 10, 1997 to January 5, 2007 and divided into two groups, those with and without pathologic OB/BOS.PH was defined as a mean pulmonary artery pressure (mPAP) > 25 mmHg by right heart catheterization (RHC) or right ventricular systolic pressure (RVSP) > or = 45 mmHg by transthoracic echocardiogram (TTE). PH was more prevalent in those LT recipients with pathologic OB/BOS (72% vs. 0%, p = 0.003). Furthermore, pulmonary arteriopathy and venopathy were more prevalent in patients with pathologic OB/BOS (84% vs. 4%, p < 0.0001, and 77% vs. 35%, p = 0.004, respectively). PH is common in LT recipients with pathologic OB/BOS and is associated with a vasculopathy of the allograft pulmonary circulation.

Lung volume reduction surgery: technique, operative mortality, and morbidity

The objective of lung volume reduction surgery (LVRS) is the safe, effective, and durable palliation of dyspnea in appropriately selected patients with moderate to severe emphysema. Appropriate patient selection and preoperative preparation are prerequisites for successful LVRS. An effective LVRS program requires participation by and communication between experts from pulmonary medicine, thoracic surgery, thoracic anesthesiology, critical care medicine, rehabilitation medicine, respiratory therapy, chest radiology, and nursing. The critical analysis of perioperative outcomes has influenced details of the conduct of the procedure and has established a bilateral, stapled approach as the standard of care for LVRS. The National Emphysema Treatment Trial (NETT) remains the world's largest multi-center, randomized trial comparing LVRS to maximal medical therapy. NETT purposely enrolled a broad spectrum of anatomic patterns of emphysema. This, along with the prospective, audited collection of extensive demographic, physiologic, radiographic, surgical and quality-of-life data, has positioned NETT as the most robust repository of evidence to guide the refinement of patient selection criteria for LVRS, to assist surgeons in providing optimal intraoperative and postoperative care, and to establish benchmarks for survival, complication rates, return to independent living, and durability of response. This article reviews the evolution of current LVRS practice with a particular emphasis on technical aspects of the operation, including the predictors and consequences of its most common complications.

Costs of pulmonary rehabilitation and predictors of adherence in the National Emphysema Treatment Trial

This study reports the costs associated with rehabilitation among participants in the National Emphysema Treatment Trial (NETT), and evaluates factors associated with adherence to rehabilitation. Pulmonary rehabilitation is recommended for moderate-to-severe COPD and required by the Centers for Medicare and Medicaid Services (CMS) prior to lung volume reduction surgery (LVRS). Between January 1998 and July 2002, 1,218 subjects with emphysema and severe airflow limitation (FEV(1) < or = 45% predicted) were randomized. Primary outcome measures were designated as mortality and maximal exercise capacity 2 years after randomization. Pre-randomization, estimated mean total cost per patient of rehabilitation was $2,218 (SD $314; 2006 dollars) for the medical group and $2,187 (SD $304) for the surgical group. Post-randomization, mean cost per patient in the medical and surgical groups was $766 and $962 respectively. Among patients who attended > or = 1 post-randomization rehabilitation session, LVRS patients, patients with an FEV(1) > or = 20% predicted, and higher education were significantly more likely to complete rehabilitation. Patients with depressive and anxiety symptoms, and those who live > 36 miles compared to < 6 miles away were less likely to be adherent. Patients who underwent LVRS completed more exercise sessions than those in the medical group and were more likely to be adherent with post-randomization rehabilitation. A better understanding of patient factors such as socioeconomic status, depression, anxiety and transportation issues may improve adherence to pulmonary rehabilitation.

A forensic evaluation of the National Emphysema Treatment Trial using the expected value of information approach

BACKGROUND/RATIONALE

Expected value of information (EVI) analyses allow researchers to estimate the returns to conducting research. We used EVI techniques to estimate the value of the National Emphysema Treatment Trial (NETT), a multicenter randomized trial of lung-volume-reduction surgery (LVRS) versus medical therapy (MT) for patients with severe emphysema, then compared that result to the trial cost.

METHODS

We gathered information on costs and benefits of LVRS and MT before the trial and the costs of conducting the NETT, and compared these data with the results of the cost-effectiveness analysis conducted alongside the trial. We used 2 thresholds to represent the societal value of a quality-adjusted life year (QALY): USD 50,000 and USD100,000.

RESULTS

The cost effectiveness of LVRS versus MT using historical (nontrial) information was USD 305,000/QALY. Based on these data and the threshold incremental cost-effectiveness ratio values, the expected value of perfect information was USD 46 million and USD 670 million for thresholds USD 50,000 and USD 100,000 per QALY, respectively. The NETT was powered for 1,250 patients in each arm; ultimately approximately 600 patients in each arm were recruited. With 1,250 patients per arm, the expected value of sample information was USD 660 million for the threshold of USD100,000. The actual cost of the NETT was approximately USD 60 million. The expected net benefit of sampling was USD 600 million.

CONCLUSIONS

Given the difference between the cost of the trial and the economic benefits of the information, the EVI analyses suggest that federal investment in the NETT trial represented good value for money.

Polymorphic variation in surfactant protein B is associated with COPD exacerbations

Exacerbations of chronic obstructive pulmonary disease (COPD) reduce quality of life and increase mortality. Genetic variation might explain the substantial variability seen in exacerbation frequency among COPD subjects with similar lung function. Polymorphisms in five candidate genes, previously associated with COPD susceptibility, were analysed in order to determine whether they demonstrated association with COPD exacerbations. A total of 88 single nucleotide polymorphisms (SNPs) in the genes microsomal epoxide hydrolase (EPHX1), transforming growth factor, beta-1 (TGFB1), serpin peptidase inhibitor, clade E (nexin, plasminogen activator inhibitor type 1), member 2 (SERPINE2), glutathione S-transferase pi (GSTP1) and surfactant protein B (SFTPB) were genotyped in 389 non-Hispanic white participants in the National Emphysema Treatment Trial. Exacerbations were defined as COPD-related emergency room visits or hospitalisations using the Centers for Medicare and Medicaid Services claims data. One or more exacerbations were experienced by 216 (56%) subjects during the study period. An SFTPB promoter polymorphism, rs3024791, was associated with COPD exacerbations. Logistic regression models, analysing a binary outcome of presence or absence of exacerbations, confirmed the association of rs3024791 with COPD exacerbations. Negative binomial regression models demonstrated association of multiple SFTPB SNPs (rs2118177, rs2304566, rs1130866 and rs3024791) with exacerbation rates. Polymorphisms in EPHX1, GSTP1, TGFB1 and SERPINE2 did not demonstrate association with COPD exacerbations. In conclusion, genetic variation in surfactant protein B is associated with chronic obstructive pulmonary disease susceptibility and exacerbation frequency.

New simple classification for operated bullous emphysema

OBJECTIVES

Optimal results in bullectomy depend on both the size of the resected bulla volume and the reexpansion of the adjacent collapsed healthy pulmonary parenchyma. We hypothesized that the bigger the bulla is compared with residual volume, the greater are the possible benefits. We suggested a new prognostic classification according to bulla volume and its relationship with residual volume.

METHODS

We retrospectively reviewed 121 patients with emphysematous bulla (>200 mL) who, from 1996 to 2006, underwent unilateral single (n = 64), unilateral multiple (n = 16), bilateral 1-stage (n = 9), and bilateral 2-stage (n = 32) bullectomies. Bulla volume and residual volume were measured by computed tomography and body plethysmography, respectively. Six-month postoperative decrement of residual volume values and their persistence below the baseline for 5 years were considered primary outcomes. Logistic regression was used to select significant variables. The receiver operating characteristic curve was used to identify the cutoff point for a possible classification system.

RESULTS

There was no postoperative mortality. Significant postoperative improvements in respiratory function were found and correlated with bulla size. Residual volume improved in 75 patients (62%) and persisted in 20 patients (35% of the patients followed for > 5 years). Logistic regression selected bulla/residual volume ratio as the most predictive variable for both outcomes (P < .0001). The best cutoff individuated by the receiver operating characteristic curve analysis was 20% to achieve a high probability of residual volume improvement and 30% to minimize residual volume recurrence.

CONCLUSIONS

Bullectomy provides good results, but more significant and long-lasting improvements are achievable with a greater ratio bulla/residual volume: scant for less than 20%, good but temporaneous for 20% to 30%, and good and long-lasting results for more than 30%.

Surgery for lung metastases from colorectal cancer: the practice examined

Operations to remove metastases in the lung have become commonplace. In this article, I give a highly critical perspective of a practice that has grown without a secure evidence base, notwithstanding more than 500 articles on the subject. The objectives are mixed and sometimes unclear. The reports are generally in the form of Kaplan-Meier survival analyses but, when challenged on the expected benefit for individuals, clinicians tend to retreat to claims for palliation rather than for 'cure'. Yet the reports include no symptom checklists, quality-of-life measures or patient-reported outcomes. I see at least four distinguishable contexts, defined by cancer types, which deserve to be considered separately: sarcoma; testicular and germ cell tumors; cancers traditionally seen as having an 'oligometastatic' pattern of behavior, such as kidney and thyroid; and the more common solid cancers, such as colorectal and breast cancer. Most surgical series group them together with a tail of one, two or three instances of the less common cancers. The inclusion in these series of all cancer types operated upon adds nothing to knowledge on cancers with low numbers and complicates the analysis for the more common ones. In this article, I will confine the discussion for the main part to colorectal cancer, which is the most common cancer in which pulmonary metastasectomy is practiced.

The effect of lung volume reduction surgery on chronic obstructive pulmonary disease exacerbations

RATIONALE

Lung volume reduction surgery (LVRS) has been demonstrated to provide a functional and mortality benefit to a select group of subjects with chronic obstructive pulmonary disease (COPD). The effect of LVRS on COPD exacerbations has not been as extensively studied, and whether improvement in postoperative lung function alters the risk of disease exacerbations is not known.

OBJECTIVES

To examine the effect, and mechanism of potential benefit, of LVRS on COPD exacerbations by comparing the medical and surgical cohorts of the National Emphysema Treatment Trial (NETT).

METHODS

A COPD exacerbation was defined using Centers for Medicare and Medicaid Services data and International Classification of Diseases, Ninth Revision, discharge diagnosis.

MEASUREMENTS AND MAIN RESULTS

There was no difference in exacerbation rate or time to first exacerbation between the medical and surgical cohorts during the year before study randomization (P = 0.58 and 0.85, respectively). Postrandomization, the surgical cohort experienced an approximate 30% reduction in exacerbation frequency (P = 0.0005). This effect was greatest in those subjects with the largest postoperative improvement in FEV(1) (P = 0.04) when controlling for changes in other spirometric measures of lung function, lung capacities, and room air arterial blood gas tensions. Finally, LVRS increased the time to first exacerbation in both those subjects with and those without a prior history of exacerbations (P = 0.0002 and P < 0.0001, respectively).

CONCLUSIONS

LVRS reduces the frequency of COPD exacerbations and increases the time to first exacerbation. One explanation for this benefit may be the postoperative improvement in lung function.

Lung elastic recoil does not correlate with pulmonary hemodynamics in severe emphysema

BACKGROUND

It has been postulated that right ventricular (RV) function may improve after lung volume reduction surgery (LVRS) for severe emphysema due to improvement in lung elastic recoil. Improved lung elastic recoil after LVRS is hypothesized to "tether" open extraalveolar vessels, thereby leading to a decrease in pulmonary vascular resistance (PVR) and improved RV function. Whether a relationship exists between static elastic lung recoil and pulmonary hemodynamics in severe emphysema, however, is unknown.

METHODS

We prospectively studied 67 patients with severe emphysema (32 women; mean age, 65.3+/-6.6 years [SD]; mean FEV1, 0.79+/-0.25 L) who had hyperinflation (total lung capacity [TLC], 122.5+/-12.3% of predicted) and gas trapping (residual volume, 209.1+/-41.1% of predicted), and were referred to the National Emphysema Treatment Trial. Lung elastic recoil was measured both at TLC (coefficient of retraction [CR]) and at functional reserve capacity (CR at functional residual capacity [CRfrc]) in each patient.

RESULTS

CR and CRfrc values were 1.3+/-0.6 cm H2O/L and 0.61+/-0.5 cm H2O/L, respectively. Hemodynamic measurements revealed a pulmonary artery (PA) systolic pressure of 35.9+/-8.9 mm Hg, mean PA pressure of 24.8+/-5.6 mm Hg, and PVR of 174+/-102 dyne*s*cm(-5). No significant correlations were found between CR and PVR (R=-0.046, p=0.71), PA systolic pressure (R=0.005, p=0.97), or mean PA pressure (R=-0.028, p=0.82). Additionally, no significant correlations were found between CRfrc and PVR (R=-0.002, p=0.99), PA systolic pressure (R=-0.062, p=0.62), or mean PA pressure (R=-0.041, p=0.74).

CONCLUSIONS

We conclude there is no correlation between lung elastic recoil and pulmonary hemodynamics in severe emphysema, suggesting that elastic lung recoil is not an important determinant of secondary pulmonary hypertension in this group. Registered with www. clinicaltrials.gov, #NCT00000606.

Physiologic variables and functional status independently predict COPD hospitalizations and emergency department visits in patients with severe COPD

Using clinical and claims records from the National Emphysema Treatment Trial, we sought to identify factors that accurately predicted COPD exacerbations. This prospective cohort study consisted of subjects with severe emphysema randomized to medical therapy. Exacerbations were defined as a hospitalization or emergency department visit for COPD. Patient characteristics obtained before randomization were entered as independent variables in multivariable logistic regression models to estimate the risk of exacerbation. Discrimination was determined using the area under the receiver operator characteristic curve (AUC). Baseline measures included demographics, body mass index, pulmonary function, arterial blood gases, radiology studies, dyspnea (Shortness of Breath Questionnaire - SOBQ), health-related quality of life (St. George's Respiratory Questionnaire - SGRQ), 6-minute walk, exercise capacity, medication use, prior exacerbations and co-morbidity. In 610 participants, 26.6% had a COPD exacerbation over 1-year follow-up. In a model incorporating spirometry, PaO2, dyspnea, prior exacerbations and co-morbidity, a 5-point decrement in percent predicted FEV1 (OR 1.16, 95% CI 1.00-1.34) and a 5-point worsening in SOBQ (OR 1.08, 1.02-1.14) independently predicted exacerbations (AUC for full model 0.68). Combining physiologic variables, dyspnea, prior exacerbations and co-morbidity may be useful in identifying patients at high risk for COPD exacerbations.

Lessons from the National Emphysema Treatment Trial

Medicare coverage for lung volume reduction surgery has been approved recently by the Centers for Medicare and Medicaid Services for the treatment of severe emphysema. The scientific basis for this approval stems largely from findings of the National Emphysema Treatment Trial (NETT). The purpose of this article is to review the contributions of the NETT to the management of chronic obstructive pulmonary disease.

Optimizing the Selection of Surgical Candidates for Lung Volume Reduction Surgery

The optimal selection of patients for lung volume reduction surgery (LVRS) is currently based on empiric clinical findings. Patients who benefit from LVRS have the common characteristics of impaired quality of life associated with apical predominant pulmonary hyperinflation and airflow obstruction. Within this category, patients who do not benefit from LVRS appear to have small airways disease that can be detected by inspiratory resistance studies. In addition to appropriate emphysema physiology, the selection of patients for LVRS must consider medical comorbidities and perioperative risk factors. Based on findings of the National Emphysema Treatment Trial, most of the perioperative morbidity and mortality of LVRS is associated with cardiopulmonary risk that needs to be considered preoperatively. Finally, a preoperative conditioning program can provide an additional screening process to identify patients physically and emotionally prepared for surgery.

Lung-volume reduction surgery for pulmonary emphysema: Improvement in body mass index, airflow obstruction, dyspnea, and exercise capacity index after 1 year

OBJECTIVES

We hypothesized that lung-volume reduction surgery for pulmonary emphysema would improve body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index, a multidimensional predictor of survival in chronic obstructive pulmonary disease. We also aimed to identify preoperative predictors of improvement in the BODE index.

METHODS

In a prospective cohort study of patients undergoing lung-volume reduction surgery at our center, with the methodology of the National Emphysema Treatment Trial, we compared clinical characteristics before and 1 year after surgery with the Wilcoxon signed rank test. Changes in the BODE index were correlated with preoperative variables with the Spearman correlation coefficient.

RESULTS

Twenty-three patients with predominantly upper-lobe pulmonary emphysema underwent lung-volume reduction surgery (14 by video-assisted thoracoscopic surgery, 9 by median sternotomy). There were no postoperative or follow-up deaths. The BODE index improved from a median of 5 (interquartile range 4-5) before surgery to 3 (interquartile range 2-4) 1 year after surgery (P < .0001). Improvements were seen in the lung function and dyspnea components of the BODE index. Lower preoperative 6-minute walk distance and lower postwalk Borg fatigue scores were each associated with greater improvement in the BODE index after 1 year.

CONCLUSION

Lung-volume reduction surgery for pulmonary emphysema improved the BODE index in patients with predominantly upper-lobe disease. Lower preoperative 6-minute walk distance correlated with greater improvement in the BODE index.

Updated evaluation of the cost-effectiveness of lung volume reduction surgery

BACKGROUND

The National Emphysema Treatment Trial, a randomized clinical trial of lung volume reduction surgery (LVRS) vs medical therapy for severe emphysema, included a prospective economic analysis. We present an updated analysis of cost-effectiveness with 1-year additional follow-up data.

METHODS

Following pulmonary rehabilitation, 1,218 patients at 17 medical centers were randomized to receive LVRS or continued medical treatment. The cost-effectiveness of LVRS vs medical therapy was calculated over the duration of the trial (January 1998 to December 2003) and estimated at 10 years using modeling based on observed trends in survival, cost, and quality of life.

RESULTS

The cost-effectiveness of LVRS vs medical therapy was $140,000 per quality-adjusted life-year (QALY) gained (95% confidence interval, $40,155 to $239,359) at 5 years, and was projected to be $54,000 per QALY gained at 10 years. In subgroup analysis, the cost-effectiveness of LVRS in patients with upper-lobe emphysema and low exercise capacity was $77,000 per QALY gained at 5 years, and was projected to be $48,000 per QALY at 10 years. Compared to the initial results, the updated results are similar for the overall cohort but vary substantially for the subgroups.

CONCLUSIONS

LVRS is costly relative to other health-care programs during the time horizon when costs and outcomes are known. The extended follow-up period offers more certainty regarding the long-term value and economic impact of this procedure.

Maximum exercise as an outcome in COPD: minimal clinically important difference

Limitation of physical activity occupies a central role in the symptom complex of patients with chronic obstructive pulmonary disease (COPD), and improvement in exercise capacity is a key outcome of response to COPD therapy. Maximum exercise capacity testing facilitates assessment of physiologic mechanisms of exercise and allows quantitation of the degree of limitation. This manuscript utilizes published data from the National Emphysema Treatment Trial to investigate the minimal clinically important difference (MCID) in maximum exercise capacity in patients with severe emphysema. Distribution- and opinion-based methods were used to estimate MCID. Expert clinician opinion yielded a value of 10 Watts as the MCID for change in maximum exercise capacity. Baseline standard deviation and error data yielded a one-half standard deviation-based estimate of 10.5 Watts and a standard error-based estimate of 4.2 Watts. In subjects randomized to medical therapy, the mean (+/-SD) 24-month change in maximum exercise capacity following medical therapy was -9.2 +/- 1.2 Watts, whereas among those randomized to lung volume reduction surgery, mean 24-month change in maximum exercise capacity was 1.7 +/- 17.7 Watts, with a mean difference between the groups of 10.9 Watts. The observed difference in maximum exercise capacity after 24 months between subjects randomized to medical versus surgical therapy conforms to both opinion- and distribution-based estimates of MCID. Further investigation is needed to develop and validate estimates of MCID for maximum exercise capacity and other key clinical outcomes in COPD.

Lung volume reduction surgery in patients with emphysema and alpha-1 antitrypsin deficiency

BACKGROUND

The role of lung volume reduction surgery (LVRS) for individuals with alpha-1 antitrypsin (AAT) deficiency is unclear.

METHODS

To assess the role of LVRS in individuals with severe deficiency of AAT, outcomes within the National Emphysema Treatment Trial were analyzed.

RESULTS

Of 1218 randomized subjects, 16 (1.3%) had severe AAT deficiency (serum level < 80 mg/dL) and a consistent phenotype (when available). Characteristics of these 16 patients include 87.5% male; median serum AAT level, 55.5 mg/dL; age, 66 years; forced expiratory volume in 1 second (FEV1), 27% predicted; and 50% had upper-lobe-predominant emphysema. All 10 subjects randomized to LVRS underwent the procedure. Although the small number of subjects hampered statistical analysis, 2-year mortality was higher with surgery (20% versus 0%) than with medical treatment. Comparison of outcomes between the 10 AAT-deficient and the 554 AAT-replete subjects undergoing LVRS showed a greater increase in exercise capacity at 6 months in replete subjects and a trend toward lower and shorter duration FEV1 rise in deficient individuals.

CONCLUSIONS

This study extends to 49 cases the published experience of LVRS in severe AAT deficiency. Although the small number of subjects precludes firm conclusions, trends of lower magnitude and duration of FEV1 rise after surgery in AAT-deficient versus AAT-replete subjects and higher mortality in deficient individuals randomized to surgery versus medical treatment suggest caution in recommending LVRS in AAT deficiency.

Lung volume reduction surgery for diffuse emphysema

BACKGROUND

Lung volume reduction surgery (LVRS) has been re-introduced for treating patients with severe diffuse emphysema. It is a procedure that aims to improve long-term daily functioning, although it is costly and may also be associated with a high risk of mortality.

OBJECTIVES

To assemble evidence from randomised controlled trials for the effectiveness of LVRS, and identify optimal surgical techniques.

SEARCH STRATEGY

Randomised controlled trials were identified using the Cochrane Airways Group Chronic Obstructive Pulmonary Disease (COPD) register. Searches are current to September 2005.

SELECTION CRITERIA

Randomised controlled trials that studied the safety and efficacy of LVRS in patients with diffuse emphysema were included. Studies were excluded if they investigated giant or bullous emphysema.

DATA COLLECTION AND ANALYSIS

Two independent review authors assessed trials for inclusion and extracted data. Where possible, data from more than one study were combined using RevMan 4.2 software.

MAIN RESULTS

Eight studies (1663 participants) met the entry criteria of the review. One study accounted for 73% of the participants recruited. Study quality was high, although blinding in studies was not possible. Ninety day mortality was significantly greater in all those who underwent LVRS (odds ratio 6.57 (95% CI 3.34 to 12.95), four studies, N = 1415). A subgroup analysis by risk status suggested that there was a subgroup of participants who were consistently at a significant risk of death, although this was only measured in one large study. The ninety day mortality data indicated that death was more likely with LVRS irrespective of risk status identified in one large study. Improvements in lung function, quality of life and exercise capacity were more likely with LVRS than with usual follow-up.

AUTHORS' CONCLUSIONS

The evidence summarised in this review is drawn from one large study, and several smaller trials. The findings from the large study indicated that in patients who survive up to three months post-surgery, there were significantly better health status and lung function outcomes in favour of surgery compared with usual medical care. Patients identified post hoc as being of high risk of death from surgery were those with particularly impaired lung function and poor diffusing capacity and/or homogenous emphysema. Further research should address the effect of this intervention on exacerbations and rate of decline in lung function and health status.