Effects of lung volume reduction surgery on gas exchange and breathing pattern during maximum exercise

Surgical and Interventional Approaches in COPD

Many patients suffer from complaints of dyspnea, cough, and sputum production, clinical symptoms that hallmark the structural abnormalities that are present in patients with COPD. Although pharmacologic and non-pharmacologic medical therapies help reduce these symptoms, many of these symptoms, especially dyspnea, remain unchecked and contribute to the burden of disease in patients with COPD. Over the last 3 decades, several surgical and interventional treatments delivered via a bronchoscopic approach have been developed to complement medical therapies and show promise to improve patient outcomes. Surgical and interventional treatments target structural abnormalities of the airway and lung parenchyma that can be identified with a combination of imaging and physiological testing, factors that are key to select patients most likely to benefit from these treatments. This paper reviews surgical and bronchoscopic interventional treatment options for patients with emphysema and airways disorders.

Analysis of Influencing Factors for Exercise Ventilation Efficiency of COPD Patients

Dynamic pulmonary hyperinflation and abnormal air exchange are the primary causes of the exercise limitation of chronic obstructive pulmonary disease (COPD) patients. During exercise, COPD sufferers' lungs are dynamically hyperinflated. Increased inefficient ventilation reduces ventilation efficiency and causes a mismatch between ventilation volume and blood flow. The ventilatory equivalent for CO2 (VeqCO2) is a physiological parameter that can be measured using cardiopulmonary exercise testing. Therefore, the aim of this exploratory study was to perform cardiopulmonary exercise testing on people with COPD, investigate the impact of static pulmonary function on ventilation efficiency under the exercise state, and screen the predictive indicators of ventilation efficiency. Subject. The aim of this study was to look at the factors that influence the exercise ventilation efficiency of people with COPD. Method. A total of 76 people with COPD were recruited during the stable period. Age, gender, body height, body mass, and other basic information were recorded. The body mass index (BMI) was determined, and forced vital capacity (FVC), forced expiratory volume in one second (FEV1), residual volume/total lung capacity (RV/TLC), diffusing capacity of the lung for carbon monoxide (DLCO), and DLCO divided by the alveolar volume (DLCO/VA) were measured. The ventilatory equivalent for carbon dioxide (VE/VCO2) under the rest state (EqCO2rest), anaerobic threshold (EqCO2at), and maximum exercise state (EqCO2 max) were calculated to investigate the influencing factors for ventilation efficiency of people with COPD. Results. FEV1% was negatively correlated with EqCO2rest (r = -0.277, P value <0.05); FEV1/FVC % was negatively correlated with EqCO2rest and EqCO2at (r = -0.311, -0.287, P value <0.05); DLCO% was negatively correlated with EqCO2rest, EqCO2at, and EqCO2max (r = -0.408, -0.462, and -0.285, P value <0.05); DLCO/VA% was negatively correlated with EqCO2rest, EqCO2at, and EqCO2max (r = -0.390, -0.392, and -0.245, P value <0.05); RV/TLC was positively correlated with EqCO2rest and EqCO2at (r = 0.289, 0.258, P-value <0.05). The prediction equation from the multivariable regression analysis equation was Y = 40.04-0.075X (Y = EqCO2, X = DLCO/VA%). Conclusions. As the degree of ventilatory obstruction increased, the ventilation efficiency of the stable people with COPD under the exercise state showed a progressive decrease; the ventilation efficiency of the people with COPD decreased significantly under the maximum exercise state, and the ventilation capacity and diffusion capacity were the significant factors that affected the exercise ventilation efficiency. The diffusion function may predict the maximum ventilation efficiency and enable primary hospitals without exercise test equipment in developing countries to predict and screen patients at risk for current exercise based on limited information.

Chest three-dimensional-computed tomography imaging data analysis for the variation of exercise capacity after lung lobectomy

BACKGROUND

Postoperative loss of exercise capacity and pulmonary function is a major concern among lung cancer patients. In this study, the time for a stair-climbing to 12-m height was used to investigate whether preoperative chest 3D-computed tomography (CT) could be a useful tool for predicting postoperative variations in exercise capacity and pulmonary function.

METHODS

Seventy-eight patients undergoing lobectomy for suspected stage I lung cancer were prospectively enrolled. Preoperatively, lobe volume and low attenuation volume (LAV) were evaluated using the SYNAPSE VINCENT system. Preoperative data on stair-climbing time, spirometry, and diffusing capacity of the lung for carbon monoxide (DL_CO ) at baseline and 6-month postoperative data were used to evaluate variations in exercise capacity and pulmonary function. Maximal oxygen uptake (VO₂ t) was evaluated based on the stair-climbing time.

RESULTS

Significant differences in the variation of exercise capacity at 6 months postoperatively were found between the groups categorized by target lobe volume and LAV status: The large volume/LAV (+) group had a greater decline in VO₂ t. Mean loss of VO₂ t was -6.2%, -1.4%, -1.6%, and -0.1% in the large volume/LAV (+), large volume/LAV (-), small volume/LAV (+), and small volume/LAV (-) groups, respectively. The large volume/LAV (-) group had a greater decline in forced expiratory volume in 1 s. The small volume/LAV (+) group showed a reduced decline in the DL_CO .

CONCLUSIONS

Analysis of chest 3D-CT scans is a potential tool for predicting the loss of exercise capacity and pulmonary function after lung lobectomy. This article is protected by copyright. All rights reserved.

Lung Function Testing in Chronic Obstructive Pulmonary Disease

Lung function testing has undisputed value in the comprehensive assessment and individualized management of chronic obstructive pulmonary disease, a pathologic condition in which a functional abnormality, poorly reversible expiratory airway obstruction, is at the core of its definition. After an overview of the physiologic underpinnings of the disease, the authors outline the role of lung function testing in this disease, including diagnosis, assessment of severity, and indication for and responses to pharmacologic and nonpharmacologic interventions. They discuss the current controversies surrounding test interpretation with these purposes in mind and provide balanced recommendations to optimize their usefulness in different clinical scenarios.

The effects of lung volume reduction treatment on diffusing capacity and gas exchange

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.

Surgical Therapies for Chronic Obstructive Pulmonary Disease

Patients with severe chronic obstructive pulmonary disease who fail maximal medical therapy and bronchoscopic interventions have surgical options to improve lung function, quality of life, and exercise performance. Carefully selected patients with upper lobe predominant emphysema can consider lung volume reduction surgery. Patients with upper lobe-predominant emphysema and low exercise performance have a survival advantage. Patients with large bulla compressing adjacent lung tissue occupying more than one-third of the lung benefit from bullectomy. Patients with advanced chronic obstructive pulmonary disease ineligible for or failing other surgical or bronchoscopic interventions can consider lung transplantation if free from major comorbidities.

Effect of Zephyr Endobronchial Valves on Dyspnea, Activity Levels, and Quality of Life at One Year. Results from a Randomized Clinical Trial

Rationale: Bronchoscopic lung volume reduction with Zephyr Valves improves lung function, exercise tolerance, and quality of life of patients with hyperinflated emphysema and little to no collateral ventilation.Objectives:Post hoc analysis of patient-reported outcomes (PROs), including multidimensional measures of dyspnea, activity, and quality of life, in the LIBERATE (Lung Function Improvement after Bronchoscopic Lung Volume Reduction with Pulmonx Endobronchial Valves used in Treatment of Emphysema) study are reported.Methods: A total of 190 patients with severe heterogeneous emphysema and little to no collateral ventilation in the target lobe were randomized 2:1 to the Zephyr Valve or standard of care. Changes in PROs at 12 months in the two groups were compared: dyspnea with the Transitional Dyspnea Index (TDI), focal score; the Chronic Obstructive Pulmonary Disease Assessment Test (CAT; breathlessness on hill/stairs); Borg; the EXAcerbations of Chronic pulmonary disease Tool-PRO, dyspnea domain; activity with the TDI, magnitude of task/effort/functional impairment, CAT (limited activities), and the St. George's Respiratory Questionnaire (SGRQ), activity domain; and psychosocial status with the SGRQ, impacts domain, and CAT (confidence and energy).Results: At 12 months, patients using the Zephyr Valve achieved statistically significant and clinically meaningful improvements in the SGRQ; CAT; and the TDI, focal score, compared with standard of care. Improvements in the SGRQ were driven by the impacts and activity domains (P < 0.05 and P < 0.001, respectively). Reduction in CAT was through improvements in breathlessness (P < 0.05), energy level (P < 0.05), activities (P < 0.001), and increased confidence when leaving home (P < 0.05). The TDI measures of effort, task, and functional impairment were uniformly improved (P < 0.001). The EXAcerbations of Chronic Pulmonary Disease Tool (EXACT)-PRO, dyspnea domain, was significantly improved in the Zephyr Valve group. Improvements correlated with changes in residual volume and residual volume/TLC ratio.Conclusions: Patients with severe hyperinflated emphysema achieving lung volume reductions with Zephyr Valves experience improvements in multidimensional scores for breathlessness, activity, and psychosocial parameters out to at least 12 months.Clinical trial registered with www.clinicaltrials.gov (NCT01796392).

Lung volume reduction surgery or bronchoscopic lung volume reduction: is there an algorithm for allocation?

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the world with the annual number of deaths increasing every year. Alterations in chest wall mechanics, respiratory muscle mechanics, and impaired cardiac function that result from increased air-trapping are well known sequelae of COPD and contribute to increased morbidity and mortality. A reduction in hyperinflation can improve cardiopulmonary function. In selected patients with COPD and an emphysema phenotype, lung volume reduction surgery (LVRS) has demonstrated improvements in symptom burden and mortality. Minimally invasive bronchoscopic techniques that reduce end-expiratory lung volume have shown improvements in lung function, dyspnea and quality of life. In this review, we review selection criteria, risks, and benefits of surgical and bronchoscopic lung volume reduction (BLVR). Recommendations are provided to guide treatment decisions based on the current literature.

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.

Emphysema on Thoracic CT and Exercise Ventilatory Inefficiency in Mild-to-Moderate COPD

There is growing evidence that emphysema on thoracic computed tomography (CT) is associated with poor exercise tolerance in COPD patients with only mild-to-moderate airflow obstruction. We hypothesized that an excessive ventilatory response to exercise (ventilatory inefficiency) would underlie these abnormalities. In a prospective study, 19 patients (FEV₁ = 82 ± 13%, 12 Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage 1) and 26 controls underwent an incremental exercise test. Ventilatory inefficiency was assessed by the ventilation ([Formula: see text]E)/CO₂ output ([Formula: see text]CO₂) nadir. Pulmonary blood flow (PBF) in a submaximal test was calculated by inert gas rebreathing. Emphysema was quantified as % of attenuation areas below 950 HU. Patients typically presented with centrilobular emphysema (76.8 ± 10.1% of total emphysema) in the upper lobes (upper/total lung ratio = 0.82 ± 0.04). They had lower peak oxygen uptake ([Formula: see text]O₂), higher [Formula: see text]E/[Formula: see text]CO₂ nadir, and greater dyspnea scores than controls (p < 0.05). Lower peak [Formula: see text]O₂ and worse dyspnea were found in patients with higher [Formula: see text]E/[Formula: see text]CO₂ nadirs (≥30). Patients had blunted increases in PBF from rest to iso-[Formula: see text]O₂ exercise (p < 0.05). Higher [Formula: see text]E/[Formula: see text]CO₂ nadir in COPD was associated with emphysema severity (r = 0.63) which, in turn, was related to reduced lung diffusing capacity (r = -0.72) and blunted changes in PBF from rest to exercise (r = -0.69) (p < 0.01). Ventilation "wasted" in emphysematous areas is associated with impaired exercise ventilatory efficiency in mild-to-moderate COPD. Exercise ventilatory inefficiency links structure (emphysema) and function (D_LCO) to a key clinical outcome (poor exercise tolerance) in COPD patients with only modest spirometric abnormalities.

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.

Cachexia in chronic obstructive pulmonary disease: new insights and therapeutic perspective

Cachexia and muscle wasting are well recognized as common and partly reversible features of chronic obstructive pulmonary disease (COPD), adversely affecting disease progression and prognosis. This argues for integration of weight and muscle maintenance in patient care. In this review, recent insights are presented in the diagnosis of muscle wasting in COPD, the pathophysiology of muscle wasting, and putative mechanisms involved in a disturbed energy balance as cachexia driver. We discuss the therapeutic implications of these new insights for optimizing and personalizing management of COPD-induced cachexia.

Effective Bronchoscopic Lung Volume Reduction Accelerates Exercise Oxygen Uptake Kinetics in Emphysema

BACKGROUND

The impact of bronchoscopic lung volume reduction (BLVR) on physiologic responses to exercise in patients with advanced emphysema remains incompletely understood. We hypothesized that effective BLVR (e-BLVR), defined as a reduction in residual volume > 350 mL, would improve cardiovascular responses to exercise and accelerate oxygen uptake (Vo₂) kinetics.

METHODS

Thirty-one patients (FEV1, 36% ± 9% predicted; residual volume, 219% ± 57% predicted) underwent a constant intensity exercise test at 70% peak work rate to the limit of tolerance before and after treatment bronchoscopy (n = 24) or sham bronchoscopy (n = 7). Physiologic responses in patients who had e-BLVR (n = 16) were compared with control subjects (ineffective BLVR or sham bronchoscopy; n = 15).

RESULTS

e-BLVR reduced residual volume (-1.1 ± 0.5 L, P = .001), improved lung diffusing capacity by 12% ± 13% (P = .001), and increased exercise tolerance by 181 ± 214 s (P = .004). Vo₂ kinetics were accelerated in the e-BLVR group but remained unchanged in control subjects (Δ mean response time, -20% ± 29% vs 1% ± 25%, P = .04). Acceleration of Vo₂ kinetics was associated with reductions in heart rate and oxygen pulse response half-times by 8% (84 ± 14 to 76 ± 15 s, P = .04) and 20% (49 ± 16 to 34 ± 16 s, P = .01), respectively. There were also increases in heart rate and oxygen pulse amplitudes during the cardiodynamic phase post e-BLVR. Faster Vo₂ kinetics in the e-BLVR group were significantly correlated with reductions in residual volume (r = 0.66, P = .005) and improvements in inspiratory reserve volume (r = 0.56, P = .024) and exercise tolerance (r = 0.63, P = .008).

CONCLUSIONS

Lung deflation induced by e-BLVR accelerated exercise Vo₂ kinetics in patients with emphysema. This beneficial effect appears to be related mechanistically to an enhanced cardiovascular response to exercise, which may contribute to improved functional capacity.

Morphologic Response of the Pulmonary Vasculature to Endoscopic Lung Volume Reduction

INTRODUCTION

Endoscopic Lung Volume Reduction has been used to reduce lung hyperinflation in selected patients with severe emphysema. Little is known about the effect of this procedure on the intraparenchymal pulmonary vasculature. In this study we used CT based vascular reconstruction to quantify the effect of the procedure on the pulmonary vasculature.

METHODS

Intraparenchymal vasculature was reconstructed and quantified in 12 patients with CT scans at baseline and 12 weeks following bilateral introduction of sealants in the upper lobes. The volume of each lung and each lobe was measured, and the vascular volume profile was calculated for both lower lobes. The detected vasculature was further labeled manually as arterial or venous in the right lower lobe.

RESULTS

There was an increase in the volume of the lower lobes (3.14L to 3.25L, p=0.0005). There was an increase in BV5, defined as the volume of blood vessels with cross sectional area of less than 5mm², (53.2ml to 57.9ml, p=0.03). This was found to be correlated with the increase in lower lobe volumes (R=0.65, p=0.02). The changes appear to be symmetric for veins and arteries with a correlation coefficient of 0.87 and a slope of near identity.

CONCLUSION

In the subjects studied, there was an increase, from baseline, in BV5 in the lower lobes that correlated with the change in the volume of the lower lobes. The change appeared to be symmetric for both arteries and veins. The study illustrates the use of intraparenchymal pulmonary vascular reconstruction to study morphologic changes in response to interventions.

Reduced dynamic hyperinflation after LVRS is associated with improved exercise tolerance

INTRODUCTION

Dynamic hyperinflation (DH) after lung volume reduction surgery (LVRS) has not been well studied. It is not known if reductions in DH correlate with improvements in exercise performance post-LVRS.

METHODS

Forty-two upper-lobe predominant emphysema patients who underwent LVRS were analyzed. Inspiratory capacity was measured every 2 min during symptom-limited cardiopulmonary exercise test (CPET) and end-expiratory lung volumes (EELV) were calculated. The main measure of DH was EELV/TLC ratio matched at metabolic isotimes (based on the post-rehabilitation VCO2max).

RESULTS

Patients had very severe airflow obstruction (FEV1 28.3 ± 7.0% predicted), were hyperinflated (TLC 125 ± 17% predicted) and gas trapped (RV 198 ± 39% predicted). Compared to the post-rehab baseline, dynamic hyperinflation (EELV/TLC) was significantly reduced after LVRS at 6, 12, 24, and 36 months. There were also increases in inspiratory reserve volume at matched isotimes after surgery. Patients adopted a slower, deeper breathing pattern during exercise after LVRS, which strongly correlated to reductions in DH. There were significant correlations between reductions in DH (EELV/TLC @50% VCO2max) and improvements in 6 min walk distance (Pearson r = -0.411, p = 0.02, n = 33) and maximal watts on CPET (Spearman r = -0.536, p = 0.001, n = 33) when comparing post-rehabilitation and 6 month post-LVRS values.

CONCLUSION

Dynamic hyperinflation during exercise was reduced after LVRS (up to 3 years) and there was a strong association between alterations in breathing pattern and reduced DH after LVRS. This is the first study to demonstrate that reductions in DH correlated with improved exercise performance following LVRS.

Outcomes in lung transplantation after previous lung volume reduction surgery in a contemporary cohort

OBJECTIVES

Lung volume reduction surgery (LVRS) provides palliation and improved quality of life in select patients with end-stage chronic obstructive pulmonary disease (COPD). The effect of previous LVRS on lung transplant outcomes has been inadequately studied. We report our experience in the largest single institution series of these combined procedures.

METHODS

The records of 472 patients with COPD undergoing lung transplantation or LVRS between 1995 and 2010 were reviewed. Outcomes of patients undergoing transplant after LVRS were compared with outcomes of patients undergoing transplant or LVRS alone. Survival was compared using log-rank tests and the Kaplan-Meier method.

RESULTS

Demographics, comorbidities, and spirometry were similar at the time of transplantation. Patients who had undergone lung transplant after LVRS had longer transplant operative times (mean 4.4 vs 5.6 hours; P = .020) and greater hospital length of stay (mean 17.6 vs 29.1 days; P = .005). Thirty-day mortality and major morbidity were similar. Posttransplant survival was reduced for transplant after LVRS (median, 49 months; 95% confidence interval [CI], 16, 85 months) compared with transplant alone (median, 96 months; 95% CI, 82, 106 months; P = .008). The composite benefit of combined procedures, defined as bridge from LVRS to transplant of 55 months and posttransplant survival of 49 months (total 104 months), was comparable with survival of patients undergoing either procedure alone.

CONCLUSIONS

Lung transplant after LVRS leads to minimal additional perioperative risk. The reduced posttransplant survival in patients undergoing combined procedures is in contradistinction to reports from other smaller series. When determining the best surgical treatment for patients with more severe disease, the benefit of LVRS before transplant should be weighed against the consequence of reduced posttransplant survival.

Heterogeneity of lung volume reduction surgery outcomes in patients selected by use of evidence-based criteria

BACKGROUND

Despite its benefit, lung volume reduction surgery (LVRS) is underused, partially because of the heterogeneous responses and lack of recent outcomes data.

METHODS

Data from 59 consecutive emphysema patients who underwent LVRS were analyzed. The proportion of patients responding based on 6-minute walk distance (6-MWD), exercise capacity (watts), and forced expiratory volume in 1 second (FEV1) were calculated. Baseline variables were correlated with improvements in 6-MWD, maximal watts, and FEV1.

RESULTS

Eighty-eight percent of patients responded to LVRS, with a higher proportion of FEV1 and 6-MWD responders in our cohort compared with similar patients from the National Emphysema Treatment Trial. Significant associations existed between lower baseline 6-MWD and increased 6-MWD after operation (r = -0.423), more extensive emphysema and increased FEV1 (r = 0.491), and hyperinflation and increased maximal watts (r = 0.438). The probability of survival was 0.93 at 90 days, 0.90 at 1 year, and 0.80 (3 years). The lowest exercise group (<20 watts on baseline testing) had an increased risk for death (RR 13.3, p = 0.001).

CONCLUSIONS

There were durable improvements in FEV1 and exercise capacity in patients meeting the National Emphysema Treatment Trial criteria. Survival was comparable to that in similar patients from the National Emphysema Treatment Trial; response rates were higher in our cohort for FEV1 and 6-MWD. Those with lower 6-MWD, more emphysema, and more hyperinflation at baseline were most likely to respond to LVRS. Those with lowest exercise capacity at baseline may have a higher risk of death after LVRS.

Weight gain after lung reduction surgery is related to improved lung function and ventilatory efficiency

RATIONALE

Lung volume reduction surgery (LVRS) is associated with weight gain in some patients, but the group that gains weight after LVRS and the mechanisms underlying this phenomenon have not been well characterized.

OBJECTIVES

To describe the weight change profiles of LVRS patients enrolled in the National Emphysema Treatment Trial (NETT) and to correlate alterations in lung physiological parameters with changes in weight.

METHODS

We divided 1,077 non-high-risk patients in the NETT into groups according to baseline body mass index (BMI): underweight (<21 kg/m(2)), normal weight (21-25 kg/m(2)), overweight (25-30 kg/m(2)), and obese (>30 kg/m(2)). We compared BMI groups and LVRS and medical groups within each BMI stratum with respect to baseline characteristics and percent change in BMI (%ΔBMI) from baseline. We examined patients with (ΔBMI ≥ 5%) and without (ΔBMI < 5%) significant weight gain at 6 months and assessed changes in lung function and ventilatory efficiency (Ve/Vco(2)).

MEASUREMENTS AND MAIN RESULTS

The percent change in BMI was greater in the LVRS arm than in the medical arm in the underweight and normal weight groups at all follow-up time points, and at 12 and 24 months in the overweight group. In the LVRS group, patients with ΔBMI ≥ 5% at 6 months had greater improvements in FEV(1) (11.53 ± 9.31 vs. 6.58 ± 8.68%; P < 0.0001), FVC (17.51 ± 15.20 vs. 7.55 ± 14.88%; P < 0.0001), residual volume (-66.20 ± 40.26 vs. -47.06 ± 39.87%; P < 0.0001), 6-minute walk distance (38.70 ± 69.57 vs. 7.57 ± 73.37 m; P < 0.0001), maximal expiratory pressures (12.73 ± 49.08 vs. 3.54 ± 32.22; P = 0.0205), and Ve/Vco(2) (-1.58 ± 6.20 vs. 0.22 ± 8.20; P = 0.0306) at 6 months than patients with ΔBMI < 5% at 6 months.

CONCLUSIONS

LVRS leads to weight gain in nonobese patients, which is associated with improvement in lung function, exercise capacity, respiratory muscle strength, and ventilatory efficiency. These physiological changes may be partially responsible for weight gain in patients who undergo LVRS.

The effect of lung volume reduction surgery on chronotropic incompetence

BACKGROUND

Chronotropic incompetence (CI) is a marker of poor prognosis in patients with COPD. Treatments that improve pulmonary function and exercise capacity may affect CI. Objectives are to evaluate CI before and after lung volume reduction surgery (LVRS) and determine if changes in CI are associated with changes in pulmonary function and exercise capacity.

METHODS

We performed a retrospective review of 75 patients who underwent LVRS and who had complete cardiopulmonary exercise testing and concurrent pulmonary function tests two months before and about 6 months after surgery. Additionally we evaluated 28 control patients that were randomized to medical treatment as part of the National Emphysema Treatment Trial at our center. We studied CI using the percent of predicted heart rate reserve=(heart rate peak-heart rate rest)/((208-0.7×age)-heart rate rest)×100, before and after surgery and compared it to the control group.

RESULTS

Mean percent of predicted heart rate reserve improved from 41% to 50% (p-value <0.001) after LVRS, while the control group did not change. The mean forced vital capacity and expiratory volume in 1s, peak oxygen consumption, carbon dioxide production, ventilation, tidal volume and maximal workload all improved in the surgery group, while the controls did not improve.

CONCLUSIONS

CI improves after LVRS in a population of patients with COPD. CI improvements are associated with the increases in pulmonary function and exercise capacity. This improvement is seen in a domain of known cardiopulmonary impairment prior to surgery that improves as a positive response to the therapy of LVRS.

The National Emphysema Treatment Trial (NETT) Part II: Lessons learned about lung volume reduction surgery

Substantial information regarding the role of lung volume reduction surgery (LVRS) in severe emphysema emanates from the National Emphysema Treatment Trial (NETT). The NETT was not a crossover trial and therefore was able to examine the effects of optimal medical management and LVRS on short- and long-term survival,as well as lung function, exercise performance, and quality of life.The NETT generated multiple insights into the preoperative, perioperative,and postoperative management of patients undergoing thoracotomy; described pain control techniques that were safe and effective; and emphasized the need to address nonpulmonary issues to optimize surgical outcomes. After the NETT, newer investigation has focused on bronchoscopic endobronchial interventions and other techniques less invasive than LVRS to achieve lung reduction.In this review, we summarize what we currently know about the role of LVRS in the treatment of severe emphysema as a result of insights gained from the NETT and provide a brief review of the newer techniques of lung volume reduction.

The National Emphysema Treatment Trial (NETT): Part I: Lessons learned about emphysema

The National Emphysema Treatment Trial (NETT) was a multicenter prospective randomized controlled trial that compared optimal medical treatment, including pulmonary rehabilitation, with optimal medical treatment plus lung volume reduction surgery (LVRS). It was the largest and most complete collection of patient demographic, clinical, physiological, and radiographic data ever compiled in severe emphysema. NETT investigated the effects of optimal medical management and LVRS on short- and long-term survival, as well as lung function, exercise performance, and quality of life. NETT also provided much information regarding the evaluation and prognosis of severe emphysema; specifically the important negative influences that hyperinflation and small airway disease have on survival. NETT emphasized the importance of addressing nonpulmonary issues such as nutrition, cardiac disease, anxiety, and depression in emphysema. NETT demonstrated that physiological, genomic, and radiographic phenotype can predict patient survival as well as response to treatment. Because the major purpose of NETT was to compare bilateral LVRS with optimal medical treatment in emphysema, patients enrolled into NETT were comprehensively characterized and selected to have a specific window of airflow obstruction and hyperinflation and to lack significant comorbidities. The NETT patient population’s restrictive features offer distinct advantages (well-characterized predominant emphysematous phenotype) and disadvantages (lack of comorbidities and significant chronic bronchitis) that must be considered when interpreting the implications of these results. Herein, we provide a summary of the major NETT findings that provide insight into the evaluation and medical treatment of 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.

Outcome measures in chronic obstructive pulmonary disease (COPD): strengths and limitations

Current methods for assessing clinical outcomes in COPD mainly rely on physiological tests combined with the use of questionnaires. The present review considers commonly used outcome measures such as lung function, health status, exercise capacity and physical activity, dyspnoea, exacerbations, the multi-dimensional BODE score, and mortality. Based on current published data, we provide a concise overview of the principles, strengths and weaknesses, and discuss open questions related to each methodology. Reviewed is the current set of markers for measuring clinically relevant outcomes with particular emphasis on their limitations and opportunities that should be recognized when assessing and interpreting their use in clinical trials of COPD.