Lung volume reduction surgery for emphysema

Evaluation of the Global Lung Function Initiative reference equations in Belgian adults

Background

Over the past decade, the Global Lung Function Initiative (GLI) Network has published all-age reference equations on spirometry, diffusing capacity of the lung for carbon monoxide (D_LCO) and lung volumes.

Methods

We evaluated the appropriateness of these equations in an adult Caucasian population. Retrospective lung function data on subjects who performed tests prior to a diagnostic sleep investigation were analysed. From the medical records, lung healthy, lifetime nonsmoking, nonobese subjects were selected, resulting in a population of 1311 subjects (68% male; age range 18–88 years).

Results

Multiple linear regression analysis revealed that lung function z-scores did not differ between subjects with and without sleep apnoea but did depend on height and age. The average forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) z-score was 0 but exhibited an inverse association with height in both sexes (p<0.01). Values of FEV₁ and FVC in both sexes were larger than predicted (mean±sd z-score +0.30±0.96 or 104±13% pred; p<0.01). Overall, static lung volumes and D_LCO were adequately predicted. However, D_LCO z-scores were inversely associated with height in males and age in females (p<0.01). For all lung function indices, the observed scatter was reduced compared with the prediction. Therefore, for all indices <5% of the data were below the GLI-proposed lower limit of normal (LLN) threshold.

Conclusion

GLI reference equations provide an adequate fit in Belgian adults. However, the GLI-proposed LLN is too low for our Antwerp population, resulting in underdiagnosis of disease. Furthermore, airway obstruction and diffusion disorders might be misclassified due to height and age associations.

Overall, GLI reference equations for lung function appropriately describe the data in Belgian adults. However, airway obstruction and diffusion disorders might be misdiagnosed at age and height extremes, and the GLI LLN was too low in this population.https://bit.ly/3jdauLE

Chronic obstructive pulmonary disease

COPD is characterized by airflow limitation that is not fully reversible. The morphological basis for airflow obstruction results from a varying combination of obstructive changes in peripheral conducting airways and destructive changes in respiratory bronchioles, alveolar ducts, and alveoli. A reduction of vascularity within the alveolar septa has been reported in emphysema. Typical physiological changes reflect these structural abnormalities. Spirometry documents airflow obstruction when the FEV1/FVC ratio is reduced below the lower limit of normality, although in early disease stages FEV1 and airway conductance are not affected. Current guidelines recommend testing for bronchoreversibility at least once and the postbronchodilator FEV1/FVC be used for COPD diagnosis; the nature of bronchodilator response remains controversial, however. One major functional consequence of altered lung mechanics is lung hyperinflation. FRC may increase as a result of static or dynamic mechanisms, or both. The link between dynamic lung hyperinflation and expiratory flow limitation during tidal breathing has been demonstrated. Hyperinflation may increase the load on inspiratory muscles, with resulting length adaptation of diaphragm. Reduction of exercise tolerance is frequently noted, with compelling evidence that breathlessness and altered lung mechanics play a major role. Lung function measurements have been traditionally used as prognostic indices and to monitor disease progression; FEV1 has been most widely used. An increase in FVC is also considered as proof of bronchodilatation. Decades of work has provided insight into the histological, functional, and biological features of COPD. This has provided a clearer understanding of important pathobiological processes and has provided additional therapeutic options.

Lung volume reduction surgery and lung transplantation in chronic obstructive pulmonary disease

Medical treatment of emphysema does not alter the natural progression of the disease. Surgical techniques are an attractive conceptual approach to treat hyperinflation in these patients. Lung volume reduction surgery and lung transplantation are appropriate therapeutic options for a selected population with emphysema. We will review the available evidence to support these approaches.

Functional results of unilateral lung volume reduction surgery in alpha1-antitrypsin deficient patients

Lung volume reduction surgery (LVRS) has been shown to improve lung function and exercise tolerance in patients with severe emphysema. Some predictors of poor outcome have been described but the role of alpha₁-antitrypsin (α₁-AT) deficiency is still not well known. The aim of this study was to analyze the results of unilateral LVRS in our center according to the α₁-AT status. The results of LVRS in 17 deficient patients and 35 nondeficient patients were analyzed at 3–6 months and 1 year after surgery. Compared with baseline, a significant improvement of FEV₁, partial pressure in arterial blood (PaO₂), dyspnea score and walking distance was observed in the two groups at 3–6 months after surgery and the studied parameters remained significantly improved at 1 year in the nondeficient group. By contrast, PaO₂ and walking distance returned towards baseline in the deficient group at 1 year whereas improvement of FEV₁ and dyspnea score was persistent. Mean values of FEV₁ at baseline, 3–6 months, and 1 year were 22 ± 6%, 29 ± 11%, and 26 ± 9% and 28 ± 12%, 38 ± 17%, and 40 ± 17% predicted in the deficient group and in the non-deficient group, respectively. In conclusion, the functional benefit is short-lasting in α₁-AT deficient patients after unilateral LVRS.

Update in Surgical Therapy for Chronic Obstructive Pulmonary Disease

Bullectomy for giant bullae, lung volume reduction surgery, and lung transplantation are three surgical therapies that may benefit highly selected patients with advanced chronic obstructive pulmonary disease. In this article, each procedure is reviewed, with an emphasis on guidelines for patient selection and clinical outcomes for the practicing pulmonologist. Recent results from the National Emphysema Treatment Trial, updated International Society for Heart and Lung Transplantation Registry data, and revised guidelines for patient selection for lung transplantation are discussed.

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.

Lung volume reduction surgery as a bridge to lung transplantation

Lung volume reduction surgery (LVRS) improves lung function, exercise capacity, and quality of life in patients with advanced emphysema. In some patients with emphysema who are candidates for lung transplantation, LVRS is an alternative treatment option to lung transplantation, or may be used as a bridge to lung transplantation. Generally accepted criteria for LVRS include severe non-reversible airflow obstruction due to emphysema associated with significant evidence of lung hyperinflation and air trapping. Both high resolution computed tomography (CT) scan of the chest and quantitative ventilation/perfusion scan are used to identify lung regions with severe emphysema which would be used as targets for lung resection. Bilateral LVRS is the preferred surgical approach compared with the unilateral procedure because of better functional outcome. Lung transplantation is the preferred surgical treatment in patients with emphysema with alpha1 antitrypsin deficiency and in patients with very severe disease who have homogeneous emphysema pattern on CT scan of the chest or very low diffusion capacity.

Quality of life after lung volume reduction surgery

The common physiologic and functional variables that quantify limitation in emphysema patients have been the most common outcomes measured after LVRS. Spirometric values and exercise capacity are merely surrogates, however, for their impact on symptoms and QOL in patients with severe emphysema. Because LVRS has been developed as a surgery to palliate disabling symptoms of emphysema, many studies now have included HRQOL outcomes along with the commonly measured physiologic and functional outcomes. Some studies have centered on the QOL as the primary outcome instead of physiologic variables. Many symptom scales and disease-specific and general instruments of HRQOL have been used for evaluating emphysema patients before and after LVRS. Case-control studies and randomized studies have shown a consistent improvement in symptoms related to emphysema and general QOL. These studies validate the use of LVRS as a palliative therapy for selected patients with emphysema. The NETT suggests that this benefit is applicable primarily to patients with an upper lobe-predominant pattern of emphysema or patients with low exercise capacity. Validation or refinement of these criteria depends on the continued contributions of the many investigators performing LVRS.

[Surgery for emphysema: recent advances]

INTRODUCTION

The treatment of chronic obstructive pulmonary disease has progressed considerably over the past 40 Years but, for most patients with advanced disease, medical management does not often produce more than limited benefits, particularly in terms of quality of life.

STATE OF ART

Over the last decade the surgical treatment of emphysema, which was previously limited to bullectomy, has seen important developments: for carefully selected patients lung Volume reduction surgery and lung transplantation now offer the possibility of real symptomatic improvement and even prolonged survival. Thanks to the thousands of patients who have received these treatments our understanding of the pathophysiological mechanisms, surgical techniques, risks and benefits, medium and long-term results, and selection criteria has improved considerably.

PERSPECTIVES AND CONCLUSIONS

This review summarises the most important aspects of these developments and discusses the role of Volume reduction and lung transplantation in the treatment of advanced emphysema.

Pathophysiology and classification of emphysema

Current research is providing new understanding in the pathophysiology of emphysema, and this knowledge will be translated in finding better modalities of therapy for patients currently affected by COPD. The single best effort that can alter the course of COPD is promoting policies to remove smoking as an available option to young people, before they become addicted and thus prey of tobacco-producing companies. Landmark studies like NETT and the GOLD initiative are providing tool classify emphysema in the context of physiological criteria and possible therapeutic alternatives.

Results of lung volume reduction surgery for emphysema

LVRS provides an exciting opportunity for palliation of symptoms and improvement in quality of life for patients who have severe end-stage emphysema. Because no medical therapy has been able to improve pulmonary function or reverse the inexorable decline of breathless patients who have emphysema, this opportunity to improve lung function and quality of life is one of the most innovative additions to thoracic surgery since the first successful lung transplant procedure 20 years ago. Although initial short-term, case-controlled surgeries were criticized because of incomplete and short follow-up care, substantial long-term data now exist to support the use of LVRS for select patients who have severe emphysema. Patients who have upper lobe predominant disease or low exercise capacity are more likely to have a benefit in exercise capacity and quality of life after LVRS. Selected patients who have upper lobe emphysema and poor exercise capacity are also more likely to have improved survival after LVRS. The individual contributions by the large number of investigators pioneering LVRS development, along with the collective contributions of the NETT investigators, have propelled the knowledge surrounding LVRS far beyond that of any similar new technology or procedure in its adolescence.

Patient selection for lung volume reduction surgery

LVRS represents a valid surgical option for a limited number of patients who have symptomatic emphysema. The results of recent controlled studies have provided a realistic view of LVRS outcomes and yielded a validated algorithm for selection of optimal candidates for surgery. Furthermore, the NETT has provided simultaneously collected cost data that have provided a unique view of the costs and benefits of LVRS in patients who have advanced emphysema. Additional data collection will better define the long-term benefits of such surgical intervention in patients who have COPD.

Lung Volume Reduction Surgery in Australia and New Zealand

BACKGROUND

Lung volume reduction surgery (LVRS) has been shown to improve lung function, exercise performance, and quality of life in highly selected individuals with severe emphysema; however, major questions regarding the efficacy and long-term outcomes of LVRS still remain unanswered. Pending the results of large randomized controlled trials (RCTs), the Australian and New Zealand LVRS Database was created to audit local clinical practice and patient outcomes.

AIMS

To review patient selection, surgical activity, and patient outcomes related to LVRS in Australia and New Zealand.

METHODS

Prospective data were voluntarily submitted by hospitals performing LVRS in Australia and New Zealand. Preoperative, surgical, perioperative, and follow-up variables were analyzed.

RESULTS

Data were collected from 15 hospitals regarding 529 patients. Mean age (+/- SD) at surgery was 63 +/- 7 years. Preoperatively, FEV(1) was 29 +/- 9% predicted, total lung capacity (TLC) was 138 +/- 20% predicted, residual volume (RV) was 250 +/- 64% predicted, and 6-min walk (6MW) distance was 327 +/- 111 m. There has been a reduction in the overall number of cases and hospitals performing LVRS since 1999. Improvements in lung function following LVRS (ie, FEV(1) increase of 38%, RV decrease of 27%, TLC decrease of 17%) and exercise capacity (ie, 6MW distance increase of 24%) appear to be maintained for approximately 3 years.

CONCLUSIONS

LVRS continues to be performed in Australia and New Zealand, predominantly in large tertiary teaching hospitals with similar outcomes to those described in the literature. It remains difficult to capture long-term lung function and survival outcomes in this population. Ongoing audit and RCTs are both required to resolve the confusion that still shrouds this procedure.

Apical perfusion fraction as a predictor of short-term functional outcome following bilateral lung volume reduction surgery

STUDY OBJECTIVES

To examine whether relative hypoperfusion to the apical one third of the lungs as determined by lung scintigraphy predicts a favorable functional outcome following bilateral lung volume reduction surgery (LVRS).

METHODS

We performed a retrospective analysis of 128 patients who underwent bilateral LVRS. An apical perfusion fraction (AP%), defined as the percentage of total lung perfusion to the apical one third of both lungs, was derived for each patient by quantitative scintigraphy technique. Pulmonary function testing and 6-min walk test (6MWT) data were obtained preoperatively and 3 to 6 months postoperatively.

RESULTS

The mean (+/- SD) improvement in FEV(1) was 309 +/- 240 mL, 209 +/- 293 mL, and 116 +/- 224 mL for patients with an AP% of <or= 10%, 11 to 20%, and > 20%, respectively (p = 0.01, analysis of variance [ANOVA]). The likelihood of experiencing an increase in FEV(1) >or= 200 mL was 68% for those with an AP% <or= 10% but only 31% for those with an AP% > 20%. Preoperative and postoperative 6MWT data were available for 109 of 128 patients. Improvement was 250 +/- 252 feet, 205 +/- 299 feet, and 77 +/- 200 feet for patients with AP% <or= 10%, 11 to 20%, and > 20%, respectively (p = 0.04, ANOVA). While 50% of those with an AP% <or= 10% improved their 6MWT by >or= 180 feet, only 21% of those with an AP% > 20% did so.

CONCLUSION

This retrospective analysis suggests that quantification of apical perfusion by nuclear scintigraphy assists in predicting the likelihood of short-term functional improvement after LVRS.

Lung function 5 yr after lung volume reduction surgery for emphysema

Current datum more than 2 yr after lung volume reduction surgery (LVRS) for emphysema is limited. This prospective study evaluates pre-LVRS baseline and 5-yr results in 26 symptomatic patients (mean age 67 +/- 6 yr) (mean +/- SD) who underwent bilateral, targeted upper lobe stapled LVRS using video-assisted thoracoscopy. Baseline forced expiratory volume in 1 s (FEV(1)) was 0.7 +/- 0.2 L (mean +/- SD), 29 +/- 10% predicted. Following LVRS, with none lost to follow-up, mortality due to respiratory failure at 0.5, 1, 2, 3, 4, and 5 yr was 4%, 4%, 19%, 31%, 46%, and 58%, respectively. Increase above baseline for FEV(1) > 200 ml and/or FVC > 400 ml at 1, 2, 3, 4, and 5 yr post-LVRS was noted in 73%, 46%, 35%, 27%, and 8% of all patients; decrease in dyspnea grade >/= 1 in 88%, 69%, 46%, 27%, and 15%; and elimination of initial oxygen dependence in 18 patients in 78%, 50%, 33%, 22%, and 0%, respectively. Expiratory airflow improved due to the increase in both lung elastic recoil and small airway intraluminal caliber. Five patients decreased FEV(1) 141 +/- 60 ml/yr and FVC 102 +/- 189 ml/yr over 3.8 +/- 1.2 yr post-LVRS, similar to their pre-LVRS rate of decline. In the 11 patients who survived 5 yr, at 0.5-1.0 yr post-LVRS peak increase in FEV(1) was 438 +/- 366 ml, with a decline of 149 +/- 157 ml the following year and 78 +/- 59 ml/yr over 4.0-4.5 yr. Bilateral LVRS provided palliative clinical and physiological improvement in 9 of 26 patients at 3 yr, 7 at 4 yr, and 2 at 5 yr.