Thoracoscopic lung volume reduction surgery reduces dyspnea and improves exercise capacity in patients with emphysema

Lung hyperinflation in chronic obstructive pulmonary disease: mechanisms, clinical implications and treatment

Lung hyperinflation is highly prevalent in patients with chronic obstructive pulmonary disease and occurs across the continuum of the disease. A growing body of evidence suggests that lung hyperinflation contributes to dyspnea and activity limitation in chronic obstructive pulmonary disease and is an important independent risk factor for mortality. In this review, we will summarize the recent literature on pathogenesis and clinical implications of lung hyperinflation. We will outline the contribution of lung hyperinflation to exercise limitation and discuss its impact on symptoms and physical activity. Finally, we will examine the physiological rationale and efficacy of selected pharmacological and non-pharmacological 'lung deflating' interventions aimed at improving symptoms and physical functioning.

Pathogenesis of hyperinflation in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable lung disease characterized by airflow limitation that is not fully reversible. In a significant proportion of patients with COPD, reduced lung elastic recoil combined with expiratory flow limitation leads to lung hyperinflation during the course of the disease. Development of hyperinflation during the course of COPD is insidious. Dynamic hyperinflation is highly prevalent in the advanced stages of COPD, and new evidence suggests that it also occurs in many patients with mild disease, independently of the presence of resting hyperinflation. Hyperinflation is clinically relevant for patients with COPD mainly because it contributes to dyspnea, exercise intolerance, skeletal muscle limitations, morbidity, and reduced physical activity levels associated with the disease. Various pharmacological and nonpharmacological interventions have been shown to reduce hyperinflation and delay the onset of ventilatory limitation in patients with COPD. The aim of this review is to address the more recent literature regarding the pathogenesis, assessment, and management of both static and dynamic lung hyperinflation in patients with COPD. We also address the influence of biological sex and obesity and new developments in our understanding of hyperinflation in patients with mild COPD and its evolution during progression of the disease.

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

BACKGROUND

The National Emphysema Treatment Trial studied lung volume reduction surgery (LVRS) for its effects on gas exchange, breathing pattern, and dyspnea during exercise in severe emphysema.

METHODS

Exercise testing was performed at baseline, and 6, 12, and 24 months. Minute ventilation (Ve), tidal volume (Vt), carbon dioxide output (Vco(2)), dyspnea rating, and workload were recorded at rest, 3 min of unloaded pedaling, and maximum exercise. Pao(2), Paco(2), pH, fraction of expired carbon dioxide, and bicarbonate were also collected in some subjects at these time points and each minute of testing. There were 1,218 patients enrolled in the study (mean [+/- SD] age, 66.6 +/- 6.1 years; mean, 61%; mean FEV(1), 0.77 +/- 0.24 L), with 238 patients participating in this substudy (mean age, 66.1 +/- 6.8 years; mean, 67%; mean FEV(1), 0.78 +/- 0.25 L).

RESULTS

At 6 months, LVRS patients had higher maximum Ve (32.8 vs 29.6 L/min, respectively; p = 0.001), Vco(2), (0.923 vs 0.820 L/min, respectively; p = 0.0003), Vt (1.18 vs 1.07 L, respectively; p = 0.001), heart rate (124 vs 121 beats/min, respectively; p = 0.02), and workload (49.3 vs 45.1 W, respectively; p = 0.04), but less breathlessness (as measured by Borg dyspnea scale score) [4.4 vs 5.2, respectively; p = 0.0001] and exercise ventilatory limitation (49.5% vs 71.9%, respectively; p = 0.001) than medical patients. LVRS patients with upper-lobe emphysema showed a downward shift in Paco(2) vs Vco(2) (p = 0.001). During exercise, LVRS patients breathed slower and deeper at 6 months (p = 0.01) and 12 months (p = 0.006), with reduced dead space at 6 months (p = 0.007) and 24 months (p = 0.006). Twelve months after patients underwent LVRS, dyspnea was less in patients with upper-lobe emphysema (p = 0.001) and non-upper-lobe emphysema (p = 0.007).

CONCLUSION

During exercise following LVRS, patients with severe emphysema improve carbon dioxide elimination and dead space, breathe slower and deeper, and report less dyspnea.

Long-term beneficial effects of lung volume reduction surgery on quality of life in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by progressive airflow limitation, which results in exertional dyspnea and physical disability. Subsequently, those cause a difficulty in performing routine activities of daily living and affect their health-related quality of life (HRQOL). Lung volume reduction surgery (LVRS) has been reported to be an effective treatment for selected patients with advanced COPD to improve pulmonary function, lung mechanics, exercise tolerance, and dyspnea. However, the long-term effects of LVRS on HRQOL have not been fully investigated. Therefore the effects of LVRS on generic and disease-specific HRQOL were assessed in patients with COPD following LVRS for 36 months. Nineteen patients (65.1 +/- 7.0 [mean +/- S.D.] years old) who underwent pulmonary rehabilitation plus LVRS (LVRS group), and 8 patients (67.2 +/- 5.8 years old) who did pulmonary rehabilitation but not LVRS (Medical group) were studied. In both groups, optimal medication was given throughout this period. Generic HRQOL and disease-specific HRQOL were evaluated before rehabilitation, and 3, 12, 24, and 36 months after LVRS. Following LVRS, the generic HRQOL was significantly improved and the disease-specific HRQOL was maintained up to 36 months. In Medical group, disease-specific HRQOL rapidly deteriorated. In conclusion, the long-term effects of LVRS on HRQOL in COPD patients were maintained up to 36 months compared with Medical group. Both generic and disease-specific HRQOL changed differently, suggesting the importance of both assessments especially in long-term follow up.

Lung volume reduction surgery

Lung volume reduction surgery (LVRS) has been widely studied and has been available for the treatment of advanced emphysema for 10 years. This paper reviews some of the historical attempts at surgical treatment of emphysema, the physiology of LVRS, and the modern data on patient selection, risks, and benefits. Data from the National Emphysema Treatment Trial are presented in the context of the large body of case series and smaller randomized trials that have preceded that study. Future technologies of bronchoscopic lung volume reduction are also discussed.

Relation of interlobar collaterals to radiological heterogeneity in severe emphysema

BACKGROUND

A study was undertaken to assess the prevalence of interlobar collateral ventilation in patients with severe emphysema to identify factors that may help to predict patients with significant collateral ventilation.

METHODS

Between April 2002 and August 2003, ex vivo assessment of the lungs 17 consecutive patients with smoking related severe emphysema was performed. To assess collateral flow, all lobes of explanted specimens were selectively intubated using a wedged cuffed microlaryngeal intubation tube and then manually ventilated using a bagging circuit. Interlobar collateral ventilation was defined as the ability to easily inflate a non-intubated lobe at physiological pressures. Pre-transplant demographic characteristics, physiological data, radiological results, and explant histology were assessed for retrospective relationships with the degree of interlobar collateral ventilation in the explanted lung.

RESULTS

A total of 23 lungs were evaluated, 15 of which (66%) had significant collateral interlobar airflow. There were no significant differences in any demographic, physiological, or pathological variables between patients with collateral ventilation and those with no collateral ventilation. However, there was a significant relationship between the presence of interlobar collateral ventilation and radiological scores (p<0.05).

CONCLUSIONS

Interlobar collateral ventilation occurs to a much greater extent in patients with radiologically homogeneous emphysema than in those with heterogeneous emphysema. Heterogeneity of emphysema may predict patients with a significantly reduced risk of interlobar collateral ventilation.

Effects of lung volume reduction surgery on sleep quality and nocturnal gas exchange in patients with severe emphysema

STUDY OBJECTIVES

We hypothesized that associated with improvements in respiratory mechanics, lung volume reduction surgery (LVRS) would result in an improvement in both sleep quality and nocturnal oxygenation in patients with severe emphysema.

DESIGN

Prospective randomized controlled trial.

SETTING

University hospital.

PATIENTS

Sixteen patients (10 men, 63 +/- 6 years [+/- SD]) with severe airflow limitation (FEV(1), 28 +/- 10% predicted) and hyperinflation (total lung capacity, 123 +/- 14% predicted) who were part of the National Emphysema Treatment Trial.

INTERVENTIONS AND MEASUREMENTS

Patients completed 6 to 10 weeks of outpatient pulmonary rehabilitation. Spirometry, measurement of lung volumes, arterial blood gas analysis, and polysomnography were performed prior to randomization and again 6 months after therapy. Ten patients underwent LVRS and optimal medical therapy, while 6 patients received optimal medical therapy only.

RESULTS

Total sleep time and sleep efficiency improved following LVRS (from 184 +/- 111 to 272 +/- 126 min [p = 0.007], and from 45 +/- 26 to 61 +/- 26% [p = 0.01], respectively), while there was no change with medical therapy alone (236 +/- 75 to 211 +/- 125 min [p = 0.8], and from 60 +/- 18 to 52 +/- 17% [p = 0.5], respectively). The mean and lowest oxygen saturation during the night improved with LVRS (from 90 +/- 7 to 93 +/- 4% [p = 0.05], and from 83 +/- 10 to 86 +/- 10% [p = 0.03], respectively), while no change was noted in the medical therapy group (from 91 +/- 5 to 91 +/- 5 [p = 1.0], and from 84 +/- 5 to 82 +/- 6% [p = 0.3], respectively). There was a correlation between the change in FEV(1) and change in the lowest oxygen saturation during the night (r = 0.6, p = 0.02). In addition, there was an inverse correlation between the change in the lowest oxygen saturation during the night and the change in residual volume (- r = 0.5, p = 0.04) and functional residual capacity (- r = 0.6, p = 0.03).

CONCLUSION

In patients with severe emphysema, LVRS, but not continued optimal medical therapy, results in improved sleep quality and nocturnal oxygenation. Improvements in nocturnal oxygenation correlate with improved airflow and a decrease in hyperinflation and air trapping.

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.

Improved activities of daily living, psychological state and health-related quality of life for 12 months following lung volume reduction surgery in patients with severe emphysema

OBJECTIVE

The aim of the present study was to evaluate the effect of lung volume reduction surgery (LVRS), with an emphasis on improvement in activities of daily living (ADL), psychological state and health-related quality of life (HRQL), for 12 months in patients with severe emphysema.

METHODOLOGY

Eighteen male patients (mean age +/- SD: 65.2 +/- 6.4 years) who underwent LVRS following pulmonary rehabilitation (LVRS group) and 12 patients (67.0 +/- 8.1 years) who were medicated and underwent pulmonary rehabilitation (non-LVRS group) were studied. LVRS was performed by video-assisted thoracoscopic surgery. Serial measurements of lung function, 6-min walking distance (6MWD), ADL, HRQL and psychological state scores were performed before surgery and 3, 6, and 12 months after surgery (in the LVRS group), or on the day of discharge (in the non-LVRS group).

RESULTS

As well as an improvement in FEV(1) and 6MWD, ADL scores were significantly improved in the items of 'face washing and teeth brushing', and 'indoor walking' at 3 months after LVRS (P < 0.05). At 12 months, an improvement was still found in 'indoor walking' and 'bathing'. HRQL scores were ameliorated at 3-12 months after LVRS. In the non-LVRS group, ADL and HRQL scores failed to improve in any items during the 12 months of observation. Psychological state scores were maintained in the LVRS group and were better than those in the non-LVRS group at 12 months (P < 0.05).

CONCLUSIONS

Lung volume reduction surgery improves not only lung function and exercise performance but also ADL, HRQL and psychological state for at least 12 months.

Innovative approaches to lung volume reduction for emphysema

The 10 years of resurgent interest in lung volume reduction surgery (LVRS) and recent National Emphysema Treatment Trial findings for emphysema have stimulated a range of innovative alternative ideas aimed at improving outcomes and reducing complications associated with current LVRS techniques. Concepts being actively investigated at this time include surgical resection with compression/banding devices, endobronchial blockers, sealants, obstructing devices and valves, and bronchial bypass methods. These novel approaches are reaching the stage of clinical trials at this time. Theory, design issues, methods, potential advantages and limitations, and available results are presented. Extensive research in the near future will help to determine the potential clinical applicability of these new approaches to the treatment of emphysema symptoms.

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.

Effects of emphysema and lung volume reduction surgery on transdiaphragmatic pressure and diaphragm length

STUDY OBJECTIVES

To determine the effect of emphysema and lung volume reduction surgery (LVRS) on diaphragm length (Ldi) and its capacity to generate transdiaphragmatic pressure (Pdi).

DESIGN

Prospective clinical trial with a parallel group design.

SETTING

Laboratory investigations in normal volunteers recruited by advertisement and in emphysema outpatients being evaluated for elective LVRS.

STUDY POPULATION

Thirteen normal subjects and 13 emphysema patients matched for age and sex. Six emphysema patients underwent LVRS.

MEASUREMENTS

Ldi and maximal Pdi during static inspiratory efforts (PdiMax) were measured at three different lung volumes (LVs). Pdi during maximal bilateral phrenic nerve twitch stimulation (PdiTw) was measured at functional residual capacity (FRC). All measurements were repeated at 3, 6, and 12 months postoperatively.

RESULTS

Ldi, PdiMax, and PdiTw were lower in emphysema patients than in normal subjects at their respective LVs. PdiMax and PdiTw at FRC returned within the normal range after LVRS in emphysema patients. The relationships between PdiMax and LV or Ldi were shifted respectively to higher LV and shorter Ldi in emphysema patients relative to normal subjects, both before and after LVRS. LVRS effected craniad displacement of the diaphragm but no change in rib cage dimensions. Improvements in dyspnea and quality of life after LVRS correlated with changes in LV and Ldi but not with changes in airway caliber.

CONCLUSION

Adaptive mechanisms, consistent with sarcomere deletion, tend to restore diaphragm strength in emphysema patients at FRC, which are fully expressed after LVRS. Lung remodeling by LVRS may alter pleural surface pressure distribution, causing a sustained change in chest wall shape.

Distribution of muscle mass and maximal exercise performance in patients with COPD

STUDY OBJECTIVE

To investigate the distribution of reduction in lean body mass (LBM) and whether LBM in legs (LBMlegs) can be a determinant of maximal exercise performance in COPD patients.

METHODS

Thirty-eight male outpatients with COPD (mean +/- SD FEV1, 47.4 +/- 24.0% of predicted) who underwent complete pulmonary function testing were classified into two groups according to FEV1 expressed as a percentage of predicted value. Group A comprised 21 patients with mild-to-moderate airflow limitation (FEV(1) > or =35% predicted), and group B comprised 17 patients with severe airflow limitation (FEV1 < 35% predicted). LBM, which represents skeletal muscle mass, was measured by dual energy x-ray absorptiometry (DXA) and was assessed separately in arms, legs, and trunk. Maximal oxygen uptake VO2max was measured during maximal exercise on a cycle ergometer.

RESULTS

LBM in each region was expressed as a percentage of ideal body weight (IBW). LBM in arms (LBMarms)/IBW, LBMlegs/IBW, and LBM in trunk (LBMtrunk)/IBW were significantly depleted in group B compared with group A (p < 0.01). LBMlegs expressed as a percentage of total LBM (LBMlegs/total LBM) was significantly lower in group B (p < 0.05), although there was no significant difference in LBMarms/total LBM and LBMtrunk/total LBM between the two groups. VO2max correlated significantly with LBMlegs/IBW in group A, but not in group B. By stepwise regression analysis, LBMlegs/IBW appeared to be a significant predictor of VO2max in group A, while not in group B.

CONCLUSION

LBMlegs was a significant predictor of maximal exercise performance in patients with mild-to-moderate airflow limitation, but not in patients with severe airflow limitation who had disproportional reduction in LBMlegs.

Lung volume reduction surgery for emphysema

Over the past decades, extensive literature has been published regarding surgical therapies for advanced COPD. Lung-volume reduction surgery would be an option for a significantly larger number of patients than classic bullectomy or lung transplantation. Unfortunately, the initial enthusiasm has been tempered by major questions regarding the optimal surgical approach, safety, firm selection criteria, and confirmation of long-term benefits. In fact, the long-term follow-up reported in patients undergoing classical bullectomy should serve to caution against unbridled enthusiasm for the indiscriminate application of LVRS. Those with the worst long-term outcome despite favourable short-term improvements after bullectomy have consistently been those with the lowest pulmonary function and significant emphysema in the remaining lung who appear remarkably similar to those being evaluated for LVRS. With this in mind, the National Heart, Lung and Blood Institute partnered with the Health Care Finance Administration to establish a multicenter, prospective, randomized study of intensive medical management, including pulmonary rehabilitation versus the same plus bilateral (by MS or VATS), known as the National Emphysema Treatment Trial. The primary objectives are to determine whether LVRS improves survival and exercise capacity. The secondary objectives will examine effects on pulmonary function and HRQL, compare surgical techniques, examine selection criteria for optimal response, identify criteria to determine those who are at prohibitive surgical risk, and examine long-term cost effectiveness. It is hoped that data collected from this novel, multicenter collaboration will place the role of LVRS in a clearer perspective for the physician caring for patients with advanced emphysema.

Reduction pneumoplasty versus respiratory rehabilitation in severe emphysema: a randomized study. Pulmonary Emphysema Research Group

BACKGROUND

The purpose of the study was to determine in a prospective randomized trial the independent short-term physiologic impact of reduction pneumoplasty (RP) on respiratory rehabilitation (RR).

METHODS

Sixty patients eligible for RP were randomly selected by computer to receive either RP (n = 30) or comprehensive RR (n = 30). Pulmonary function tests, analysis of blood gas levels, measurement of respiratory muscle strength (maximal inspiratory and expiratory pressures), 6-minute walk test (6MWT), and incremental treadmill test (ITT), were performed at baseline and at 3 and 6 months.

RESULTS

Two treatment-related deaths occurred after RP and one after RR. At 6 months dyspnea index, maximal inspiratory pressure, 6MWT, ITT, and PaO2 were significantly improved in both groups whereas forced expiratory volume in 1 second and residual volume were significantly improved only in the surgical arm. In addition at 6 months, dyspnea index, 6MWT, maximal ITT, and PaO2 improved significantly more after RP than after RR.

CONCLUSIONS

In our study short-term improvements in dyspnea index, oxygenation, inspiratory muscle strength, and exercise capacity occurred after either RP and RR. However dyspnea index, PaO2, and exercise capacity improved more after RP than after RR whereas pulmonary function improved only after RP.

Clinical evaluation of 99mTc-Technegas SPECT in thoracoscopic lung volume reduction surgery in patients with pulmonary emphysema

99mTc-Technegas (Tcgas) SPECT is useful for evaluating the patency of the airway and highly sensitive in detecting regional pulmonary function in pulmonary emphysema. The aim of this study is to evaluate regional ventilation impairment by this method pre and post thoracoscopic lung volume reduction surgery (LVRS) in patients with pulmonary emphysema.

METHODS

There were 11 patients with pulmonary emphysema. The mean age of patients was 64.1 years. All patients were males. LVRS was performed bilaterally in 8 patients and unilaterally in 3 patients. Post inhalation of Tcgas in the sitting position, the subjects were placed in the supine position and SPECT was performed. Distribution of Tcgas on axial images was classified into 4 types, A: homogeneous, B: inhomogeneous, C: hot spot, D: defect. Three slices of axial SPECT images, the upper, middle and lower fields were selected, and changes in deposition patterns post LVRS were scored (Tcgas score).

RESULTS

Post LVRS, dyspnea on exertion and pulmonary function tests were improved. Pre LVRS, inhomogeneous distribution, hot spots and defects were observed in all patients. Post LVRS, improvement in distribution was obtained not only in the surgical field and other fields, but also in the contralateral lung of unilaterally operated patients. In 5 patients some fields showed deterioration. The Tcgas score correlated with improvements in FEV1.0, FEV1.0% and %FEV1.0.

CONCLUSION

Tcgas SPECT is useful for evaluating changes in regional pulmonary function post LVRS.

Long-term survival after thoracoscopic lung volume reduction: a multiinstitutional review

BACKGROUND

It has been suggested that bilateral thoracoscopic lung volume reduction (BTLVR) yields significantly better long-term survival than unilateral thoracoscopic lung volume reduction (UTLVR).

METHODS

All perioperative data were collected at the time of the procedure. Follow-up data were obtained during office visits or by telephone.

RESULTS

A total of 673 patients underwent thoracoscopic LVR: 343 had either simultaneous or staged BTLVR and 330, UTLVR. As of July 1998, follow-up was available on 667 (99%) of the 673 patients with a mean follow-up of 24.3 months. The patients in the BTLVR group were significantly younger (62.6+/-8.0 years versus 65.4+/-8.1 years; p < 0.0001), had a higher preoperative arterial oxygen tension (69.7+/-12 mm Hg versus 65.3+/-11 mm Hg; p < 0.0001), and had a superior preoperative 6-minute walk performance (279.9+/-93.6 m [933+/-312 feet] versus 244.5+/-101.4 m [815+/-338 feet] p < 0.0001). There was no difference in the operative mortality rate between the two groups (UTLVR, 5.1%, and BTLVR, 7%). Actuarial survival rates for the UTLVR group at 1 year, 2 years, and 3 years were 86%, 75%, and 69%, respectively versus 90%, 81%, and 74%, respectively, for the BTLVR group (p = not significant).

CONCLUSIONS

Contrary to previous reports, survival after BTLVR was not superior to that after UTLVR even though the former group appeared to have a lower risk preoperatively because of younger age, higher arterial oxygen tension, more advantageous anatomy, and better functional status. Despite thoracoscopic LVR, the actuarial mortality rate approached 30% at 3 years, and this calls into question whether this procedure offers any survival advantage to patients with end-stage emphysema.

A pilot study of expiratory flow limitation and lung volume reduction surgery

STUDY OBJECTIVES

To examine the relationships between changes in expiratory flow limitation (FL) during anesthesia and postoperative responses to lung volume reduction surgery (LVRS).

DESIGN

Prospective consecutive case comparison.

SETTING

University medical center.

PATIENTS

Eight patients with severe emphysema.

INTERVENTIONS

General anesthesia with muscle paralysis and thoracic epidural analgesia were provided for LVRS via median sternotomy.

MEASUREMENTS

FEV(1), functional residual capacity (FRC), and total lung capacity (TLC) were measured preoperatively and 3 months postoperatively. Tidal volume (VT) flow/volume (F/V) curves were obtained with a Pitot-type spirometer. VT, expiratory flow rate at 0. 25 x VT (V'VT,25% ), and peak expiratory flow rate (V'VT,MAX) were obtained from VT F/V curves to derive V'VT,25%/V'VT,MAX ratio as a measure of FL.

RESULTS

Closed chest VT F/V curves during anesthesia pre-LVRS showed four patients with FL (group A) whose V'VT,25%/V'VT, MAX ratio was 0.38 +/- 0.06 (mean +/- SD) and four patients without FL (group B) whose V'VT,25%/V'VT,MAX ratio was 0.82 +/- 0.06 (p = 0. 0001). Closed chest post-LVRS V'VT,25%/V'VT,MAX ratio during anesthesia increased by 0.48 +/- 0.08 in group A, compared with a 0. 19 +/- 0.16 reduction in group B (p = 0.0001). Preoperative FEV(1) was 0.57 +/- 0.10 L for group A vs 0.82 +/- 0.13 L for group B (p = 0.02). Postoperative FEV(1) increased by 67 +/- 40% for group A (p = 0.03) vs 29 +/- 21% for group B (not significant). FRC decreased by 33 +/- 3% for group A vs 17 +/- 5% for group B (p = 0.0007), and FRC/TLC decreased by 0.14 +/- 0.05 for group A vs 0.01 +/- 0.07 for group B (p = 0.026). Post-LVRS V'VT,25%/V'VT,MAX ratio change during anesthesia correlated with postoperative reduction in FRC (r(2) = 0. 89, p = 0.0004) and FRC/TLC (r(2) = 0.52, p = 0.045).

CONCLUSION

Post-LVRS change in V'VT,25%/V'VT,MAX ratio during anesthesia showed a linear relationship with 3-month postoperative improvement in dynamic hyperinflation. Thus, V'VT,25%/V'VT,MAX ratio may help provide valuable insights into the interactions between chest wall recoil, dynamic hyperinflation, and VT flow rates in patients with severe COPD and LVRS.

Development of a giant bulla after lung volume reduction surgery

Lung volume reduction surgery (LVRS) is being evaluated in the treatment of emphysema. The proposed mechanisms of improvement are increased elastic recoil of the lung and improved mechanical efficiency of the muscles of respiration. We report a unique patient with emphysema who developed a giant bulla 3 years subsequent to LVRS. The patient underwent extensive evaluation, including measurements of lung mechanics. Bullectomy was performed, but it was unsuccessful. Although the mechanisms behind the development of giant bullous disease remain speculative, heterogeneous improvement in elastic recoil following LVRS may be one of the responsible mechanisms.

Lung function 4 years after lung volume reduction surgery for emphysema

STUDY OBJECTIVES

Current data for patients > 2 years after lung volume reduction surgery (LVRS) for emphysema is limited. This prospective study evaluates pre-LVRS baseline data and provides long-term results in 26 patients.

INTERVENTION

Bilateral targeted upper lobe stapled LVRS using video thoracoscopy was performed in 26 symptomatic patients (18 men) aged 67 +/- 6 years (mean +/- SD) with severe and heterogenous distribution of emphysema on lung CT. Lung function studies were measured before and up to 4 years after LVRS unless death intervened.

RESULTS

No patients were lost to follow-up. Baseline FEV(1) was 0.7 +/- 0.2 L, 29 +/- 10% predicted; FVC, 2.1 +/- 0.6 L, 58 +/- 14% predicted (mean +/- SD); maximum oxygen consumption, 5.7 +/- 3.8 mL/min/kg (normal, > 18 mL/min/kg); dyspneic class > or = 3 (able to walk < or = 100 yards) and oxygen dependence part- or full-time in 18 patients. Following LVRS, mortality due to respiratory failure at 1, 2, 3, and 4 years was 4%, 19%, 31%, and 46%, respectively. At 1, 2, 3, and 4 years after LVRS, an increase above baseline for FEV(1) > 200 mL and/or FVC > 400 mL was noted in 73%, 46%, 35%, and 27% of patients, respectively; a decrease in dyspnea grade > or = 1 in 88%, 69%, 46%, and 27% of patients, respectively; and elimination of oxygen dependence in 78%, 50%, 33%, and 22% of patients, respectively. The mechanism for expiratory airflow improvement was accounted for by the increase in both lung elastic recoil and small airway intraluminal caliber and reduction in hyperinflation. Only FVC and vital capacity (VC) of all preoperative lung function studies could identify the 9 patients with significant physiologic improvement at > 3 years after LVRS, respectively, from 10 patients who responded < or = 2 years and died within 4 years (p < 0.01).

CONCLUSIONS

Bilateral LVRS provides clinical and physiologic improvement for > 3 years in 9 of 26 patients with emphysema primarily due to both increased lung elastic recoil and small airway caliber and decreased hyperinflation. The 9 patients had VC and FVC greater at baseline (p < 0.01) when compared to 10 short-term responders who died < 4 years after LVRS.

Lung volume reduction surgery (LVRS) for chronic obstructive pulmonary disease (COPD) with underlying severe emphysema

BACKGROUND

Lung volume reduction surgery (LVRS) has recently re-emerged as a surgical option for the treatment of end stage chronic obstructive pulmonary disease (COPD) due to underlying severe emphysema. Advocates of LVRS claim that it represents a significant breakthrough in the management of this challenging group of patients while sceptics point to uncertainty about the effectiveness of the operation.

METHODS

A systematic review was conducted of the evidence on the effects of LVRS in patients with end stage COPD secondary to severe emphysema.

RESULTS

The most rigorous evidence on the effectiveness of LVRS came from case series. Seventy five potentially relevant studies were identified and 19 individual series met the methodological criteria for inclusion. The pattern of results was consistent across individual studies despite a significant degree of clinical heterogeneity. Significant short term benefits occurred across a range of outcomes which appeared to continue into the longer term. Physiological improvements were matched by functional and subjective improvements. Early mortality rates were low and late mortality rates compared favourably with those of the general COPD population. However, the entire research base for the intervention is subject to the limitations of study designs without parallel control groups.

CONCLUSIONS

LVRS appears to represent a promising option in the management of patients with severe end stage emphysema. However, until the results of ongoing clinical trials are available, the considerable uncertainty that exists around the effectiveness and cost effectiveness of the procedure will remain.

Effect of lung volume reduction surgery on bony thorax configuration in severe COPD

STUDY OBJECTIVES

Hyperinflation in patients with severe COPD is associated with an increased anteroposterior (AP) rib cage diameter. We sought to determine whether bilateral lung volume reduction surgery (LVRS) affects bony thorax configuration.

DESIGN

Prospective of clinical data collection before and after LVRS.

SETTING

Tertiary-care university medical center.

PATIENTS

We measured multiple AP and transverse thoracic diameters, by using plain chest roentgenograms (CXRs) in 25 patients (11 men, 14 women), and thoracic CT scans in 14 patients (7 men, 7 women), preoperatively and 3 months postoperatively. A subgroup of 7 patients (reference data) also had CXR thoracic diameter measurements made, using films obtained previously within a year of their presurgical evaluation. Another subgroup of 10 patients had CT scan measurements also made 12 months postoperatively.

MEASUREMENTS AND RESULTS

CXR dimensions were taken at the level of the manubrium sterni (M) and thoracic T7 and T11 levels. CT dimensions were taken at T4, T6, T8, and T10 levels. At each level, left (L), midsagittal (C), and right (R) AP and maximal transverse diameters were measured. The sum of the three AP diameters (Total) was used for calculations. Patients also underwent tests such as spirometry, lung volumes, diffusing capacity of the lung for carbon monoxide, 6-min walk distance (6MWD), and transdiaphragmatic pressures during maximum static inspiratory efforts (Pdimax sniff) measured before and 3 months after LVRS. Patients were (mean +/- SD) 58+/-8 years old, with severe COPD and hyperinflation (FEV1, 0.68+/-0.23 L; FVC, 2.56+/-7.3 L; and total lung capacity [TLC], 143+/-22% predicted). After LVRS, AP diameters were reduced at thoracic level T7 (from 24.2+/-2.0 cm to 23.3+/-2.2 cm, p = 0.0002), and transverse diameters were reduced at T7 (from 26.8+/-1.9 cm to 26.4+/-1.7 cm, p = 0.001) and T11 (from 29.9+/-2.2 cm to 29.5+/-2.2 cm, p = 0.03), as measured using the CXR. In contrast, thoracic diameters were similar in subjects with CXRs before LVRS and within 1 year before evaluation. CT-measured AP diameters were significantly reduced 3 months after LVRS at T6, (from 48.8+/-6.0 cm to 46.7+/-5.4 cm, p = 0.02), T8 (from 54.2+/-7.0 cm to 52.3+/-6.5 cm, p = 0.004), and T10 (from 53.8+/-7.5 cm to 51.2+/-8.0 cm, p = 0.001), but not at T4. These AP diameter reductions directly correlated with the postoperative reductions in TLC and residual volume, and also with the increases in Pdimax sniff and 6MWD after LVRS. The reduction in AP diameters at thoracic levels T8 and T10 seen 3 months after LVRS remained stable at 12-month follow-up, whereas those measured at T6 lost statistical significance. CT-measured transverse diameters were unchanged at all levels after LVRS.

CONCLUSIONS

We conclude that LVRS decreases mid-to-lower AP rib cage diameter as assessed by CXR and thoracic CT. Although transverse diameters were reduced on CXR, the magnitude was small and was not confirmed with CT. After LVRS, AP diameter reductions are most likely the result of reduction in lung volume, and they are associated with improvements in diaphragm strength and exercise endurance.

Effect of lung volume reduction surgery on diaphragm length in severe chronic obstructive pulmonary disease

Lung volume reduction surgery (LVRS) has been suggested as improving respiratory mechanics in patients with severe chronic obstructive pulmonary disease (COPD). We hypothesized that LVRS might lengthen the diaphragm, increase its area of apposition with the chest wall, and thereby improve its mechanical function. To determine the effect of bilateral LVRS on diaphragm length, we measured diaphragm length at TLC, using plain chest roentgenograms (CXRs), in 25 patients (11 males and 14 females) before LVRS and 3 to 6 mo after LVRS. A subgroup of seven patients (reference data) also had diaphragm length measurements made with CXRs, using films made within a year before their presurgical evaluation. Right hemidiaphragm silhouette length (PADL) and the length of the most vertically oriented portion of the right hemidiaphragm muscle (VDML) were measured. Diaphragm dome height was determined from the: (1) distance between the dome and transverse diameter at the manubrium; and (2) highest point of the dome referenced horizontally to the vertebral column. Patients also underwent spirometry, measurements of lung volumes and diffusion capacity, an incremental symptom-limited maximum exercise test, and measurements of 6 min walk distance (6MWD) and transdiaphragmatic pressures during maximum static inspiratory efforts (Pdimax sniff) and bilateral supramaximal electrophrenic twitch stimulation (Pditwitch) both before and 3 mo after LVRS. Patients were 58 +/- 8 yr of age, with severe COPD and hyperinflation (FEV1 = 0.68 +/- 0.23 L, FVC = 2.56 +/- 7.3 L, and TLC = 143 +/- 22% predicted). Following LVRS, PADL increased by 4% (from 13.9 +/- 1.9 cm to 14.5 +/- 1.7 cm; p = 0.02), VDML increased by 44% (from 2.08 +/- 1.5 cm to 3.00 +/- 1.6 cm, p = 0.01), and diaphragm dome height increased by more than 10%. In contrast, diaphragm lengths were similar in subjects with CXRs made before LVRS and within 1 yr before evaluation. The increase in diaphragm length correlated directly with postoperative reductions in TLC and RV, and also with increases in transdiaphragmatic pressure with maximal sniff (Pdimax sniff), maximal oxygen consumption (V O2max), maximal minute ventilation (V Emax), and maximum voluntary ventilation following LVRS. We conclude that LVRS leads to a significant increase in diaphragm length, especially in the area of apposition of the diaphragm with the rib cage. Diaphragm lengthening after LVRS is most likely the result of a reduction in lung volume. Increases in diaphragm length after LVRS correlate with postoperative improvements in diaphragm strength, exercise capacity, and maximum voluntary ventilation.

Survival following bilateral staple lung volume reduction surgery for emphysema

STUDY OBJECTIVES

Despite numerous reports of short-term response to lung volume reduction surgery (LVRS) for treatment of emphysema, to our knowledge, longer-term survival has not been reported. We describe survival following LVRS in a large cohort of 256 patients treated with bilateral staple LVRS (n = 236 video-assisted thoracic surgery [VATS] approaches, n = 20 median sternotomy) by a single group of physicians over a 3 1/2-year period from April 1994 to November 1997.

DESIGN

Prospective survival study. Overall survival, survival stratified by preoperative presentation, and acute postoperative response were investigated using Kaplan-Meier methods. The simultaneous effects of preoperative predictors and postoperative response variables on survival were examined using a Cox proportional hazards model.

SETTING

Community hospital and university medical center.

PATIENTS

We studied 256 consecutive patients with severe emphysema treated with LVRS.

INTERVENTIONS

Bilateral staple LVRS by VATS.

MEASUREMENTS AND RESULTS

Overall survival information was known with certainty for 246 of 256 patients as of February 1, 1998. Median follow-up time was 623 days (range, 0 to 1,545 days). Mean FEV1 was 0.635L+/-0.015 L preoperatively and rose to 1.068L+/-0.029 L postoperatively. By standard analysis methods (missing patients censored at the time of last contact), 1-year survival was 85+/-2.3% compared with 83+/-2.4% 1-year survival with "worst case" analytic methods (assuming all missing patients died). Two-year survival averaged 81+/-2.7% by standard analysis vs 76+/-2.9% by worst case evaluation. Survival was significantly better for patients who were younger (< or = 70 years old, p = 0.02) and with higher baseline FEV1 (> 0.5, p < 0.03) and PO2 (> 54, p < 0.001). Patients who had greatest short-term improvement in FEV1 following surgery (> 0.56 L increase) also had significantly better longer-term survival following LVRS.

CONCLUSIONS

To our knowledge, this is the first longer-term survival analysis of a large series of patients who underwent bilateral staple LVRS for emphysema. Substantial long-term mortality is seen, particularly within identifiable high-risk subgroups. Careful comparison to comparably matched control patients will be needed to definitively assess the benefits and risks of LVRS. This study suggests that prospective, controlled trials may need to stratify patient randomization based on preoperative risk factors to obtain meaningful results.

Measurement of symptoms, lung hyperinflation, and endurance during exercise in chronic obstructive pulmonary disease

Changes in lung hyperinflation, dyspnea, and exercise endurance are important outcomes in assessing therapeutic responses in chronic obstructive pulmonary disease (COPD). Therefore, we studied the reproducibility of Borg dyspnea ratings, inspiratory capacity (IC; to monitor lung hyperinflation), and endurance time during constant-load symptom-limited cycle exercise in 29 patients with COPD (FEV1 = 40 +/- 2% predicted; mean +/- SEM). Responsiveness was also studied by determining the acute effects of nebulized 500 micrograms ipratropium bromide (IB) or saline placebo (P) on these measurements. During each of four visits conducted over an 8-wk period, spirometry and exercise testing were performed before and 1 h after receiving IB or P (randomized, double-blinded). Highly reproducible measurements included: endurance time (intraclass correlation R = 0.77, p < 0.0001); Borg ratings and IC at rest, at a standardized exercise time (STD), and at peak exercise (R > 0.6, p < 0.0001); and slopes of Borg ratings over time, oxygen consumption (V O2), and ventilation (R > 0.6, p < 0.0001). Responsiveness was confirmed by finding a significant drug effect for: change (Delta) in endurance time (p = 0.0001); DeltaBorgSTD and DeltaBorg-time slopes (p < 0.05); and DeltaIC at rest, at STD, and at peak exercise (p = 0.0001). With all completed visits, DeltaBorgSTD correlated better with DeltaICSTD than any other resting or exercise parameter (n = 115, r = -0.35, p < 0.001). We concluded that Borg dyspnea ratings, and measurements of IC and endurance time during submaximal cycle exercise testing are highly reproducible and responsive to change in severe COPD.

Lung volume reduction surgery for emphysema: out on a limb without a NETT

Lung volume reduction surgery (LVRS) has recently been rediscovered and offers the potential of improving the quality of life of patients with advanced emphysema. In this article, we discuss the historical and contemporary versions of LVRS. Although initial enthusiasm has been substantial, existing data seem insufficient to demonstrate the safety and efficacy of the procedure in comparison with conventional medical therapy. Fundamental questions remain regarding the long-term effects of an operation versus medical therapy, the optimal selection criteria, the best measures of efficacy, the mechanisms of improvement, the cost-effectiveness of the procedure, and the optimal surgical technique. Until such questions are answered, advising patients about the best management their emphysema will be difficult. The National Emphysema Treatment Trial will address many of these issues and should be embraced by both health-care providers and patients.

Serial lung function and elastic recoil 2 years after lung volume reduction surgery for emphysema

STUDY OBJECTIVE

To evaluate serial lung function studies, including elastic recoil, in patients with severe emphysema who undergo lung volume reduction surgery (LVRS). To determine mechanism(s) responsible for changes in airflow limitation.

METHODS

We studied 12 (10 male) patients aged 68+/-9 years (mean+/-SD) 6 to 12 months prior to and at 6-month intervals for 2 years after thoracoscopic bilateral LVRS for emphysema.

RESULTS

At 2 years post-LVRS, relief of dyspnea remained improved in 10 of 12 patients, and partial or full-time oxygen dependency was eliminated in 2 of 7 patients. There was significant reduction in total lung capacity (TLC) compared with pre-LVRS baseline, 7.8+/-0.6 L (mean+/-SEM) (133+/-5% predicted) vs 8.6+/-0.6 L (144+/-5% predicted) (p=0.003); functional residual capacity, 5.6+/-0.5 L (157+/-9% predicted) vs 6.7+/-0.5 L (185+/-10% predicted) (p=0.001); and residual volume, 4.9+/-0.5 L (210+/-16% predicted) vs 6.0+/-0.5 L (260+/-13% predicted) (p=0.000). Increases were noted in FEV1, 0.88+/-0.08 L (37+/-6% predicted) vs 0.72+/-0.05 L (29+/-3% predicted) (p=0.02); diffusing capacity, 8.5+/-1.0 mL/min/mm Hg (43+/-3% predicted) vs 4.2+/-0.7 mL/min/mm Hg (18+/-3% predicted) (p=0.001); static lung elastic recoil pressure at TLC (Pstat), 13.7+/-0.5 cm H2O vs 11.3+/-0.6 cm H2O (p=0.008); and maximum oxygen consumption, 8.7+/-0.8 mL/min/kg vs 6.9+/-1.5 mL/min/kg (p=0.03). Increase in FEV1 correlated with the increase in TLC Pstat/TLC (r=0.75, p=0.03), but not with any baseline parameter.

CONCLUSION

Two years post-LVRS, there is variable clinical and physiologic improvement that does not correlate with any baseline parameter. Increased lung elastic recoil appears to be the primary mechanism for improved airflow limitation.

Effect of lung volume reduction surgery on diaphragm strength

Since lung volume reduction surgery (LVRS) reduces end-expiratory lung volume, we hypothesized that it may improve diaphragm strength. We evaluated 37 patients for pulmonary rehabilitation and LVRS. Before and 8 wk after pulmonary rehabilitation, 24 patients had spirometry, lung volumes, diffusion capacity, incremental symptom limited maximum exercise test, 6-min walk test, maximal static inspiratory and expiratory mouth pressures, and transdiaphragmatic pressures during maximum static inspiratory efforts and bilateral supramaximal electrophrenic twitch stimulation measured. Twenty patients (including 7 patients who crossed over after completing pulmonary rehabilitation) had baseline measurements postrehabilitation, and 3 mo post-LVRS. Patients were 58 +/- 8 yr of age, with severe COPD and hyperinflation (FEV1, 0.69 +/- 0.21 L; RV, 4.7 +/- 1.4 L). Nineteen patients had bilateral LVRS performed via median sternotomy and stapling, and 1 patient had unilateral LVRS via thorascopy with stapling. After rehabilitation, spirometry and DL(CO)/VA were not different, and lung volumes showed a slight worsening in hyperinflation. Gas exchange, 6-min walk distance, maximum oxygen uptake (VO2max), and breathing pattern during maximum exercise did not change after rehabilitation, but total exercise time was significantly longer. Inspiratory muscle strength (PImax, Pdi(max combined), Pdi(max sniff), Pdi(max), Pdi(twitch)), was unchanged after rehabilitation. In contrast, after LVRS, FVC increased 21%, FEV1 increased 34%, TLC decreased 13%, FRC decreased 23%, and FRC(trapped gas) and RV decreased by 57 and 28%, respectively. PCO2 was lower (44 +/- 6 versus 48 +/- 6 mm Hg, p < 0.003) and 6-min walk distance increased (343 +/- 79 versus 250 +/- 89 m, p < 0.001), as did total exercise time during maximum exercise (9.2 +/- 1.9 versus 6.9 +/- 2.7 min, p < 0.01). Minute ventilation (29 +/- 8 versus 21 +/- 6 L/min, p < 0.001) and tidal volume (1.0 +/- 0.33 versus 0.84 +/- 0.25 L, p < 0.001) during maximum exercise increased whereas respiratory rate was lower (28 +/- 6 versus 32 +/- 7 breaths/min, p < 0.02). Measurements of respiratory muscle strength (PImax, 74 +/- 28 versus 50 +/- 18 cm H2O, p < 0.002; Pdi(max combined), 80 +/- 25 versus 56 +/- 29 cm H2O, p < 0.01; Pdi(max sniff), 71 +/- 7 versus 46 +/- 27 cm H2O, p < 0.01; Pdi(twitch), 15 +/- 5 versus 7 +/- 5 cm H2O, p < 0.01) were all greater post-LVRS. Inspiratory muscle workload as measured by Pdi TTI was lower following LVRS (0.07 +/- 0.02 versus 0.09 +/- 0.03, p < 0.03). On multiple regression analysis, increases in PImax correlated significantly with decreases in RV and FRC(trapped gas) after LVRS (r = 0.67, p < 0.03). We conclude that LVRS significantly improves diaphragm strength that is associated with a reduction in lung volumes and an improvement in exercise performance. Future studies are needed to determine the relationship and stability of these changes over time.

Surgery for severe COPD. Lung volume reduction and lung transplantation

A management strategy for patients with severe emphysema is shown in figure 2 on page 199. Although the reported physiologic improvements after LVRS are significantly less than those seen after lung transplantation, LVRS has the potential to improve functional performance in a larger number of patients because of wider availability. Moreover, it accomplishes these goals without the attendant risks associated with transplantation and immunosuppression. The efficacy of LVRS over standard medical therapy in influencing survival and favorably affecting physiologic variables at rest and during exercise remains to be elucidated in NETT. Lung transplantation should be reserved for those patients deemed unsuitable or too ill for LVRS. It is to be hoped that future developments in organ preservation techniques and immunosuppressive regimens will expand the donor pool and decrease the incidence of posttransplantation bronchiolitis.

Improved exercise performance following lung volume reduction surgery for emphysema

Lung volume reduction surgery (LVRS) for emphysema has been suggested to improve patient lung function and activity. The short-term impact of LVRS on exercise performance was evaluated using maximal and submaximal steady-state exercise testing in 27 patients with severe hypoxemic chronic obstructive pulmonary disease (COPD), along with measurements of patient function, dyspnea, and quality of life. LVRS significantly improved exercise performance, due to ventilatory improvements associated with increased ventilatory reserve, enhanced tidal volume recruitment, and improved alveolar ventilation. Preoperative measurements of ventilatory reserve and dead space ventilation during exercise testing were closely associated with improved exercise performance. Improvements in patient dyspnea, walk distances, and quality of life also occurred following LVRS and were associated with improvements in exercise performance. Surgical mortality from LVRS was low (4%), but short-term all-cause mortality was increased (19%). Short-term mortality was associated with reduced expiratory muscle strength and markedly elevated dead space ventilation. We conclude that LVRS produces significant improvements in exercise performance, dyspnea, and quality of life in selected patients with COPD. Physiologic prediction of patients most likely to survive for an extended period and have significant benefit following LVRS may also be possible.