Relationship between resting hypercapnia and physiologic parameters before and after lung volume reduction surgery in severe chronic obstructive pulmonary disease

Targeting Hypercapnia in Chronic Lung Disease and Obesity Hypoventilation: Benefits and Challenges

Hypoventilation is a complication that is not uncommon in chronic obstructive pulmonary disease and calls for both medical treatment of the underlying disease and, frequently, noninvasive ventilation either during exacerbations requiring hospitalization or in a chronic state in the patient at home. Obesity hypoventilation syndrome by definition is associated with ventilatory failure and hypercapnia. It may or may not be accompanied by obstructive sleep apnea, which when detected becomes an additional target for positive airway pressure treatment. Intensive research has not completely resolved the best choice of treatment, and the simplest modality, continuous positive airway pressure, may still be entertained.

Chronic hypoxaemia and gender status modulate adiponectin plasmatic level and its multimer proportion in severe COPD patients: new endotypic presentation?

BACKGROUND

Disease progression in COPD patient is associated to lung function decline, leading to a higher risk of hypoxaemia and associated comorbidities, notably cardiovascular diseases (CVD). Adiponectin (Ad) is an adipokine with cardio-protective properties. In COPD patients, conflicting results were previously reported regarding Ad plasmatic (Adpl) level, probably because COPD is a heterogeneous disease with multifactorial influence. Among these factors, gender and hypoxaemia could interact in a variety of ways with Ad pathway. Therefore, we postulated that these components could influence Adpl level and its multimers in COPD patients and contribute to the appearance of a distinct endotype associated to an altered CVD risk.

METHODS

One hundred COPD patients were recruited: 61 were men and 39 were women. Patients who were not severely hypoxemic were allocated to non-hypoxemic group which included 46 patients: 27 men and 19 women. Hypoxemic group included 54 patients: 34 men and 20 women. For all patients, Adpl level and proportion of its different forms were measured. Differences between groups were evaluated by Rank-Sum tests. The relationship between these measures and BMI, blood gas analysis (PaO2, PaCO2), or lung function (FEV1, FEV1/FVC, TLCO, TLC, RV) were evaluated by Pearson correlation analysis.

RESULTS

Despite similar age, BMI and obstruction severity, women had a higher TLC and RV (median: TLC = 105%; RV = 166%) than men (median: TLC = 87%; RV = 132%). Adpl level was higher in women (median = 11,152 ng/ml) than in men (median = 10,239 ng/ml) and was negatively associated with hyperinflation (R = - 0,43) and hypercapnia (R = - 0,42). The proportion of the most active forms of Ad (HMW) was increased in hypoxemic women (median = 10%) compared with non-hypoxemic women (median = 8%) but was not modulated in men.

CONCLUSION

COPD pathophysiology seemed to be different in hypoxemic women and was associated to Ad modulations. Hyperinflation and air-trapping in association with hypercapnia and hypoxaemia, could contribute to a modulation of Adpl level and of its HMW forms. These results suggest the development of a distinct endotypic presentation, based on gender.

Is preoperative hypercapnia a justified exclusion criterion for lung volume reduction surgery?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was whether potential surgical candidates for lung volume reduction surgery (LVRS), who have preoperative hypercapnia, should be excluded on this basis. Using the reported search, 45 papers were found, of which 14 represented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses were tabulated. Of these, seven papers showed a significant (P < 0.05) improvement in postoperative forced expiratory volume in 1 second (FEV1) at up to 6 months in hypercapnic patients. There were six papers which found significant decreases in postoperative arterial carbon dioxide partial pressures (PaCO2) levels following LVRS up to 6 months. There were three papers which showed significant (P < 0.05) improvements in the 6-min walk test in hypercapnic patients following LVRS. Only two papers showed an increased operative mortality in the hypercapnic group compared to the normocapnic group, while nine papers did not find a difference in perioperative mortality. The only randomized controlled study, the landmark NETT study, excluded patients with severe hypercapnia (PaCO2 >55 mmHg and >60 mmHg) and the mean PaCO2 in the surgical and medical group were 43.3 ± 5.9 and 43.0 ± 5.8, respectively. We conclude that the evidence is not strong enough to consider hypercapnia in isolation as high risk or unsuitable for LVRS.

Endoscopic lung volume reduction coil treatment in patients with chronic hypercapnic respiratory failure: an observational study

Background:

Endoscopic lung volume reduction coil (LVRC) treatment is an option for selected patients with severe emphysema. In the advanced stages, emphysema leads to respiratory failure: hypoxemia and eventually chronic hypercapnic respiratory failure. It can be hypothesized that LVRC treatment, a procedure targeting hyperinflation and thereby reducing ventilatory workload, may be especially beneficial in patients with chronic hypercapnic respiratory failure. This study was conducted to gain first insights into the effects and the safety of LVRC treatment in patients with emphysema and chronic hypercapnic respiratory failure.

Methods:

A retrospective observational study conducted in the Department of Respiratory Medicine at the University Medical Center Hamburg-Eppendorf, Germany on all patients with chronic hypercapnic respiratory failure in whom bilateral LVRC treatment was performed between 1 April 2012 and 30 September 2015.

Results:

During the study period, bilateral LVRC treatment was performed in 10 patients with chronic hypercapnic respiratory failure. Compared with baseline, bilateral LVRC treatment led to a significant increase in mean forced expiratory volume in one second (FEV₁) from 0.5 ± 0.1 l to 0.6 ± 0.2 l (p = 0.004), a decrease in residual volume (RV) from 6.1 ± 0.9 l to 5.6 ± 1.1 l (p = 0.02) and a reduction in partial pressure of carbon dioxide in arterial blood (PaCO₂) from 53 ± 5 mmHg to 48 ± 4 mmHg (p = 0.03). One case of hemoptysis requiring readmission to hospital was the only severe adverse event.

Conclusions:

LVRC treatment was safe and effective in patients with nonsevere chronic hypercapnic respiratory failure. It led not only to an improvement in lung function but also to a significant decrease in PaCO₂.

Lung transplantation and lung volume reduction surgery

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

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

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

Hypoventilation syndromes

A wide variety of mechanisms can lead to the hypoventilation associated with various medical disorders, including derangements in central ventilatory control, mechanical impediments to breathing, and abnormalities in gas exchange leading to increased dead space ventilation. The pathogenesis of hypercapnia in obesity hypoventilation syndrome remains somewhat obscure, although in many patients comorbid obstructive sleep apnea appears to play an important role. Hypoventilation in neurologic or neuromuscular disorders is primarily explained by weakness of respiratory muscles, although some central nervous system diseases may affect control of breathing. In other chest wall disorders, obstructive airways disease, and cystic fibrosis, much of the pathogenesis is explained by mechanical impediments to breathing, but an element of increased dead space ventilation also often occurs. Central alveolar hypoventilation syndrome involves a genetically determined defect in central respiratory control. Treatment in all of these disorders involves coordinated management of the primary disorder (when possible) and, increasingly, the use of noninvasive positive pressure ventilation.

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.

Effect of lung transplant and volume reduction surgery on respiratory muscle function

Lung transplantation and lung volume reduction surgery have opened a new therapeutic era for patients with advanced emphysema. In addition to providing impressive clinical benefits, they have helped us better understand how the chest wall and respiratory muscles adapt to chronic hyperinflation. This article reviews the effects of these procedures on respiratory muscle and chest wall function. Inspiratory (including diaphragm) and expiratory muscle strength are often close to normal after unilateral and bilateral transplantation, although some patients have marked weakness. After bilateral transplantation for emphysema, graft volume is normal at full inflation but remains greater than normal at end expiration, which results from structural changes in the chest wall. In contrast, patients with unilateral transplantation have a reduction in graft volume at full inflation. The mediastinum is displaced toward the graft at end expiration, which reduces the surface area of the diaphragm on the transplanted side, and it moves toward the native lung during tidal and full inspiration and toward the graft during tidal and forced expiration. Lung volume reduction produces an increase in contractility, length and surface area of the diaphragm, and increases its contribution to tidal volume; at the same time, neural drive to the muscle and respiratory load are reduced, such that diaphragm neuromechanical coupling is improved. Diaphragm configuration and rib cage dimensions are only minimally affected by the procedure. Single-lung transplantation and lung volume reduction favorably impact on the disadvantageous size interaction by which the lungs are functionally restricted by the chest wall in emphysema.

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

Lung transplantation and lung volume reduction surgery are surgical options for patients with advanced chronic obstructive pulmonary disease that is refractory to medical treatment. In this review, we discuss the differential indications for each procedure, as well as compare their risks and benefits. We also present an algorithm for selecting the most appropriate procedure for individual patients. Finally, we discuss the feasibility and role of lung transplantation after lung volume reduction surgery in the management of selected patients with chronic obstructive pulmonary disease.

Changes in arterial oxygenation and self-reported oxygen use after lung volume reduction surgery

RATIONALE

Lung volume reduction surgery (LVRS) is inconsistently reported to improve arterial oxygenation in patients with chronic obstructive pulmonary disease.

OBJECTIVES

We studied the effects of surgery on oxygenation in a large cohort and identified predictors of postoperative oxygenation improvement.

METHODS

We evaluated oxygenation in 1,078 subjects with chronic obstructive pulmonary disease enrolled in the National Emphysema Treatment Trial after LVRS compared with medical control subjects, including arterial blood gases, use of supplemental oxygen during treadmill walking, and self-reported use of oxygen during rest, exertion, and sleep.

MEASUREMENTS AND MAIN RESULTS

Pa(O(2)) breathing room air was equal in medical and surgical subjects at baseline (64.8 vs. 65.0 mm Hg, P = not significant), but lower in medical subjects at 6 months (63.6 vs. 70.0 mm Hg, P < 0.001), 12 months (63.9 vs. 68.7 mm Hg, P < 0.001), and 24 months (62.4 vs. 68.0 mm Hg, P < 0.001). Fewer medical subjects required oxygen for treadmill walking at baseline compared with surgical subjects (46 vs. 53%, P = 0.02). However, more medical subjects required oxygen for this activity at 6 months (49 vs. 33%, P < 0.001), 12 months (50 vs. 36%, P < 0.001), and 24 months (52 vs. 42%, P = 0.02). Self-reported oxygen use was greater in medical than in surgical subjects at 6, 12, and 24 months. Multivariate modeling of preoperative characteristics showed baseline oxygenation status was the best predictor of postoperative oxygenation.

CONCLUSIONS

LVRS increases Pa(O(2)), and decreases treadmill and self-reported use of oxygen for up to 24 months post-procedure. Clinical trial registered with www.clinicaltrials.gov (NCT 00000606).

Bronchoscopic lung volume reduction: indications, effects and prospects

PURPOSE OF REVIEW

Despite optimal pharmacological treatment, many patients with chronic obstructive pulmonary disease remain very disabled. Bronchoscopic lung volume reduction involves the insertion of valves into the airways supplying emphysematous areas of lung with the intention of causing atelectasis and thus improving operating lung volumes. Bronchoscopic techniques are less hazardous than lung volume reduction surgery.

RECENT FINDINGS

Case series in the literature are reviewed. The presence of extensive pathological collateral ventilation, particularly in patients with homogeneous disease, means that atelectasis occurs relatively infrequently even with complete lobar occlusion. Benefit is greatest in the presence of atelectasis but does not occur only in this group of patients. Endobronchial valves have also been used to treat persistent air leaks in a number of clinical contexts.

SUMMARY

A number of case series have been published which show promise and the results of a large multicentre randomized controlled study are anticipated in 2007. A number of other bronchoscopic treatments for emphysema are also under development, including airway bypass techniques and tissue glues.

Lung volume reduction surgery for emphysema: What the radiologist needs to know

Imaging plays a pivotal role in the selection of patients for the surgical treatment of emphysema. In this article, the imaging features of emphysema are reviewed along with the surgical options for treatment. Particular emphasis is given to lung volume reduction surgery as this technique has gained wide acceptance within the thoracic surgical community in recent years. Radiologists need to have an understanding of which patients may be potentially suitable for this technique.

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.

[VENT: International study of bronchoscopic lung volume reduction as a palliative treatment for emphysema]

BACKGROUND

Therapeutic options for patients with severe emphysema remain limited. In selected patients, lung volume reduction surgery has been shown to improve pulmonary function, exercise capacity, quality of life and also survival. The technique of inserting one-way valves endoscopically into the airways supplying the most affected areas of lung provides the possibility of achieving similar results to surgery (i.e. volume reduction) in a less invasive way, which is also reversible, since the valves can be removed at any time. This technique has been shown to be safe. The aim of this study is to evaluate the efficacy of this technique compared to optimal medical therapy in patients with heterogeneous emphysema defined according to radiological criteria.

METHODS

A prospective, international, multicentre (20 centres) randomised trial is underway to establish the efficacy and safety of endobronchial valve placement in this patient group. This study will enrol 270 patients and be analysed on an intention to treat basis. Patients are randomised either to valve insertion or optimal medical treatment alone in a ratio of 2 to 1. Follow up will be ensured for at least one year.

EXPECTED RESULTS

The two principal outcome measures will be improvement at six months in FEV1 and in six minute walk distance. The safety of the technique will be evaluated over the same period. Details of the study are available online for patients and their physicians at www.euroemphysema.com.

Effect of bronchoscopic lung volume reduction on dynamic hyperinflation and exercise in emphysema

Endobronchial valve placement improves pulmonary function in some patients with chronic obstructive pulmonary disease, but its effects on exercise physiology have not been investigated. In 19 patients with a mean (SD) FEV(1) of 28.4 (11.9)% predicted, studied before and 4 weeks after unilateral valve insertion, functional residual capacity decreased from 7.1 (1.5) to 6.6 (1.7) L (p = 0.03) and diffusing capacity rose from 3.3 (1.1) to 3.7 (1.2) mmol . minute(-1) . kPa(-1) (p = 0.03). Cycle endurance time at 80% of peak workload increased from 227 (129) to 315 (195) seconds (p = 0.03). This was associated with a reduction in end-expiratory lung volume at peak exercise from 7.6 (1.6) to 7.2 (1.7) L (p = 0.03). Using stepwise logistic regression analysis, a model containing changes in transfer factor and resting inspiratory capacity explained 81% of the variation in change in exercise time (p < 0.0001). The same variables were retained if the five patients with radiologic atelectasis were excluded from analysis. In a subgroup of patients in whom invasive measurements were performed, improvement in exercise capacity was associated with a reduction in lung compliance (r(2) = 0.43; p = 0.03) and isotime esophageal pressure-time product (r(2) = 0.47; p = 0.03). Endobronchial valve placement can improve lung volumes and gas transfer in patients with chronic obstructive pulmonary disease and prolong exercise time by reducing dynamic hyperinflation.

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.

Thoracoscopic lung volume reduction surgery for pulmonary emphysema patients with severe hypercapnia

OBJECTIVES

We assessed whether hypercapnia patients with an extremely high level of PaCO2 > or = 60 mmHg were suitable candidates for lung volume reduction in the treatment of severe pulmonary emphysema.

METHODS

Of 65 patients undergoing lung volume reduction surgery between May 1993 and August 1997, 6 (9.23%) who had a preoperative rest room air blood gas level of PaCO2 > or = 60 mmHg were selected for study. All patients underwent video-assisted thoracoscopic surgery. Of the 6 with severe hypercapnia, 5 underwent the unilateral procedure and 1 the bilateral procedure.

RESULTS

All severe hypercapnia patients showed significant clinical improvement. When assessed at 3 to 6 months after lung volume reduction surgery, significant improvements were seen in mean forced expiratory volume in 1 second (preop: 0.44 +/- 0.04 L; postop: 0.74 +/- 0.20 L; p < 0.01), for a magnitude improvement of 69.8%, and in trapped gas volume (preop: 3.28 +/- 1.11 L; postop: 1.61 +/- 1.02 L; p < 0.05). Arterial blood gas analysis showed significant improvement in PaO2 from 51.1 +/- 6.68 mmHg to 69.8 +/- 7.87 mmHg (p < 0.001) with a decrease in PaCO2 from 70.4 +/- 9.41 mmHg to 46.9 +/- 3.44 mmHg (p < 0.01). Postoperative follow-up averaged 55 months (43-69 months). All but 1 patient remain alive and well.

CONCLUSION

Patients with severe pulmonary emphysema accompanied by hypercapnia can gain relief and a better quality of life through volume reduction surgery and should not be excluded from surgical treatment simply based on this condition. Selection should involve a comprehensive view of the patient's condition that includes criteria such as the results of radiographic diagnosis and detailed pulmonary function tests.

Surgery for chronic obstructive pulmonary disease: the place for lung volume reduction and transplantation

Lung volume reduction surgery and lung transplantation have been shown to improve lung function, exercise capacity, and quality of life in patients with advanced emphysema. Because the indications for both surgical procedures overlap, lung volume reduction surgery may be used as an alternative treatment or as a "bridge" to lung transplantation. In this article, we discuss patient selection, clinical outcome parameters, and the morbidity and mortality associated with each surgical procedure. We focus on the different preoperative predictors of good and poor outcomes after lung volume reduction surgery, the role of pulmonary rehabilitation, and the preferred surgical techniques for lung volume reduction surgery. An overview of the postoperative care of emphysema patients who undergo single-lung transplantation is also discussed.

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.

Pulmonary function after cardiac and thoracic surgery

Cardiac and thoracic surgery cause alterations in ventilatory function that can lead to significant postoperative pulmonary complications. These complications often occur among patients with pre-existing pulmonary dysfunction and cause significantly longer hospital stays. This review explores some of the recent literature concerning this issue, including the effects of lung reduction surgery.