Lung volume reduction surgery (LVRS) is one of the most interesting and controversial areas in thoracic surgery. The purpose of the operation is to palliate dyspnea and improve functional status and quality of life for highly selected patients with emphysema. Chronic obstructive pulmonary disease (COPD) affects approximately 16 million Americans and is the fourth leading cause of death in the United States.¹ Worldwide there are estimated to be a billion smokers and, thanks to a global increase in the number of smokers each year, COPD is projected to be the third leading cause of death by the year 2020.² When pulmonary function tests demonstrate a forced expiratory volume in one second (FEV₁) of less than 30% of predicted values, a patient’s 3-year mortality risk has been estimated at 40% to 50%. While medical therapy remains the mainstay of treatment for these patients,³ no medical therapy is able to improve pulmonary function or reverse the progressive nature of the disease. Three situations have emerged in which surgery is useful to palliate emphysema: lung transplantation, bullectomy, and LVRS. This chapter addresses the LVRS strategy.

The goal of LVRS is to palliate some of the distressing symptoms and limitations imposed by end-stage emphysema. Past controversy around this operation has focused on the procedure, interpretation of the results of trials and case series, issues about how new surgical procedures should be introduced and scientifically evaluated, and questions about how they should be funded by health care providers. Ideal candidates for LVRS have marked hyperinflation and significant regions of severe destruction with other distinct areas of more well-preserved lung parenchyma. The areas to be removed, frequently referred to as “target areas,” are usually, but not always, located in the upper lobes and have little pulmonary perfusion when studied with contrast CT or nuclear medicine perfusion scans. Surgical excision of these areas improves respiratory mechanics and function of the remaining lung. Clinically, the anticipated benefits are a reduction in dyspnea and improved exercise tolerance. A subset of highly selected patients may experience a survival benefit as well.⁴

Emphysema is characterized by abnormal permanent enlargement of air spaces distal to the terminal bronchiole accompanied by destruction of the airspace walls in the absence of obvious fibrosis.⁵ The destruction of pulmonary parenchyma causes a decreased mass of functioning lung tissue and also decreases the amount of gas exchange that can take place. As the lung tissue is destroyed, the lung loses elastic recoil and expands in volume. This leads to the typical hyperexpanded chest seen in emphysema patients with common findings including flattened diaphragms, widened intercostal spaces, and horizontal ribs. The increased distensibility of emphysematous lung results in a lung that is easily inflated but tends to remain pathologically inflated throughout the breathing cycle. An important consequence of this defect is that portions of severely emphysematous lung act as nonfunctional, volume-occupying areas. These anatomic changes result in the loss of mechanical advantages exploited in normal breathing and thus lead to an increased work of breathing and dyspnea.⁶ When the destruction and expansion occur in a nonuniform manner, the most affected lung tissue can expand disproportionally to compress and crowd the relatively spared lung tissue and thus impair ventilation of the functioning lung. Finally, there is obstruction in the small airways, likely caused by a combination of reversible bronchospasm and irreversible loss of elastic recoil by adjacent lung parenchyma. The suitability of a given patient for surgical treatment of emphysema depends in part on the relative contributions of lung destruction, lung compression, and small airways obstruction to the overall physiologic impairment of that patient. Sputum production, and the impact of excessive sputum on lung health and quality of life, would also play a role in predicting outcomes of LVRS.

The removal of severely diseased, poorly ventilated, and expanded lung tissue may decrease hyperinflation and improve the mechanical function of the diaphragm and thoracic cage. If the most severely diseased lung can be identified and resected, hyperinflation is reduced and overall breathing function will improve by restoring elastic recoil of the remaining lung. This will result in increased expiratory flow rates and allow the more normal lung to function without compression. LVRS may improve alveolar gas exchange and improve ventilation/perfusion mismatch. The end result is a marked improvement in respiratory mechanics and a decreased work of breathing, both of which help patients to function more normally and avoid the sensation of dyspnea. It is interesting to note that the true etiology or etiologies for dyspnea remain poorly understood. Although dyspnea is associated with severe airflow limitation, it is also linked to hyperinflation, respiratory muscle dysfunction, increases in respiratory drive, and abnormalities in alveolar gas exchange. Unfortunately, the correlation between the symptom of breathlessness and routinely measured physiologic parameters of pulmonary function are imprecise.⁷

The debilitating symptoms of pulmonary emphysema have attracted the interest of surgeons throughout the 20th century. Many creative but ineffective operations have been devised to treat the dyspnea caused by this disease. Costochondrectomy, phrenic crush, pneumoperitoneum, pleural abrasion, lung denervation, and thoracoplasty all have been offered up as surgical treatments for the hyperexpanded and poorly perfused emphysematous lung.⁸ As Laforet⁹ explained: “The alleged benefits of these maneuvers were frequently lost on patients whose worsening dyspnea left them with little energy to debate with their surgeons.”

LVRS was proposed by Brantigan¹⁰ in conjunction with lung denervation. Among 33 patients having the operation, there were 6 operative deaths (18% mortality) and no objective data to support the claim that survivors were subjectively better. LVRS was thus discarded after this initial experience showed the operation to be too risky with uncertain benefit. Over the following four decades, different groups attempted variations on Brantigan procedure with limited success. Observations about the physiologic behavior of emphysema patients during and after lung transplantation led to the reconsideration of volume reduction by Cooper.¹¹ Similar to Brantigan procedure, Cooper removed approximately 30% of the patient’s lung volume by performing peripheral resection of the most emphysematous portions. However, the new approach used linear cutting/stapling devices and was performed as a bilateral procedure via median sternotomy. The procedure was designed to reduce dyspnea, increase exercise tolerance and performance in activities of daily living, and to improve quality of life.

Following this sentinel report by Cooper et al., LVRS enjoyed widespread application within the United States. A critical analysis of Medicare patients undergoing the procedure, however, revealed an unacceptably high mortality associated with the procedure, 23% at 12 months.¹² This led to cessation of Medicare funding for the operation and a decrease in enthusiasm for the procedure. As a way to rigorously evaluate the benefit of the operation, the National Institutes of Health sponsored a large, multicenter trial that began enrolling patients in 1999.¹³ The trial, called the National Emphysema Treatment Trial (NETT), was a prospective randomized study of 1218 patients and it has provided strong evidence for the efficacy, safety, and durability of LVRS.^4,14 The outcomes from the NETT analysis, in conjunction with data from earlier trials, help provide the criteria for defining which patients will benefit from LVRS.

History and Physical Examination

The evaluation of candidates for LVRS should be aimed at identifying patients with a physiologic profile that is most likely to respond to LVRS (Table 99-1). This includes patients with severe hyperinflation and reduced elastic recoil but less-pronounced airway disease, relatively well-preserved gas exchange, and no major comorbidities that carry an unacceptable perioperative risk.¹⁵ Because LVRS is a palliative procedure, the first evaluation step is to assess symptoms and the degree of quality of life impairment attributable to emphysema. The medical history needs to be thorough and include questions on daily activities and limitations caused by symptoms. The Medical Research Council (MRC) dyspnea score allows standardized grading of symptoms. Patients considered for LVRS typically have severe, incapacitating emphysema. They must have stopped smoking for at least 6 months and have received optimal medical management for their COPD, which includes pulmonary rehabilitation and nutritional support if necessary. Patients must be highly motivated to undergo surgical treatment and be willing to accept the risk associated with LVRS. The evaluation needs to differentiate COPD with predominant airways disease (chronic bronchitis and bronchiectasis) from COPD with predominant features of emphysema. Because the mean age of candidates is in the mid-60s, medical comorbidities are common and cardiovascular disease, cerebrovascular disease, obesity, and cachexia deserve particular attention. Patients with cardiovascular disease may be difficult to evaluate by elicited symptoms or signs as their emphysema limits their ability to induce anginal symptoms. It is important to note that exercise testing is often not useful because of the patient’s inability to exercise to heart rate limits. Echocardiography may be limited by chest hyperinflation resulting in poor visualization of the heart. The use of dipyridamole or adenosine during cardiac testing is limited due to concern for inducing bronchoconstriction. Ultimately, because of the barriers to noninvasive evaluation, many candidates for LVRS undergo cardiac catheterization to obtain a definitive answer regarding their cardiovascular risk.

Pulmonary Function

The cornerstone of pulmonary function testing is spirometry. It is used to quantify the degree of airflow obstruction as well as its reversibility with bronchodilator drugs. Airflow obstruction is the most significant abnormality with emphysema and it can be estimated accurately by forced expiratory maneuvers. Lung volumes are measured by plethysmography rather than by dilution techniques because the latter measurements tend to underestimate the degree of trapped gas and residual volume. Additional parameters of pulmonary function that are assessed include resting and formal exercise arterial blood gas analysis. These are indicative of the patient’s pulmonary reserve and reflect their potential for recovery after surgery. In addition, diffusing capacity, as measured by D_LCO values, estimates the severity of damage to the pulmonary capillary bed.

Exercise Capacity

The distance walked in 6 minutes is frequently used to assess exercise capacity. This test evaluates cardiopulmonary function and documents the amount of supplemental oxygen necessary to maintain oxygen saturation above 90%. It is also a useful parameter for the objective documentation of functional improvement following LVRS. Other approaches, including that used by the NETT, have used formal cardiopulmonary testing which results in a maximal exercise capacity expressed in Watts to provide an objective measure of functional capacity.

Radiologic Evaluation

The purpose of imaging in patient selection is to identify findings favorable for LVRS. The presence of hyperinflation, the severity of emphysema, and the distribution of emphysema are the main features to assess. These features are important based on the rationale for LVRS as well as to understand the relationship of preoperative radiographic findings with postoperative outcomes.¹⁶

The presence of hyperinflation is accurately assessed from inspiratory posteroanterior and lateral chest radiographs (Fig. 99-1A,B). Paired inspiratory and expiratory views show the maximum achievable diaphragm excursion and subjectively estimate the potential for improvement in diaphragm function if the lung volume is reduced by LVRS. The main indicators of hyperinflation are a low, flat diaphragm, increased AP diameter, and increased width of the intercostal spaces. Hyperinflated upper lobes may expand anterior to the upper mediastinum and increase the retrosternal space. Hyperinflation does not occur until emphysema is moderately severe and is a relatively specific sign for emphysema. Although hyperinflation should be present in a patient being considered for LVRS, there is no convincing evidence that the degree of hyperinflation predicts the surgical outcome.

The severity and distribution of emphysema on imaging studies correlates with clinical outcome after surgery. The best outcomes, as demonstrated by improvements in FEV₁ and exercise capacity, tend to occur in patients with more severe, heterogeneous disease that predominates in the upper lobes.^17,18 The most severe extreme of heterogeneous target areas is a giant bulla, but the term LVRS refers to lesser degrees of focal destruction in which some lung tissue is present that needs to be excised. The standard chest computed tomography (CT) examination is the most accurate means of evaluating the severity and distribution of emphysema (Fig. 99-2A,B). Unfortunately, there is considerable variation in the interpretation of CT scans in these patients, since the entire lung is affected to some degree by emphysema, and it may be difficult to assess the heterogeneity of the disease. Studies have demonstrated considerable interobserver variability in interpretation of the distribution of emphysema on CT scan.¹⁹ Despite this, the CT scan remains the central component of preoperative imaging. It is the most useful tool available for identification of potential target areas for resection, and also serves as a more rigorous screen than the radiograph for other underlying pathologies that would preclude LVRS. Lung cancer has been discovered in 2% to 8% of candidates for LVRS and some patients are candidates for combined cancer resection and volume reduction.^20,21 Pleural thickening and calcification raise concern for adhesions. In addition, bronchiectasis, inflammatory disease or asymptomatic infiltrates, and pulmonary hypertension may also be identified or suggested by CT and require additional investigation.

Nuclear medicine ventilation-perfusion lung scans depicting regional blood flow patterns provide a valuable roadmap for surgery. Although the absolute severity of emphysema is not accurately assessed, the presence of diffuse or upper or lower lobe predominant disease can be identified. Importantly, a right- or left-sided predominance of lung function may direct surgery toward a unilateral approach if corroborated by CT.