99: Lung Volume Reduction Surgery

Introduction

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

Pathophysiology of Emphysema

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, ...