72 - Acute Respiratory Distress Syndrome
Editors: Shields, Thomas W.; LoCicero, Joseph; Ponn, Ronald B.; Rusch, Valerie W.
Title: General Thoracic Surgery, 6th Edition
Copyright 2005 Lippincott Williams & Wilkins
> Table of Contents > Volume I - The Lung, Pleura, Diaphragm, and Chest Wall > Section XIV - Congenital, Structural, and Inflammatory Diseases of the Lung > Chapter 85 - Emphysema of the Lung and Lung Volume Reduction Operations
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Chapter 85
Emphysema of the Lung and Lung Volume Reduction Operations
Jean Deslauriers
Pierre LeBlanc
Emphysema is one of several conditions collectively referred to as chronic obstructive pulmonary disease (COPD). It is an insidious, progressive, and disabling condition that leads to permanent destruction of functional air spaces in the lung.
The pathology of emphysema involves permanent enlargement of the alveoli and alveolar ducts accompanied by destruction of the alveolar walls. In severe disease, damage to parenchymal tissue reduces mechanical support for the airway, leading to its eventual collapse. These obstructive changes are implicated in the extensive gas trapping occurring in the lung, which is characteristic of emphysema.
Physiologically, the effects of emphysema are compounded by decreased elastic recoil in the lung and loss of pulmonary capillary surface area in the alveoli. The loss of the mechanical support of small airways combined with inflammation reduces the expiratory airflow and cause hyperinflation of the lung. Because of the progressive increase in thoracic volume, the function of the respiratory muscles of the chest wall and diaphragm become further impaired, making it even harder to breathe. Disruption of the microcirculation around the alveoli has additional detrimental effects on respiratory function by decreasing the efficiency of gas exchange. As the disease advances, patients suffer increasing dyspnea after mild exertion or even at rest, and become progressively restricted in their ability to carry out normal living activities. Significant mortality occurs in patients whose forced expiratory volume in one second (FEV1) falls below 0.75 to 0.8 L or below 30% of predicted values.
Several forms of medical therapy are available for emphysema, and these include not only drugs but also pulmonary rehabilitation, exercise programs, and the use of supplemental oxygen. However, such treatments have only a limited impact on the quality of life and survival of patients, particularly those who are severely affected. This poor patient response to medical approaches, particularly in the advanced disease state, has encouraged efforts to explore other forms of therapy, including the use of surgical intervention.
At the present time, the only cure for emphysema is lung transplantation, but the option is only viable for a minority of patients because most emphysema sufferers are beyond the age limit for consideration as transplant recipients. An alternative surgical solution is lung volume reduction surgery (LVRS), which has been shown to produce early significant functional and symptomatic improvements.
TERMINOLOGY AND DEFINITIONS
Emphysema
The American Thoracic Society (1962) defines emphysema as a condition of the lung characterized by abnormal and permanent enlargement of air spaces distal to the terminal bronchiole accompanied by destruction of their walls and without obvious fibrosis. It differs from chronic bronchitis, although both disorders are characterized by obstruction of the pulmonary airflow, and in general, patients have a combination of both. The two features in the definition of emphysema that are most important to surgeons are the permanence of enlargement and the destruction of the alveolar wall because they indicate that the process is irreversible and that surgery should, at best, be considered palliative. Azary and co-workers (1962) have shown that, in general, emphysema is closely associated with aging.
At the close of the 19th century, Matthew Baillie (1799, 1807) was the first to describe unnatural holes in the lungs. As reported by Rosenblatt (1972), he clearly defined some of the pathologic features of emphysema, such as failure of the lung to collapse when the thorax was opened, dissemination of distended vesicles on its surfaces, and the occurrence of large air spaces enclosed by their membranes of pulmonary tissue. In his volume on diseases of the chest, Laennec (1819) collected further important observations about emphysematous lungs and introduced the term emphysema. He recognized that air spaces were dilated
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and that, in this disorder, there was partial obstruction of the smaller bronchi and bronchioles.
Gough (1952) and Gough and Wentworth (1949), as well as Leopold and Gough (1957), used sections of whole inflation-fixed lungs mounted on paper to lay the foundations for our current understanding of the anatomy of emphysema. Based on the portion of acinus predominantly involved (an acinus being a unit of bronchopulmonary tissue distal to a terminal bronchiole), three pathologic subsets of emphysema can be observed in minor to moderate disease (Fig. 85-1). As emphysema progresses, classification into specific subtypes becomes increasingly difficult, and the significance of these patterns is unknown.
Centriacinar Emphysema (Centrilobular, Proximal)
Centriacinar emphysema develops in the proximal portion of the acinus and is associated with destruction of the respiratory bronchioles typically caused by cigarette smoking. Snider (1983) has shown that, as the emphysematous process spreads outward from the respiratory bronchiole to adjacent respiratory structures, a microbulla is produced. Centriacinar emphysema is most common in the upper lung fields.
Panacinar Emphysema (Panlobular)
In the panacinar variety, all portions of the acinus are similarly and uniformly destroyed; panacinar emphysema is often called diffuse emphysema. Progressive loss of orderly arrangement of the tissues results in progressive enlargement of the air spaces. Ultimately, little remains other than the supporting framework of vessels, septa, and bronchi. It is sometimes associated with 1-antitrypsin deficiencies, as described by Laudell and Eriksson (1963). Panacinar emphysema is classically associated with low diffusing capacity, decreased arterial oxygen saturation on exercise, and pruning of the peripheral vasculature as seen on computed tomographic (CT) scans or pulmonary angiograms.
As described by Hugh-Jones and Whimster (1978), panlobular and centrilobular emphysema are believed to be truly distinct entities, not only because of their different appearance within the lobule, but also because the lobules affected by centrilobular disease tend to be confined to the lung apices, whereas those affected by panlobular disease are more generally distributed throughout the lung.
Paraseptal Emphysema (Distal)
Paraseptal emphysema results from disruption of subpleural alveoli. Gaensler and associates (1983) noted that initial tiny disruptions tend to coalesce into larger air spaces (blebs) with possible formation of giant subpleural bullae. These blebs and bullae commonly are located along the upper borders of the lung and are responsible for most spontaneous pneumothoraces. Giant bullae associated with paraseptal emphysema are usually well demarcated and offer the best results after surgical intervention.
Cicatricial Emphysema
Air space enlargement with fibrosis is common but bears little clinical significance. It is seen with scarred tuberculosis (cicatricial emphysema) or with diffuse and chronic inflammatory
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disease, such as sarcoidosis, granulomatosis, or pneumoconiosis (honeycomb lung) (Fig. 85-2).
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Fig. 85-1. A. Normal secondary pulmonary lobule. A normal lobule has 5 to 15 acini (a partial acinus is depicted here). The terminal bronchiole (TB) is the last of the ciliated airways. One to three alveolated respiratory bronchioles (RB) lead to alveolar ducts and sacs. The first- and second-order lobule is incompletely surrounded by interlobular sepsis. B. Centriacinar emphysema. In centriacinar emphysema, enlargement and destruction are centered in the first- and second-order respiratory bronchiole. C. Panacinar emphysema. In this form of emphysema, enlargement and destruction are relatively uniform through the acinus. D. Paraseptal emphysema. Enlargement and destruction occur in the periphery of the secondary pulmonary lobule, along the interlobular septa. From Gurney JW: Pathophysiology of obstructive airways disease. Radiol Clin North Am 36:15, 1998. With permission. |
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Fig. 85-2. Posteroanterior chest radiograph (A) and computed tomography scan (B) of a 47-year-old woman with end-stage pulmonary fibrosis. Note the multiple bullae throughout both lungs. |
AIRFLOW OBSTRUCTION
The major determinant of functional impairment in COPD is airflow obstruction that allows outgoing air to be trapped within the alveoli. Thurlbeck (1976, 1977) has shown that there is generally a good correlation between indexes of airflow obstruction such as FEV1 and severity of emphysema.
In 1960, Wright published the results of an autopsy study in which he compared the lungs of 20 patients with severe emphysema to those of 20 other patients with no pulmonary disease. He was able to demonstrate that cartilage atrophy in the walls of the segmental and first three orders of subsegmental bronchi in emphysematous lungs was a significant factor in the airflow obstruction seen in advanced lesions. This cartilage atrophy makes the small bronchi more vulnerable to expiratory collapse, thereby producing airflow obstruction. Linhartova (1977) and Thurlbeck (1974) and their colleagues have also documented cartilage atrophy, as well as gross irregularities in shape, with tortuosity and narrowing of peripheral airways in emphysema.
Anderson and Furaker (1962) and Pratt and colleagues (1961) have shown that the small bronchi and bronchioles are almost entirely dependent on the radial traction forces of the surrounding expanded lung to remain open during expiration. If the elastic properties of the pulmonary tissues are altered by emphysema, these radial forces are lost, and the smaller airways will collapse during expiration, further contributing to airflow obstruction. Nagai and co-workers (1985a, 1985b) have also demonstrated that airflow obstruction may be due to cigarette-associated bronchiolar disease such as chronic bronchitis, increased airway irritability (bronchoconstriction), bronchiolar narrowing and deformities, and further narrowing of already stenotic bronchioles as seen in end-stage emphysema. According to Snider (1983), emphysematous lungs also have an increased amount of mucus in the lumens of small airways.
Many of those changes are reversible or at least can be improved by proper medical therapy, including cessation of smoking and the use of drugs. Airflow limitation resulting from a loss of elastic recoil may also be improved by the surgical resection of nonfunctional parenchyma such as is done in LVRS.
COURSE AND PROGNOSIS OF CHRONIC OBSTRUCTIVE LUNG DISEASE
The natural history of emphysema is poorly understood because some patients may have a rapid downfall, whereas others remain relatively stable for long periods. If the patient does not stop smoking, however, it is likely that the disease will progress rapidly and that annual declines in FEV1 will be in the range of 80 to 100 mL per year, as opposed to 30 mL per year if the patient stops smoking or has never smoked. Dornhorst (1985) has also shown that patients with clinical signs of chronic bronchitis (blue bloaters), recurrent infections, or marked weight loss have a worse prognosis, and all of these criteria are considered important in the selection of patients for emphysema surgery.
In 1975, Diener and Burrows presented long-term survival data for 200 patients with chronic airway obstruction
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who had been enrolled in a prospective study approximately 14 years previously. All patients selected for this study had FEV1 less than 60% of both predicted and measured vital capacities. Survival data for the entire series (Figs. 85-3 and 85-4) show the poor long-term prognosis for patients with chronic obstructive lung disease. According to Figure 85-4, the risk for death was relatively low in patients who were mildly impaired on entry into the study, whereas it approached 10% per year when the FEV1 was a mean of 1.0 L. Five-year survival figures on the order of 25% were noted in patients whose FEV1 values were 0.75 mL or less.
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Fig. 85-3. Survival data for the entire series (200 patients). Open circle, all deaths; closed triangle, respiratory deaths. From Diener CV, Burrows B: Further observations on the course and prognosis of chronic obstructive lung disease. Am Rev Respir Dis 111:719, 1975. With permission. |
Lung volume reduction surgery or any other kind of surgery for emphysema can possibly move the patient from the lower to the upper survival curve (see Fig. 85-4) by increasing the patient's FEV1. This may be more so if the patient stops smoking and has optimal medical treatment. These expectations form the basis for the renewed interest in emphysema surgery and should remain the best standard of achievement for these procedures.
HISTORY OF SURGERY FOR CHRONIC OBSTRUCTIVE LUNG DISEASE
During most of the 20th century, surgery has been used in an attempt to improve the quality of life of patients with emphysema. Knudson and Gaensler (1965) noted that these procedures included operations on the chest wall, the diaphragm, the pleura, the nervous system and pulmonary innervation, the major airways, and the lungs themselves.
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Fig. 85-4. Survival of groups distinguished on the basis of their FEV1 at the time of enrollment in the study. Closed circle, FEV1 > 1.25 L; closed square, FEV1 0.75 L but 1.25 L; and open triangle, FEV1 > 0.75 L. From Diener CV, Burrows B: Further observations on the course and prognosis of chronic obstructive lung disease. Am Rev Respir Dis 111:719, 1975. With permission. |
Based on the observed development of a barrel chest, Freund (1906) described the operation of costochondrectomy, which was conceived as a way of allowing the lungs to expand further, without constriction of the chest wall. Typically, and often under local anesthesia, 4 to 6 costal cartilages would be divided. This was frequently performed bilaterally, and often in association with a transverse sternotomy, totally disrupting the integrity of the thoracic cage and so allowing further expansion of the enlarged lungs. Bircher (1918) reported the success of this procedure, claiming improvement as cure in 26 of his 30 patients. However, the operation did not become established, and it was soon recognized that it did not touch the true basis of emphysema.
Attempts were then made to deal with the hyperinflation of COPD by reducing the thoracic and lung volumes. Thoracoplasty and phrenic denervation were tried, and although early results seem promising, this initial optimism proved unfounded. As Laforet (1972) explained, Undaunted, and starting with a new set of premises, surgeons were soon advocating such procedures as thoracoplasty and phrenic nerve
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interruption, each calculated to reduce the volume of the over-distended lung. The alleged benefits of these maneuvers were frequently lost on patients whose worsening dyspnea left them with little energy to debate with their surgeons.
After the chest wall, the next structure to be attacked was the diaphragm. It was thought that this structure was the main cause of dyspnea in emphysema: if the flattening could be corrected, its function would be improved and patients would feel better. The first published attempts to use this approach employed abdominal belts. Compression of the upper abdomen using a screw mechanism aimed to raise the diaphragm and improve respiratory function. Apart from the disadvantage of its impracticality, only patients with small abdomens could wear the device. Despite these drawbacks, Alexander and Kountz (1934) published the outcome of a study involving 25 patients treated with the belt. Nineteen reported improvement with a mean increase in forced vital capacity (FVC) of 39%. A similar kind of thinking ran behind the introduction of pneumoperitoneum. In order to restore the normal curvature of the diaphragm and to improve its function during normal respiration and cough, about 800 mL of a helium-oxygen mixture was introduced into the abdomen. As was the case with previous procedures, the early results were impressive. In a study reported by Carter and colleagues (1950), 10 of 18 patients improved with an average increase in vital capacity (VC) of 18%, which was associated with improved diaphragmatic excursion on radiographic image. However, the procedure was abandoned as impractical, rather than ineffective, because gas had to be replaced every 2 weeks and such refills were associated with pain, discomfort, nausea, and the risk for infection.
The next group of anatomic structures to gain attention were the nerves of the thoracic wall and viscera, and almost every identifiable anatomic nervous structure related to the lung became at risk in the effort to relieve patients with COPD. The rationale behind total lung denervation was to abolish reflex bronchoconstriction and hypersecretion. These were complex procedures that did not gain widespread acceptance. Glomectomy, on the other hand, became a relatively common procedure in the 1950s. The glomus or carotid body is a small group of nerve cells located between the origin of the internal and external carotid arteries. It is a chemoreceptor, sensitive to changes in arterial oxygen tension (Pao2), arterial carbon dioxide tension (Paco2), and pH, and its removal was aimed at reducing bronchoconstriction and hypoxic drive. Nakayama (1961) published a series of almost 4,000 glomectomies with improvement in 80% of patients at 6 months falling to 58% by 5 years. However, controlled trials failed to confirm the value of the operation. The Albuquerque trial reported by Curran and Graham (1971), for instance, compared glomectomy to a sham operation. Although the numbers are small, it showed that patients undergoing sham surgery did better in terms of symptoms and lung function measurement than those having glomectomy. The operation was condemned by the American Thoracic Society in a statement by the Committee on Therapy (1968) and is no longer performed.
Other interesting operations were aimed at treating airway collapse or were designed to increase blood supply to the lung by stimulating collateral circulation from the chest wall through parietal pleurectomy or talc poudrage.
The only operation that has somewhat stood the test of time is bullectomy, in which distended air spaces are resected to allow the reexpansion of restricted but potentially functional adjacent lung tissue (see Chapter 84). Better preoperative workup through the use of high-resolution CT and less traumatic surgical techniques such as video-assisted thoracic surgery (VATS) have improved the outcome of patients suitable for bullectomy. The application of similar volume reduction surgery in diffuse emphysema was first advocated by Brantigan and Mueller (1957) as a way of improving the mechanical function of the lung. In the mid-1990s, this concept was reintroduced by Cooper and associates (1995), and since then, early sustained improvements in lung function parameters have been reported postoperatively.
SURGICAL MANAGMENT OF DIFFUSE EMPHYSEMA
Historical Background
In the late 1950s, Brantigan (1957) and co-workers (1957, 1959) were the first to present the concept of lung reduction for emphysema. They theorized that in the normal state, the elasticity of the expanded lung is transmitted to the pliable bronchi, which are held open by a circumferential elastic pull. In emphysema, the lung has lost its elasticity and the circumferential pull holding the bronchioles open is greatly impaired, therefore accounting for a greater obstruction to airflow (Fig. 85-5). Brantigan postulated that by surgically reducing lung volume, one could restore part of this circumferential pull upon the bronchioles, therefore reducing airflow obstruction and improving dyspnea (Fig. 85-6). In addition, he hoped that, by volume reduction, one could bring about a higher diaphragm with more efficient function and reduce the size of the thoracic cage, allowing for better contraction of the intercostal muscles.
Brantigan's operation consisted of reducing lung volume by the resection of the most useless areas of the lung, so that at the end, the lung would fit the volume of the pleural space on full expiration. Denervation of the lung was also added to the procedure. Among 33 patients who had this operation, there were six operative deaths (18%), and according to Brantigan, at least two of the six deaths were due to technical errors. All patients who survived the operation were subjectively helped, although no objective data were presented.
Soon after, Kennedy and co-workers (1960) presented a similar series of 13 patients with one operative death, one later death, and variable degree of subjective improvement among the survivors. Function measurements were inconclusive. Other procedures such as bronchial diversion operations (D. Munro, personal communication, 1995), in
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which the bronchus and lung fissures were divided, were also done to achieve volume reduction.
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Fig. 85-5. A. The negative intrapleural presure and the elastic fibers of the lung acting together to assert a circumferantial pull on the bronchi. B. Loss of normal negative intrapleural pressure and the pull of the elastic fibers with no circumferential pull on bronchi to keep them open. From Brantigan OC, et al: A surgical approach to pulmonary emphysema. Am Rev Respir Dis 80:194, 1959. With permission. |
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Fig. 85-6. Brantigan's method of reducing lung volume for generalized emphysema. It is done by clamp excision of the most useless areas. From Brantigan OC, et al: A surgical approach to pulmonary emphysema. Am Rev Respir Dis 80:194, 1959. With permission. |
A review of the previous work done by Georges (1966), Even (1980), and Dahan (1989) and their colleagues presented an interesting study on the use of hemodynamic data to select patients who might be candidates for volume reduction. Based on the concept of dynamic expiratory compression of both venous and pulmonary arterial flow, 10 patients were identified for disabling dyspnea, diffuse bullous emphysema, and evidence of hemodynamic impairment. Five of 10 patients who had a high compression index before surgery were improved after unilateral volume reduction.
Three years later, Crosa-Dorado and co-workers (1992) presented a detailed account of their technique involving hemostatic and pneumostatic suturing of the emphysematous lungs. The technique had been done in 76 patients between 1980 and 1991 with apparently good results in remodeling the lung for diffuse emphysema.
The most recent chapter on volume reduction was written by Cooper and colleagues (1995), who presented data on 20 patients who had undergone bilateral volume reduction done through a median sternotomy incision. Preliminary results showed improvement in dyspnea, quality of life, and pulmonary function in nearly all patients who had been prepared for surgery by enrollment in a supervised rehabilitation program for a minimum of 6 weeks. Numerous trials have since been carried out by various groups and have generated an increasing amount of data from which to assess the short-term effect of this procedure. An important aspect of this evaluation is the identification of selection criteria which can predict a successful outcome.
Rationale for Surgery
The rationale of lung volume reduction procedures is the surgical excision of nonfunctional distended air spaces thought to interfere with optimal function of the surrounding, more normal parenchyma. Several physiologic factors
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are interactive in the benefits that may be obtained after these operations.
Airflow Obstruction
In emphysema, airflow obstruction results from the loss of elastic recoil combined with an increase in airway resistance. In the normal individual, there is a linear relationship between airflow and alveolar pressure, this relationship being due to the constant caliber of the small airways at the beginning of expiration. At the end of expiration or during forced expiration, there is no longer an increase in airflow because of dynamic compression of small airways by the surrounding lung. Hogg and co-workers (1968) have shown that because of hyperinflation, this phenomenon is increased with displacement of the airflow alveolar pressure curve to the left, suggesting that because of the loss of elastic recoil, the lowered alveolar pressure at the beginning of expiration cannot overcome the collapse of the small airways. One of the principles of volume reduction procedures, therefore, involves the resection of hyperinflated but nonfunctional areas of emphysematous tissue to improve elastic recoil in the remaining lung. This, in turn, increases radial traction around terminal bronchioles, allowing them to remain open throughout the respiratory cycle, thus improving ventilation and relieving dyspnea.
Respiratory Muscles
Derenne and colleagues (1978) have shown that respiratory muscles such as the diaphragm, the intercostals, or even the scalenes have an efficiency that is directly proportional to their shortening index and therefore to the length of their fibers during active contraction.
The anatomic modifications associated with thoracic hyperinflation places these muscles at a disadvantageous position for adequate function. Loring and Mead (1982) have shown that this phenomenon is particularly significant for the diaphragm whose lowered position limits its contractility. In addition to being at a disadvantageous position, the elevated alveolar pressures seen at end expiration add to the load that these muscles must work against. One of the objectives of a volume reduction procedure is therefore to improve contractility of the diaphragm by restoring its normal curvature.
Two additional goals can be achieved by surgery. Sweer and Zwillich (1990) have shown that in severe emphysema, patients are often in a state of denutrition with significant muscle atrophy. Correction of this status by rehabilitation programs such as described by Cockcroft and co-workers (1981), by supplemented diets, or by surgery can significantly improve function and therefore decrease the severity of dyspnea. Bellemare and Grassino (1983) have also shown that the arterial hypoxemia seen in emphysema can place the diaphragm as well as other respiratory muscles in unfavorable conditions of anaerobiosis with increased fatiguability. Correction of this hypoxemia by volume reduction may therefore improve muscle function.
Ventilation-Perfusion Mismatch
Cosio and Majo (1995) have shown that when distended air spaces do not have a homogeneous distribution, as is the case in most patients with emphysema, some areas of the lung have a greatly lowered elastic recoil, although it is preserved in other areas. It is this heterogeneity that defines targets to be resected because these are areas of poor ventilation and even poorer perfusion. In addition, compressed lung adjacent to these distended air spaces is generally well perfused but poorly ventilated, creating physiologic shunting and contributing to the arterial hypoxemia.
Cardiovascular Hemodynamics
As noted in bullous emphysema (see Chapter 84), the low-pressure pulmonary circulation may be the site of dynamic expiratory compression. Nakhjavan and co-workers (1966), as well as Butler (1988), have shown that excessive contraction of respiratory muscles, notably during expiration, can raise intrathoracic pressures to levels high enough to generate significant decreases in systemic venous return as well as having a negative mechanical effect on cardiac contractility.
Pulmonary hypertension is generally seen at a late stage of emphysema. Naunheim and Ferguson (1996) have shown that elevated pulmonary vascular resistance stems from disruption in the microcirculation, which by itself is rarely sufficient to generate resting pulmonary hypertension. In a study of 21 patients who underwent LVRS, Thurnheer and colleagues (1998) found that no patient had significant pulmonary hypertension and that only six had mild elevation of pulmonary artery pressure (mean, 20 and 25 mm Hg). In that study, the pulmonary artery pressure did not change after surgery. Often, this pulmonary hypertension is secondary to arterial hypoxia, and Stark and colleagues (1973) have shown that it can be lowered by oxygen therapy.
Fixed pulmonary hyprtension with secondary cor pulmonale is the result of severe destruction of the pulmonary capillary bed, but that is unlikely to be improved by volume reduction surgery.
Variety of Emphysema
In general terms, patients with both variations of emphysema, centriacinar and panacinar, can be candidates for volume reduction surgery. Centriacinar emphysema is commonly seen in smokers and is characterized by heterogenous patterns of disease affecting mostly the upper lobes of the lungs. In this type of emphysema, there is often added intrinsic small airway disease related to chronic inflammatory processes.
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In panacinar emphysema, the disease is more uniform throughout the lung so that there is less possibility of recruiting normal lung after volume reduction. In addition, less improvement in airway expiratory collapse can be expected because these small airways are intrinsically normal. One must also consider that in panacinar emphysema, reduction of lung volume may create increased inflation pressures aggravating already existing hyperinflation.
Current Status of Lung Volume Reduction
Preoperative Assessment
Lung volume reduction surgery is a palliative procedure that, at the present time, is considered appropriate treatment for a rigorously selected group of patients. Although preoperative assessment may vary among institutions, the major prerequisite is the presence of severe emphysema, as documented by CT and pulmonary function studies. The preoperative evaluation currently suggested can be divided into investigations trying to define the morphology of the disease and those measuring pulmonary function.
Morphology
Inspiratory and expiratory chest radiographs provide information regarding general thoracic configuration, hyperinflation, position of the hemidiaphragm, and severity of emphysema. Slone and Gierada (1996) have shown that chest radiographs might also be useful to demonstrate associated pulmonary abnormalities such as infectious processes, interstitial diseases, or lung nodules.
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Fig. 85-7. High heterogeneity. High-resolution computed tomography scan showing very high heterogeneity with striking contrast between areas of lung destruction (D) and normal lung (N). From Slone RM, Gierada DS, Yusen RD: Preoperative and postoperative imaging in the surgical management of pulmonary emphysema. Radiol Clin North Am 36:57, 1998. With permission. |
CT provides a more detailed examination of the lung parenchyma. Structural changes associated with emphysema include areas of low attenuation, pruning of blood vessels, and decreased lung density gradients. Modern technologies such as high-resolution CT (thin-section thickness and high-resolution reconstruction) or spiral CT allow for the calculation of the severity of emphysema as well as the three-dimensional reconstruction of the parenchyma. CT may be used to categorize the disease as being (a) markedly heterogeneous, (b) intermediately heterogenous, or (c) homogeneous in its morphology (Figs. 85-7 through 85-9).
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Combined inspiratory and expiratory CT can be used to calculate lung volume and chest wall excursion.
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Fig. 85-8. Lung volume reduction surgery candidate with upper lobe target areas for surgical resection. A, B. Computed tomography scans through the upper and lower lobes showing a heterogeneous pattern of predominant upper lobe emphsyema typical of patients with a favorable outcome. From Slone RM, Gierada DS, Yusen RD: Preoperative and postoperative imaging in the surgical management of pulmonary emphysema. Radiol Clin North Am 36:57, 1998. With permission. |
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Fig. 85-9. Diffuse emphysema. A. Posteroanterior chest radiograph and B. Computed tomography scan showing moderate diffuse emphysema without target area of marked hyperinflation. From Slone RM, Gierada DS, Yusen RD: Preoperative and postoperative imaging in the surgical management of pulmonary emphysema. Radiol Clin North Am 36:57, 1998. With permission. |
In an interesting study, Wisser and co-workers (1998a) defined four variables identified to quantify the severity of emphysema: (a) the degree of hyperinflation (0 4), (b) degree of impairment of diaphragmatic mechanics (0 4), (c) degree of heterogeneity (0 4), and (d) severity of parenchymal destruction (0 48). In a series of 47 consecutive patients, the authors were able to show that the degree of heterogeneity had a significant influence on functional improvement as documented by FEV1 increase (p = 0.0413), and that the severity of parenchymal destruction was significantly associated with 30-day mortality. In a similar study, Weder and colleagues (1997) showed that the morphology of emphysema was an important predictor of outcome. In their study of 50 consecutive patients, functional improvement after LVRS was best in markedly heterogenous emphysema as defined by CT scanning. In that group, the increase in FEV1 was 81% 17%, as compared with 44% 10% for intermediately heterogenous emphysema. Similarly, Thurnheer and associates (1999) reported that in 70 patients, the FEV1 was increased above the baseline value by 57% 8% in the markedly heterogeneous group (n = 42), 38% 9% in the intermediately heterogeneous group (n = 18), and only 23% 9% in the homogeneous group (n = 10), 3 months after LVRS.
Several centers finally recommend fiberoptic bronchoscopy to study endobronchial morphology in patients scheduled to have LVRS. This examination is useful to assess and grade the severity of associated malacia as well as to evaluate the significance of airway inflammation. Indeed, bronchoscopy is also useful to rule out occult bronchial carcinomas.
As mentioned by Naunheim and Ferguson (1996), most evaluations include a quantitative ventilation-perfusion isotope scan because this examination allows for the identification of target areas characterized by low perfusion and greatest gas retention. In addition, the amount of gas retention in various lung zones is used to predict the morphologic grade (Fig. 85-10) and the potential for function of the residual lung (Fig. 85-11). However, Thurnheer and colleagues (1999) found that functional improvement after LVRS was more closely related to the findings on CT than with the degree of perfusion heterogeneity assessed by scintigraphy.
Pulmonary Function
The cornerstone of pulmonary function testing is spirometry, which is used to appreciate the significance of airflow obstruction as well as its reversibility with bronchodilator drugs. Lung volumes are measured by phletysmography rather than by dilution techniques because the latter measurements tend to underestimate the degree of trapped gas and residual volume.
Other parameters of pulmonary function routinely assessed include resting arterial blood gases (arterial Po2 and Pco2) as well as those recorded during standard exercise testing. These are indicative of the patient's pulmonary reserve and in many ways of its potential for recovery after volume reduction. The diffusing capacity as measured by Dlco values is used to evaluate the severity of destruction of the pulmonary capillary bed.
Exercise Capacity
The 6-minute walk test evaluates the cardiorespiratory function quantified by the distance walked during the 6-minute exercise and by the oxygen supplement necessary to maintain oxygen saturation above 90%. More extensive evaluation of exercise capacity may be done by an ergocycle
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exercise test. The ventilatory response and gas exchanges may be assessed more precisely by this method.
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Fig. 85-10. Perfusion scintigrams were assessed in the posteroanterior (dors), anteroposterior (ventr), and left and right posterior oblique views (LPO, RPO). According to the distribution of activity, the set of scans from each patient was assigned to one of three heterogeneity grades. Examples of markedly and intermediately heterogenous distributions are displayed in panels A and B, and an example of homogeneous distribution is shown in panel C. From Thurnheer R, et al: Role of lung perfusion scintigraphy in relation to chest computed tomography and pulmonary function in the evaluation of candidates for lung volume reduction surgery. Am J Respir Crit Care Med 159:301, 1999. With permission. |
Cardiovascular Function
A careful evaluation of cardiac function is always done before volume reduction surgery. This evaluation includes careful taking of medical history, routine electrocardiography, and in most cases, Doppler echocardiography to estimate ventricular function and pulmonary artery pressure. In patients with suspected coronary artery disease, a thallium-dipyridamole study should also be done.
Right heart catheterization with a Swan-Ganz catheter is performed if pulmonary hypertension is suspected not only because this finding increases the operative risk but also because it often compromises functional improvement. The test also allows for some documentation of the hemodynamic abnormalities associated with severe emphysema.
Diaphragmatic Function
Benditt (1997) and Teschler (1996) and their co-workers have shown that the evaluation of diaphragmatic function may be important if one is to understand the benefits of volume
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reduction surgery on the respiratory mechanics. One method commonly used is to record abdominal and pleural pressures simultaneously through catheters located in the stomach and esophagus. Because of inefficient diaphragmatic function seen in advanced emphysema, the intraabdominal pressure becomes negative during inspiration. As shown by Dodd and associates (1984), it will also beome positive early during expiration because of the recruitment of abdominal muscles whose action is to reposition the diaphragm favorably before the next inspiration.
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Fig. 85-11. Ventilation-perfusion scan. Amount of xenon retained in various lung zones. Areas of low retention are likely to be functional after resection of target areas. In this figure, the lower curve represents the upper one third of the lung with little ventilation and poor washout at 1 minute (44%). The upper curve represents the lower lung, which has good ventilation and good washout at 1 minute (85%). This is an ideal case for lung volume reduction surgery because the remaining lung (lower lung) has good potential for function based on an excellent washout. |
There is some direct and indirect evidence to confirm improved diaphragmatic function after LVRS. Studies of the effects of LVRS for emphysema on diaphragmatic dimensions and configuration have been carried out by numerous investigators. Cassart and colleagues (2001) have noted that LVRS in emphsema patients results in significant increases in the total suface of the diaphragm as well as an increase in the zone of apposition of the diaphragm to the chest wall. The surface area and zone of apposition, however, remain smaller than in normal individuals. Bellemare and coinvestigators (2002) found that LVRS resulted in a craniad displacement of the diaphragm but was not accompanied by any change in rib cage dimensions. Decrease in dyspnea was correlated with the change in diaphragm length. Our own experience, as well as that of Slone and Gierada (1996), shows radiologic improvement in thoracic configuration, with less distention of the chest wall, as well as increased curvature and higher position of the diaphragm (Fig. 85-12). Many questions remain, and additional physiologic studies are indicated.
Nutritional Status
Careful nutritional assessment must always be done because most patients with chronic obstructive lung disease are protein deficient, as shown by Donahoe and Rogers (1990). Some individuals are also overweight, a feature that may have added detremental effect on diaphragmatic function.
Selection for Surgery
Although selection criteria may vary between institutions, important prerequisites are the presence of severe emphysema as documented by CT scanning, airflow obstruction, disabling dyspnea despite optimal medical treatment, and hyperinflated lungs by chest radiographs and lung volume measurements. Other criteria include the presence of defined target areas of emphysema, smoking cessation, high personal motivation, and ability and willingness to participate in a vigorous pulmonary rehabilitation program. Conversely, reasons to exclude patients from surgical interventions include advanced age, pulmonary hypertension, lack of suitable target areas, poor diffusing capacity, or high corticosteroid dependency, which is often indicative of associated chronic bronchitis or asthma.
Understanding that several patients are in a gray zone and that no preoperative test is absolutely predictive of good postoperative result, patients should be selected for surgery based on a profile determined by complete clinical, morphologic, and functional assessment. Patients with best
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profiles are accepted for LVRS, whereas surgery is not offered to patients with worse profiles. As a general rule, most patients referred for surgery are not appropriate candidates, and only 5% to 10% of referrals will eventually have volume reduction. Indeed, Miller (JI) and colleagues (1996) recommend that the selection process be extremely strict and selective.
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Fig. 85-12. Inspiratory posteroanterior chest radiograph of a 50-year-old male patient (A) before and (B) 6 months after bilateral lung volume reduction surgery done through median sternotomy. Improvements in diaphragmatic position are observed with higher position, increased curvature, and restored zone of apposition of the diaphragm. |
Best Profile for Lung Volume Reduction Surgery
The criteria used in most institutions to select patients for surgery are outlined in Table 85-1. Like Miller (JI) and associates (1996), we believe that the age of 70 years should be used as a cutoff point, not only because older patients are likely to have a significantly higher postoperative morbidity or mortality but also because they have poor functional recovery. McKenna and colleagues (1997) have shown that patients aged 70 years or older experienced a 48% improvement in FEV1 compared with an increase of 76% in younger patients. Despite these findings, and because there were no operative deaths in 17 patients older than 75 years of age, these authors concluded that no absolute upper age limit could be identified.
It is essential that patients have stopped smoking for at least 6 months before operation, and random checks for nicotine are performed to ensure compliance. Patients should also be taking no more than 10 mg of corticosteroids daily because higher doses may increase the risk for postoperative morbidity, specifically prolonged air leaks, or pulmonary infection.
The ability to complete a preoperative rehabilitation program of 6 to 10 weeks is considered essential in most centers. As originally described by Biggar and associates (1993) and reemphasized by Miller (JI) and co-workers (1996), these programs include exercise arm ergometry, stationary bicycle, and exercise treadmill. Ergometry strengthens the upper extremities, whereas the stationary bike and treadmill improve overall endurance and lower extremity strength. Miller (JI) and colleagues (1996) even stated that pulmonary rehabilitation was undoubtedly the most important component of the entire program and that patients who could not meet the targeted rehabilitation goals of 30 consecutive minutes on the stationary bicycle and 30 consecutive minutes on the treadmill should not be operated upon. As demonstrated by Debigar and colleagues (1999), pulmonary rehabilitation programs can now be carried out entirely
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at home. It is also during that 6- to 10-week period that patients are better educated about their disease and eventual surgery, that their nutritional status is improved, that the amount of corticosteroids taken daily is decreased to 10 mg or less daily, and that psychological counseling and support are provided. A summary of clinical guidelines abstracted fom leading articles is given in Table 85-1. The more recent series of Naunheim (1999), Brenner (1999), Serna (1999), Gierada (2000), and Bloch (2002) and their associates had similar guidelines, with some minor exceptions, as those noted in Table 85-1.
Table 85-1. Best Profile for Lung Volume Reduction Surgery | |
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Morphogically, the ideal candidate for LVRS is the one whose distribution of disease is heterogenous with clearly defined targets of diseased lung. Not all agree with the exclusion of all patients with homogeneous emphysema. In highly selected patients with homogeneous emphysema, Hamacher and coinvestigators (1999) recorded somewhat similar improvement in the FEV1 at 6 months after LVRS in the homogeneous emphysema group and the intermediately homogeneous group (to 38% 2% and 44% 4.5%, respectively), although greater improvement was observed in the markedly heterogenous group (to 52% 4%). After 6 months, there was a slow decline in the FEV1 in all groups over a 2-year follow-up. Bloch and associates (2002) in 115 patients (51 in the markedly heterogeneous group, 37 in the intermediately homogeneous group, and 27 in the homogeneous emphysema group) found the mean predicted FEV1 at baseline to be 27% (21% to 33%), 26% (24% to 32%), and 25% (23% to 32%), respectively. Three months after LVRS, the median FEV1 values were 42% (35% to 54%), 37% (31% to 45%), and 36% (29% to 46%) in the aforementioned groups. At 4 years in the eight, seven, and five patients evaluable in the three groups, the FEV1 was 37% (28% to 46%), 31% (25% to 37%), and 29% (27% to 32%), respectively. The decline in the improvement occurred in an exponential manner.
We find that ventilation-perfusion scans provide reliable information not only about diseased areas of the lung but also on the potential for reexpansion of the residual lung and availability of sufficient residual functional capacity. In general, patients with upper lobe disease (Fig. 85-13) are better candidates for surgery than those whose disease predominates in the lower lobes, although in lower lobe disease, diaphragmatic function can sometimes be most compromised. Patients with 1-antitrypsin deficiencies are not ideal candidates because the entire lung is involved by disease and over time, the residual lung will also become hyperinflated with loss of function. In Cooper and co-workers' series (1996) of 150 consecutive bilateral lung volume reduction, 18 patients had lower lobe disease (11 with 1-antitrypsin deficiency), and in these 18 individuals, the mean improvement in FEV1 was 26%, the reduction in residual volume was 28%, and the increase in Pao2 was 5 mm Hg. These values were considerably less than for the overall series, but nonetheless, Cooper and associates (1996) believed that most of these patients had experienced significant functional improvement. Ideally, the patient best suited for surgery also has radiologic signs clearly indicative of hyperinflation with outward flaring of the lateral aspects of the thoracic cage, diaphragmatic depression and
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scalloping of diaphragmatic insertion, and a large anterior air space between sternum and cardiac shadow.
Table 85-2. Summary of Clinical Guidelines for the Selection of Patients for Lung Volume Reduction Surgery | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Fig. 85-13. Upper lobe disease. A. Chest radiograph of a suitable candidate for lung volume reduction surgery: increased lucency of the upper zones, without bullae, and relatively normal lower zones (centriacinar emphysema). B. Computed tomography scan showing more severe disease in the upper lobes (C) than in lower lobes, therefore providing adequate target areas. This patient underwent open bilateral lung volume reduction surgery, and his forced expiratory volume in 1 second improved from 1.35 L to 2.19 L 1 year after surgery. |
Physiologic parameters indicative of a good outcome after surgery include FEV1 in the range of 20% to 35% of the predicted value and total lung capacity more than 130% of predicted, suggesting significant pulmonary hyperinflation. Miller (JI) and co-workers (1996) have shown that patients who cannot reach an FEV1 of at least 0.5 L and patients whose diffusion is less than 20% of predicted should not have LVRS procedures and are better suited for lung transplantation or maintenance on rehabilitation programs.
Eugene and associates (1997), however, prospectively evaluated 44 patients with FEV1of 0.5 L or less who underwent volume reduction for dyspnea uncontrolled by medical management. In that series, the mean FEV1 was 0.41 L (range, 0.23 to 0.50 L), with 80% of patients having hypercarbia and 66% pulmonary hypertension. There was one death within 30 days, and subjective improvement was noted in 89% of the cohort. FEV1 was 0.62 L at 1 year, a 51% improvement. The authors concluded that patients with severely impaired lung function can successfully undergo operation for emphysema. In a similar study, Argenziano and colleagues (1996) concluded that profound pulmonary dysfunction characterized by an FEV1of less than 0.5 L did not preclude successful lung volume reduction and should not be regarded as an absolute contraindication to surgery. Despite the results of these two studies, most investigators do not advocate surgery for patients with severe lung dysfunction.
It is generally agreed that patients with the best profile have a resting arterial Pco2 of less than 50 mm Hg and a mean pulmonary artery pressure of less than 35 mm Hg. In a group of four patients with hypercapnia, Miller (JI) and co-workers (1996) reported a 100% incidence of major complications, resulting in death in two of the four patients. Wisser and associates (1998b) studied functional improvement
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and clinical outcome in 22 patients with chronic hypercapnia (Pco2 > 45 mm Hg) who underwent LVRS, and these were compared with all other patients (n = 58) without hypercapnia. They concluded that hypercapnia alone was not associated with significantly higher mortality and morbidity and therefore should not be considered an exclusion to LVRS. However, the presence of additional risk factors, such as homogeneity of disease, high degree of parenchymal destruction, or pulmonary hypertension, should be considered as contraindications to the procedure.
A summary of physiologic and morphologic guidelines generally accepted for the selection of patients is given in Table 85-3.
Worst Profile for Lung Volume Reduction Surgery
The criteria used in most institutions to exclude patients for surgery are given in Table 85-4. Most of these criteria, however, do not represent absolute contraindications to surgery, and none taken by itself is an absolute exclusionary criterion. It is, rather, the presence of several risk factors for poor outcome that is the contraindication for the procedure. In the first report of the National Emphysema Treatment Trial (NETT) group (2001), 69 patients with an FEV1 of less than 20% of the predicted value and either a homogeneous morphology or a Dlco of less than 20% of predicted had a 30-day operative mortality rate of 16%, and a total of 33 patients (including the 11 postoperative deaths) died during the 3-year period of follow-up (an overall mortality rate of 0.43 deaths per person-year). The implications of this will be discussed subsequently.
Dependence on a ventilator and being bedridden or wheelchair bound are almost absolute contraindications. In a series of 44 patients with advanced emphysema in which FEV1 was less than 500 mL presented by Eugene and associates (1997), only 6 were bedridden or wheelchair bound and none was dependent on the ventilator. Similarly, none of the 85 patients reported by Argenziano and colleagues (1996) were ventilator dependent although 35 (41%) were unable to complete the rehabilitation program and 9 (11%) had a Pco2 greater than 55 mm Hg.
Table 85-3. Summary of Physiologic and Morphologic Guidelines for the Selection of Patients for Lung Volume Reduction Surgery | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Table 85-4. Worse Profile for Lung Volume Reduction Surgery | |
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Severe impairment of gas exchange as documented by low Dlco (#20% of predicted value), low Pao2 (>40 mm Hg at room air), and high Paco2 (>55 mm Hg) are also considered contraindications because these values reflect the poor quality of the residual lung as well as the near absence of pulmonary reserve. In a series of 154 consecutive patients who underwent bilateral thoracoscopic staple lung volume reduction reported by McKenna and co-workers (1997), 68% of patients receiving oxygen before the operation were weaned from oxygen supplementation completely after the procedure. In contrast, only 4 (22%) of the 18 patients with preoperative Pao2 less than 50 mm Hg were successfully weaned from supplementary oxygen. In the same series, 10 patients had room air Paco2 greater than 55 mm Hg, and in this group, the postoperative room air blood gas showed a mean Paco2 of 42.1 mm Hg. More recently, Shade and associates (1999) showed in 33 consecutive patients with a preoperative Paco2 between 32 and 56 mm Hg that patients with higher baseline values of Paco2
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had the greatest reduction in Paco2 after LVRS. There are no substantial data for patients with Paco2 at higher levels.
Signs of cor pulmonale associated with fixed pulmonary hypertension (mean, > 35 mm Hg; systolic, > 45 mm Hg) are poor prognostic signs and generally accepted exclusion criteria for LVRS. Similarly, anatomic airway disease such as acquired tracheobronchomalacia, bronchitis, or bronchiectasis are also considered indicative of a poor outcome.
The problem of tracheobronchomalacia is particularly interesting and has never really been investigated in relation to volume reduction. This disorder, which is associated with advanced emphysema, is characterized by abnormalities in the elastic fibers of the membranous airways and by bronchial cartilage atrophy. Because of these features, the membranous portion of the airway becomes very floppy and collapses during expiration, particularly at the level of the trachea and main bronchi, where there is no pulmonary retraction capable of counteracting the collapse (soft trachea). The degree of collapse is greater during forced expiration or cough because at that point, the transmural pressure (difference between intrathoracic pressure surrounding the airways and intraluminal pressure) is greater. Several surgical methods, including the use of bone chips, Gore-Tex rectus sheath, and fascia lata, have been proposed to help stabilize the trachea, but none has ever become popular because the results are variable and unpredictable.
Other anatomic conditions that may preclude successful surgery must be taken into account before intervention. These include pleural symphysis due to previous surgery or pleurodesis and acquired thoracic deformities such as cyphoscoliosis or narrowing of vertebral bodies, which because of the secondary fixity of the thoracic cage, will prevent improvement even if the hyperinflation is corrected.
Miller (JI) and colleagues (1996) have shown that obese patients should not be operated on because their excess weight prevents them from performing early postoperative rehabilitation. In their series, four patients were considered obese, and only one did well postoperatively. Similarly, they recommend against operation if a patient is receiving significant preoperative tranquilizers because the incidence of postoperative panic attacks approaches 35% to 40% in this group, such attacks being associated with a marked increase in complications. We also exclude from surgery patients without a low level of motivation or willingness to accept the postoperative risks, patients without strong family support, and patients with significant uncontrolled comorbidity.
Pulmonary Rehabilitation
At most institutions, pulmonary rehabilitation is the norm before performing LVRS, and in general, the goal is to achieve 30 minutes of aerobic capacity on a treadmill or bicycle with supplemented O2 as needed. This type of program is believed to be important to improve the strength and aerobic conditioning of the patients, making surgery less traumatic and postsurgical recovery faster. Indeed, at some institutions, attainment of the exercise goals is a requirement for surgery, whereas other centers encourage patients to participate in rehabilitation programs but do not require its goals to be met before surgery.
At present, there are few data to demonstrate how useful is rehabilitation in preparing for LVRS. Although rehabilitation seldom changes the parameters of pulmonary function, it improves quality of life, as demonstrated by Debigar and co-workers (1999). Postoperative rehabilitation is also essential because patients need to relearn how to breathe and use atrophied muscles again.
Regardless of the time spent getting actual pulmonary and general physical rehabilitation, patients are expected to maintain their general fitness for the rest of their lives.
Anesthetic Considerations
Patients subjected to LVRS have friable lungs, and Triantafillou (1996) has shown that in such cases, positive-pressure ventilation may contribute to overdistention of the lungs with secondary decrease in venous return and cardiac output. It may also cause tension pneumothoraces due to the rupture of bullae or other abnormal tissues. In providing general anesthesia, the anesthetist must finally take into consideration the fact that these patients have severe underlying lung disease often associated with hypoxemia and hypercarbia.
In general, the same principles as described for the management of bullous disease (see Chapter 84) are applicable to LVRS. General anesthesia is given with a double-lumen tube and administration of long-acting narcotics or anesthetic is avoided in order that extubation be carried out immediately at the end of surgery.
Postoperative pain control is achieved through a thoracic epidural catheter located at the T3 to T4 level. Cooper and co-workers (1996) recommend that the thoracic epidural catheter be placed under fluoroscopic guidance and be used during surgery in order to decrease the need for narcotics or respiratory depressants and premit extubation at the end of the procedure. In their series, this goal was achieved in all (n = 149) but one patient, who was successfully extubated the following morning. Miller (JI) and co-workers (1996) have shown that during the first 24 hours after operation, pain control should be optimized to its maximum extent using fentanyl, buvicaine, and ketorolac tromethamine. Beginning on the third postoperative day, and subsequently thereafter, pain control is optimized with buvicaine and tromethamine because this combination tends to minimize postoperative gastrointestinal problems seen in this particular group of patients. Subsequently, all patients are placed on a patient-controlled analgesia regimen using morphine.
Surgical Options
Two procedures, laser ablation and lung reduction by stapling, are currently available for the surgical treatment of diffuse emhysema, amid continuing debate concerning the
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relative merits of these techniques. The proponents of each method claim that the lung so treated is made smaller, therefore achieving the primary goal of volume reduction.
The theoretic basis for laser action is through thermal coagulation and contraction of peripheral, emphysematous lung tissue, and Wakabayashi (1996) and colleagues (1991) have published several studies claiming success of this method. Their results are, however, open to criticism because of inclusion of patients with large bullae and a lack of comprehensive follow-up. Two papers authored by McKenna (1996b) and Hazelrigg (1996) and their associates have found laser ablation to be less satisfactory than stapling and have recommended that laser use be discontinued. In McKenna and colleagues' study (1996a), the efficacy of these two procedures was compared, and patients (n = 72) were prospectively randomized to either neodynium:yttrium-aluminium-garnet (Nd:YAG) contact laser surgery or stapled lung reduction surgery by unilateral thoracoscopy. The mean postoperative improvement in FEV1 at 6 months was significantly greater for the patients undergoing the staple technique (32.9% versus 13.4%; p = 0.01) than for the laser treatment group, and the authors were also able to demonstrate fewer delayed air leaks in the stapler group.
Little (1997b) and co-workers (1995) also showed that improvements after laser reduction were only between 50% and 60% of those obtained with a resection technique. These authors recommend that laser be used only in areas difficult to resect, such as deep in a fissure, or in parts of the lung where resection is not planned, as an adjunctive measure to resection elsewhere. Eugene and colleagues (1995) and Wakabayashi (1996) have also presented data suggesting that the combined approach (laser and stapler) may be optimal. The report by Wakabayashi (1996) concerns 500 consecutive procedures using a combination of stapled resection and Nd:YAG ablation of bullous disease. At follow-up, patients were found to have a statistically significant improvement in their FEV1 of 26%, but only 203 patients of the initial 500 were analyzed.
Further debate surrounds the relative merits of unilateral and bilateral procedures, and the use of median sternotomy versus VATS surgery. In general, bilateral procedures have been found to give better results than unilateral reductions, with no increase in morbidity or mortality, as demonstrated by McKenna and associates (1996b). In that study, bilateral procedures (thoracoscopic stapled lung volume reduction) produced a mean improvement in the FEV1 of 57% compared with 31% for unilateral reduction procedures (p > 0.01). In a similar study, Argenziano and co-workers (1997) showed that unilateral LVRS resulted in comparable improvements in exercise capacity and dyspnea but that improvements in spirometric indices of pulmonary function were less in patients undergoing unilateral than bilateral LVRS. Kotloff and associates (1998), however, recorded a significant difference in hospital mortality (10% versus 0%), in postoperative respiratory failure (12.6% versus 0%), and in the length of hospital stay in the bilateral (n = 119) and the unilateral (n = 32) patients after LVRS, respectively. However, with respect to FEV1, FVC, residual volume, and the 6-minute walking distance, the magnitude of improvement was significantly greater after the bilateral LVRS.
There are still individual patients in whom a unilateral operation is more appropriate, such as when only one lung is diseased or in patients with contraindications to operation on one side, such as those with prior thoracotomy or pleurodesis. In a series of 34 patietns presented by Mineo and colleagues (1998), 14 selected patients had assymetric distribution of emphysema, and they underwent unilateral volume reduction. There were no operative deaths, and at the 3-month follow-up, the mean FEV1 increased from 0.8 to 1.2 L (p > 0.001). The authors concluded that assymetric distribution was not an uncommon finding and that unilateral thoracoscopic reduction pneumoplasty may represent an ideal approach in this group. Two other groups have shown good results with unilateral thoracoscopic volume reduction. Naunheim and colleagues (1996) reported their experience with the application of unilateral VATS stapled LVRS in 50 patients. Early follow-up obtained in 25 patients revealed a 30% improvement in FEV1 and a significant improvement in Pao2. Keenan and co-workers (1996) reported their experience with 57 patients who underwent stapled unilateral VATS LVRS. Early follow-up at 3 months revealed a 25% improvement in FEV1.
Surgical Access and Resection of Lung
Access to the lung for volume reduction may be obtained by one of two approaches: median sternotomy and thoracoscopy. Lateral thoracotomy is no longer used, and muscle-sparing anterior thoracotomy has only been advocated by de Perrot and co-workers (1998). In their paper, they reported that the main advantage of this approach was the excellent exposure offered to both upper and lower lobes, thus contributing to reduce the operating time and minimizing lung trauma.
In their initial paper, Cooper and associates (1995) advocated the open approach by median sternotomy. The use of this method was predicated on the desire to achieve maximum benefit at one operation with a minimum of overall morbidity. In that initial series of 20 patients, there was no operative mortality, with an 82% increase in FEV1, 6-mm Hg increase in oxygen tension, marked diminution in oxygen use, and significant improvement in quality of life. The follow-up paper by Cooper and colleagues (1996) and those of other authors such as Miller (JI) (1996), Miller (DL) (1996), Daniel (1996), and Date (1998) and their associates, also advocate the use of median sternotomy. For all these authors, the operative technique involves staple resection of 20% to 30% of the volume of each lung (Fig. 85-14). The worse lung is done first and in upper lobe disease, a continuous staple line is used to excise the upper one half to two thirds of the upper lobe (Fig. 85-15). It is to be noted, however,
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in the discussion of their group's long-term results, Ciccone (2003) stated that no precise guidelines exist, and the aforementioned inverted U-shaped technique has been changed. The resection now starts in the front and is carried straight toward the back, removing almost all of the upper lobe on the right; on the left, the portion of the upper lobe is removed almost completely, and just the lingula is left intact. In most cases, some destroyed lung must be left behind because as Cooper and Patterson (1996) have pointed out, excessive removal has the potential for leaving postoperative air spaces that will promote prolonged air leaks. If such an air space is likely to be a problem, a pleural tent can be made by dissecting the parietal pleura from the chest wall (Fig. 85-16). As shown by Cooper and Patterson (1996), this maneuver reduces the boundaries of the free pleural space and allows the pleural surfaces to be in apposition in the hope to seal air leaks. With lower lobe disease, the inferior pulmonary ligament is divided, and a standard U-shaped resection is carried out. As described by Cooper (1994), most authors reinforce the staple lines with the use of bovine pericardial strips, which have been shown to reduce air leakage often due to tearing of the lung by the staples. Hazelrigg and colleagues (1997a) have also shown that bovine pericardial sleeves result in shorter duration of
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postoperative air leaks and hospital stay. In a randomized three-center study, Stammberger and associates (2000) reported similar salutory results with the reduction of the length of air leaks with the use of the bovine pericardial strips.
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Fig. 85-14. Operative specimen showing resected lung with lung volume reduction surgery. |
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Fig. 85-15. Upper lobe lung volume reduction. A continuous staple line is used to excise the upper one half to two thirds of the upper lobes. the excision begins at the medial aspect of the lobe and is directed upward, over the top, and down the back side at a 45-degree angle to the sagittal pleura. From Cooper JD, Patterson GA: Lung volume reduction for severe emphysema. Chest Surg Clin N Am 5:815, 1995. |
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Fig. 85-16. Pleural tent. Cut-away view of the right anterior chest wall illustrating the parietal pleura (arrow) stripped away from the chest wall to interface with the downsized right upper lobe (RUL) and obliterate the pleural space. A small apical pneumothorax space (arrows) is also shown. Note row of surgical staples and pericardial strips used to reduce incidence of air leaks. From Gierada DS, Slone RM: Lung volume reduction surgery: radiographic findings in the early postoperative period. AJR Am J Roentgenol 168:755, 1997. With permission. |
After completion of the first side, ventilation is resumed to that lung, and the opposite lung is done in a similar fashion. As reported by Argenziano and co-workers (1996), a clamshell incision can be used for the same purpose with perhaps less chances of wound dehiscence and infection. In addition, access to lower lobes may be better than through a sternotomy.
Volume reduction appears to be an ideal procedure for VATS not only because the technique is associated with lower operative morbidity, a not insignificant factor in patients with advanced emphysema, but also because the operation involves the resection of peripheral lung that is readily accessed with thoracoscopic instrumentation. One of the inconveniences of the VATS approach, however, is the repositioning of the patient, which is necessary if a bilateral volume reduction is to be performed in one stage. Despite this inconvenience, Little (1997a) believes that the potential benefit to these typically elderly and malnourished patients of the least stressful operative challenge is considerable. To alleviate the problem of changing position during the operation, Vigneswaran and Podbielski (1997) have described a technique whereby the patient is positioned supine on the operating table with both arms extended over the head.
Kotloff and colleagues (1996) have reported similar improvements in pulmonary function and exercise tolerance following bilateral volume reduction by either median sternotomy (n = 80) or VATS (n = 40). VATS, however, was associated with a lower incidence of respiratory failure and in-hospital mortality, from which the authors concluded that this procedure may be preferable for high-risk patients. In another study reported by Roberts and associates (1998), VATS bilateral volume reduction was compared with median sternotomy with regards to postoperative complications. Significant differences were found in intensive care unit stay, days intubated, life-threatening complications, respiratory complications, requirement for tracheostomy, and death that favored VATS over sternotomy. Success has also been reported by Bingisser and co-workers (1996) who, in 20 bilateral VATS volume reduction, demonstrated a 38% increase in FEV1 with a concomitant 39% increase in functional capacity as measured by a 12-minute walk test. By contrast, Wisser and colleagues (1997) found that both surgical approaches resulted in similar improvement in lung function and that the incidence of air leakage, the duration of chest tube drainage, and the hospital stay were the same for both procedures.
Postoperative Management
In order to minimize complications and shorten hospital stay, the postoperative management of LVRS patients must be optimal. As previously described, all patients are extubated immediately after completion of the procedure, if possible. This strategy is considered important by Cooper and co-workers (1996) because early extubation tends to decrease the importance and severity of air leaks.
In most institutions, patients have two chest tubes in each pleural space. These are placed to underwater seal, which tends to reduce the severity of air leaks as well as prevent the suctioning of a large percentage of inspired air. Occasionally, severe dryness of the airways will occur if a large air leak is present and is suctioned out by active systems. If a pleural tent has been used, the tubes are placed below the tent, and if a lower lobe volume reduction has been carried out, chest tubes (straight or right angled) are left above the diaphragm. Indications for active suction drainage are the presence of a major air leak or major persistent air space. McKenna and associates (1996c) recommend the use of a Heimlich valve to facilitate earlier hospital discharge. In their series of 107 patients who underwent LVRS, 25 experienced a prolonged air leak (>5 days) and were discharged from the hospital after a mean postoperative stay of 9.1 days. Chest tubes were removed an average of 7.7 days later, all apical air spaces resolved, and there were no deaths, empyemas, or pneumonias.
Active respiratory care must be started before the operation and compulsively carried out in the recovery room as soon as the patient has recovered from the anesthetic. This includes the use of physical therapies, breathing exercises, early mobilization, and bronchodilator drugs. Patients receiving systemic corticosteroids must have larger doses for 2 to 3 days postoperatively and then are reverted and maintained on the same dosage as before surgery.
Careful monitoring of the patient is important at least for the first few postoperative days. This monitoring includes blood pressure, heart rate, and urinary output as well as arterial blood gases and oxygen saturation. In these patients, it is also important to monitor breathing patterns and state of conscience because they will occasionally retain CO2 and become lethargic or confused.
Adequate pain control is essential for patient cooperation with bronchopulmonary hygiene and early ambulation, and this is best accomplished through the use of a thoracic epidural catheter. Other drugs routinely used during the postoperative period include broad-spectrum antibiotics and prophylactic heparin given at a dosage of 5,000 units twice a day.
Results
Operative Morbidity and Mortality
Of the centers who have reported results of LVRS done since 1995, the operative mortality has varied from below 5% to as high as 10%. Most deaths have been caused by pulmonary insufficiency, lung infection, or cardiac events. Little (1997b) has shown that respiratory failure is usually
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multifactorial and induced by lung infection, prolonged air leak, or chronic malnutrition and that cardiac complications leading to death included right heart failure and myocardial ischemia. As more experience has been gained, many institutions have reported operative mortality rates below 5%, undoubtedly the result of better patient selection as well as improved familiarity with the procedure. In Ciccone and associates' (2003) report from Washington University (249 patients), the 90-day mortality rate was 4%, and in the report of Bloch and colleagues (2002), 30-day mortality in 115 patients was less than 2%. In the 2003 report of the NETT investigators, the 90-day mortality in 538 surgical patients exclusive of the high-risk group was 5.2%. This varied in four subgroups (to be discussed later) from 2.9% to 10.1%. Unfortunately, it is still likely that the operative mortality is higher in smaller institutions with less expertise and lower case load.
Major morbidity is encountered in an additional 15% to 20% of patients. Rigorous selection criteria and preoperative rehabilitation have kept the incidence of respiratory failure relatively low. Occasionally, however, patients will need short- or long-term ventilatory assistance, which in some cases requires tracheotomy. Pneumonia is relatively uncommon because of adequate preoperative preparation, good postoperative pain control and use of prophylactic antibiotics. If the presence of a pulmonary infiltrate is noted on chest radigraph, specific antibiotics are quickly started, and daily bronchoscopies may be needed to aspirate retained mucus or pus.
Prolonged air leaks (greater than 7 days) are the most frequent complications reported after LVRS, and their incidence varies from 10% to 50%. Improvement in surgical techniques, including the use of reinforced stapler lines and avoidance of chest suction, have helped lessen this problem. We have found that in cases of prolonged air leaks, the use of pneumoperitoneum to raise the diaphragm and reduce the boundaries of the pleural space is helpful. Occasionally, a patient with a significant air leak will need reexploration, especially if the importance of the air leak prevents effective ventilation. It is generally thought, although not clear from the literature, that thoracoscopic volume reduction has less associated morbidity than open surgery.
Miller (JI) and co-workers (1996) have shown that panic attacks and gastrointestinal complications are specific to volume reduction, being almost never seen following other types of pulmonary surgery such as lung resection for carcinoma. Panic attacks or anxiety crises are usually due to breathing difficulties, and their incidence can be reduced or their importance minimized by proper preoperative counseling and refusal to operate on patients with psychiatric backgrounds or patients who rely on heavy doses of tranquilizers. The familiarity of the patient with all health workers involved in the postoperative care and the involvement of close relatives during that period have also helped to reduce the incidence of these problems. Another specific complication described by Miller (JI) and co-workers (1996) consists of marked colon distention, likely due to the slower intestinal peristalsis associated with epidural analgesia combined with the enormous swallowing of air by patients anxious about their inability to breathe properly. This latter factor can be partially corrected by discussing it openly with the patient and his or her relatives before surgery. A relatively late (3 to 20 months postoperatively) complication is the coughing up of metallic staples, which may or may not be associated with hemoptysis. No other serious effects have been noted. Ahmed and colleagues (2001) and Oey and Waller (2001) each reported patients (one and three, respectively) that presented with this event, now called metalloptysis. Yates and associates (2003) reported one additional case. The cause is unknown, but it has been postulated that it may be due to a reaction to the bovine pericardial strips. Even though the metalloptysis continues episodically, as reported by Yates and colleagues (2003), no treatment is necessary. It might be prudent, however, to advise LVRS patients of its rare possible occurrence.
Functional Results
The early functional results in the major nonrandomized reports of LVRS before 2000 are listed in Table 85-5. The report of Cooper and associates (1996) deserves special attention. These authors analyzed a consecutive series of 150 patients, with only one patient lost to follow-up. In that series, clinical evaluation at 6 months showed a significant reduction in dyspnea as quantified on a dyspnea scale and index and improvement in the quality of life as documented by two questionnaires. Overall, 80% of operated patients believed that they were much better than before the surgery. Spirometry showed an improvement of FEV1 by 51% and of FVC of 20%. Both TLC (<14%) and RV (<28%) were significantly reduced. In that same series, gas exchange was also improved with the Pao2 being +8 mm Hg and the Pco2 <4 mm Hg as compared with preoperative values. This improvement in gas exchange translated into a lower proportion of patients requiring O2 supplements at rest (<30%) and during exercise (<48%). These data were updated by Ciccone and colleagues (2003). In this latter report, the long-term results in 249 consecutive patients with emphysema treated by bilateral LVRS were recorded (Table 85-6). The FEV1 and RV showed significant improvement between the preoperative values and each time of follow-up, although there was a gradual decrease in the mean value at each subsequent evaluation after the first 6 months. The Dlco data showed significant improvement (25% increase) at 6 months and 1 year, but the increase was not significant at 3 or 5 years postoperatvely. The Pao2 increased from a basline value of 64 mm Hg to a high of 72 mm Hg until the fifth year, when it decreased slightly by 6%. At 6 months and 5 years of follow-up, supplemental O2 at rest was required only by 11.3% and 22.6%, respectively; although during exercise O2 was necessary in 80% of the 106 patients. The 6-minute walk distance still showed an increase
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of 235 feet at 5 years over the baseline figure but was essentially the same as that after respiratory rehabilitation. Exercise tolerance scores at 5 years were essentially the same as the preoperative scores. Thus, despite the fact that pulmonary function and alveolar gas exchange reached the maximum improvement at 6 months, some improvement persisted as long as 5 years. Patient satisfaction was positive in 80% of the study group. These overall positive results were observed despite the inclusion of a cohort of 21 patients who we generally now believe to be poor candidates for LVRS those with lower lobe disease, the presence of 1-antitrypsin deficiency, and some with an FEV1 or DLCO values less than 20% of the predicted value at the time of operation.
Table 85-5. Postoperative Functional Results after Lung Volume Reduction Surgery | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Table 85-6. Pulmonary Function and Exercise Test Results before and after Surgery | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Kaiser (2003), in a discussion of Ciccone and colleagues' report, stated that they have delineated the selection factors and have convincingly demonstrated that for these selected patients LVRS is a superior alternative to the best medical therapy. Furthermore, he noted that a well-designed observational trial study may provide results equivalent to those obtained by a randomized trial. As noted by Wood (2003), however, despite efforts to overcome any biases for a given therapy, case-control evidence or observational studies inherently contain biases including selection bias, survivorship bias, and statistical bias, as well as problems of reproducibiity of the results at the given institution or elsewhere. Prospective randomized studies likewise have some inherent problems. Nonetheless, such
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studies are necessary to temporize either pro or con the enthusiasm for any new therapeutic endeavor. Thus, a number of studies to compare the outcome of LVRS versus medical therapy or pulmonary rehabilitation alone have been conducted and published in the late 1990s and early 2000s. The trials published by Criner (1999), Pompeo (2000), Geddes (2000), and Wilkens (2000) and their coinvestigators all showed the early significant superiority of LVRS over conservative medical pulmonary rehabilitation in selected small numbers of patients followed for a relatively short period of time (up to 18 months, but often less than 1 year of follow-up). In an interesting study, Meyers and colleagues (1998) compared 22 volume reduction candidates denied operation with 65 contemporaneous and comparable volume reduction recipients. Patients denied operation experienced a progressive worsening of their function whereas volume reduction patients experienced sustained improvements. Absolute survival at the time of publication was 82% for the surgical group and 64% for the nonsurgical group.
Table 85-7. Evaluation and Screening for NETT Enrollees | ||
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Table 85-8. Inclusion Criteria (Patients Must Meet All Criteria to Participate) | ||||||||||||||||||||||
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The NETT Research Group (1999) set out on a very ambitious prospective randomized trial to evaluate the long-term value, as well as the early and late mortality, in a large number of patients (2,500) treated at 17 medical centers throughout the United States. The study duration was set at 4.5 years, with a 6-month close-out period. Evaluation and screening for NETT enrollees are shown in Table 85-7. Inclusion criteria are listed in Table 85-8, and the trial outcomes assessment is listed in Table 85-9. Exclusionary criteria are presented in Table 85-10. The final randomization to either LVRS (median sternotomy or VATS) or to medical therapy was made at the completion of the prescribed (mandatory) respiratory rehabilitation. Treatment comparisons were to be between medical therapy and LVRS of either type. Morbidity and mortality, functional outcomes, and patient satisfaction in each group and selected subgroups of like patients who appear to receive disproportionate benefit (or risk) from the surgical procedure were evaluated. The first NETT report, which included 1,032 patients, appeared 2 years later (2001) and described a group of 70 LVRS patients who were at high risk for
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death after LVRS and compared their course with that of 70 medically treated patients with the same functional and radiographic characteristics at the time of randomization after the initial respiratory rehabilitation. The essential characteristics for these patients were (a) an FEV1 of less than 20% of predicted value, and (b) either a homogeneous distribution on CT or a Dlco capacity of no more than 20% of the predicted value. The 30-day mortality rate after LVRS was 16%, as compared with 0% in the medical group. The survivors of surgery demonstrated small improvements at 6 months in the maximal workload and distance walked in 6 minutes, and a signficant increase in FEV1 over that seen in the medical group, but there was a similar health-related quality of life in both groups. In the medical group, the patients with an FEV1 less than 20% of predicted, and a homogeneous distribution on CT did better than the subgroup with an FEV1 of less than 20% of predicted and a Dlco less than 20% of the predicted value. The overall mortality rate was higher in the LVRS group than in the medically treated group (0.43 deaths per person-year versus 0.11 deaths per person-year, respectively) (Table 85-11). As a result of these findings in this subgroup of patients, the NETT research group advised against LVRS in such patients because of the high risk for death after surgery and a remote likelihood of major benefit from the surgery. They also discontinued the admission of such patients into the randomized study group. Two years later, the NETT Research Group (2003) published their final report on a total of 1,218 patients that had been randomized into the trial. In addition to the aforementioned high-risk group (140 patients), they divided the 1,078 non high-risk patients into four subgroups: (a) upper lobe predominance, low baseline exercise capacity (n = 290); (b) upper lobe predominance, high baseline exercise capacity (n = 419);
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(c) nonupper lobe predominance, low baseline exercise capacity (n = 49); and (d) nonupper lobe predominance, high baseline exercise capacity (n = 220). The mortality rates are shown in Table 85-12 and Figure 85-17. The improvement of exercise capacity and health-related quality of life at 24 months is presented in Table 85-13.
Table 85-9. Trial Outcomes Assessment | ||||||||||
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Table 85-10. Exclusionary Criteria (Presence of Any Criterion Makes the Patient Ineligible) | ||||||||||||
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Table 85-11. Mortality Rates among High-Risk Patientsa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Overall in the long-term follow-up, the mortality rate in both the LVRS and medically treated groups was similar and remained so even when the high-risk group was excluded. However, LVRS was associated with improvement at 6, 12, and 24 months in exercise capacity, lung function, and quality of life (Fig. 85-18). Reduction in dyspnea and increase in the 6-minute walk were also obtained, but after the second year of follow-up, the functional status of survivors in the LVRS group had fallen almost to the baseline levels; although, in the medical group, these values had deteriorated below the baseline levels from the time of randomization.
The greatest benefit of LVRS was seen in the patients with predominately upper lobe emphysema and a low baseline exercise capacity. Some benefit was seen in patients with predominately upper lobe emphysema and a high baseline exercise capacity as well as in patients with nonupper lobe emphysema and a low baseline exercise capacity. The last subset, those with predominantly nonupper lobe emphysema and a high exercise capacity, appeared to have received little benefit and had a high associated mortality.
How these data from the extensive prospective randomized trial conducted by the NETT investigators will affect decisions as to when to or not to recommend LVRS in patients with severe emphysema remains to be seen.
Fessler and Wise (1999) reviewed the results of all reports, providing follow-ups longer than 12 months postoperatively. In that paper, the authors showed that the best FEV1 was obtained at 6 months after operation and that thereafter the annual loss of FEV1 was in the range of 150 to 200 mL, a rate that exceeds what is normally expected in patients with COPD. These data suggest that LVRS may accelerate the functional deterioration of the lung left behind. The NETT trial (2003), and even that of Ciccone and associates (2003), certainly shows the observed functional improvement is relatively short-lived.
Special Problems
Volume Reduction and Lung Cancer
Because lung cancer and emphysema have common etiologic patterns, it is not surprising to find that both conditions are often seen in the same individual. Indeed, Marshall and Olsen (1993) have estimated that 90% of patients with lung cancer have some degree of COPD and that at least 20% have severe disease with FEV1 of 1.2 L or less. Hazelrigg and colleagues (1997b) also reported an incidence
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of cancer of 6.4% in a group of 281 patients who underwent a lung volume reduction operation, and Pigula and associates (1996) showed that 7.8% of 128 patients who underwent LVRS had lung cancer identified during preoperative evaluation or at pathologic analysis of resected tissue. In this group, surgery is often denied because of inadequate reserve, or a limited resection is carried out with higher local recurrence rates as compared with lobectomy.
Table 85-12. Mortality among All Patients and in Subgroupsa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Two papers have addressed the issue of combined adequate cancer resection with volume reduction. In DeMeester and co-workers' paper (1998), five patients with severe emphysema and proven or suspected lung cancer underwent lobectomy combined with volume reduction of one or more additional lobes. All five patients did well postoperatively, and each had subjective and objective improvement in respiratory function on serial postoperative studies. DeRose and colleagues (1998) also presented a series of 14 patients who underwent combined lung volume reduction and pulmonary nodule resection (11 wide wedges and 3 lobectomies). There was one operative death, and at 6-months' follow-up, all survivors were improved in dyspnea index, FEV1, and 6-minute walk test. The authors concluded that simultaneous lung volume reduction and tumor resection should be considered in patients with emphysema and marginal reserves. Similar results were recorded by Korst (1998), Ojo (1997), and McKenna (1996d) and their associates.
Lung Volume Reduction Surgery Versus Lung Transpantation
Gaissert and co-workers (1996) compared the functional results after volume reduction (n = 33) and lung transplantation (single: n = 39; bilateral: n = 27). At 6 months, mean FEV1 was improved by 79% (LVRS), by 231% (single-lung transplantation), and by 498% (bilateral-lung transplantation) over preoperative values. Exercise endurance, as measured by the 6-minute walk distance, increased by 28% (LVRS), by 47% (single-lung transplantation) and by 79% (bilateral-lung transplantation) over preoperative values. The authors concluded that LVRS was a suitable alternative in selected patients eligible for transplantation and that LVRS provided an earlier treatment option in patients who may require transplantation at some future date.
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Fig. 85-17. Kaplan-Meier estimates of the probability of death as a function of the number of months after randomization. The p values were derived by Fisher's exact test for the comparison between groups over a mean follow-up period of 29.2 months. High-risk patients were defined as those with a forced expiratory volume in 1 second that was 20% or less of the predicted value and either homogeneous emphysema or a carbon monoxide diffusing capacity that was 20% or less of the predicted value. A low baseline exercise capacity was defined as a maximal workload at or below the sex-specific 40th percentile (25 W for women and 40 W for men); a high exercise capacity was defined as a workload above this threshold. This was an intention-to-treat analysis. From Fishman A, et al: National Emphysema Treatment Trial Research Group: A randomized trial comparing lung-volume-reduction surgery with medical therapy for severe emphysema. N Engl J Med 348:2059, 2003. With permission. |
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In general, patients with an FEV1 of 20% to 30% of predicted and heterogeneous pattern of disease on CT should have LVRS. Patients with an FEV1 less than 20% and homogeneous pattern are better suited for transplantation, whereas patients with an FEV1 less than 20% of predicted but with ideal anatomic circumstances may benefit from LVRS. Zenati and associates (1998) studied 20 patients who underwent LVRS as an alternative to transplantation. At follow-up of 32 4 months, 19 patients were alive, and 15 were off the transplantation list with FEV1 of 40% 18% predicted at 2 years compared with 22.7% 6% preoperatively. The authors concluded that LVRS has the potential
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to offer an effective palliation alternative to lung transplantation. This is even more so in the context that a substantial number of emphysema patients are in fact ineligible for transplantation because of age or comorbidity.
Table 85-13. Improvement in Exercise Capacity and Health-Related Quality of Life at 24 Monthsa | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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The experience of institutions performing both LVRS and lung transplantation suggests that 30% to 50% of patients with advanced disease are concerned with both procedures. Cooper (1996) and Naunheim (1996) and their colleagues have suggested that LVRS can improve the quality of life of patients on a waiting list for transplantation and in some cases delay transplantation. Further, Zenati and associates (1995) have shown that ipsilateral LVRS does not compromise the chances of a technically successful transplantation at a later date. Kapelanski (1996) and Kroshus (1996) and their co-workers have also shown that some patients may benefit from LVRS on the native lung if it overexpands after contralateral single-lung transplantation. In Kroshus and colleagues' series (1996), 3 of 66 patients who underwent single-lung transplantation had development of native lung hyperexpansion and mediastinal shifting, causing compression of the transplanted lung 12 to 42 months after transplantation. Unilateral LVRS was performed in all 3 patients, who experienced substantial relief of dyspnea and improvement in exercise tolerance after the procedure.
A New Horizon in the Treatment of Emphysema?
Lausberg and associates (2003) from Washington University suggested the use of bronchial fenestration in the treatment of severe emphysema. Using a flexible bronchoscope inserted into various segmental bronchi of 12 emphysematous lungs that had been removed at the time of transplantation, a passage was created through the segmental bronchial wall by a radiofrequency catheter. An expandable metal stent was inserted to keep open the passageway into the lung (Fig. 85-19). Simulated FEV1 was measured and was found to increase almost twofold after the placement of three such stents. Rendina and colleagues (2003) from the same group subsequently published the extension of the bronchial fenestration in 15 living subjects (10
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lobectomy candidates and 5 patients before lung transplantation). Safety by the use of a Doppler catheter to avoid injury to the adjacent blood vessels was evaluated and was found to be adequate. Twenty-nine passages (one to five per subject) in the lobectomy group and 18 passages (three to four per subject) in the transplantation group were carried out. Two instances of bleeding occurred in the lobectomy patients, but each was controlled readily by topical application of epinephrine. The authors concluded that such airway bypass procedures could be done safely in patients with emphysema. Whether or not the procedure can be carried out safely and improve pulmonary function in emphysema patients remains to be seen. One of us [2003 (JD)], noted in the discussion of this publication, raised questions regarding: (a) safety of the use of the bronchial stents (massive hemorrhage or pneumothorax); (b) patency or erosion of the foreign body (with stent); and (c) the occurrence of infection and abscess formation. Finally, one of us (JD) is concerned
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about the stent, central rather than peripheral, where the actual pathology is present.
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Fig. 85-18. Supplementary Appendix 7: Box Plots of Changes from Postrehabilitation Base Line in Exercise Capacity (Maximal Work), Percentage of the Predicted Value for Forced Expiratory Volume in 1 Second (FEV1), Health-Related Quality of Life (St. George's Respiratory), and General Quality of Life (Quality of Well-Being), among Patients who Completed the Procedure after 6, 12, or 24 Months of Follow-up. High-risk patients were excluded. Solid boxes represent patients assigned to lung volume reduction surgery (LVRS); open boxes represent patients assigned to medical therapy. The line inside each box indicates the median value, the top and bottom of each box indicate the first and third quartiles, and the tails of the boxes extend to the most extreme values not considered to be outliers. Values outside the tails of the box plot are considered to be outliers. From National Emphysema Treatment Trial Research Group: A randomized trial comparing lung-volume-reduction surgery with medical therapy for severe emphysema. N Engl J Med 348:2059, 2003. Available from http://www.nejm.org. |
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Fig. 85-19. Technique for insertion of bronchopulmonary stents. A. The flexible bronchoscope is inserted to the level of the segmental bronchus. B. A radiofrequency probe inserted through the bronchoscope is used to create a hole through the bronchial wall into the adjacent lung parenchyma. C. A balloon-expandable stent is passed down the bronchoscope and expanded with the proximal end just inside the bronchial lumen. From Lausberg HF, et al: Bronchial fenestration improves expiratory flow in emphysematous human lungs. Ann Thorac Surg 75:393, 2003. With permission. |
CONCLUSION
Lung volume reduction for emphysema is still a recent innovation, but many clinical trials have been published. The most important ones have been published in 2003, and some conclusions can be drawn from the still limited information available: (a) surgery appears to offer benefits in terms of quality of life for rigorously selected subsets of patients who have exhausted other treatment options; (b) there is some evidence that bilateral LVRS offers a better result than unilateral resection and that LVRS done by thoracoscopy results in lower postoperative morbidity; (c) stapling appears to offer more consistent results than laser ablation, and in several direct comparative studies has been found to be superior; (d) pulmonary rehabilitation before surgery facilitates recovery; and (e) surgery for emphysema should be considered a palliative procedure because the remaining parenchyma must be expected to deteriorate further. Finally, benefit versus early and late mortality should be included in the decision-making process regarding who should undergo LVRS.
Other issues concerning LVRS are still outstanding, as highlighted in an editorial written by Rusch (1996). For instance, the most appropriate and predictable patient profiles have yet to be defined and validated. Similarly, we must improve our understanding of the role played by preoperative exercise on treatment outcomes as well as develop methods ofobjective assessment of the type, range, and frequency of tests that are necessary to monitor and evaluate postoperative progress. Some questions, such as the potential duration of benefit from LVRS, will only emerge with time. As with any new treatment, there is need for carefully controlled, prospective, randomized clinical trials to generate the necessary information. Such trials are being done in Canada, as reported by Miller and co-workers (1999), and in the United States in the NETT (2003). A final consideration is the cost-effectiveness of LVRS related to prolonged medical treatment. This issue has not yet been carefully addressed.
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