INTRODUCTION
Emphysema is a worldwide problem causing significant morbidity and mortality. It is usually related to cigarette smoking, although it can occur occasionally without this exposure, notably in alpha-1-antitrypsin deficiency. Emphysema is a chronic progressive disorder that ultimately leads to disability and early death in up to 47 men and 20 women out of 100,000 people, thus representing the fourth major cause of death. Standard non-surgical treatment of emphysema over several decades has included the use of inhaled bronchodilator therapy, theophylline, and corticosteroids. Unfortunately, medical therapy provides only limited benefits and no significant improvement in pulmonary function, quality of life and survival. The use of supplemental long-term oxygen therapy is the only non-surgical means prolonging survival. Pulmonary rehabilitation, nutrition and psychosocial support may improve exercise capacity. However, these modalities neither improve pulmonary function nor prove capable of affecting the progression of emphysematous lung destruction. Lung transplantation and reduction pneumoplasty are the only surgical procedures that have evolved and survived the test of time for the treatment of pulmonary emphysema. Lung transplantation was first attempted in 1963 by Hardy and, after a prolonged period of incremental progress, became clinically feasible during the early 1980s. Reduction pneumoplasty was first proposed by Brantigan and was discarded when the initial experience proved the operation to be too risky, with a 16% mortality rate. Reintroduced by Cooper in 1995, RP has rapidly spread worldwide as a promising surgical option for emphysematous patients. We too have enthusiastically adopted it since 1995, achieving satisfactory early and long-term clinical results.
HISTORY
The failure of medical treatment to provide sustained clinical improvement has led researchers to seek alternative forms of therapy, through the introduction of various surgical procedures over the past 90 years, in an attempt to improve the clinical picture and quality of life in emphysematous patients. Unfortunately, all the proposed surgical procedures were rapidly abandoned, mainly due to unsatisfactory clinical results. The concept of reduction pneumoplasty (RP) was originally introduced by Brantigan, who performed non-anatomic resection of peripheral lung tissue via thoracotomy. The theory underlying the operation was that removal of poorly functioning portions of lung parenchyma would reduce the lung volume. When the remaining lung expanded to fill the chest cavity, it produced radial traction on the bronchi, thereby reducing expiratory flow obstruction and restoring more normal airflow. In more recent years, the concept of reducing lung volume surgically in emphysema has been re-explored. In 1991 Wakabayashi first reported thoracoscopic laser ablation of bullae in patients with diffuse emphysema, whereas in 1992 Crosa Dorado proposed an original technique based on the plication of emphysematous tissue to reduce the lung volume. In 1995, Cooper and associates reported a modification of Brantigan’s volume reduction operation, in which lung tissue was resected from both lungs via a median sternotomy. In the initial 20 cases reported, there was no operative mortality and the operation produced an 82% mean increase in the forced expiratory volume in one second and significant improvement in the walking distance covered in 6 minutes. Moreover, many patients were able to discontinue supplemented oxygen. Subsequent randomised studies suggested that the results with stapled resection were superior to those obtained by laser ablation, and that bilateral resection was superior to unilateral resection. Video-assisted thoracic surgery seemed to provide a minimally invasive technique to achieve reduction pneumoplasty without the need for sternotomy. For this reason it has been adopted by us and other surgeons as the technique of choice.
The failure of medical treatment to provide sustained clinical improvement has led researchers to seek alternative forms of therapy, through the introduction of various surgical procedures over the past 90 years, in an attempt to improve the clinical picture and quality of life in emphysematous patients. Unfortunately, all the proposed surgical procedures were rapidly abandoned, mainly due to unsatisfactory clinical results. The concept of reduction pneumoplasty (RP) was originally introduced by Brantigan, who performed non-anatomic resection of peripheral lung tissue via thoracotomy. The theory underlying the operation was that removal of poorly functioning portions of lung parenchyma would reduce the lung volume. When the remaining lung expanded to fill the chest cavity, it produced radial traction on the bronchi, thereby reducing expiratory flow obstruction and restoring more normal airflow. In more recent years, the concept of reducing lung volume surgically in emphysema has been re-explored. In 1991 Wakabayashi first reported thoracoscopic laser ablation of bullae in patients with diffuse emphysema, whereas in 1992 Crosa Dorado proposed an original technique based on the plication of emphysematous tissue to reduce the lung volume. In 1995, Cooper and associates reported a modification of Brantigan’s volume reduction operation, in which lung tissue was resected from both lungs via a median sternotomy. In the initial 20 cases reported, there was no operative mortality and the operation produced an 82% mean increase in the forced expiratory volume in one second and significant improvement in the walking distance covered in 6 minutes. Moreover, many patients were able to discontinue supplemented oxygen. Subsequent randomised studies suggested that the results with stapled resection were superior to those obtained by laser ablation, and that bilateral resection was superior to unilateral resection. Video-assisted thoracic surgery seemed to provide a minimally invasive technique to achieve reduction pneumoplasty without the need for sternotomy. For this reason it has been adopted by us and other surgeons as the technique of choice.
The goals of preoperative testing are the identification of patients who would benefit most from the procedure with an acceptable morbidity. We currently consider as the best candidates the patients with heterogeneous emphysema preferably distributed in the upper lobes and associated with severe airflow obstruction and lung hyperinflation (Fig.1). Medical history, physical examination, serum chemistries, electrocardiography, and urinalysis are the standard initial evaluations. Functional tests include pulmonary function tests aimed at assessing respiratory flow by spirometry and lung volumes by gas diffusion or better by plethysmography, which allows a more precise measurement of the trapped gas volume. Inspiratory and expiratory digital chest roentgenograms provide important information on the degree of lung hyperinflation and the motility of the diaphragm. High resolution computed tomography is performed to analyse the lung structure and identify the most damaged regions, the so-called “target areas”. Ventilation-perfusion scans are performed to evaluate the pattern of perfusion in both lungs and aid detection of the target areas. A 6-minute walk test is performed as a sub-maximal exercise test to evaluate exercise tolerance. In addition, right and left ventricular function is assessed by means of echocardiocolordoppler and, in selected patients, right heart catheterisation and coronary artery angiography. The most widely accepted selection criteria for reduction pneumoplasty include radiologic features of heterogeneous emphysema with severe lung hyperinflation and resectable target areas, disabling dyspnea, altered spirometry with a forced expiratory volume in one second (FEV1) <40%, a residual volume (RV) >180% and a total lung capacity (TLC) >120% (Table 1). Reasons for exclusion are age over 80 years, tobacco use within the last 6 months, body weight 25% greater than ideal, empyema or pleurodesis on side of proposed operation, significant hypercapnia, pulmonary hypertension, chronic bronchitis, asthma, severe cardiovascular disease, coexisting terminal medical condition and inability to complete a pulmonary rehabilitation programme. Rehabilitation including breathing retraining, pulmonary toilet, upper and lower arm exercises as well as nutritional and psychological support may help reduce early complications. We routinely encourage our surgical candidates to participate in a 6-week-based preoperative respiratory rehabilitation programme.
OPERATIVE TECHINQUE
Several surgical approaches have been used to perform RP, including median sternotomy, mono or bilateral video-assisted thoracoscopy, and, less commonly, single or sequential anterior or lateral thoracotomy. Three techniques to perform RP have been described: stapled resection, stapled plication and laser ablation. In 1995 we started our VATS RP programme to perform tailored unilateral and bilateral staple reductions. Bilateral RP has been carried out as a one-stage or a staged procedure in patients with bilateral heterogeneous emphysema. Unilateral reduction has been intentionally carried out in patients with an asymmetric distribution of the emphysema in the lungs. The procedure is performed under general anesthesia with a double-lumen endotracheal tube. The epidural catheter is placed for postoperative pain management. Patients are positioned in the lateral decubitus position and prepared as for thoracotomy. Target areas of the lung, identified as the lung regions that fail to deflate after ventilatory exclusion, are lifted with sponge forceps and resected by endoscopic stapling device. The area and amount of lung to be resected is identified also with the aid of preoperative CT and lung perfusion scans. For upper lobe emphysema, approximately 50% of each upper lobe is resected, which accounts for approximately 75 g of tissue per side (Fig. 2). The resection line follows a curvilinear shape to allow remodelling of the remaining lung parenchyma, in order to facilitate its complete re-expansion and filling of the pleural space. In patients with lower lobe emphysema we usually carry out multiple wedge resections. The chest tubes are attached to water seal drainage and suction is avoided to minimize air leaks. We routinely extubate operated patients in the operating theatre, and less than 3% of our patients have required reintubation. Starting on the first postoperative day, vigorous chest respiratory and physical therapy is started to clear bronchial secretions and enhance mobilization. The intensity of the programme is increased on an individual basis.
IMPROVEMENT MECHANISMS
Investigations into the physiology of improvement has been undertaken only in patients undergoing RP by stapled resection. Proposed mechanisms of improvement include increased elastic recoil, decreased airway resistance and improved respiratory muscle function. The patients displaying the greatest increase in elastic recoil showed the best improvements in exercise tolerance and the largest decrease in residual volume. Also, increased elastic recoil decreased transmural pressure and improved airway conductance and expiratory airflow. A decrease in residual volume may also lead to a reconfiguration of the thorax and diaphragm towards a normal shape, which results in better neuromuscular coupling and improved respiratory muscle efficiency. In addition, ventilatory mechanics indicated by an assessment of breathing action, intrinsic positive end-expiratory pressure and dynamic compliance, has been found to improve immediately after RP, owing to the reduction in airway resistance and relief of thoracic distension. Finally, RP may exert a beneficial effect on right ventricular function owing to an increased venous return and a reduced afterload.
LONG CANCER ENPHYSEMA
Reduction pneumoplasty allows resection of lung cancer in some patients who are otherwise not candidates for resection because of poor pulmonary function. Thus, the ideal candidate for a combined resection is a patient with a peripheral tumour located within a severely emphysematous area targeted for RP. Nonetheless, there is some evidence that even lobectomy can be carried out in selected patients, particularly when the lobe to be resected is severely hyperinflated and poorly perfused. If the lung cancer is in the better part of the lung, a wedge resection and a reduction pneumoplasty are separately performed. In addition, we have recently carried out a combined resection in patients with emphysema and a solitary pulmonary metastasis with promising results. The early results of combined RP and lung cancer resections suggest a favourable outcome in most patients with a mortality rate of 3.5% and a negligible recurrence rate after a 9-12 months follow-up period.
REDUCTION PNEUMOPLASTY AND LUNG TRANSPLANTATION
Per ogni paziente con enfisema grave riteniamo indispensabile una valutazione che contempli entrambe le opzioni chirurgiche. Alla pneumoplastica riduttiva vengono avviati pazienti con iperinflazione, con distribuzione eterogenea dell’enfisema, con FEV1>20% e pCO2 normale. Al contrario, il trapianto sarà prescelto in presenza di enfisema omogeneamente distribuito, bassa FEV1, ipercapnia ed ipertensione polmonare. Il trapianto sarà preferito inoltre nei pazienti con deficienza di alfa-1-antitripsina. Infine, non privo di interesse e di risultati soddisfacenti può dimostrarsi l’impiego combinato della pneumoplastica e del trapianto per ottimizzare, in pazienti selezionati, il trattamento dell’enfisema. Queste combinazioni vedono la pneumoplastica riduttiva come fase di attesa al trapianto, o un trapianto singolo di polmone e contemporanea pneumoplastica unilaterale per prevenire l’iperespansione del polmone nativo, o ancora, la pneumoplastica unilaterale post-trapianto per trattare l’iperespansione acuta o cronica del polmone nativo.
CONCLUSION
The available data and our current experience support the recently re-emerged RP as a valid albeit palliative surgical option for improving subjective dyspnea, pulmonary function, exercise capacity and quality of life in selected patients with severe emphysema. Randomised studies have shown that the benefit achieved through bilateral or unilateral RP is superior to that achievable by maximized medical therapy including respiratory rehabilitation. Intermediate-term data also suggest that clinical improvements can be maintained for up to 4 years, although a gradual deterioration has to be expected after the first postoperative 12 months. Bilateral RP is recommended as the procedure of choice for patients with a bilateral pattern of heterogeneous emphysema. Bilateral operations produced greater improvement in the FEV1, oxygen and prednisone independence and dyspnea. Furthermore, the one-year mortality was significantly lower when compared to that of patients operated on unilaterally. However, unilateral RP has a role in patients with disease prevailing in one lung or with contraindications to resection on one side such as previous surgery, empyema or prior pleurodesis. The type of surgical approach does not affect the outcome since nearly identical improvements have been achieved after median sternotomy or VATS. Nonetheless, recent data indicated that VATS may be better tolerated than sternotomy especially in patients over 65 years of age. There still are controversies around several issues. What are the exact mechanisms of improvement? Is it better to perform a one-stage bilateral RP in all cases or is it preferable to tailor unilateral and bilateral procedures in selected patients? How long does the improvement last? Which patients do not benefit from RP? Is RP capable of modifying the natural history of emphysema by improving long-term survival? What are the cost implications of a widespread application of this attractive surgical option? In recent years, the application of lung transplantation for emphysema has quickly increased. The advantages of lung transplantation are obvious: complete replacement of the non-functioning lung with a new and healthy lung allows a dramatic improvement in pulmonary function and exercise tolerance with elimination of supplemental oxygen. However, the scarcity of available donor lung lengthens the waiting list and may be responsible, once the lungs become available, for an increased post-transplant early mortality and morbidity that exceeds that of RP. To overcome at least in part these problems, an increased use of RP as a bridge to lung transplantation may be hypothesized. Finally, RP may be offered as a first step to allow subsequent surgical treatment of secondary extra-pulmonary malignancy or vascular diseases, in patients otherwise considered inoperable due to end-stage emphysema. More definitive answers to several open questions will probably be provided in the near future by the results of ongoing multicentric studies. However, although Brantigan’s idea remained forgotten for decades, its recent resurrection and widespread enthusiastic acceptance in our technological era represents in our opinion the best proof that it was an excellent idea. (traduzione dell'Autore)
Tommaso Claudio Mineo
Docente al Dipartmento di Chirurgia
Univesità di Tor Vergata Roma
Docente al Dipartmento di Chirurgia
Univesità di Tor Vergata Roma