Emphysema is a chronic lung disease largely attributable to smoking, characterised by alveolar wall destruction distal of the terminal bronchioles.
Alveoli in the lung weaken and may coalesce to form bullae, abnormally large air-filled sacs that trap air during expiration. These air spaces have high ventilation-perfusion ratios, and create a dead space, while reduced elastic recoil and expiratory airway collapse causes hyperinflation in overly-compliant emphysematous lung.
These hyperinflated areas then compress areas of more normal lung, and as the total surface area of alveoli reduces, gas exchange becomes significantly less efficient.
The mainstays of treatment are bronchodilators, steroids, oxygen supplementation, and pulmonary rehabilitation. Lung volume reduction surgery (LVRS) may also be an option for patients who have shortness of breath.
The objectives of LVRS are to provide symptomatic relief and improve quality of life by removing the least functional part of the lungs to improve airflow, chest-wall mechanics and alveolar gas exchange in the remaining lung. This may be achieved by midline sternotomy, thoracotomy or video-assisted thorascopy (VATS) with stapled resection of tissue bilaterally. The most common complication related to LVRS is persistent air leak.
Interpretation of the available studies is not always simple because they often include patients who have undergone a variety of surgical techniques to reduce lung volume. Some may have an element of confounding because they include patients who have undergone pulmonary rehabilitation.
This surgery is carried out relatively infrequently and when performed it is carried out in specialist centres.
Much of the guidance regarding patient selection for LVRS comes from The National Emphysema Treatment Trial (NETT), which was the first multi-centre trial to assess the role, safety and effectiveness of bilateral LVRS. NETT involved 3,777 patients that were evaluated and 1,218 patients who underwent randomisation.
Before randomisation patients completed four to six weeks of pulmonary rehabilitation, including medical therapy, counselling, exercise and breathing methods.
Some 580 patients received surgery 406 median sternotomies and 174 VATS procedures. In centres with expertise in using both techniques, patients were assigned randomly to each technique for LVRS. The total mortality rate was 0.11 deaths per person-year in both groups. To study the benefits of LVRS, lung function, quality of life scores, exercise capacity, survival and hospitalisation rates were assessed.
NETT found that at 24 months, exercise capacity had improved in 15 per cent of patients in the surgery arm of the trial compared with 3 per cent in the medical arm.
Mortality was also lower in the surgical group compared with the medical therapy group in patients with upper lobe emphysema and low exercise capacity.
However, in the surgical group those with a high exercise capacity and non-upper-lobe emphysema had a higher mortality when compared to the medical therapy group. The authors commented that patients with upper-lobe disease were more likely to benefit from LVRS compared with patients with non-upper lobe distribution of emphysema.
Shortness of breath decreased following surgery and continued to fall throughout 24 months of follow-up; by comparison, medically-treated patients reported a slight increase in shortness of breath over the same period.
A prospective cost-effectiveness analysis over three years of follow up was carried out as part of NETT; in the third year of follow up, total medical care costs were equivalent in both the LVRS and medical therapy-only groups.
A 2006 Cochrane Database review of randomised controlled trials looking at the efficacy and safety of LVRS confirmed that in suitable candidates outcomes following surgery were better than with usual medical care.
The Brompton trial reported by Lim et al showed that that following LVRS the immediate increase in FEV1 was not sustained, but the mechanical effects on increasing FVC appear to be maintained. Alternative methods of achieving LVRS through collapse of distal alveoli include surgical resection with compression or banding devices, endobronchial blockers, obstructing devices and valves.
The 2003 report on COPD by Meyers and Patterson suggested that patients with large bullae, filling half the thoracic volume and compressing relatively normal lung tissue, may be offered bullectomy.
The authors added that bullectomy may not be appropriate if there are also multiple smaller bullae, advanced emphysema in the non-bullous adjacent lung or if there are significant co-morbidities. However, if nearly a whole lobe is involved and the fissures are complete, lobectomy may be more appropriate.
Current NICE guidelines recommend LVRS in those with severe COPD whose shortness of breath impairs their daily living activities, despite maximal medical therapy.
Referral to a specialist centre for consideration of LVRS is recommended if FEV1 is more than 20 per cent of predicted, if PaCO2 is less than 7.3kPa and if the upper lobe is most affected.
Patients should also have stopped smoking for at least three months and undergone pulmonary rehabilitation.
|Dr. Kochhar is SHO in thoracic surgery and Mrs. Harrison-Phipps is consultant in thoracic surgery at Guy’s Hospital, London|