Produced by the Royal College of Physicians of Edinburgh and Royal College of Physicians and Surgeons of Glasgow

Lung volume reduction surgery for emphysema: the national emphysema treatment trial (NETT)

  • Professor W MacNee, Professor of Respiratory & Environmental Medicine and Honorary Consultant Physician, University of Edinburgh, Scotland


Lung-volume reduction surgery has been proposed as a means of alleviating severe emphysema. How much of a benefit could this procedure have on alleviating symptoms and prolonging life? And do the benefits outweigh the costs? Prof Bill MacNee reviews a major study which set out to answer these questions.

Key Points

  • Emphysema is part of an important component of chronic obstructive pulmonary disease (COPD) which causes high disability associated with over inflated lungs, poor lung elasticity and impaired transfer of oxygen to the blood.
  • Reducing lung volume may allow respiratory muscles to work better and improve lung elasticity.
  • Patients should have pulmonary rehabilitation before surgery is considered.
  • A North American study has shown that patients with heterogeneous emphysema in the upper lobes of the lungs, and poor access post rehabilitation can benefit from lung-volume reduction surgery.
  • The benefits of this option still need to be shown.

Declaration of interests: No conflict of interests declared

Lung-volume-reduction surgery (LVRS) has been proposed as a palliative treatment for patients with severe emphysema. The procedure leads to a decrease in lung volumes and an increase in elastic recoil of the lungs. Decreasing lung volumes improves respiratory muscle geometry and hence performance, while increasing elastic recoil increases expiratory airflow, leading to improved exercise performance and reduced dyspnoea. However uncertainty over the preoperative predictors of benefit and the effects on morbidity and mortality led to a National Institutes of Health-sponsored multicentre randomised control trial in the US, comparing LVRS with medical therapy for patients with severe emphysema. The outcome of this trial has recently been published in the New England Journal of Medicine.1,2

Before randomisation, all of the patients in this trial underwent pulmonary rehabilitation. The primary outcome measurements were overall mortality and maximum exercise capacity two years after randomisation with secondary outcomes including results of six-minute walking test, lung-function tests and general health-related quality of life.

In the trial, 1,218 patients with severe emphysema as shown on CT scan assessment were randomised to either LVRS or medical therapy. An interim analysis of the study showed that patients with the most severe disease (FEV1 20% predicted and either homogeneous emphysema on HRCT or a car