When small is better: volume reduction in severe emphysema.

Severe emphysema radically diminishes quality of life. The disease is a result of destruction of lung parenchyma and is most commonly associated with cigarette smoke exposure or the congenital absence of α1-antitrypsin. The elastic fibres of the lung, which in a healthy state strive to retract the lungs, are particularly affected. The inward force determined by these fibres is balanced by the chest wall, which strives to push outwards. The result is a finely balanced system where only minimal work is needed in quiet breathing. Emphysema results in a loss of elasticity of the lungs, and thus the inward traction, while the outward force of the thorax remains unopposed, resulting in lung hyperinflation. Further, the small airways, that in normal lungs are kept open and wide by the elastic recoil from the lung parenchyma [1, 2], will have predilection for collapse due to the diminished elasticity of emphysema. Thus, even mild exertion may result in dynamic hyperinflation with air trapping adding to the increased work of breathing. In the 1950s it was shown that removal of emphysematous regions of the lung could considerably enhance lung function and quality of life by improving the total elasticity of the lungs [1]. If successful, residual volume is diminished, small airways collapse is reduced, and the chest will be less hyperinflated allowing the respiratory muscles to work more efficiently.