Emphysema. Coloured computed tomography (CT) scan of an axial section through the lungs of a 60 year old patient with emphysema. The front of the body is at the top of the image. Emphysema causes the alveoli (tiny air sacs) of the lungs to become damaged and enlarged. This makes their walls thinner, until eventually they break leaving large spaces (bright spots). This reduces gas exchange in the lungs leading to shortness of breath, which can develop into a serious lack of oxygen in the blood and cyanosis (blue colouring), or even respiratory and heart failure. Emphysema is caused by smoking and is incurable. Treatment is aimed at preventing further damage.