COPD

BARREL CHEST Barrel chest refers to an increase in the anterioposterior diameter of the chest wall resembling the shape of a barrel.A ratio of anterioposterior (AP) to lateral chest diameter of greater than 0.9. The normal AP diameter should be less than the lateral diameter and the ratio of AP to lateral should lie between 0.70 and 0.75. The term "barrel chest" describes a rounded, bulging chest that resembles the shape of a barrel. Barrel chest isn't a disease, but it may indicate an underlying condition. CONDITIONS ASSOCIATED WITH Chronic bronchitis Emphysema Also occurs in elderly people without disease.  MECHANISMS It occurs because the lungs are chronically overinflated with air, so the rib cage stays partially expanded all the time.Considered to be due to over-activity of the scalene and sternocleidomastoid muscles, which lift the upper ribs and sternum.9 With time, this overuse causes remodelling of the chest. 

Barrel chest