Chronic Obstructive Pulmonary Disease (COPD) causes difficulties with breathing and increased breathlessness. With chronic bronchitis, the tubes (bronchi) that take air in and out of the lungs become inflamed, causing excessive mucus production and coughing. The presence of inflammation and mucus causes the bronchi to narrow. This not only limits the normal amount of air from reaching the lungs but also prevents them from fully deflating, leaving lots of residual air in the lungs1.
With emphysema, the presence of inflammation in the alveoli (air sacs) reduces their flexibility. In some cases, they collapse, making it difficult for air to enter and leave the lungs. As a result, they contain more air than normal, a state known as hyperinflation. The combination of hyperinflation and the extra effort needed to breathe results in the sensation of breathlessness1.