In chronic bronchitis exposure to an irritant over many years causes inflammation in the lungs which leads to the following changes:
- The smooth muscle in the airway becomes thicker and narrows the breathing tubes (airways). The narrowing is permanent and cannot be reversed. You may feel breathless because your lungs and muscles are working harder to move air in and out. However, this does not necessarily mean that your oxygen levels are low (because the breathing muscles around your chest are compensating for the narrowing). You may also experience wheeze due to narrowed breathing tubes.
- Because the breathing muscles are working harder, this is why you may feel more tiredness and fatigue.
- The mucus glands get bigger and secrete more sputum and the brush lining (cilia) is damaged. Thicker sputum is harder for the damaged brush lining to clear. This might make you prone to a flare up of symptoms, which is sometimes called an exacerbation.
- Germs thrive in warm, moist environments so this could cause a flare-up or an infection.