There are four stages of chronic obstructive pulmonary disease, each with it's own series of various and intermediate symptoms, explains Healthline. Common symptoms include increasing shortness of breath, wheezing, chronic cough, fatigue and respiratory infection. These symptoms tend to compound and increase in severity as the disease progresses.
As the stages of COPD progress, the symptoms may change or increase in severity, says Healthline. Prominent symptoms of stage one are often a mild shortness of breath, usually resulting in a grade of 80 percent or better on the pulmonary function test. Stage two symptoms can be an increased shortness of breath, accompanied by cough and/or phlegm; pulmonary function test results range from 50 to 80 percent. Stage three begins with severe symptoms, such as a noticeable difficulty in breathing, chronic cough and/or phlegm and an onset of fatigue.
The severity of stage three symptoms can begin to noticeably affect the quality of life, leading to pulmonary function test results as low as 30 percent. Stage four brings a potentially life-threatening level of breathing difficulties, as the aforementioned symptoms begin to reach their most severe states and pulmonary function results drop to below 30 percent, indicating a greatly increased difficulty in breathing.