What’s the difference between chronic obstructive pulmonary disease and asthma?
Asthma and COPD cause similar symptoms. However, they are different diseases. Briefly:
Both asthma and COPD are common, and some people have both conditions.
Do I need any tests?
COPD may be suspected by your doctor because of your symptoms. Examination of your chest can be normal in mild or early COPD. Using a stethoscope, your doctor may hear wheezes in your chest, or find signs of a chest infection. Your chest may show signs of being overinflated (hyperinflation). This is because the airways are obstructed and, as well as it being difficult for air to get into your lungs, it is also difficult for it to escape. Your history (symptoms) and physical examination will help your doctor decide if COPD is likely.
The most common test used in helping to diagnose the condition is called spirometry. The FEV1 compared with the predicted value shows how bad the COPD is. COPD is divided into mild, moderate and severe groups, depending on the level of airflow obstruction. The airflow obstruction is the FEV1, measured with spirometry.
A chest X-ray may show signs of COPD and can be used to help exclude other serious conditions (including lung cancer). Occasionally, a special CT scan of the chest – high-resolution CT (HRCT) is needed. A blood test to make sure you are not anaemic is often helpful. (Anaemia can lead to breathlessness.) Sometimes a blood test can show changes (called polycythaemia) that suggest you have chronically low levels of oxygen (hypoxia). A pulse oximeter is a device can be clipped on to your finger to measure your heart rate (pulse) and measure the amount of oxygen in your circulation (oxygen saturation). Lower levels than normal tend to be found in people who have COPD, especially if you have an exacerbation of your symptoms.
What is the progression and outlook?
Symptoms of COPD typically begin in people aged over 40 who have smoked for 20 years or more. A ‘smoker’s cough’ tends to develop at first. Once symptoms start, if you continue to smoke, there is usually a gradual decline over several years. You tend to become more and more breathless. In time your mobility and general quality of life may become poor due to increasing breathing difficulties. Chest infections tend to become more frequent as time goes by. Flare-ups of symptoms (exacerbations) occur from time to time, typically during a chest infection. If the condition becomes severe then heart failure may develop. This is due to the reduced level of oxygen in the blood and changes in the lung tissue which can cause an increase in pressure in the blood vessels in the lungs. This increase in pressure can put a strain on the heart muscle leading to heart failure. Heart failure can cause various symptoms including worsening breathlessness and fluid retention. (Note: heart failure does not mean the heart stops beating (that is called cardiac arrest). Heart failure is when the heart does not pump blood very well. Respiratory failure is the final stage of COPD. At this point the lungs are so damaged that the levels of oxygen in the blood are low. The waste product of breathing called carbon dioxide (CO2) builds up in the blood stream. People with end-stage COPD need palliative care to make them more comfortable and ease any symptoms. Many of these people have several years of ill health and poor quality of life before they die. About 8 in 10 men with mild COPD will survive for five years or more after diagnosis, compared with 7 in 10 women. The survival rate is lower in severe COPD. About 3 in 10 men and just over 2 in 10 women with severe disease will survive five years from diagnosis. Depression and/or anxiety affect at least 6 in 10 people with COPD, and can be treated if recognised.