As explained in the previous section, spirometry should be performed if the individual is showing symptoms, has a history of smoking and other environmental/occupational pollutants. The following is a list of characteristics a spirometry candidate should have:
- Symptoms of coughing (with and without sputum), wheezing, and shortness of breath.
- A history of smoking.
- A history of exposure to environmental risk factors including second-hand smoking and occupational pollutants.
- A family history of chronic lung disease.
The “How To” of Spirometry Testing
A spirometer is an effective (and necessary) tool to diagnose COPD in a person. This machine can be of various sizes, including equipment that are large found in pulmonary function testing labs, or hand-held and battery-operated. Some of the hand-held spirometers have computer docks available that allow you to download the data collected.
In order to maximize the quality of the test, here are a few simple rules to giving spirometry:
1. Make sure the individual taking the test feels comfortable— Explain the process of taking the test and the goals you both are trying to achieve. Reassure the individual that the test is simple. It is also best for the individual to take the test while they’re seated.
2. Breathe, Seal, Blow!— Ask the individual to take in a very deep breath, hold their breath while they seal their lips around the mouthpiece, and to then exhale as fast and as long as they can. Their goal is to empty out their lungs and to continue blowing for the duration of the 6 seconds of the test. During this time, they should try not to breathe in or stop exhaling. A demonstration before taking the actual test could be useful.
3. Repeat— Explain to the individual that they need to repeat the test at least two more times in order for the machine to take an accurate account of their measurements. The quality of the test must also be satisfactory so that the machine can derive measurements from consistent curves.
Interpreting the Results
Spirometry will show the measurements of a Forced Expiratory Volume in the first second of the person blowing into a spirometer (FEV1) and the Forced Vital Capacity (FVC) for the total 6 seconds of the blow. If the FEV1/FVC ratio is between or above 70-80%, the person’s lung health is normal. Below 70% may be an indication of some obstruction. Note that the FEV1 is subject to the age, gender, height, and weight of the individual being tested.
The ATS/ERS guidelines states that single measurement of FEV1 is not sufficient to diagnose COPD because: “1) many patients are practically asymptomatic; 2) persistent cough and sputum production often precede the development of airflow limitation [3] and, in others, the first symptom may be the development of dyspnea with previously tolerated activities; and 3) in the clinical course of the disease, systemic consequences, such as weight loss, and peripheral muscle wasting and dysfunction, may develop.”
Stages of COPD
According to the GOLD guidelines, the classification of COPD can be divided into four stages: Mild, Moderate, Severe, Very Severe. The following table shows the FEV1/FVC classification of each stage:
Mild
FEV1/FVC < 0.70
FEV1 >= 80% predicted
- At this stage, the individual may not know their lung function is abnormal.
Moderate
FEV1/FVC < 0.70
50% <= FEV1 < 80% predicted
- At this stage, symptoms are more noticeable to the individual and they are more likely to seek medical attention.
Severe
FEV1/FVC < 0.70
30% <= FEV1 < 50% predicted
- At this stage, there’s greater shortness of breath and decrease in physical activity which will have a large impact on the individual’s quality of life.
Very Severe
FEV1/FVC < 0.70
FEV1 < 30% predicted, or FEV1 < 50% predicted plus chronic respiratory failure
- At this stage, the quality of life is severely affected and exacerbations can be life-threatening.
(For a free pocket-sized guide with the above table and additional management information, fill out a request here.)