Chronic obstructive pulmonary disease (COPD) is grossly under-diagnosed and is one of the commonest lung problems affecting smokers. The diagnosis is usually made after consultation with a Chest Physician who specializes in lung diseases. However, diagnosis may also be made by a General physician.
An early diagnosis is desirable as it gives an opportunity to manage a patient and prevent the rapidity of the progressive lung damage.
What does diagnosis involve?
- Detailed history of smoking, exposure to chemicals, fumes, dust, air pollutants or passive smoke. Smoking is one of the most important causes of COPD and needs to be asked while assessing a patient with suspected COPD.
- The patient is then examined. Anemia, cyanosis (bluing of the tips of the fingers, ears and nose due to lack of oxygen), clubbing (a feature then tips of the fingers become swollen due to chronic lack of oxygen) and general physical health is assessed. The body mass index (BMI) is also assessed.
- Spirometry – spirometry involves testing breathing. It is suggested in patients at high risk including:-
- smokers or ex-smokers 40 years of age or older
- persistent cough or sputum and phlegm production
- frequent and recurrent respiratory infections
- unexplained breathlessness or shortness of breath caused by little or no physical activity
In this test the patient is asked to breathe into a machine called a spirometer. The spirometer takes two measurements – one is the volume of air a person can breathe out in 1 second (called Forced expiratory volume 1 or FEV1) and the other is the total amount of air a person can breathe out called the forced vital capacity or FVC.
This may be repeated several times before diagnosis may be confirmed. The readings are compared with normal measurements of the same age to reveal if there is airway obstruction.
Breathing test called post bronchodilator FEV1 / FVC. This test involves testing the Forced Expiratory Volume at 1 second (FEV1) and the Forced Vital Capacity (FVC) of the lungs in the patient.
Thereafter the patient is given an inhaled bronchodilator. When this ratio despite a bronchodilator that helps dilate the narrow airways remains less than 0.7 it signifies that the airflow obstruction not fully reversible with a bronchodilator and COPD is confirmed.
To rule out asthma FEV1 is compared. Asthmatic patients will have a 12% or greater improvement in FEV1 15 minutes after the use of an inhaled short-acting beta2 agonist or a bronchodilator.
Peak flow test – this is yet another breathing test. A peak flow meter can be used several times a day over several days to detect how fast the person can breathe out. This helps differentiate COPD from asthma.
- Chest X-ray – this is one of the commonest imaging studies that is suggested to detect emphysema changes in the lungs.
- Routine blood tests – these may detect anemia and other abnormalities. White blood cell counts may be raised in case of infections.
- Blood oxygen levels are also tested using a pulse oximeter. Airway obstruction may reduce the amount of oxygen in blood making it inadequate. This is detected using arterial blood gas assessment and blood oxygen measurements.
- Blood test for alpha-1-antitrypsin deficiency – alpha 1 antityrpsin is a protein that protects the lungs. In its absence, as seen rarely in some genetically susceptible individuals, there is risk of COPD. COPD in non-smokers below 35 is an indication towards alpha 1 antitrypsin deficiency.
- Electrocardiogram (ECG) and echocardiogram – COPD may co-exist with heart disease. These can be ruled out using ECG and echocardiograms
- Computerised Tomography (CT) scan – this is more sophisticated imaging study than X ray and can show the extent of lung damage
- Laboratory assessment of the sputum or phlegm. This may show presence of infective microorganisms in cases of chest infections associated with COPD.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)