How Chronic Obstructive Pulmonary Disease (COPD) Is Diagnosed

Diagnosing chronic obstructive pulmonary disease (COPD) involves several assessments, including blood work, pulse oximetry, pulmonary function tests, imaging tests, and others. Spirometry (a breathing test) is of particular use in the COPD diagnostic process, as it can both indicate the disease before symptoms occur and gauge progression of the condition.

COPD may be suspected if you have persistent or recurrent breathing problems, especially (but not only) if you have a history of smoking or other risk factors. Sometimes COPD diagnosis can be complicated since it may have similar effects as some other illnesses, such as asthma and recurrent pneumonia.

Self-Checks

Even if you think you are at high risk for COPD and exhibit classic COPD symptoms, you cannot diagnose yourself with this disease. You should see a healthcare provider if you have a persistent cough, frequent respiratory infections, and/or dyspnea (shortness of breath) with mild to moderate activity or at rest.

Some people who have COPD notice early signs—activities like climbing the stairs or exercising can become more difficult, and you may need to stop due to shortness of breath. Problems like snoring, feeling tired after a full night's sleep, and recurrent unexplained sore throat in the morning can signal sleep apnea, which is frequently associated with COPD.

If you smoke, are exposed to secondhand smoke, high air pollution, or workplace fumes, you should be on the lookout for these early signs, as they can signal the irreversible lung changes of COPD.

Physical Examination

Your medical team will start your assessment with a detailed review of your symptoms and your medical history. For example, factors such as whether you have triggers or bouts of dyspnea can help distinguish COPD from similar conditions like asthma or allergies.

Your healthcare provider will perform a thorough physical examination, which can identify signs of COPD and its complications.

Vital Signs

Your temperature, pulse, respiratory rate (breaths per minute), and blood pressure will be measured. A respiratory rate above 12 to 20 breaths per minute is considered too high for an adult and is a sign of respiratory distress or another serious illness like anemia.

Systemic Examination

Your healthcare provider will observe you for signs of respiratory distress. Struggling to breathe and loud wheezing can indicate advanced lung disease. Advanced COPD causes right heart failure, which can result in prominence of the veins in your neck.

Your practitioner will listen to your heart and lungs with a stethoscope. Lung sounds such as wheezing can be indications of COPD or a lung infection.

Examination of Your Extremities

Your extremities can show signs of advanced COPD. Pale or bluish fingers or toes signal cyanosis, which is a sign of oxygen deprivation. And swelling of the legs, ankles, or feet signal pulmonary hypertension and right heart failure (late-stage complications of COPD).

Six-Minute Walk Test

You may also have a six-minute walk test, which is a measure of the distance you can walk in six minutes. Sometimes this test is done before and after treatment with a bronchodilator to see if your distance improves in response to the medication (improvement is common in COPD).

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Labs and Tests

In addition to your physical examination, your healthcare provider may also order blood tests or ask you to participate in breathing tests to compare your values to standardized measures. This can give an objective assessment of your lung function.

Pulse Oximetry

Pulse oximetry is a noninvasive method of measuring how well your tissues are being supplied with oxygen. The probe or sensor used to get this reading is normally attached to your finger, forehead, earlobe, or the bridge of your nose, and the reading is available within a few seconds.

Pulse oximetry can be continuous or intermittent, and a measurement of 95% to 100% is considered normal.

Pulmonary Functions Tests (PFTs)

Pulmonary function tests that can be helpful when evaluating lung function in COPD.

Lung diffusion tests measure how much carbon monoxide your lungs are able to process.

• Body plethysmography assesses the volume of air in your lungs at different stages of breathing and the total volume of air in your lungs (known as total lung capacity, or TLC).

Spirometry

A spirometry test, another PFT, is helpful in making a clinical diagnosis of COPD and it is the primary tool for evaluating the severity of the condition. You will need to participate in this test by inhaling and exhaling into a plastic tube as directed.

Spirometry measures several components of lung function, including:

• How much air you can forcibly exhale after taking a deep breath (known as forced vital capacity, or FVC)
• How much air you can forcibly exhale in one second (known as forced expiratory volume in one second, or FEV1)
• The percentage of air left in your lungs after full exhalation (known as the ratio of FEV1 to FVC)
  

These measures assess your ability to inhale and exhale and can give your medical team an idea of your lung airflow.

Blood Tests

Several blood tests can provide your medical team with information about whether you have an infection and how well your lungs are transferring oxygen and carbon dioxide.

• Complete blood count (CBC): A complete blood count (CBC) may alert your healthcare provider if you have an infection. High levels of hemoglobin may suggest the body's compensation for chronic hypoxemia related to COPD.
• Arterial blood gas (ABG): In COPD, the amount of air that you breathe in and out of your lungs is impaired. ABG measures the oxygen and carbon dioxide levels in your blood and determines your body's pH and sodium bicarbonate levels. In an emergency situation, such as a COPD exacerbation, ABG is more sensitive than pulse oximetry when it comes to assessing low oxygen levels. This test is also used when healthcare providers are deciding whether you need mechanical respiratory support or oxygen therapy.
• Alpha-1-antitrypsin deficiency screening: AAT deficiency is a genetic condition that can lead to COPD. If you have a high risk of AAT deficiency, the World Health Organization (WHO) recommends that you be tested for this disorder with this simple blood test. You might have this blood test if you are diagnosed with COPD before age 45. Treatment for COPD caused by AAT deficiency is different than the standard treatment for COPD.

Imaging

As you are being evaluated for a possible diagnosis of COPD, you might need to have an imaging test so that your healthcare providers can evaluate the structure of your lungs.

Chest X-ray

A chest X-ray alone does not establish a diagnosis of COPD, but lung changes can support the diagnosis.

Late-stage COPD is associated with changes that can be seen with a chest X-ray, including:

• Flattening of the diaphragm caused by lung hyperinflation
• An enlarged heart due to COPD-associated right-sided heart failure
• Bullae, areas of a damaged lung that can develop due to COPD

After you receive a diagnosis of COPD, you may need periodic chest X-rays to monitor your response to treatment and disease progression.

Computerized Tomography (CT) Scan

A chest CT scan may show fine details that aren't seen clearly on a chest X-ray. Sometimes, prior to a CT scan, a contrast material may be injected into your vein. This allows your healthcare provider to see the outline of certain lung abnormalities.

Differential Diagnoses

There are several medical illnesses that have features similar to those of COPD. The diagnosis can be especially complicated if you have another medical condition contributing to your respiratory symptoms (e.g., heart failure or lung cancer).

In the course of COPD diagnosis, some of the more common diagnostic considerations include asthma, congestive heart failure, bronchiectasis, tuberculosis, and bronchiolitis obliterans.

Asthma

Asthma may be considered in the differential diagnosis of COPD. Both conditions cause wheezing, shortness of breath, and exercise intolerance.

There are some key differences between asthma and COPD:

Asthma and COPD can co-exist, which can greatly interfere with a person's capacity for strenuous physical activity.

Congestive Heart Failure

Congestive heart failure (CHF) is a condition in which the heart muscle weakens and becomes unable to efficiently pump blood. Symptoms of CHF include fatigue, shortness of breath, and general weakness, but unlike COPD, this condition usually develops after a myocardial infarction (heart attack) causes damage to the heart muscle.

Other features of CHF include:

• Swelling of the legs and feet
• Enlargement of the heart (seen on chest X-ray)
• Characteristic impairment of heart movement that can be seen on echocardiogram

Both conditions can make you feel like you are suffocating, and you may find yourself panting when you exert yourself. As such, it is difficult to know the difference on your own. And since smoking is a leading risk factor for COPD and CHF, it's not uncommon to have both conditions.

Your diagnostic testing will help you and your medical team determine whether you have COPD, CHF, or both.

Bronchiectasis

Bronchiectasis is an obstructive lung disorder that can either be congenital (present at birth) or caused by early childhood diseases such as pneumonia, measles, influenza, or tuberculosis. Bronchiectasis can exist alone or co-occur alongside COPD.

The symptoms of the two conditions are similar, and definitively distinguishing them from each other requires diagnostic imaging tests.

The characteristics of bronchiectasis include:

• Producing large amounts of sputum
• Recurrent bouts of bacterial lung infection
• Coarse lung crackles heard via stethoscope (COPD generally causes wheezing sounds)
• Chest X-ray shows dilated bronchial tubes and thickened bronchial walls (COPD produces a different pattern and rarely causes changes until late stages, when the disease is already established.)
• Clubbing of the fingers

Tuberculosis

Tuberculosis (TB) is a contagious bacterial infection caused by Mycobacterium tuberculosis. Symptoms of TB include fever, weight loss, fatigue, persistent cough, breathing difficulty, chest pain, and thick or bloody sputum.

Because it causes a chronic infection (sometimes with just a low-grade fever), the persistent effects of TB can be mistaken for COPD. However, the infection usually causes a fever, and the cough is more productive than a typical COPD cough.

Other characteristics of TB include:

• Air spaces filled with fluid seen on chest X-ray
• Presence of M. tuberculosis detected by blood or sputum tests

While TB normally affects the lungs, it can spread to other parts of the body as well, including the brain, kidneys, bones, and lymph nodes.

Obliterative Bronchiolitis

Obliterative bronchiolitis is a rare form of bronchiolitis that can be life-threatening. It occurs when the small air passages of the lungs, known as the bronchioles, become inflamed and scarred, causing them to narrow or close.

This condition generally affects one or a few small areas of the lungs, and it progresses rapidly (over the course of days or weeks) as opposed to COPD, which causes worsening symptoms over the course of months and years.

Characteristics of obliterative bronchiolitis include:

• Generally occurs at a younger age in non-smokers
• Possible history of rheumatoid arthritis or exposure to toxic fumes
• CT scan shows areas of hypodensity where the lung tissue has thinned
• Airway obstruction, as measured by the FEV1, is usually below 40%

Grades and Groups

With COPD, your disease is assessed based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) systems. Airflow limitation is used to assign a grade from one to four. The occurrence of exacerbations is then used to assign groups A, B, and E.

Utilizing grades and groups can help your healthcare provider come up with the best treatment plan for your individual needs.

A Word From Verywell

Once you are diagnosed with COPD, you can prevent progression to more advanced grades and stages by avoiding toxins like cigarette smoke, preventing infections, and using your treatments as prescribed.