Chronic obstructive pulmonary disease: Clinical sciences

Chronic Obstructive Pulmonary Disease, or COPD, refers to a heterogeneous, usually progressive lung condition that results in airflow obstruction and breathing difficulties, often due to long-term exposure to irritants, such as tobacco smoke. Over time, COPD can lead to irreversible lung damage, making breathing difficult and limiting everyday activities, such as physical exercise.

Some patients with COPD may first show up with chronic breathing difficulties and no prior history of COPD, while others might come in with COPD flare-ups, which are also known as COPD exacerbations.

Now, if your patient presents with signs and symptoms suggestive of COPD, you should perform an ABCDE assessment to determine if they are unstable or stable. If unstable, stabilize the airway, breathing, and circulation. Next, obtain IV access and put your patient on continuous vital sign monitoring, including heart rate, blood pressure, and pulse oximetry.

Most of the time, these individuals will present with severe respiratory distress that requires supplemental oxygen or even mechanical ventilation.

Now, here’s a clinical pearl to keep in mind. When treating individuals with severe respiratory distress, always be on the lookout for signs of life-threatening respiratory failure. These include altered mental status, the use of accessory respiratory muscles, and a respiratory rate greater than 24 breaths per minute.

It’s also important to recognize abnormal arterial blood gas analysis results that suggest impaired alveolar gas exchange, such as acidosis, hypercarbia, and hypoxemia.

Now, let’s go back to the ABCDE assessment and take a look at stable individuals. Start by obtaining a focused history and physical exam as well as pulse oximetry.

First, let's focus on individuals with no previous diagnosis of COPD who are reporting persistent and slowly progressive shortness of breath, which worsens with exercise.

In this case, history typically reveals fatigue, chest tightness, recurrent wheezing, and chronic cough that could be either productive or nonproductive.

It’s also helpful to ask about frequent winter colds or recurrent lower respiratory infections, as these can be signs of COPD.

Finally, check for risk factors like tobacco use and exposure to occupational hazards, such as dust, asbestos, chemicals, or fumes.

On the flip side, the physical exam could be entirely normal, especially in the early stages of the disease.

However, as the disease progresses, you might hear wheezing, particularly during forced expiration due to airway obstruction.

In most cases, pulse oximetry will show normal oxygen saturation, but in more severe cases, saturation might drop to 92% or below, indicating significant impairment in respiratory function.

With these findings, you should suspect COPD.

Your next step is to obtain spirometry. Start with pre-bronchodilator spirometry, meaning the patient shouldn't use any bronchodilators beforehand. This will give you a baseline measurement of lung function.

Next, calculate the FEV1 to FVC ratio.

FVC, or Forced Vital Capacity, refers to the total amount of air the patient can exhale during the forced breath,

while FEV1, or Forced Expiratory Volume in 1 second, is the amount of air exhaled during the first second of this forced exhalation.

If the FEV1/FVC ratio is equal to or greater than 0.7, consider an alternative diagnosis.

On the other hand, values below 0.7 suggest an airflow obstruction, so the next step is post-bronchodilator spirometry.

First, give your patient an inhaled bronchodilator like albuterol, wait 15 minutes, and then repeat the spirometry.

Next, calculate the FEV1/FVC ratio to see if the obstruction is reversible.

If the ratio goes up to 0.7 or above, the obstruction is reversible, so you should think of alternative diagnoses. But, if the ratio stays below 0.7, the obstruction is not reversible, confirming the diagnosis of COPD.

Now, here’s a clinical pearl to keep in mind. When evaluating individuals with suspected COPD, be sure to obtain chest imaging to rule out comorbidities, such as interstitial lung disease and heart failure.

Once you confirm the diagnosis, the next step is to initiate management. Which covers lifestyle modifications, vaccination, initial pharmacotherapy, and sometimes supplemental oxygen therapy.

First, you should encourage lifestyle modifications like smoking cessation and physical exercise. In severe cases, a patient might also benefit from a pulmonary rehabilitation program, which focuses on endurance, strength, flexibility, and inspiratory muscle training.

Next, be sure to provide vaccinations, such as influenza, COVID-19, pneumococcal, zoster, RSV, and pertussis vaccines in line with local guidelines. Moving on to initial pharmacotherapy. For individuals who have had one or fewer COPD exacerbations per year and experience only mild symptoms, like shortness of breath during intense exercise or when rushing up a hill, start with a single inhaled long-acting bronchodilator; either a long-acting beta-agonist, or LABA, or a long-acting muscarinic antagonist, or LAMA.