LEARNING OUTCOME AND OBJECTIVES:  Upon completion of this course, you will have increased your understanding of the causes of and the current treatments for chronic obstructive pulmonary disease (COPD). Specific learning objectives to address potential knowledge gaps include:

• Discuss the characteristics of COPD.
• Describe the physiology of normal lungs vs. lungs damaged by COPD.
• Identify the causes, functional effects, and preventive measures for COPD.
• Summarize the characteristic clinical findings in a patient presenting with COPD.
• Outline the lifestyle changes and pulmonary rehabilitation components of a long-term treatment plan.
• Describe pharmacologic, oxygen therapy, and surgical interventions for COPD.
• Discuss acute exacerbations of COPD and their treatment.

WHAT IS COPD?

Chronic obstructive pulmonary disease is a preventable condition that makes it difficult to move air into and out of a person’s lungs. Difficulty moving air in the lungs is called airflow obstruction or airflow resistance. COPD is characterized by a progressively increasing airflow obstruction that cannot be fully reversed, although it can sometimes be temporarily improved by medications. In almost all cases, COPD has been caused by the long-term inhalation of pollutants, especially cigarette smoke (GOLD, 2021; NIH, 2021a).

COPD develops quietly. Early in their disease, patients have measurable declines in their lung function before they develop symptoms. The first symptoms are usually an intermittent cough and some shortness of breath during exercise. Patients often dismiss these as temporary lung irritations or as a lack of physical conditioning. After many years, the cough becomes chronic or the spells of breathlessness become more frequent. Typically, this is the stage at which people first seek medical help.

COPD is the fourth leading cause of death and disability in the United States (NIH, 2021a). The specific form that COPD takes falls along a spectrum. At one end of the spectrum, people get emphysema, and at the other end of the spectrum, people get chronic bronchitis. Many people with COPD have a mix of both emphysema and chronic bronchitis. (These two forms of COPD are discussed in detail below.)

Regardless of its form, COPD causes dyspnea (difficulty breathing). Dyspnea feels like shortness of breath. Initially, shortness of breath occurs only during vigorous exercise. Subsequently, the dyspnea begins to happen with mild exercise. Eventually, normal activities of daily living cause dyspnea. Finally, a person with COPD is short of breath even when at rest. This relentless increase of dyspnea gradually limits a person’s activities, and at some point, it becomes hard for a person with COPD to do anything but sit or lie down (Harding et al., 2020).

Patients with COPD have little to no reserve capacity or volume in their lungs, placing them at greater risk of developing hypoxemia. Hypoxemia occurs when air peripheral oxyhemoglobin saturation (SpO₂) (normal range 94%–100%) and arterial oxygen tension (PaO₂) (normal range 80%–100%) are less than normal. This causes a reduction of oxygen in the blood. Patients with COPD also exhibit hypercapnia with a partial carbon dioxide (PaCO₂) level greater than 45%. In earlier stages of COPD, hypercapnia may contribute to the person’s respiratory drive, helping to increase the depth and quality of breathing (Harding et al., 2020).

Respiratory infections, increases in inhaled pollutants, and the occurrence of other medical diagnoses will further reduce the lungs’ ability to absorb oxygen and to expel carbon dioxide. These problems can send patients with COPD into hypoxemia. Such stresses are unavoidable, so patients with COPD suffer repeated episodes of significantly worsened symptoms, called acute exacerbations. Acute exacerbations are more frequent in patients who are susceptible to infections (GOLD, 2021). Acute exacerbations resolve slowly over weeks or months, even with medical treatment, and sometimes must be managed in a hospital.

After COPD has become symptomatic, the disease is treated with bronchodilators, which can ease the patient’s dyspnea so that a wider range of activities remains tolerable. Using the combination of a corticosteroid inhaler and a muscarinic antagonist can reduce the severity and duration of exacerbations and the occurrence of hospital admissions.

However, COPD follows a relentless downward course. Even with bronchodilator therapy and other treatment parameters, the patient’s lung function continues to gradually decline. Eventually, dyspnea limits a COPD patient to only minimal activity. Patients are continually fatigued, they lose weight, and at some point, they typically succumb to a respiratory illness, cor pulmonale, heart failure, renal failure, diabetes with neuropathy, acute respiratory failure, or lung cancer. Supplemental oxygen therapy can prolong some patients’ lives, and a few select patients can benefit temporarily from lung surgery (discussed later in this course).

Acute exacerbations continue for all patients, and most patients eventually succumb to an acute exacerbation that cannot be reversed (Harding et al., 2020).

Airflow Obstruction: The Essence of COPD

In the past, patients with COPD with emphysema were said to have type A COPD and were sometimes called pink puffers. Patients with COPD with chronic bronchitis were said to have type B COPD and were sometimes called blue bloaters (OA, 2021).

Although these names are still used, the division of COPD into two alternative types is too simple because many patients have a mix of emphysema and chronic bronchitis. Currently, the emphasis is on the common feature of all patients with COPD: airflow obstruction. Whether it appears as emphysema, chronic bronchitis, or a mixture of the two, COPD is characterized by chronic, worsening, and irreversible airflow obstruction (Harding et al., 2020).

Prevention

COPD can be almost entirely prevented by avoiding long-term inhalation of pollutants, mainly cigarette smoke. As they age, all people suffer a decline in lung function. Smokers who quit before developing symptoms of COPD can often reduce the decline in lung function to nearly normal levels within a few years of remaining smoke free, although established damage will not improve (GOLD, 2021).