Your lungs are vital for providing your body with fresh oxygen while ridding it of carbon dioxide. This process is called gas exchange.

In some individuals, such as those with chronic obstructive pulmonary disease (COPD), gas exchange can become impaired. When this happens, it’s hard to provide your body with enough oxygen to support daily activities and to remove enough carbon dioxide — a condition called hypercapnia.

Learn more about impaired gas exchange in COPD — its causes, symptoms, potential treatment options, and more.

COPD is a group of lung conditions that make it hard to breathe. These conditions are progressive, which means that they can get worse over time.

Two of the most common conditions that fall under the umbrella of COPD are emphysema and chronic bronchitis. These conditions impact the lungs in different ways.

In emphysema, the tiny air sacs in the lungs, called alveoli, become damaged. Meanwhile, chronic bronchitis involves long-term inflammation of the airways.

According to the Centers for Disease Control and Prevention (CDC), about 15.7 million people in the United States, or about 6.4 percent of the population, have COPD, making it the fourth leading cause of death in the United States in 2018.

Gas exchange is the process where carbon dioxide, a waste gas, is exchanged in the lungs for fresh oxygen. Let’s examine how it works.

  1. When you breathe in, your lungs expand and air enters through your nose and mouth.
  2. This air travels through airways that gradually get smaller until it reaches the alveoli. These are the tiny air sacs in your lungs where gas exchange occurs.
  3. Oxygen from the air moves through the walls of the alveoli and enters into the bloodstream via tiny blood vessels called capillaries.
  4. At the same time as oxygen is moving into the blood, carbon dioxide moves from the blood into the alveoli.
  5. When you breathe out, the lungs deflate, pushing carbon dioxide up through your airways where it exits your body through your nose and mouth.

The health and flexibility of your airways and alveoli are vital in promoting effective gas exchange. However, in COPD, these structures have become damaged. Due to this, gas exchange cannot occur as efficiently.

Some mechanisms behind impaired gas exchange in COPD can include one or a combination of the following:

  • airways or alveoli that have lost elasticity and cannot expand and deflate to their full capacity when you breathe in and out
  • alveoli walls that have been destroyed, leading to reduced surface area for gas exchange
  • long-term inflammation that’s led to thickening of the airway walls
  • airways that have become clogged with thick mucus

When gas exchange is impaired, you cannot effectively get enough oxygen or rid your body of carbon dioxide. This can lead to a variety of symptoms, such as:

Impaired gas exchange is also characterized by hypoxemia and hypercapnia. Hypoxemia is a decreased level of oxygen in the blood while hypercapnia is an excess of carbon dioxide in the blood.

COPD, and by extension the impaired gas exchange associated with it, is caused by long-term exposure to environmental irritants. When you breathe in these irritants over a long period of time, they can damage your lung tissue.

Overall, cigarette smoking is the most common irritant that causes COPD worldwide. Others can include:

Tests can help to detect and diagnose impaired gas exchange in COPD. There are two primary methods of detecting impaired gas exchange:

  • Pulse oximetery. During this noninvasive test, light clip-like devise is attached to your finger to measure the amount of oxygen in your blood.
  • Arterial blood gas analysis (ABG). This blood test measures oxygen and carbon dioxide levels in the blood.

In addition to these tests, in rare cases, a doctor may also perform a pulmonary ventilation/perfusion scan (VQ scan) which compares airflow in your lungs to the amount of oxygen in your blood.

Impaired gas exchange is often treated using supplemental oxygen. This helps counteract the effects of hypoxemia by delivering oxygen directly into your lungs. You’ll breathe in supplemental oxygen through a nasal cannula or a mask.

Depending on the severity of your symptoms, you may need supplemental oxygen all the time or only at certain times. Oxygen therapy needs to be carefully monitored, as it can worsen hypercapnia in some situations.

Treatment for hypercapnia involves noninvasive ventilation therapy, often called BiPAP, which is the name of a brand of ventilation therapy machine. During BiPAP, you wear a mask that provides a continuous flow of air into the lungs, creating positive pressure and helping the lungs expand and stay expanded longer.

Other types of COPD treatments that may be recommended include:

  • Bronchodilators. Bronchodilators are medications that help open up your airways, making breathing easier. They’re typically given by an inhaler. In some instances, a bronchodilator may be combined with a steroid.
  • Lifestyle changes. If you smoke, your doctor will encourage you to quit smoking. They’ll also recommend that you avoid other irritants like secondhand smoke and air pollution.
  • Vaccines. A lung infection can make your condition worse. Because of this, your doctor will recommend that you stay up-to-date on your flu, pneumococcal, and COVID-19 vaccines.
  • Pulmonary rehabilitation. Pulmonary rehabilitation can teach you strategies on how to go about your daily activities when you have COPD. It may involve breathing techniques, an exercise plan, and counseling.
  • Surgery. Surgeries are typically only recommended for people with severe COPD. Potential surgical options include:

Your doctor will work with you to develop a treatment plan for your COPD and impaired gas exchange.

Smoking cigarettes is the most important risk factor for COPD. According to the National Heart, Lung, and Blood Institute, up to 75 percent of people with COPD currently smoke or used to smoke.

Smoking when you have COPD can make your condition worse and can contribute to an increased impairment in gas exchange.

There are a few other risk factors for developing COPD:

  • Other environmental irritants. Frequent exposure to other environmental irritants like secondhand smoke, air pollution, or dust also increases COPD risk.
  • Age. COPD mainly occurs in people over the age of 40.
  • Genetics. A genetic condition called alpha-1 antitrypsin deficiency (AATD) can raise the risk of COPD. It’s estimated that 1 in 100 people with COPD have AATD. Risk level increases in people with AATD that smoke.

COPD with impaired gas exchange is associated with hypoxemia. A 2016 study found that, of 678 participants with COPD, 46 (7 percent) developed hypoxemia. Compared to those with normal blood oxygen levels, those with hypoxemia had greater declines in 5-year quality of life.

Having certain other health conditions is also associated with a poorer COPD outlook. These include things like heart disease, pulmonary hypertension, and lung cancer.

Overall, treatment for COPD with impaired gas exchange focuses on reducing symptoms and slowing disease progression. In order to improve your outlook and reduce the risk of complications, it’s important that you stick to your COPD treatment plan.

Gas exchange happens in the alveoli in the lungs. During this process, oxygen enters the bloodstream while carbon dioxide is removed. In people with COPD, gas exchange is often impaired. This is because COPD is associated with progressive damage to the alveoli and airways.

Impaired gas exchange in COPD can cause symptoms like shortness of breath, coughing, and fatigue. It also leads to hypoxemia and hypercapnia.

If you have COPD with impaired gas exchange you may need to be treated with supplemental oxygen as well as other COPD treatments. Adhering to your treatment plan can help improve outlook and boost quality of life.