What to know about lung hyperinflation and COPD

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Lung hyperinflation, also called pulmonary hyperinflation, occurs when the lungs expand beyond their normal size due to air trapping. COPD may cause lung hyperinflation.

The air that becomes trapped in the lungs may prevent a person from taking in a normal breath. When this occurs, it results in less oxygen circulating in the body, making the heart work harder and leading to fatigue.

Doctors classify hyperinflation as either static or dynamic. Static hyperinflation occurs when air becomes trapped in the lungs during exhalation, often at rest. Dynamic hyperinflation occurs when a person inhales before they exhale. It typically happens during physical activity.

With COPD, the walls of the air sacs, known as alveoli, are damaged. The air sacs are the gas-exchanging surfaces of the lung.

Usually, the air sacs stretch and deflate back to normal when breathing in and out. However, the damage causes the sacs to lose their elasticity and not spring back to normal. This prevents the lungs from emptying normally during exhalation.

People with COPD can get air in. However, the air becomes trapped in the lungs, which causes the lungs to expand beyond normal.

Some of the air a person inhales remains in the lungs and accumulates with each breath. Hyperinflation makes it difficult to fully take in subsequent breaths and can lead to shortness of breath.

The symptoms of lung hyperinflation may vary depending on how severe the abnormal expansion of the lungs becomes.

The underlying cause of lung hyperinflation may also play a role in symptoms.

Possible symptoms of lung hyperinflation in COPD may include:

• Shortness of breath: Doctors may refer to shortness of breath as “air hunger.” This sensation may feel like someone cannot get enough air into their lungs.
• Decreased exercise tolerance: According to 2018 research, hyperinflation and shortness of breath are closely related to physical activity limitations.
• Barrel chest: “Barrel chest” refers to an increased anterior-posterior chest wall diameter. The hyperinflation of the lungs causes an increase in the chest wall. It is often a feature of COPD.
• Fatigue: Lung hyperinflation makes breathing harder, which can increase fatigue. Additionally, the body may take in less oxygen, which can also cause fatigue.

Over time, it is also possible for lung hyperinflation to have an adverse effect on the heart. Increased pressure in the chest cavity from the hyperinflation can cause left ventricle changes. A weakened left ventricle can affect the heart’s ability to efficiently pump blood to the body.

Doctors diagnose lung hyperinflation after a physical exam, imaging tests, and possibly a pulmonary function test.

A physical exam may include a doctor listening to lung sounds, checking oxygen levels, and reviewing symptoms.

Imaging tests also help confirm a diagnosis of lung hyperinflation. Imaging tests may include:

• chest X-ray (pictures of the chest wall and lungs)
• CT scan (3D images of the chest cavity)
• pulmonary function test (measures lung function, including obstruction and air trapping)
• echocardiogram (checks for heart abnormalities)

Read more about COPD lungs vs. normal lungs.

Treatment of lung hyperinflation aims to decrease shortness of breath. Reducing hyperinflation along with shortness of breath is vital for improving overall functioning and activity in people with COPD.

Treatment also targets the underlying cause of lung disease. Treatment of lung hyperinflation may include:

• Bronchodilators: Bronchodilators are medications, such as albuterol, that relax the muscles of the airway. A bronchodilator may help open the airways and improve dynamic hyperinflation.
• Oxygen therapy: If lung hyperinflation leads to decreased oxygen levels in the body, oxygen therapy may help return levels to a normal range.
• Pursed-lip breathing exercises: Pursed-lip breathing involves inhaling through the nose and prolonged exhalation through pursed or puckered lips. This creates back pressure in the airways to help the air sacs stay open. The longer exhalation promotes getting trapped air out of the lungs.
• Lung reduction surgery: Lung reduction surgery may become an option for people with severe COPD. According to the American Lung Association, the goal of surgery is to remove about 30% of the diseased lung. The surgery helps relieve compression of the lungs and heart from hyperinflation. Although this does not cure COPD, it may improve quality of life and exercise and activity tolerance.

In addition to COPD, which includes emphysema and chronic bronchitis, other lung conditions may also lead to lung hyperinflation.

Typically, these include other obstructive lung conditions. This refers to diseases that can cause more air than normal to stay in the lungs after breathing out.

Possible causes include:

• Asthma: Asthma is a lung condition that causes inflammation and narrowing of the airways. A small 2019 study found that 81% of the 77 people in the study with asthma had dynamic hyperinflation.
• Bronchiectasis: Bronchiectasis involves damage to the bronchial tubes. This damage causes the tubes to become loose and scarred and may lead to hyperinflation.
• Cystic fibrosis: Cystic fibrosis is a genetic condition that affects the lungs and pancreas. Lung hyperinflation may also occur.

Lung hyperinflation is a common complication of COPD. It occurs when damage to the lungs means they are unable to properly push air out when a person breathes.

The damage to the lungs can cause the air sacs, known as alveoli, to lose their ability to inflate and deflate properly. This results in air trapping, causing the lungs to expand beyond their usual size.

Symptoms include shortness of breath, fatigue, and development of a barrel chest. Treatment may include pursed-lip breathing and bronchodilators. In severe cases, lung reduction surgery may be an option.