What to Know About Hypoventilation: Causes, Signs, and More

Medically Reviewed By Adithya Cattamanchi, M.D.
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Hypoventilation, or respiratory depression, occurs when breathing impairments prevent enough air from entering the lungs. The condition can cause low blood oxygen levels and carbon dioxide buildup in the body, which can be life threatening.  When you breathe in, you draw air into the lungs. This air has oxygen, which will then diffuse into the blood to supply the body’s tissues. While this is happening, the lungs breathe out carbon dioxide, a waste product of the respiratory process.

If your breathing rate is impaired and does not exchange the gases efficiently, this can harm your health.

This article will discuss hypoventilation, its causes, and related conditions. It will also explain the symptoms of hypoventilation, when to seek help, and what to expect from treatment.

Signs and symptoms 

A woman uses an inhaler while sitting outside.
Javier Zayas Photography/Getty Images

Hypoventilation is when you experience a breathing impairment that reduces respiration. This can happen due to slow breathing and shallow breathing, or a combination of both.

Hypoventilation can occur while sleeping, so you may not be aware of the symptoms initially. 

Symptoms of hypoventilation include:

As hypoventilation progresses, you may develop hypoxemia, the lack of oxygen in the blood, and respiratory acidosis, the toxic buildup of carbon dioxide in the body. This can lead to signs and symptoms such as:

  • restlessness
  • anxiety
  • headache
  • confusion, impaired awareness, or drowsiness
  • reduced reflexes
  • memory loss
  • fast heart rate
  • changes to personality
  • atypical movement, such as while walking
  • tremors
  • sudden, involuntary jerking known as myoclonic jerking
  • seizures

Learn more about respiratory acidosis and its risk factors and treatment.

When to seek medical help 

If you are experiencing symptoms of hypoventilation, call your doctor right away. 

Without treatment, hypoventilation can damage your organs over time and put stress on your heart. 

Seek emergency treatment or call 911 immediately if you find a person breathing slowly, shallowly or both, and is showing symptoms such as:

  • confusion
  • loss of consciousness, even if only briefly
  • memory loss
  • chest pain
  • difficulty breathing
  • fast heart rate
  • seizures
  • involuntary or uncontrolled movement

Causes

Hypoventilation occurs when you are not breathing in enough oxygen and breathing out carbon dioxide sufficiently.

Causes of this can include:

  • breathing too slowly
  • breathing too shallowly
  • having obstructed airways
  • lung damage or restriction
  • respiratory muscle impairment
  • impaired brain control of the breathing process

These impairments can be the result of other underlying causes and conditions. For example, chronic lung disease may result in lung damage or obstruction, which causes an inability to take in enough air.

Other factors that may contribute to breathing impairments include:

  • genetic disorders 
  • brain injury or neuromuscular diseases that affect the muscles that coordinate breathing
  • severe obesity resulting in obesity hypoventilation syndrome
  • obstructive sleep apnea
  • physical differences in lung structure, such as abnormalities of the chest wall
  • chronic lung disease, such as chronic obstructive pulmonary disease (COPD) and asthma
  • swelling of the airways
  • toxins
  • misuse of alcohol
  • certain medications and drugs such as:
    • anesthetics
    • sedatives
    • muscle relaxants
    • opioids
  • medication or drug misuse

Diagnosis

To diagnose your condition and underlying cause, a doctor will ask about your symptoms and medical and family histories.

They can also check your blood gas levels. 

After your initial assessment, they may order:

  • a chest X-ray
  • a lung test function to see how well your lungs work
  • blood or urine tests to screen for alcohol or drug misuse
  • blood tests to check for:
    • arterial blood gas levels, including the amount of carbon dioxide and oxygen in the blood
    • hematocrit and hemoglobin levels, which analyzes the red blood cells that carry oxygen
  • a CT or MRI to check for brain damage
  • an ECG to determine whether there is strain on the heart
  • an EEG to check the electrical patterns in your brain
  • a sleep study, which monitors how well you breathe during sleep

Treatment 

Treatment for hypoventilation may focus on improving breathing and addressing the underlying cause. The specific treatment your doctor recommends will depend on your condition.

For example, if hypoventilation is the result of medication use, doctors may advise changing medications. They may also prescribe other medications to counteract respiratory suppression and restore breathing.

Other treatments approaches may include:

  • oxygen therapy
  • maintaining a moderate weight
  • the use of a CPAP or BiPAP machine while you sleep to keep your airway open, which is known as positive airway pressure therapy
  • surgery to correct structural differences affecting breathing
  • using an inhaler with medication to open your airways

A doctor may recommend additional treatment if you experience complications because of hypoventilation. For example, if you experience respiratory acidosis from a buildup of carbon dioxide, clinicians may put you on a ventilator to correct the respiratory process.

Possible complications

Without treatment, severe cases of hypoventilation can lead to coma or life threatening complications. 

Respiratory depression can lead to respiratory failure, meaning the lungs cannot get enough oxygen to the blood.

Hypoxia can occur as a result. Hypoxia is when the body’s tissues do not receive enough oxygen. Without enough oxygen, your organs cannot function and will begin to shut down.

This can sometimes cause permanent damage and death.

Regular breathing allows for the exchange of oxygen and carbon dioxide, which also keeps your blood pH or acid in a healthy range.

Carbon dioxide is a waste product from natural cellular function. An increase of carbon dioxide in the bloodstream due to hypoventilation can alter the pH level and make your body acidic, leading to respiratory acidosis. 

Respiratory acidosis can occur without symptoms. Severe cases can be fatal.

However, while the complications of hypoventilation can be severe, prompt diagnosis and treatment can help improve the outcome of the condition.

Outlook 

Treatment can be effective in resolving some cases of hypoventilation and its complications, such as respiratory acidosis. However, the exact outlook will depend on the underlying cause of the condition.

Following your doctor’s treatment plan can help improve your outlook and symptoms. It may also prevent the condition’s progression or reduce the risk of severe complications.

Seek immediate treatment for anyone experiencing symptoms of hypoventilation or breathing difficulty.

Frequently asked questions

Adithya Cattamanchi, M.D., has reviewed the following frequently asked questions.

What is the difference between hypoventilation and hyperventilation?

Hypoventilation is the opposite of hyperventilation

Hyperventilation occurs when a person breathes quickly or takes in a lot of air because of deep breathing or a combination of both. This results in low carbon dioxide in the blood. This differs from hypoventilation. Hypoventilation, repressed or slow breathing, results in high levels of carbon dioxide in the blood.

What is the difference between hypoventilation and hypoxia?

Hypoxia is when the organs and other tissues of the body do not receive enough oxygen. 

This can occur if there is not enough oxygen in the blood or there is not enough blood flowing to the tissue.

While hypoxia is a different condition, hypoventilation can cause hypoxia due to a low intake of oxygen while breathing. 

Learn more about hypoxia and hypoxemia and how they relate to breathing.

Summary

Hypoventilation or respiratory depression is when breathing difficulty causes a low intake of oxygen and a buildup of carbon dioxide. Breathing impairments can cause slow or shallow breaths.

The resulting imbalance of gases in the body can lead to respiratory failure, a lack of oxygen, and a buildup of acid.

Without treatment, hypoventilation can lead to severe complications and death. However, prompt treatment can be effective.

Seek immediate medical care or call 911 for symptoms of breathing impairments such as shortness of breath, confusion, or chest pain.

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Medical Reviewer: Adithya Cattamanchi, M.D.
Last Review Date: 2022 Aug 22
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