An Overview of Hypoxemia

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Your blood is responsible for carrying oxygen throughout your body, and it successfully controls the amount of oxygen rather precisely. Hypoxemia is a condition that occurs when you don't have enough oxygen in your blood—for various reasons. Hypoxemia appears to be relatively common in people with advanced chronic obstructive pulmonary disease (COPD), although it also may result from other lung conditions, such as lung cancer, pneumonia, asthma, and sleep apnea.


Symptoms of hypoxemia include confusion, shortness of breath and increases in your blood pressure and your heart rate as your body tries to compensate for the low oxygen in your bloodstream. People with COPD who suffer from hypoxemia when they're at rest are more likely to have problems concentrating or remembering things, and those problems get worse as their hypoxemia worsens.

In severe hypoxemia, you might start to sweat or wheeze, your skin may get cold and clammy, and you may start to turn blue. This last symptom, called cyanosis, indicates that there's not enough oxygenated blood reaching your cells. These symptoms indicate an emergency situation, and you should seek help immediately by calling 911.

Hypoxemia often leads to hypoxia, which means you don't have enough oxygen getting to your tissues. In fact, many people confuse the term "hypoxemia" with the term "hypoxia," but the two are not the same—hypoxemia refers to low oxygen in your blood, while hypoxia refers to low oxygen in your tissues.

It's possible to have hypoxemia without hypoxia if your body compensates for your low blood levels of oxygen by boosting the amount of oxygen that actually reaches your tissues (for example, by making your heart beat faster to move oxygen-carrying blood around more quickly). It's also possible to have hypoxia without hypoxemia, if the actual oxygen delivery to your cells isn't working properly, or if your cells aren't able to use the oxygen properly.


Any condition that affects the efficient exchange of oxygen and carbon dioxide or the flow of blood in the body could result in hypoxemia. Some of the most common causes of hypoxemia include:

  • Sleep apnea
  • Asthma
  • Anemia
  • Exercising or having an illness at high altitude
  • COPD exacerbation
  • Pneumonia
  • Narcotics and other medications that suppress breathing
  • Pulmonary fibrosis
  • Pulmonary embolism
  • Pulmonary edema
  • Interstitial lung disease
  • Congenital heart defects
  • Congenital heart disease
  • Pneumothorax (collapsed lung)
  • Acute Respiratory Distress Syndrome (ARDS)
  • Lung cancer


Hypoxemia is diagnosed by measuring the blood oxygen level via a blood test known as arterial blood gases (ABG) or via pulse oximetry, a noninvasive scanning probe that is usually clipped to a finger that or earlobe and uses light to measure the amount of oxygen in your blood.

In an ABG test, oxygen blood level is measured in millimeters of mercury (mm Hg). A normal oxygen level in your arteries is about 80 to 100 mm Hg. People with COPD usually have lower levels. If you have a very low level—usually around 60 mm Hg—you may need supplemental oxygen. However, providing too much oxygen can be dangerous, too, so your doctor will need to work with you to get the correct balance.

With pulse oximetry, normal blood oxygen levels are around 95 to 100 percent. A low level is below 90 percent. It's possible to use pulse oximetry to measure your blood oxygen level at home. Talk to your doctor about what readings you should expect from pulse oximetry depending on your condition and when to seek medical help for a low reading.


Severe hypoxemia is a medical emergency. If you have symptoms of severe hypoxemia, especially if you have COPD or another illness that predisposes you to hypoxemia, seek emergency care immediately.

If your medical testing indicates you have chronic hypoxemia, your doctor may recommend you go on supplemental oxygen. However, supplemental oxygen may not help everyone, so you'll need to discuss the pros and cons with your doctor.

Some people with sleep apnea, COPD, or other lung conditions may suffer from hypoxemia more at night. This occurs because of breathing changes during sleep that decrease the amount of oxygen reaching your bloodstream. In people without a preexisting lung or heart condition, these breathing changes may not have such an effect, but in people who have COPD, for example, they can cause hypoxemia.

Some patients with mild hypoxemia problems during the day may be more prone to hypoxemia at night. Talk to your doctor if you're having symptoms at night.

A Word From Verywell

Hypoxemia may be a life-threatening condition. If you or a loved one are experiencing symptoms such as confusion, severe shortness of breath, and rapid heart rate, seek emergency medical care immediately.

If instead, you are starting to notice more episodes of shortness of breath while resting, after exercise or exertion, or during sleep, make an appointment with your doctor to discuss options for combatting potential hypoxemia.

In the meantime, be sure to stop smoking if you're a smoker, avoid places where there may be secondhand smoke, and attempt to get regular exercise to boost your lung function.

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Article Sources

  • Kent BD et al. Hypoxemia in patients with COPD: cause, effects, and disease progression. International Journal of Chronic Obstructive Pulmonary Disease. 2011; 6: 199–208.
  • Stoller JK et al. Chronic Obstructive Pulmonary Disease. Cleveland Clinic Center for Continuing Medical Education. October 2012.