An Overview of Hypoxemia

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Hypoxemia is a condition that occurs when you don't have enough oxygen in your blood. Though this can happen for a variety of reasons, hypoxemia appears to be relatively common in people with advanced chronic obstructive pulmonary disease (COPD). It also may result from other conditions, such as asthma, anemia, sleep apnea, and pneumonia.

Health professional administering oxygen
E+ / Sturti / Getty Images 


Symptoms of hypoxemia include:

  • Confusion
  • Shortness of breath
  • Increases in 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 trouble concentrating and remembering, and those problems get worse as their hypoxemia does.


Hypoxemia often leads to hypoxia, a condition in which you don't have enough oxygen getting to your tissues. While many people confuse the two because of their similar names, they are distinct (hypoxemia only involves low oxygen in the blood itself). Hypoxemia may also result in cyanosis.


In hypoxia, vital organs such as your heart and brain may suffer due to the lack of oxygen, and damage may ensue.

It's possible to have hypoxemia without hypoxia if your body compensates 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 oxygen properly.


In severe hypoxemia, you might start to sweat or wheeze, your skin may get cold and clammy, and you may start to turn blue. The latter, cyanosis, indicates that there's not enough oxygenated blood reaching your cells.

Signs of an Emergency

Hypoxemia and hypoxia may be life-threatening conditions, and cyanosis is also a medical emergency. Seek emergency care by calling 911 if you experience the following.

Symptoms of hypoxemia and hypoxia:

  • Confusion
  • Severe shortness of breath
  • Rapid heart rate

Symptoms of cyanosis:

  • Skin or membranes appearing blue or grayish, especially if you have COPD or another illness that predisposes you to hypoxemia


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
  • Emphysema
  • Bronchitis
  • Anemia
  • Exercising or having an illness at high altitude
  • COPD exacerbation
  • Pneumonia
  • Inflammation or scarring of the lung, such as 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 or earlobe and uses light to measure the amount of oxygen in your blood.

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

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


Hypoxemia is typically the result of another condition that affects how your body processes oxygen. It's imperative that your healthcare provider creates a plan that treats your underlying condition in addition to treating symptoms of hypoxemia.

If your medical testing indicates you have chronic hypoxemia, your healthcare provider 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 healthcare provider.

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 pre-existing 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 healthcare provider if you're having symptoms of hypoxia at night, such as shallow breathing, rapid heart rate, not feeling rested upon waking, snoring, mouth breathing, and sweating. Your healthcare provider may recommend a continuous positive airway pressure machine (CPAP) or surgery to remove any potential obstructions.

A Word From Verywell

Hypoxemia may be a life-threatening condition. It's important that you are aware of the above-mentioned signs of an emergency and seek medical care immediately if you notice them. If you are instead starting to notice more episodes of shortness of breath while resting, after exercise or exertion, or during sleep, make an appointment with your healthcare provider 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.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Deborah Leader, RN
 Deborah Leader RN, PHN, is a registered nurse and medical writer who focuses on COPD.