Hypoxemia: What to know

hypoxemia test
sick person's hand

Hypoxemia is a condition in which there is a lack of oxygen in the blood, specifically in arterial blood. Shortness of breath is one sign of the condition, which could indicate a problem with blood circulation or respiration.

A tiny device that clips onto the finger can be used by a doctor to determine a person’s blood oxygen level. Hypoxia can be caused by a variety of factors, including underlying medical problems such as chronic obstructive pulmonary disease (COPD), asthma, and anemia.

We’ll look at the various types and causes of hypoxemia, how it differs from hypoxia, and how a doctor might diagnose and treat the condition in this article.

What is it?

hypoxemia test

Hypoxemia is a condition in which there is a lack of oxygen in the bloodstream. This indicates that the blood oxygen level has fallen below the usual range, and there is insufficient oxygen in the blood.

An arterial blood gas analysis and measurement of the partial pressure of oxygen (PaO2) can be used by a medical expert to determine the oxygenation of blood. A healthy PaO2 ranges from 75 to 100 millimeters of mercury (mm Hg), and oxygen levels below 60 mm Hg are considered hypoxemia by the medical profession.

When to consult a doctor

If a person experiences hypoxemia symptoms such as erratic heartbeat or breathing, as well as skin discoloration, they should consult a doctor. Early detection and treatment can help prevent the condition from worsening and leading to more significant consequences.

Hypoxemia vs. hypoxia

While some people confuse the terms hypoxemia and hypoxia, they are not interchangeable. Despite the fact that they both pertain to low oxygen levels, they happen in separate tissues. Hypoxemia refers to low oxygen levels in the blood, whereas hypoxia refers to low oxygen levels in the body’s tissues.

Despite the fact that the conditions are distinct, they can coexist. Hypoxia can occur if hypoxemia is present, as low levels of oxygen in the blood prevent the body’s tissues from receiving enough oxygen. It is possible, however, for one condition to arise without the occurrence of the other.


Hypoxemia can arise for a variety of reasons. Here are a few examples:

Ventilation/perfusion mismatch

Perfusion is the circulation of blood, while ventilation is the air that a person breathes in and out. A typical ventilation/perfusion (V/Q) ratio is approximately 1.

When parts of the lungs receive oxygen but no blood circulation, or receive blood circulation but no oxygen, a V/Q mismatch ensues. The most common cause of hypoxemia, according to evidence, is a V/Q mismatch.


Hypoventilation occurs when the amount of oxygen and carbon dioxide exchanged in the body is insufficient. There is a high level of carbon dioxide (CO2) and a low level of oxygen in the blood when hypoventilation occurs. As a result, hypoxia is common, particularly during sleep.

A person suffering from hypoventilation may breathe slowly and shallowly.

Right-to-left shunt

When blood from the right side of the heart reaches the left side without any exchange of oxygen or CO2, this is referred to as a shunt.

Blood that lacks oxygen enters the right side of the heart and flows to the lungs to get oxygen in typical circumstances. The blood then goes to the left side of the heart, where it is distributed throughout the rest of the body.

Diffusion impairment

Diffusion impairment occurs when the oxygen transport between the alveoli and the capillaries is disrupted or limited. The alveoli are gas exchange sacs in the lungs, while capillaries are the blood vessels into which oxygen diffuses.

Low PaO2

Hypoxemia can be caused by low PaO2 levels in the environment. At higher elevations, for example, the partial pressure of oxygen is lower. This means that a person used to breathing at sea level may have hypoxemia as the amount of oxygen available decreases at higher altitudes.


Hypoxemia can be caused by a variety of factors. Here are a few examples:


Symptoms of hypoxemia can include:

  • drowsiness
  • rapid or irregular heartbeat
  • rapid and shallow breathing
  • blue or gray discoloration of the skin
  • shortness of breath
  • irritability
  • confusion


For an appropriate diagnosis of hypoxemia, a person should seek the counsel of a medical specialist. A doctor will first perform a physical examination, which may involve checking for color changes in the skin and nails as well as listening to the heart and lungs.

Additional tests to measure the amount of oxygen in the blood may be performed by the doctor. This could involve the following:

  • Arterial blood gas test: This test entails taking a blood sample and analyzing it in a lab to detect the amount of oxygen and carbon dioxide present.
  • Pulse oximetry: A pulse oximeter is a device that measures the amount of oxygen in the blood. Normally, the device is attached to the fingers, ears, or toes. The device measures the proportion of oxygen in the blood by shining a light through the skin.
  • Lung function tests: These tests assess how effectively the lungs function. Spirometry is an example of a lung function test. This entails blowing into a spirometer tube to determine how much air a person can breathe in and out of their lungs.


Because hypoxemia is characterized by a decrease in blood oxygen levels, the goal of treatment is to restore the level of oxygen to a healthy level.

A person may obtain oxygen therapy in order to do so. This is a treatment option that involves receiving supplementary oxygen in a hospital or at home. A person can get oxygen therapy in a variety of methods, including through a face mask or a nasal cannula, which is a tube that inserts into the nose.

If a person has an underlying condition that causes hypoxia, such as COPD or asthma, further medication may be required to treat these symptoms.


Hypoxemia left untreated can lead to various health problems since the body can’t function properly without enough oxygen in the blood. Among the potential complications are:

  • lung complications
  • kidney problems
  • brain damage and brain death
  • heart problems


People can make a few lifestyle modifications to help lower the risk of hypoxemia or prevent situations that can lead to it. This can include things like:

  • practicing breathing exercises
  • quitting smoking, as this influences ventilation
  • getting regular exercise
  • taking medication as prescribed for underlying conditions that may cause hypoxemia
  • using supplemental oxygen if necessary
  • avoiding potential pollutants
  • preventing respiratory infections by receiving vaccines and wearing face coverings


Hypoxemia is a condition in which there is a lack of oxygen in the bloodstream. This is not to be confused with hypoxia, which is a lack of oxygen in the body’s tissues. Hypoxemia can be caused by a right-to-left shunt, a V/Q mismatch, low PaO2, diffusion impairment, or hypoventilation, among other things. Hypoxemia can also be caused by medical disorders like COPD.

Shortness of breath, disorientation, a rapid heartbeat, and drowsiness are all symptoms of hypoxemia. A physical examination as well as tests such as an arterial blood gas study can help a doctor diagnose hypoxemia.

If a person experiences signs of hypoxemia, they should contact their doctor as soon as possible, as untreated hypoxemia can lead to severe difficulties in important organs such as the brain and heart.


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