Hypoxia occurs when tissues and cells do not get enough oxygen to function correctly. Symptoms include shortness of breath and unexplained exhaustion.

Hypoxia most commonly results from lung conditions but may stem from a heart or liver condition or an injury.

This article explores hypoxia in more depth, including common symptoms, when to see a doctor, and how they may diagnose the issue.

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Hypoxia refers to cells or tissues not having enough oxygen to function effectively.

When a healthy person inhales, their lungs take in oxygen from the air, then transfer it into the blood. Next, the blood transports the oxygen to tissues and cells throughout the body.

Oxygen in the blood enters cells in exchange for carbon dioxide, a waste gas created as cells function. The lungs remove carbon dioxide when the person exhales.

A related health issue is called hypoxemia. This refers to low levels of oxygen in the blood.

A lack of sufficient blood flow to tissues and cells can cause hypoxia.

Some health issues that can reduce blood flow include:

  • injury that leads to blood loss or damages arteries
  • compression, which might occur in a traumatic injury
  • heart conditions, such as heart failure or a heart attack
  • liver conditions

A related condition is hypoxemia, which refers to the blood having too little oxygen. Conditions associated with hypoxemia include:

A lack of oxygen in cells or tissues causes hypoxia symptoms, which can vary in severity.

Common symptoms of mild to moderate hypoxia and hypoxemia include:

  • shortness of breath, especially with exertion
  • wheezing
  • restlessness
  • headache
  • confusion
  • unexplained exhaustion

Symptoms of severe hypoxia include:

  • purple or bluish skin
  • a rapid heartbeat
  • a loss of consciousness
  • coma

Severe hypoxia can also be fatal.

Speak with a doctor about unexplained trouble breathing or a rapid heart rate.

Anyone with severe trouble breathing, a very rapid heart rate, discolored skin, or altered levels of consciousness should receive emergency care.

Various tools can help doctors diagnose hypoxia, particularly those that show the airways and levels of oxygen in the blood and tissues.

These tools may include:

  • pulse oximetry to determine oxygen levels in the arteries
  • gas exchange tests to determine the ratio of oxygen to carbon dioxide in the arteries
  • X-rays or CT scans of the chest and airways
  • pulmonary function tests
  • tests that measure oxygen levels during the night
  • the 6-minute walk test to determine oxygen levels in response to exercise

Treating hypoxia has three major goals:

  1. helping maintain airway function
  2. increasing the amount of oxygen inhaled
  3. improving how much oxygen passes from the blood into the lungs

Common treatments include:

  • suctioning in the upper airways to keep them clear and remove foreign objects
  • reducing any blockage in the throat, such as by tilting the head
  • using a ventilation device, such as a bilevel or continuous positive airway pressure machine
  • taking bronchodilator medications, which help open the airways
  • having chest physiotherapy
  • having an endotracheal tube
  • having a flutter valve to help keep the airways clear of mucus
  • using an incentive spirometer, a device that helps a person visualize their breathing and learn to take slower, deeper breaths
  • using nasal cannulas, which deliver oxygen through the nose
  • using a face mask to deliver oxygen to the nose and mouth
  • taking diuretics to reduce excess fluid, for people with edema
  • taking steroids, for some people with interstitial lung disease

Hypoxia occurs when there is not enough oxygen available to meet the needs of cells or tissues in the body.

Hypoxemia occurs when there is not enough oxygen in the blood.

In some cases, hypoxemia can lead to hypoxia. If the blood does not contain enough oxygen, it cannot deliver the necessary amount to the cells or tissues.

Hypoxia develops when there is too little oxygen in the cells or tissues, and this keeps them from functioning correctly.

A lack of blood flow or having too little oxygen in the blood can cause it. This may stem from a lung, heart, or liver condition, or an injury, for example.

Anyone who experiences severe trouble breathing should seek emergency care. A rapid heartbeat, altered levels of consciousness, and discoloration of the skin are other symptoms of hypoxia.

Let a doctor know about any unexplained changes in heart rate or shortness of breath.