Hypoxia & anoxia

Hypoxia is when the body or brain is partially deprived of oxygen, leading to permanent damage. Anoxia is often a result of hypoxia where the brain or body completely loses its oxygen supply. Total loss of oxygen to the brain can result in severe permanent damage.

Hypoxia and anoxia can affect all major organs, including the brain and heart. There are three main types of hypoxia:

  1. Anemic – this means a reduced ability for blood to carry oxygen, so less oxygen is distributed to the body
  2. Stagnant – this means blood flow is reduced or restricted
  3. Histotoxic – this means that tissues in the body aren’t able to properly use the oxygen delivered by the blood

There is also something called hypoxemia. Hypoxia and hypoxemia sound similar but refer to two different conditions. Hypoxia is when the body tissues aren’t getting the oxygen they need. Hypoxemia is when there is a lack of oxygen in the arterial blood.[1]

Causes of hypoxia and anoxia

Causes of hypoxia – which can lead to anoxia – include:

  • Breathing problems that affect oxygen supply, like asthma or pneumonia
  • Carbon monoxide or other toxins in the body
  • Cardiac arrest or stroke
  • Events that restrict air, like choking or near-drowning
  • High altitudes where oxygen is low
  • Significant blood loss

Symptoms of hypoxia and anoxia

In the situations where oxygen loss is more immediate – like choking or cardiac issues – symptoms will show up quickly. In other cases, like high-altitude climbing or breathing problems, they may appear more gradually.

  • Mild symptoms of hypoxia and anoxia include:
  • Difficulty concentrating
  • Difficulty moving the body
  • Dizziness
  • Memory trouble
  • Slurred speech
  • Unexpected or strange headaches

More severe symptoms include:

  • Hallucinations
  • Loss of consciousness
  • Seizures

Diagnosis and treatment for hypoxia and anoxia

Diagnosis of hypoxia or anoxia is done based on symptoms, recent activity and hospital tests. These tests could include blood work, CT or MRI scans, or an electroencephalogram (EEG). The most important step is to increase the supply of oxygen in the most appropriate way based on the findings of the medical team. Once stabilized, tests will be done to determine if there is any brain damage that could cause cognitive, behavioural or mobility changes. These effects will vary case by case depending on the location and the severity of the injury. Rehabilitation and ongoing medical treatment may be necessary.[2]


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