Hypoxic and anoxic brain injury
This section is intended as an overview of the causes, effects, treatment and rehabilitation of hypoxic brain injury and anoxic brain injury. You can access the different pages using the left-navigation, or the quick links on the right. The information will be particularly useful for the family members of people who have sustained such an injury and also provides a useful starting point for professionals who wish to improve their knowledge of the subject.
All the technical terms that are used are highlighted in bold and explained on the 'list of common brain injury terms' page, which you can access using the left-navigation.
The hypoxic and anoxic brain injury information on this website is available to download in PDF format at the bottom of this page.
What is hypoxic brain injury / anoxic brain injury?
The brain needs a continuous supply of oxygen to survive and it uses 20% of the body's oxygen intake. Oxygen is needed for the brain to make use of glucose, its major energy source. If the oxygen supply is interrupted, the functioning of the brain is disturbed immediately and irreversible damage can quickly follow. Consciousness will be lost within 15 seconds and damage to the brain begins to occur after about four minutes without oxygen.
A complete interruption of the supply of oxygen to the brain is referred to as cerebral anoxia. If there is still a partial supply of oxygen, but at a level which is inadequate to maintain normal brain function, this is known as cerebral hypoxia. In practice, these two terms tend to be used interchangeably.
For the purposes of consistency, this section of the website will use the terms anoxic brain injury or cerebral anoxia, unless hypoxic injury is specifically meant.
Causes of anoxic brain injury
There are many potential causes of cerebral anoxia, including:
Cardiac or respiratory arrest- Irregular heart rhythm or poor function of the heart muscle after a heart attack, resulting in inefficient supply of blood to the brain
- Very low blood pressure (shock), resulting from blood loss (haemorrhage) or disturbed heart function
- Suffocation
- Choking
- Strangulation
- Very severe asthma attack
- Complication of general anaesthesia (where there has been inadequate oxygen supply or cardiac arrest)
- Near drowning
- Exposure to high altitudes
- Smoke inhalation
- Carbon monoxide inhalation
- Poisoning
- Drug overdose
- Electric shock