Hypoxic and anoxic brain injury

The brain needs a continuous supply of oxygen to survive. If the oxygen supply is interrupted, the functioning of the brain is disturbed immediately and irreversible damage can quickly follow. This section is intended as an overview of the causes, effects, treatment and rehabilitation of 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. 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 Common brain injury terms page, which you can access using the left-navigation.

What is hypoxic brain injury / anoxic brain injury?

Oxygen is needed for the brain to make use of glucose, its major energy source. If the oxygen supply is interrupted, 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
My story

Smart by name...

In January 2009, when she was just 16, Lizzie Smart was struck down by an infection in her throat, causing her brain to be starved of oxygen. But this determined young lady is not one to let anything stand in the way of her dreams. 

Read story