This week doctors are trying to bring Formula One racing star Michael Schumacher out of a coma which was medically induced following a skiing accident.
To find out more about why medically induced comas are thought to help people with brain injuries Here's your Quickfire Science with Kate Lamble and Hannah Critchlow...
- A coma is a state of unconsciousness when a person is unresponsive and cannot be woken.
- Comas can be caused by a drug overdose, head injury or purposefully induced by doctors to aid in recovery from trauma
- After an injury, brain tissue swells, which can restrict the flow of blood through the brain, worsening the damage.
- Inducing a coma reduces the amount of energy that the brain requires, and so protects the areas at risk of low oxygen from hypoxia.
- Brain swelling is also tackled by cooling, which reduces the brain's requirement for oxygen
- Alternatively patients can undergo an operation to remove a section of bone from the skull; this allows the brain to swell without compressing and potentially damaging other areas.
- Patient responsiveness in comas can vary - in very deep comas - such as those that are medically induced - a patient may be unresponsive to pain. But less-sedated patients may be able to hear conversation.
- Unlike in the movies, waking up from a coma is usually agradual process. In medically induced comas, cooling is reduced by about 0.25C every hour, to avoid the brain swelling.
- When the patient is able to make a conscious response to instructions, they are no longer classed as being in a coma.
- However, any damage to the brain sustained through a traumatic brain injury is often not apparent until the patient has woken from the coma
- Schumacher's family will have to wait until the anaesthetic stops being administered to see what the long term impact of his head injury will be.