Ryder attack: Why induce a coma

Cricketer Jesse Ryder was put into an induced coma following a brutal attack outside a bar in Christchurch. Photo / Doug Sherring

Patients are put into an induced coma and given other intensive therapies to reduce brain swelling when the brain has been injured.

A combination of medicines is used to keep the patient in a deep sleep.

"That is done to keep the swelling of the brain to a minimum and in doing so, limiting the amount of further damage that occurs as a result of swelling causing pressure on the brain," says Auckland City Hospital intensive care medicine specialist Dr Tony Smith.

"When the brain is injured, it swells. Because the brain is enclosed within the skull and the skull acts like a rigid box, when the brain swells there is nowhere for the swelling to expand. The swelling causes raised pressure in the brain and raised pressure can cause damage."

"Skull fractures, in and of themselves, are not necessarily a serious injury. It's the injury that occurs to the brain underneath that fracture that is of concern."

"The presence of a skull fracture does not necessarily mean the brain is injured. We see patients with fractures and no brain injury underneath and we see patients with severe brain injury with no skull fractures."

Dr Smith says determining the degree of brain injury is complex and depends on factors such as the level of consciousness before the induced coma, the extent of injuries seen on brain scans, the results of electrical tests, whether surgery has been necessary and if so whether any brain tissue has been removed, and brain pressure.

A collapsed lung, resulting from the lung being punctured, is a very common injury following trauma and is usually relatively straightforward to treat.

A drain is inserted into the chest to remove air surrounding the lung, allowing the lung to re-expand. The body usually repairs the hole in the lung itself within a few days. Only very rarely is an operation required to repair the hole.

There is no maximum time that a person can be in an induced coma, with some patients with very severely injured brains requiring a week or two of such therapy.

Skull fractures usually heal without any specific treatment. Occasionally an operation is required to repair them.