Coma is a state of unconsciousness whereby a patient cannot react with the surrounding environment. The patient cannot be wakened with outside physical or auditory stimulation.
The brain is divided into two hemispheres:right and left cerebral hemispheres by superior sagital sinus. The reticular activating system (RAS) is located within the brain stem and is the important "on/off" switch of the brain. To be awake, the reticular activating system (RAS) must be functioning, as well as at least one cerebral hemisphere.
If a person loses consciousness, either the RAS has stopped working, or both cerebral hemispheres have shut down.Doctors have said that one side of the brain is completely dead.Moreover there is edema of the brain.As the skull is a rigid box,so there is no room for the additional fluid. This causes the brain to push up against the sides of the skull and it then compresses. Unless the pressure is relieved, the brain will continue to swell until it pushes down onto the brain steam, which then damages the RAS, which subsequently affects blood pressure and breathing control centers.Lack of oxygen even for 4-6 minutes causes death or ischaemia of that portion of the brain.Hence the person may become brain dead in a couple of minutes if the edema is uncontrollable.
There is a Glasgow coma scale which is used for the assessment of brain injury and stroke patients. The GCS score will be documented; the deeper the coma, the lower the score.You can learn more about this score from the following website:
So whether your mother in law will wake up from the sleep or not,depends on her GCS score and whether oxygen and blood supply to the brain is adequate or not.
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Take care and God bless.
Thank you so much. They removed the ventilator but she has a tracheotomy (unsure of the spelling) and is receiving oxygen. I guess this is instrumental in slowing the deterioration in the brain. I will visit the suggested website and try to expand my knowledge in this area. Again, thank you.