My friend was healthy and normal. There was a sudden bleeding in her brain due to an AVM and went through a serious brain surgery. Now around 3 weeks she is in a coma status. How can I understand this in Buddhism. Does she hear us? Can she feel what is going on? Is she in pain? Thank you.
Whether a person can hear, see, smell, taste etc. while in a coma is probably a question for medical science.
From a Buddhist perspective, it can be seen as a case of senses being shut off as in when you are in deep sleep. Only Bhavaanga Cittas(life continuum) are present in deep(dreamless) sleep.
Alternatively, it could just be a case of the patient not being able to respond in anyway. Here's such an instance.
The situation is probably different from patient to patient.