My Mother Is 76 And Has Had A Small Brain

My mother is 76 and has had a small brain aneurism at the base of her neck years ago then followed by quadruple bypass where she's since had very bad dementia. My question is today I was there where she fell "asleep" hunched over then made a few loud like exhales then vomited. (While still sleeping) any idea what that's from? My dad is main caregiver and "she'll be ok" is his old fashioned answer. Thanks