Fisher died on December 27 after reportedly suffering a massive heart attack on a flight from London days before.
The LA Times reported Reynolds complained of breathing problems to paramedics who attended to her.
The newspaper said a woman in a "fair to serious condition" was taken to Cedars Sinai Medical Centre. She never recovered after being taking to hospital.
MUM, DAUGHTER TO HAVE JOINT FUNERAL
Fisher and her mother Debbie Reynolds, who died just days after the death of her daughter, will have a have a joint funeral, Reynolds' son Todd Fisher has reportedly told ABC News.
ABC reported Fisher said there is currently no date and no confirmed location for the mother-daughter funeral, but plans are in progress.
After his mother's death, Fisher spoke to Good Morning America, recalling how Reynolds "said she missed her daughter and wanted to see her again".
"I don't think she meant it quite like that, but in 30 minutes she went to go see her again," he said.
"She literally spent her life caring after Carrie," he added. "I don't think she hardly knows what to do without having Carrie to look after. I think she wanted to be with her. I'm not joking when I say she left to be with her, and I'm happy about that. That's the only thing I'm happy about."
TMZ reports family members have discussed a dual service as part of their funeral plans for the two entertainment icons.
There is talk of a small, private ceremony and then later a bigger memorial service.
Todd Fisher and other relatives attended the Hollywood Forever Cemetery, a famous resting place for celebrities, to plan the funeral.
Reynolds was at her son's home when she fell ill and died of a suspected stroke.
