Joan Rivers remained in a medically-induced coma in a New York City hospital.
Her daughter, Melissa, and 13-year-old grandson, Cooper, flew across the country to be at Joan's side. Melissa released a statement, saying, "My mother would be so touched by the tributes and prayers that we have received from around the world. He condition remains serious but she is receiving the best treatment and care possible. We pray for her recovery."
But one source described Melissa as an "emotional wreck" as she waited for her mother's long-term prognosis.
INSIDE EDITION spoke to Dr. Jon LaPook, chief medical correspondent for CBS news.
Dr. LaPook said, "You would put somebody into a medically- induced coma in order to just sort of lower the demand of their body in terms of coming up with energy to fuel their brains and to take care of their vital organs, so you decrease the amount of work the body has to do and then you watch very closely."
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The 81-year-old comedian went into cardiac arrest at Yorkville Endoscopy, a private clinic on Manhattan's Upper East Side on Thursday morning. She was having an endoscopy, a procedure meant to determine why she was having trouble with her vocal chords.
But Juliana Rancic, Rivers' co-host on Fashion Police, said she was in fine form during the taping.
Rancic said, "She's in perfect health, so this is just such a shock that something like this would happen."
Joan is a famous work-a-holic. Here is a timeline of her schedule leading up to her medical crisis:
Monday, August 25: Rivers was in Los Angeles to cover the Emmys.
Tuesday, August 26: She taped her E! special on Emmy fashions, cracking her usual biting jokes that had made her a living legend.
Wednesday, August 27: Rivers flew back to New York for a person appearance to promote her new book Diary of a Mad Diva. That night she did a high-energy standup that lasted a whole hour at a Manhattan theatre.
INSIDE EDITION spoke to Shade Rupe, who was in the audience during Rivers' standup.
Rupe said, "She's 81, but she is running around like a four-year-old. There was absolutely no indication at all whatsoever in any form that there were any health problems or any physical ailments whatsoever."
The super-fan posed for a photo with the comic legend. It is believed to be the last photo taken of Joan before she was stricken.
Joan Rivers' carried a jam-packed schedule for anyone, let alone an 81-year-old woman.
"We are going to see in the days and weeks to come exactly what happened," said Dr. LaPook. "Obviously, we're crossing our fingers and all our prayers are for her recovery."