Joan Rivers in a medically induced coma after going into cardiac arrest

Rivers stopped breathing during surgery.

Joan RiversPhoto by David Shankbone/Wikimedia

Iconic comedienne Joan Rivers remains in a New York hospital after going into cardiac arrest on Thursday, and being placed in a medically induced coma.

The 81-year-old was rushed to Mount Sinai after she stopped breathing during a surgical procedure. She remains in critical but stable condition.

Rivers was undergoing minor throat surgery at Yorkville Endoscopy in Manhattan when the medical emergency occurred. E! News reported that Rivers was having her vocal cords examined. WABC noted that the clinic specialises in digestive issues.

During the procedure, the "Fashion Police" host stopped breathing, and clinic staff called 911.

Dr. Yosef Krespi of Lenox Hill Hospital said that there are inherent risks in operating on the throat, including the possibility of an airway spasm.

"That by itself can cause depletion of oxygen, inability to inhale air, and therefore cardiorespiratory problems," he told WABC.

Because of those risks, such procedures are not usually conducted in clinics, he said.

"Most vocal cord procedures are done in a hospital under general anesthesia or ambulatory surgery center," Krespi stated.

Rivers was taken to Mount Sinai Hospital at 9:39 a.m. and was "unconscious and unresponsive," law enforcement officials told FOX411. She was placed in a medically-induced coma, and is stable.

Her daughter, Melissa, and grandson, Cooper, flew to New York from L.A. to be with her, and released a statement to her supporters.

"I want to thank everyone for the overwhelming love and support for my mother," Melissa said. "She is resting comfortably and is with our family. We ask that you continue to keep her in your thoughts and prayers."

Mount Sinai also released a statement.

"Her family wants to thank everybody for their outpouring of love," hospital spokesman Sid Dinsay said.

Just hours before the procedure, Rivers was performing stand up at the Laurie Beechman Theatre, and joked about her age and mortality.

"She did a joke onstage, she goes, 'I'm 81 — I could go at any moment,'" an audience member, Shade Rupe, recounted.

"'I could fall over right here and you all could say, 'I was there!'"

"She was so on," Rupe continued. "If you had me guess her age, I'd say she was in her 50s. She didn't miss a step, she didn't go ditzy, she didn't forget anything and her timing was amazing."

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