Joan Rivers rushed to hospital

• Rivers stopped breathing on Thursday


• Her reality show documented a health scare last year


• She has been open about previous health issues

(CNN) -- Joan Rivers was rushed to the hospital Thursday morning after she stopped breathing, a source confirmed to CNN.

A law enforcement official told CNN the comedienne stopped breathing during throat surgery. Rivers, 81, was then rushed in critical condition to Mount Sinai Hospital in New York City.

In 2013, Rivers allowed cameras to record a health scare for her and her daughter's reality show, "Joan & Melissa: Joan Knows Best?"

Rivers said on the show that doctors found a spot on an X-ray after she had a persistent cough.

"We're just not going to be sad about this," Rivers said during the episode. "We're gonna do jokes and be up until we know. That's how I deal with things. I'm not just gonna sit around the next couple of days and go crazy."

Rivers has been open about her health issues. She was diagnosed with osteoporosis in 2002 after a fall down some stairs left her with broken bones, and she became an advocate for screenings for women.

She also admitted to not being as healthy as she could be.

"I try not to be, but I'm a terrible eater," she said. "I wish I could say I eat super-healthy, but I don't. I love junk food -- it should be its own food group -- so I help my bones with supplements and medicine."

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CNN's Doug Ganley contributed to this report.