Joan Rivers is in critical condition after she stopped breathing during a medical procedure on Thursday, police sources tell The Post. The E! Fashion critic, 81, was a patient at Yorkville Endoscopy on East 93rd street near Third Avenue in New York City, police sources told The Post. After she stopped breathing, a 911 call was placed at around 9:40 a.m. TMZ reports the caller said, “We have somebody in either cardiac or respiratory arrest.” She was reportedly rushed to Mount Sinai hospital.