Joan Rivers is in a ''critical condition'' after she stopped breathing during throat surgery yesterday (28.08.14).

The 81-year-old comedienne was rushed to Mount Sinai hospital in New York after she suffered respiratory arrest while undergoing an operation on her vocal cords at Yorkville Endoscopy this morning.

It is also believed the 'Fashion Police' host may have suffered cardiac arrest at one point during the procedure, but she is now in a stable condition.

Joan's assistant Graham Reed was allegedly overheard saying, ''She's not conscious, but she's stable,'' but he refused to comment on her condition when a reporter later approached him.

Joan's daughter Melissa 46, is currently en route to New York to be at her bedside.

A source told the New York Daily News newspaper: ''This is not looking good. No big medical decisions will be made until Melissa arrives.''

The medical emergency unravelled at the clinic on East 93rd street near Third Avenue and they called for an ambulance at 9:39am (EDT).

According to, the caller told the operator: ''We have somebody in either cardiac or respiratory arrest.''

Meanwhile, Joan gave no hint that she was undergoing surgery when she filmed her 90-minute edition of 'Fashion Police' on Tuesday (26.08.14).