Health Officials: Joan Rivers's Doctors Didn't Notice Deteriorating Vitals

11/10/2014 AT 09:20 PM EST

In a shocking new report, investigators claim Joan Rivers suffered irreversible brain damage following a series of mistakes by her personal physician as well as staffers at the Yorkville Endoscopy Clinic where she underwent both an endoscopy and laryngoscopy.

According to the report, one of the offenses included not being weighed before the procedure, which is required before administering anesthesia, in this case Propofol. In addition, the investigation, which was conducted by the New York State Dept. of Health, also found that Rivers only signed a consent form for the endoscopy, not the laryngoscopy, which was performed by the comedian's personal physician, who did not have medical privileges at the clinic.

Melissa Rivers's attorneys responded in a statement: "Our client, Melissa Rivers, is terribly disappointed to learn of the multiple failings on the part of medical personnel and the clinic as evidenced by the CMS report. As any of us would be, Ms. Rivers is outraged by the misconduct and mismanagement now shown to have occurred before, during and after the procedure."

Last month, the medical examiner said Rivers's cause of death was brain damage suffered when her heart stopped during the medical procedure, at the time calling it a "predictable complication."

But according to the report, it might not be that clear-cut, as investigators claim the staff allowed Rivers’s oxygen level to drop to a dangerously low level. In fact, at one point, her personal physician "proceeded to take pictures of the surgeon and the patient with his cell phone. Medical records indicate the patient was sedated at the time of the photograph."

"The physicians in charge of the care of the patient failed to identify deteriorating vital signs and provide timely intervention during the procedure," according to the report.

Adds Melissa's attorney: "Moving forward, Ms. Rivers will direct her efforts towards ensuring that what happened to her mother will not occur again with any other patient."