The full details surrounding the death of Joan Rivers have yet to be disclosed, but many in the medical community are wondering how an endoscopic procedure to check her vocal cords, the procedure it is widely reported she was undergoing, caused the comedy legend to stop breathing at a Manhattan surgery center.

Ms. Rivers, 81, was at Yorkville Endoscopy on Aug. 28 when she went into "respiratory or cardiac arrest," according to the New York Fire Department. She was transported to Mount Sinai Hospital, where she was put into a medically induced coma. She died Sept. 4. The state health department is "investigating the matter."

"It is doubtful that the endoscopy was done specifically to evaluate the vocal cords," says Christopher Chang, MD, a Yale- and Duke-trained ENT specialist and blogger, "mainly because sedation is not required to look at vocal cords alone."

While emphasizing that he can only speculate in the absence of details, Dr. Chang posits another theory on his blog: "The endoscopy procedure was probably an EGD an endoscopic procedure performed to check the esophagus and stomach, typically to evaluate for reflux damage. If you look at the list of physicians (at Yorkville Endoscopy, in New York, where the procedure was performed), they are all gastrointestinal specialists. It's the wrong medical specialty if a vocal cord procedure was being performed. With vocal cord procedures, it's the ENT doctors and not the GI physicians who do them."

"That was my first, second, and third impression, as well," says Aaron I. Cohn, MD, a Texas anesthesiologist. "You look at what Yorkville Endoscopy does, and the doctors affiliated with it, and it's unequivocally GI endoscopy and every last doctor listed on their website is a gastroenterologist."

If the procedure was more complex than what's been assumed, that could account for Ms. Rivers' having been exposed to a level of sedation that's deep enough to lead to respiratory arrest and eventual hypoxia.

Under deeper sedation, any of several complications might have occurred, says Dr. Chang, noting the possibility of aspiration, severe laryngospasm or over-sedation. "She may have suffered a heart attack," he adds. "Sometimes anesthesia and a procedure cause enough stress on the heart to trigger a heart attack."

Calls to Yorksville Endoscopy for comment were not returned.

Jim Burger