The state Health Department confirmed Thursday it is investigating what happened at the Upper East Side clinic where Joan Rivers underwent a procedure on Aug. 28 that apparently led to her cardiac arrest and eventual death.

The Health Department declined to elaborate about the nature of the investigation, but medical malpractice attorneys said it was likely investigators would be focusing on whether Yorkville Endoscopy, an outpatient clinic, had effective procedures in place for emergencies involving respiratory problems, and whether they were scrupulously followed.

Yorkville Endoscopy did not return phone messages left requesting comment.

Health Department investigations can be triggered by the complaints of a patient or her family, but usually take months to occur: "It's extremely unusual for an investigation to occur this quickly," said Jeffrey J. Shapiro, a Manhattan medical malpractice attorney. Rivers' eventual autopsy report will also be a factor in the investigation, Shapiro noted.

Rivers was reported to be undergoing an endoscopy of her vocal cords, but the exact nature of her procedure and the type of anesthesia -- if any -- she received is not known. But cases such as hers involve an anesthesia problem, which results in a patient being deprived of oxygen, said Shapiro.

But the intense publicity surrounding Rivers' catastrophic outcome could have also prompted the probe, added Steven Pegalis, a medical malpractice professor at New York Law School and a founding partner at Pegalis and Erickson. Since 2001, the state has required health care practitioners to submit a "root cause analysis" of all unintended adverse occurrences, noted Pegalis.

One aspect investigators will be exploring is whether Rivers, who was 81, was an appropriate candidate for a procedure in an out-patient facility, said Gerry Oginski, a medical malpractice lawyer in Great Neck.

While hospitals are better equipped to handle patients who might need emergency intubation to prevent brain damage or death, Oginski observed that even outpatient facilities "are supposed to have crash carts and certain medications and staff trained to use them in an emergency. Were they prepared?" he said.

Results of the investigation could take months, said the attorneys. Outcomes of such investigations often include findings mandating risk reduction strategies and corrective actions the facility must agree to in writing, but in certain egregious instances facilities are even shut down.

And should the family of Joan Rivers sue? "They can use the findings of fact (of the state investigation) at trial, but they cannot use the conclusions," Oginski said.

"It depends on the findings," said Shapiro. "If (the state concludes) there were departures from the standard of care, it certainly won't help," the endoscopy center.