Later, when the patient was wheeled into a private room, Anderson was called in: the girl wanted to apologize. Anderson hung in the doorway, not wanting to get any closer and the girl said, "I'm sorry, but I was just tired of waiting."

It wasn't until the next afternoon when Anderson was eating dinner with her husband did she notice something was wrong.

"I bit down, and my husband said, 'What's wrong with your jaw, Rita?'" Anderson, now 62, recalls.

It turns out her jaw was broken. It took Anderson eight weeks to recover - eight weeks of lost work days.

She pressed charges, but the assistant district attorney dropped the case. The girl was never prosecuted.

Anderson eventually left the New York hospital for an ER position in Arizona, although not because of this incident.

In some cases, nurses who treat patients coming out of surgery are at risk for drug-induced violence from patients who, under normal circumstances, are "nice as pie," says Pontus.

She remembers a nurse who was treating a patient who had just awoken from surgery. The patient bit the nurse's hand so hard the ligament was torn off the bone.

"There was no malice on the patient's part," says Pontus. "But how do you represent that? That's tough."

ER nurse Casey used to think violent patients calmed down once admitted. She's come to realize the violence is a snowball effect, reaching all the way to floor nurses.

But the ER and the psychiatric units get the brunt of the problem.

Pontus explains that due to the mental health "crisis," in which more and more mental health facilities are closing down, ERs have a lot of homeless, mentally ill patients wandering in off the street.

"[Some of the] patients getting into psychiatric wards should be in prison," she says. "There's an inappropriate placement of patients."

Diane Gurney, president of the Emergency Nurses Association (ENA), agrees, pointing out that as ERs become more crowded, the violence problem is "exacerbated."

"The issues and risks have always been there," she says.

Police who find people under the influence of drugs or alcohol - those who cannot be arrested but need medical attention - drop them off at the ER, where they pass the buck to on-staff nurses, who then become responsible for wayward patients.

Casey calls this the "dump syndrome."

As an ER nurse, she experiences violence firsthand. Once, she saw two to three violent incidents in just a 24-hour period. She attributes the increases in severity and frequency of violence to the growing number of ER patients.

According to a 2009 ENA survey, 27 percent of ER nurses reported experiencing a "high frequency" (more than 20 incidents) of physical violence in the past three years, and 4 percent reported incidents of physical abuse during every shift.

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