ROCKPORT, Maine — Combine a small hospital with increasing incidents of patient violence, often caused by bath salts poisoning, and what do you get? A $33,000 bill this month for policing, according to Pen Bay Medical Center.

The hospital, which used to have just one night-shift security guard, recently had to contract with local police agencies to keep their doctors and nurses safe from violent patients, particularly those high on the bath salts, the synthetic drug that can make people paranoid and violently aggressive.

The hospital reports dealing with about four bath salts patients each week. So far, several staff members have been injured while trying to sedate people suffering from bath salts poisoning, according to Megan Williams, director of communications for the hospital.

The problem was highlighted on Oct. 27 when, according to local police, Trevor Libby, 19, of Rockland went on a rampage inside the special care unit at the hospital. He did not injure anyone else but cut himself while thrashing at windows and equipment, causing $30,000 in damage at the hospital.

Referring to the incident, Williams said, “The patient was on bath salts and because it’s such a different drug they have superhuman strength and no pain. It’s something we’ve never had to deal with. It’s a very serious issue. It’s dangerous in the hospital.”

Both police and the hospital agree that the short-term solution of using local police for hospital security is not ideal. For one thing, the hospital is in Rockport, a small town with a police staff of six full-time patrolmen that cannot possibly provide 24-hour-a-day coverage seven days a week at the hospital while still performing regular duties for the town.

Since Nov. 1 Rockport officers have been providing some coverage at the hospital five days a week while deputies with the Knox County Sheriff’s Office have filled in two days a week.

Rockport Police Chief Mark Kelley said Friday that he is working on revising mutual aid agreements with the bordering police departments in Rockland and Camden to help with hospital coverage. Changes in the agreements are necessary to allow the neighboring police to operate independently at the hospital without Rockport police present.

Williams said the hospital is “pursuing 24-hour coverage, but we can only provide what’s available. We’re working with Rockport, but if there is a bath salts patient in the hospital, someone [from a police agency] will be there.”

The other reason the short-term solution isn’t going to work in the long-term is because it will cost Pen Bay Medical Center $400,000 a year, according to Williams.

“We are looking at other options, like transferring these patients to other facilities. We’ve been in talks with more well-equipped hospitals [that] could handle such patients easier than we would,” Williams said Friday. “Eastern Maine Medical Center [in Bangor] does have on-sight armed security already. A hospital like that could handle the risks of a violent patient much more easily than Pen Bay.”

The two hospitals must negotiate a sharing agreement for the Rockport hospital to do that.

According to Williams, the security changes are directly related to bath salts. The issue is big and growing in Knox County. According to Rockland police Sgt. Don Finnegan, Rockland’s bath salts problem is second only to Bangor’s. Knox County has seen about 200 cases in the last six months, and that figure is extremely conservative, Finnegan said.

Police have to send the drug offenders to the hospital to be calmed down and treated because, according to Finnegan, the drug can kill the user.

Meanwhile, to protect health care workers and others at the hospital from being harmed there will be a police presence at Pen Bay Medical Center seven days a week for at least the next month.