One of the most tragic and avoidable medical errors is the suicide of a depressed patient inside a health care facility.

There were at least 102 suicides in U.S. health care facilities in 2008, the latest figure available from the Joint Commission, a group that accredits hospitals. Most of the suicides and attempted suicides in hospitals are by hanging.

"The worst possible thing is somebody being successful in a suicide attempt before we can help them with medications and therapy," said Frank Cook, director of facilities at CenterPointe psychiatric hospital in St. Charles. "We do a lot of things to avoid that by identifying risk."

At CenterPointe and other psychiatric facilities, patients considered at high risk for suicide are monitored more carefully. They are stripped of their belts and shoe strings and issued paper scrubs to wear. Chairs and stools, which can assist in hangings, are removed from rooms.

Any potential hanging points like hooks or bars are made to easily break away from walls. Shower heads and nozzles are installed inside sloping metal boxes so nothing can be tied to them.

Cameras keep an eye on patients when a nurse isn't in the room.

Still, 'someone who is suicidal often is very determined," Cook said.

When Cook started working at CenterPointe six years ago, there were two to three serious suicide attempts each year — including some patients who tried to hang themselves and had to be cut down and freed, he said.

So the next challenge was doors, since patients could tie bedsheets and towels together, throw them over and hang hidden behind the door.

But Cook knew the solution was not to remove all doors.

"You want to give patients a certain amount of privacy while not allowing them to hang themselves," he said.

Cook spent a year and a half trying to figure out a way to prevent door hangings. He couldn't find any products on the market that addressed the need, so he thought back to his engineering and construction background.

He tinkered with the idea of conveyor belts that automatically shut off when they get jammed. Ribbon switches, activated by pressure, turn the belts off when products are piling up and start moving in the wrong direction.

Cook talked to a manufacturer of ribbon switches, asking if they could be made in the length of the top of a door. Prototypes were designed and sketched out. Cook worked with Total Lock and Security of St. Louis to create the hardware for the device.

The first door switch was installed at CenterPointe in 2006.

Two years later, Cook received a patent for his invention.

The Door Switch is mounted to the top of the door and consists of two stainless steel rods that are sealed and rubberized, creating a channel. If slight pressure is applied to the top of the door, the rods make contact and set off an alarm.

"You can slam the door all day long and it won't go off," Cook says, but "it's so sensitive that if somebody is making a (suicide) attempt, it catches them."

If the door switch senses two or three pounds of pressure, an audible alarm sounds at the nurse's station and a strobe light goes off outside the patient's room so they know exactly where to go.

The device also covers the entire inside length of the door to cover all the hinges and eliminate any potential hanging points.

There are now 23 door switches installed at CenterPointe, and patients are told the devices are there as a deterrent. Since the installation, the alarms have gone off once or twice when someone threw a towel over the door, but there have been no serious attempts at door hangings, Cook said.

The device is now being marketed nationwide by The Door Switch, a subsidiary of Total Lock and Security, at a cost of $2,000 to $2,500 installed. Some veterans hospitals and St. John's Mercy Medical Center in Creve Coeur have expressed interest, according to a company representative.

Cook said that people often ask him why he wants to keep people from killing themselves, if that's what they are trying to do.

"Life is valuable, and I've been charged with helping these people," Cook replies. "We have to keep them safe long enough so they can be helped."