What happens if a nurse is trying to give a sick child a powerful drug an hour too soon?

At Children's Hospital in Minneapolis, the IV pump may warn her that she's making a mistake.

In fact, it can even tell her if the doctor changed the order without her knowledge.

Since March, the hospital has been test-driving a new computerized system designed to catch medication errors before they happen.

In one month alone, it sent out 234 alerts warning nurses that something was amiss -- in some cases, they were about to give a drug to the wrong patient, said Bobbie Carroll, the director of patient safety. And that was just in one 26-bed unit, the pediatric intensive care unit, where nurses administered some 11,000 doses of medications.

"I think we were all surprised," said Carroll.

For hospitals, medication errors are a constant worry, particularly with infants and children, since the precise dose must be tailored to their weight.

To try to lower the risk of errors, Children's helped develop the new system, which relies on bar-code readers, like those used in grocery stores, and a programmable "smart pump."

In this case, a nurse scans the bar codes on the patient's armband, the medication and the pump. If they don't match -- say, the dose is too large or the doctor canceled the order -- the smart pump sends an alert.

It's worked so well, Carroll said, that Children's recently won an award from the Minnesota Alliance for Patient Safety.

After Thanksgiving, it will start rolling out the system at its St. Paul campus. In the meantime, children's hospitals in Boston and elsewhere are calling to learn more about it.

"We've just added another level of safety, and it's not just for our patients," Carroll said. It also helps nurses. "It's another backup," she said. "Humans are humans, we're fallible. No matter how diligent we try to be sometimes, errors happen. What we strive to achieve is creating as many safety nets as we can."