Chicago ? Wireless systems used by many hospitals to keep track of medical equipment can cause potentially deadly breakdowns in lifesaving devices such as breathing and dialysis machines, researchers reported Tuesday in a study that warned hospitals to conduct safety tests.

Some of the microchip-based “smart” systems are touted as improving patient safety, but a Dutch study of equipment – without the patients – suggests the systems could actually cause harm.

A U.S. patient-safety expert said the study “is of urgent significance” and said hospitals should respond immediately to the “disturbing” results.

The wireless systems send out radio waves that can interfere with equipment such as respirators, external pacemakers and kidney dialysis machines, according to the study.

Researchers discovered the problem in 123 tests they performed in an intensive-care unit at an Amsterdam hospital. Patients were not using the equipment at the time.

Electromagnetic glitches occurred in almost 30 percent of the tests when microchip devices similar to those in many types of wireless medical equipment were placed within about one foot of the lifesaving machines.

Nearly 20 percent of the cases involved hazardous malfunctions that would probably harm patients.

These included breathing machines that switched off; mechanical syringe pumps that stopped delivering medication; and external pacemakers, which regulate the heart, that malfunctioned.

The wireless systems are used to tag and keep track of medical equipment like heart-testing machines, joint replacements and surgical staplers. They can help quickly locate devices that are elsewhere in the hospital and help prevent theft.

The technology also is viewed as a way to prevent drug counterfeiting, by embedding microchips in drug containers, and to prevent harmful medical errors by keeping tabs on devices used during surgery.

The results show that it’s crucial for hospitals to test their wireless items before using them around equipment essential for keeping patients alive, said Dr. Erik Jan van Lieshout, a study co-author and critical care specialist at the University of Amsterdam’s Academic Medical Center.

His study appears in today’s Journal of the American Medical Association.