A potentially injurious incident at Utah Valley Regional Medical Center underlined for clinical engineer Larsen Holyoak the critical importance of shutting off electromagnetic energy devices in patient-care areas.

Cell phones and two-way radios are particularly troublesome around sensitive medical equipment.Holyoak tells a scary story where a baby's carbon dioxide monitor was showing readings that worried the medical staff enough that the oxygen blender was turned up to compensate.

When the mother's nearby cell phone rang and all the readings changed once again, the respiratory therapist realized the phone was affecting the readings and the baby's carbon dioxide output was actually fine.

If the baby had continued to get more oxygen than needed for a sustained amount of time, it could have been a serious problem, said Holyoak.

"You hear about these things but we had never really seen it," he said.

That incident, coupled with the fact that the numbers of cell phones being carried by people has dramatically increased, prompted Intermountain Health Care to impose a corporate policy banning cell-phone and two-way-radio use in all of its hospitals, Holyoak said.

Experts at Primary Children's Medical Center have found that the electromagnetic signal put out by the phones can disrupt heart monitors, a baby's oscillator or dozens of other kinds of electronic equipment.

Emergency personnel with two-way radios shut them off as they reach the hospital. Employees are asked to watch for visitors who miss the signs warning against them.

Everyone working in the medical facilities is asked to rely on a pager rather than a phone when moving around the hospital.

"We've been aware of the problem for the last five years," said Holyoak, team leader for clinical engineering at the Provo hospital. "Nobody was taking it very seriously until a group of doctors at Primary Children's decided to find out just how much of a concern it was."

Holyoak says the study in Salt Lake City showed that of 100 medical machines, 30 to 40 percent were adversely affected by cellular phone signals and two-way-radio transmissions.

"Some pieces will actually shut down," Holyoak said. "With others, the readings change."

Todd Thain, supervisor of clinical engineering at Primary Children's Medical Center, says the 1995 study clearly showed that transmissions from cellular phones and two-way radios affected all kinds of medical equipment.

"A lot of it has to do with how close the phones are to the equipment," he said.

But it's impossible and impractical to try and regulate the proximity, especially when a patient's family members are distracted or an employee or a doctor gets busy.

"You can have somebody actually set a phone right on top of the equipment without realizing it," Thain said. "We instigated a no-phone policy almost immediately following the study."

Pagers don't represent the same problem because they are receivers and do not include the troublesome electromagnetic component that disrupts medical equipment.

"We want to get the information out to the public," Holyoak said. "We're really trying to get people more aware by putting up signs outside the units with the more sensitive equipment."

The oscillators in newborn intensive care units are the most affected by the phones, he said.

"But there's so much variance, so many kinds of equipment, we can't keep up with them. It's safer to just ban the phones."

Older style cell phones seem to be more of a problem than newer models that have a much lower signal output.

Analog and digital phones affect the electronic equipment in similar ways.

"We've done some training videos on the danger," Holyoak said. "We found the two-way radio we were using affected the camera audio system as well as the machines."

It isn't just hospitals that are finding disruption from hand-held communication devices. Holyoak says experts are finding that cell phones interfere with a car's electronic systems.

"Eventually we're going to have to do something about electro-magnetic interference protection," he said.

"We'll see more shielding for our equipment, for instance."

Thain said many manufacturers are starting to improve their shielding, replacing plastic covers with metal and increasing the amount of shielding provided.

Right now, to protect patients and alert the public, Holyoak is posting more signs and periodically his staff conducts a sweep of the hospital to detect phones in use.

Thain has done the same at Primary Children's hospital entrance and outside of critical-care areas.

Training sessions for the medical staffs include information about the potential dangers from using two-way radios and cell phones within three to 15 feet of medical monitors and life-support equipment.

"It isn't just my department's responsibility," Thain said. "It's everyone's job."

"There's so much and it's so critical," Holyoak said, waving a hand at the myriad tubes and machines surrounding a premature infant. "You can see the potential is right there."