Art Augustine, ECRI's senior project engineer, told ABCNews.com that although medical equipment is increasingly protected from electromagnetic radiation with metallic coatings and more secure seals around the seams of devices, interference issues persist.
Ventilators, anesthesia machines, life-support equipment and infusion pumps delivering critical drugs are all vulnerable to interference from cell phones that are one meter or less away, he said.
"We advocate a partial ban in critical-care areas," he said. Doctors, nurses and other clinicians are advised to turn cell phones off when they approach patients dependent on medical equipment.
In 2005, an ECRI survey found that 48 percent of 122 participating hospitals banned cell phones from critical-care areas. Twenty-nine percent banned cell phones from all patient care areas, 12 percent had no ban and 11 percent had a complete ban.
Although the survey is a few years old, Augustine estimated that the results had not changed significantly.
Like the Mayo Clinic, Ohio's Cleveland Clinic also subjected its equipment to a 10-month-long series of cell phone interference tests that ended in 2007. But its research led the hospital to a different conclusion.
Although the research prompted the hospital to relax its total cell phone ban, the hospital decided to maintain a partial ban that prohibits cell phone use in any patient care area.
The hospital tested 12 different cell phones, including BlackBerries, that were compatible with several different carriers.
And it discovered that although it didn't happen frequently, in some cases the cell phones detracted from the performance of key medical equipment.
In one instance, a cell phone signal interfered with a telemetry unit's ability to detect a patient's heart rate. In another, the signal changed an alarm level on heart rate monitor.
"You can say 99 times out 100, it's not going to cause an issue. But do you want to be the one patient when it does cause an issue?" Paul Miklovich, administrative director of patient support services, asked ABCNews.com.
Because the clinic wanted to be sensitive to patients' and visitors' desire to stay in touch with friends and family while at the hospital, it eased up on the total ban. But, Miklovich said, its research could only support a limited-use approach.
Miklovich said his clinic constantly reviews the research and regularly submits medical equipment to batteries of tests. But, he acknowledges that not all hospitals have the same resources and must establish policies that match their different needs.
Hospitals with older equipment, for example, might need stricter policies.
"A lot of hospitals don't have the resources to do that testing," Miklovich said. "Each hospital has to judge what they can do."