Use of cellular phones in Mayo Clinic does not interfere with communications among medical equipment and devices, prompting the leaders of the hospital to consider an end of the cell phone ban, according to Mayo Clinic campus in Rochester.

Many hospitals and clinics ban use of cell phones because early studies suggest that the radio frequencies would disrupt normal functions of certain medical instruments, devices and equipments, posing a risk to patient health.

In the study, two common signal transmission technologies used in wireless phones were tested 300 times in 75 rooms in 11 patient-care areas including telemetry-laden ICUs, according to David L. Hayes, MD of the Division of Cardiovascular Diseases and colleagues who reported the results in the March issue of Mayo Clinic Proceedings.

The researchers found in no case did the signals used by cell phones cause any interference with any medical devices as long as the phone was used in an ordinary way. That is, the cell phone should not be placed too close to any medical devices.

The findings confirmed early studies by others that have showed that cell phones used now, mostly if not all digital rather than analog, do not pose a risk to patient as there is no inference with critical or non-critical medical equipment.

Hayes and colleagues said the findings should prompt hospitals to alter or abandon their bans on cell phone use just as Mayo Clinic is doing.   A ban on cell phone use in hospital causes inconvenience to patients and their families.

"If no clinically important adverse effects occur as a result of using cellular telephones in the hospital, then it seems that the advantages that this technology brings to institution and patients would be well received," the researchers wrote.

However, they cautioned that use of cell phones in hospitals may have a negative effect not because of the radio frequencies the cell phones use, but because of the way people use.

Some individuals when using cell phones talk roundly and obnoxiously, which would bother other patients and visitors.

Many medical institutions ban cell phone use in hospitals, clinics, and physician offices because some early studies indicated cell phone use would have the potential to disrupt radio signals used by medical devices such as remote heart monitors.

But those studies were conducted in unreal settings.   For instance, in those tests, the cell phone was placed too close to medical equipment, which is not the way how people use cell phones.   And also old cell phones use an analog mode rather than now a digital mode.   And modern cell phones use less energy.

Some studies disprove any potential hazard cell phone use could pose.   For instance, a study presented in 2006 at the annual meeting of the American College of Emergency Physicians by researchers from the University of Mississippi Medical Center in Jackson found that cell phone use in the emergency department did not disrupt electrocardiograms.

The authors of that study noted that although cell phones are not allowed in patient care areas, other wireless technologies are actually used often including Blackberries, personal digitals and wireless internet cards etc.

Early the Mayo Clinic researchers did find that cell phone use interferes with some medical equipment, but that was tested in a way that the phone was set too close to the equipment such as on the top of a ventilator or the telephone uses an analog mode.

In the current study, Hayes and colleagues tested two modes of mobile communication protocols, CDMA used by AllTel, Sprint and Verizon and GSM used by ATT/Cingular and T-Mobile in a variety of medical settings including the medical cardiology unit, echocardiography laboratory and cardiovascular surgery ICU.

They exposed 192 medical devices such as ventilators and vital signs monitors and external pacemakers to the radio frequencies used by cell phones in the way the telephone was actually used.   They found that cell phone signals did not interfere with any medical devices.

Similarly, they found that wireless technologies like Blackberry wireless handheld devices did not interact with any medical signals as tested 40 times with 24 devices.

Although cell phone use does not seem to have any negative impact on the communication of medical equipment or devices, some studies reported in the same issue of Mayo Clinic Proceedings show that other wireless technologies may pose a risk in patients with wired wireless devices.

A letter to the editor reported a case in which a portable CD player caused an abnormal electrocardiographic recording within a hospital setting.   Once the CD player was shut off, the recording returned back to normal.

Patients with implantable rhythm devices such as pacemakers and defibrillators outside the hospital setting need to be careful as some researchers reported two cases in the journal in which two patients, one with a pacemaker and the other with an implantable cardiac defibrillator, experienced adverse reactions induced by anti-theft devices commonly used in stores.   As a result, both patients were rushed to emergency rooms for evaluation.

Experts advise that patients with medical devices should keep away from any wireless devices including cell phones that may potentially interfere with their medical devices.

For more information about cell phones and their health effects, read http://www.fda.gov/cellphones/qa.html

What about wireless phone interference with medical equipment?

Update July 29 2003 by the FDA

Radiofrequency energy (RF) from wireless phones can interact with some electronic devices. For this reason, FDA helped develop a detailed test method to measure electromagnetic interference (EMI) of implanted cardiac pacemakers and defibrillators from wireless telephones. This test method is now part of a standard sponsored by the Association for the Advancement of Medical instrumentation (AAMI). The final draft, a joint effort by FDA, medical device manufacturers, and many other groups, was completed in late 2000. This standard will allow manufacturers to ensure that cardiac pacemakers and defibrillators are safe from wireless phone EMI.

FDA has tested hearing aids for interference from handheld wireless phones and helped develop a voluntary standard sponsored by the Institute of Electrical and Electronic Engineers (IEEE). This standard specifies test methods and performance requirements for hearing aids and wireless phones so that that no interference occurs when a person uses a “compatible” phone and a “compatible” hearing aid at the same time. This standard was approved by the IEEE in 2000.

FDA continues to monitor the use of wireless phones for possible interactions with other medical devices. Should harmful interference be found to occur, FDA will conduct testing to assess the interference and work to resolve the problem.