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EMI Control: Pulling the Plug on a Global Problem

Medical Device & Diagnostic Industry
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An MD&DI February 1997
Feature Article


What can U.S. manufacturers do in the face of ambiguous FDA and strict European electromagnetic interference requirements?

With the rapid proliferation of electronics in medicine, the potential for electromagnetic interference (EMI) in critical situations is also increasing. EMI, which is the adverse effect of electromagnetic energy on an electronic device as well as the escape, or emission, of such adverse energy from a device itself, is obviously an important concern in today's complex hospital environments. A device may be safe when it is used alone, but when it is hooked up to a patient who is connected to many other electronic devices as well, the effect can sometimes be difficult to predict.

According to Don Witters, chairman of the electromagnetic compatibility (EMC) working group at the Center for Devices and Radiological Health (CDRH) in Rockville, MD, the danger from EMI is often not clearly defined. Says Witters, "Because of the nature of radio transmissions, the closer you get to the transmitter antenna, the greater the field strength. On the other hand, medical devices can be susceptible to field strengths that are not very high. And it's not predictable whether medical devices will interact with other medical devices. It's a very complex situation, not easily modeled or well understood.

A recent open letter from FDA's Lillian Gill, the director of CDRH's Office of Compliance, identified examples of common types of problems that have been caused by EMI.

  • A monitor failed to detect a patient's critical condition.

  • A defibrillator failed to resuscitate a patient.

  • A wheelchair suddenly moved toward street traffic.

  • A laser beam moved into the audience area of a light show.

  • A radiation beam shutter did not close.

As these examples show, the effects of EMI in medical electronics, while difficult to predict, can also be devastating.

For U.S. device manufacturers, one major obstacle to planning for EMI control is the lack of clear-cut, global standards. In fact, although FDA does voice concern about the need for EMI safety, it offers manufacturers very few concrete directions.

The European Union (EU), on the other hand, has articulated very clear EMI requirements, embedded them in laws, and set an ironclad date for compliance. The Medical Devices Directive, which will become mandatory on June 15, 1998, has specific guidelines for emissions as well as for immunity from interference that will apply to medical electronics intended for sale in Europe.

Faced with this ambiguity from FDA, how are U.S. manufacturers to ensure EMI control in their medical electronics? Clear global standards are needed to deal with this dilemma, and developing them will require a major shift in FDA policy.


FDA has been involved in EMI control for many years, but only in an ad hoc way. With EMI, as with many other issues, FDA has taken a strong stance only after the problem hit the headlines. For example, in the late 1960s considerable concern developed about microwave ovens interfering with cardiac pacemakers. After FDA became involved, microwave manufacturers tightened their emission standards and pacemaker manufacturers improved their protection standards, so the problem abated.

Similarly, FDA involvement also led to the development of appropriate filters for apnea monitors, shielding for the cables that lead to joysticks on wheelchairs, and, most recently, simple instructions for keeping cellular phones at least 6 in. away from pacemakers.

Witters reports that over the past three years, FDA has intensified its efforts and is attempting to present a more comprehensive program for dealing with EMI. This program has included dissemination of information on EMI to medical device manufacturers, health-care personnel, and patients; working with various industry and regulatory bodies to achieve standards; participating in related forums and workshops; and, especially, attempting to serve as a communications link between the makers of medical devices and vendors of products or services that emit electromagnetic discharge.

"We would like as much as possible to promote cooperation between the parties and help them solve potential EMI problems at the design stage," says Witters. "We see this as a central role for us, in addition to regulating medical devices."

Consultant William Kimmel of Kimmel Gerke Associates, Ltd. (St. Paul, MN), says that although FDA has taken these new steps to make its EMI policy more coherent, compliance with FDA recommendations is still voluntary. According to Kimmel, the lack of clearly stated rules and regulations means that some manufacturers can slip through the cracks, while the majority of those who are truly conscientious are faced with solving extensive and often largely undefined problems.

Ensuring EMI control can be complex. "Device manufacturers are faced with a great difficulty," Kimmel says. "EMI is not a new issue. I've been working at this for the past eight years, and every reputable manufacturer I know has done a lot of work on it. But it's very difficult to arrive at definite solutions. For instance, you can make portable equipment immune with heavy shielding, but that makes it that much less portable."

EMI control can also be costly. Kimmel says that medical equipment is already expensive, the medical industry is already under fire for cost control, and an overly burdensome regulatory environment will thus effectively drive some devices off the market. "The cost of a product's life cycle and the cost of compliance will be an increasing problem," he says. "Testing is not cheap. A lot of independent test labs charge $1500 per day, and the cost of testing any particular product can be more than half a million dollars."

Clear and detailed standards will be needed to help U.S. manufacturers with this difficult and expensive aspect of device manufacturing.


Despite this climate of confusion, some U.S. manufacturers have found the problem of EMI control relatively easy to solve. For manufacturers of pacemakers, for example, EMI from cellular phones was dealt with simply and inexpensively.

"When the issue of cellular phones and pacemakers came up about two years ago, we started to do our in-house testing, and then worked with FDA to test our products," says Charles Swanson, vice president of pacing regulatory affairs and compliance and audit for Medtronic, Inc. (Minneapolis). "What we did was provide instructions on how to use the phone. The research showed that if you kept the cellular phone about 6 in. away from the pacemaker and didn't put it into your shirt or vest coat pocket, there would not be a problem."

But many other device manufacturers are reticent to even talk about the issue of EMI control. "I've had a great deal of difficulty getting input from the medical device industry," says Bernard Segal, PhD, an associate professor at McGill University based at Jewish General Hospital (Montreal) and head of an investigative team for Health Canada, the Canadian equivalent of FDA.

Segal says he requested industry comments on a paper his task force prepared for Health Canada addressing the issue of EMI in hospitals, but has not received a single comment from medical device manufacturers. He says he understands why manufacturers might hesitate to speak about EMI. "You can't be overly critical of device manufacturers, because they have incredibly difficult problems to solve.

"The key problem is the application of electronics to the patient. When you go into an intensive-care unit, you can count the large number of wires and fluid lines electrically connected, each one acting as an antenna, with the biggest antenna being the patient him- or herself. It's a complex situation in which one device can interact with another through the patient. A manufacturer might rightly ask, "How can I be responsible for someone else's equipment?"

Segal also says that small manufacturers have a particularly difficult time solving these problems.

One reason for the lack of industry input on EMI, according to Kimmel, is competition. Companies do not want to reveal how hard they are working at compliance so they can be a step ahead of others in securing approval. Another reason may be the fear of liability; in this present state of ambiguity in which nothing is clearly illegal, everything is a potential source of liability. Are U.S. device manufacturers working hard at EMI solutions, then, but simply not talking about it? Kimmel says that most are.

One person in a position to see how well U.S. manufacturers are controlling EMI is W. David Paperman, a clinical engineer at Texas Children's Hospital's Biomedical Engineering Department (Houston). Although the hospital does not test for compliance, it is one of a growing number of hospitals and clinics that have set forth more aggressive standards for purchasing. "We now do what we call fingerprinting of characteristic areas in the hospital. Each new device is fingerprinted to see that it fits in without contributing to or creating an EMI disturbance."

Paperman says that "most manufacturers are cleaning up their act. I walk through trade shows now testing for emissions, with my own portable equipment, and find that devices are significantly improved. Complaints of equipment malfunctions at the hospital have fallen off."

Penny Caran, CEO of Technology International, Inc. (Richmond, VA), a subsidiary of London-based Interference Technology International, Ltd., offers a different view. She says that U.S. medical device manufacturers are still falling short of the standards being promulgated by the EU.

Caran says that the difference between the U.S. and European approaches is one of basic philosophy. "In Europe, it's assumed that the government's responsible for ensuring that people are protected from safety hazards," she says. "But we Americans are an independent people, and don't want government interfering in business and safety issues any more than is absolutely necessary."

She doesn't blame FDA weakness for the lack of clear EMI policy. In fact, she says that FDA is one of the most hated bureaucracies because when it punishes misconduct it tends to be harsh. But FDA can fully function only with a congressional mandate, says Caran, and for such a mandate, the public must be galvanized. Therefore, a systematic, overall, and enforceable approach to an issue like EMI will probably not be within FDA's scope of power.

Caran says that regulatory authorities in the EU as well as Canada take a more clearly defined and stringent approach to EMI than FDA does. According to Caran, many U.S. manufacturers are "lulled into a false security in that they believe that the EU requirements might be similar to those of FDA." It is understandable that U.S. manufacturers might have this impression. After all, FDA is working with various industry and regulatory groups toward the ostensible goal of meeting the International Organization for Standardization (ISO) 9000 standard. But when Caran is asked whether FDA's position is therefore similar to that of the EU, she replies, "What a wonderful world it would be."

According to Paperman, the reason U.S. manufacturers often don't meet EU requirements for EMI is not because U.S. standards are too lax, but because the EU keeps adding new requirements.


Until FDA's position becomes more in line with that of the EU, how should U.S. manufacturers approach the problem of EMI control?

For any device company that hopes to be part of the global market, even in the distant future, the safest approach is to make sure that all products meet EU requirements, rather than be satisfied with FDA approval. Europe is too large a market for most U.S. device makers to ignore. According to the U.S. Department of Commerce International Trade Administration's U.S. Global Trade Outlook, 1995-2000, $9.2 billion of medical equipment was exported from the United States in 1994, and most of these products went to Europe. Exports from the United States are expected to reach $18 billion by 2000.

Paperman says that it would make no sense for a manufacturer to design two versions of a product, one that meets EU standards and one that meets U.S. ones. And according to Kimmel, the EU standards may actually be easier for manufacturers to follow because they don't leave any room for interpretation.

Certainly those manufacturers who plan to enter the European market in the near future must not hesitate to begin following the EU standards. Caran says that "test cycles typically take two to three years, and the product has to be in actual operation for 90 days before it can even be given an assessment, much less approval. The deadline for compliance is June 15, 1998. There will be no extensions. You may have been making a product for 30 years, but if you don't have that approval, it will be a criminal offense to sell it in Europe."

Caran's company, Technology International, helps U.S. manufacturers get European approval. Based on the number of applications she has now, she predicts "mass panic as U.S. manufacturers wait until the last minute before seeking EU approval. Obviously, the time to get started is now."

Copyright © 1997 Medical Device & Diagnostic Industry

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