Playing by The Rules

DN Staff

December 14, 2009

5 Min Read
Playing by The Rules

Regulations and standards are playing a more significant role in medical system design every year. Design teams that were once only tangentially impacted by regulations must now consider a number of different rules throughout the design cycle.

Regulators say there's good reason for strengthening their focus on design. An FDA study of data from the late 1980s found that almost half of all medical device recalls stemmed from design flaws. Environmental watchdogs note that the components used in a large percentage of medical products have included too many materials that create environmental problems.

The focus on the design side began back in the late 1990s, when the FDA began requiring companies to follow some design control principles. The 21 CFR Part 820 is one of the critical aspects of the FDA's family, focusing on design controls.

While this, and other FDA documents, set many of the rules engineers must follow, they aren't the only ones. A host of environmental regulations now impact the majority of system designs, with standards bodies also creating specifications that engineers must integrate into their plans.

Many Techniques

Suppliers have a range of techniques for addressing these requirements. MasterControl of Salt Lake City, UT contends that using Web-based tools provides a holistic way to manage the design control process. This cloud concept ensures all data is stored in the same place, and it makes critical revision tracking simpler, making the audit process smoother.

As these design concepts change, many OEMs are turning to contractors who can handle all aspects of the design. That's another way to keep the entirety of the project in one place.

"Over the past few years, we've seen more demand for turnkey outsourcing as companies look for outside help earlier in the design process," says Dave Schiff, director of engineering for the Bresslergroup Inc., an industrial design firm based in Philadelphia, PA.

Regardless of who does the engineering work, the medical industry is changing the way its products are designed. Companies as diverse as National Instruments and The MathWorks are urging companies to adopt model-based design and simulation to help ensure the requirement specifications are correct.

When design ideas are validated in a virtual environment, errors can be spotted earlier in the process when they're easier to fix. But simply using modeling won't meet the demands of regulators who want lots of documentation on the reasoning behind the testing techniques. "The validation and verification processes need to be proven," Schiff says.

This approach also helps keep costs down, since fewer prototypes are needed. Using models also helps companies perform risk assessment. The Occupational Safety and Health Administration is putting more emphasis on risk assessment, urging designers to determine acceptable risks. This approach is being adopted fairly broadly as more engineers understand its benefits.

"We're doing more and more in failure mode effect analysis at the design phase," Schiff says. "At each step in the usage scenario, we look at the likelihood of something happening and determine the impact of the problem. Then we figure out how to eliminate or mitigate the problem."

Using risk assessment helped the Bresslergroup find potential problems with a needle guard that protects caretakers from inadvertent needle sticks. A spring plays a critical role, so the tolerances used to manufacture it have to be extremely tight.

"If the spring isn't molded appropriately, it might not snap over the needle. We specified a tolerance for the spring force and made that part of the verification test," Schiff says. "A document that describes the tolerances for this spring are one part of the handoff that goes to manufacturing."

That's a prime example of the way the designer's role extends into manufacturing. Maintaining data integrity is another.

Companies must first ensure that all the CAD files compiled during design are translated correctly when data is converted to the formats used in manufacturing. When either manufacturing or design teams make changes, each side must be sure the alterations don't bring any unexpected consequences.

Documentation and communication are key facets of this issue. "Everything has to be tightly tied to manufacturing," Schiff says. "You also need much more of a paper trail."

Following The Rules

While design engineers worry about documenting their side of the job, they also have to keep an eye on documents created by regulators and standards bodies. Keeping track of updates to standards is becoming an important aspect of design management. "There can be all kinds of catastrophic results from not having all the proper standards," says Alison Ruger, business development director at IHS Inc. of Englewood, CO.

If a product uses 10 standards and regulations that each update once a year, design teams with a quick 18-month development and approval cycle will need to factor in around 15 specification changes. If a material is banned or a specification is revised significantly, products could be barred from sale in some countries or lose market share because they're out of date.

In electronic designs, regulations like RoHS, REACH and WEEE continue to expand the number of banned substances that already includes lead, cadmium and mercury. More plastics are also being added, and the U.S. government is even proposing a bill that will make vendors keep track of where ore for tin and other materials was mined. "There's a proliferation of environmental regulations," Ruger says.

Though engineers realize it's important to document all the actions they take to create solid designs, it's not something most of them want to do. "Bookkeeping and document management can be time-consuming, usually taking a dedicated full-time or half-time person," Schiff says. "It can bog down a rapid turnaround project if the engineers are keeping track of documentation."

However, many product developers agree that while the paperwork issue is annoying, the concepts and techniques connected to them have worthwhile payoffs.

"Good design controls lay the foundation for the healthy design and development of medical devices in general," says Kathryn Kukulka, regulatory affairs director at Omnica Corp. of Irvine, CA. "Properly instituted, these guidelines provide the manufacturer with the opportunity to address and/or correct problems early in the process."

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