Machine Design
New rules for Medical Devices

New rules for Medical Devices

New standards go into effect for medical devices this year. They center on risk management.

Authored by:
Patrick Kinyanjui
Senior Engineer Fischer Connectors
Alpharetta, Ga.
Edited by Stephen J. Mraz
Senior Editor
[email protected]

Companies that make medical devices, as well as subcomponents such as cables and connectors, must ensure their practices and products meet a new regulatory standard by July of this year: the third edition of the International Electrotechnical Commission’s 60601-1:2005 (IEC 60601). In fact, the U.ŒS. will be a latecomer to these new regulations as Canada and European companies have been operating under this new standard since last June.

Managing risk
The major thrust of the standard is to force companies to assess the safety and risk the medical devices they design and manufacture pose to patients, health-care workers, and maintenance technicians.

U.ŒS. regulations have long recognized and tried to limit the dangers inherent in medical devices. FDA regulations, for example, mandate different review and permitting processes depending on how risky the new device is. Various medical devices pose different levels of risk, so the FDA breaks devices down into three categories:

• Class I: Low-risk devices. These devices are actually exempt from any formal review prior to being marketed.
• Class II: Moderate-risk devices. The FDA requires these devices be substantially equivalent to an already approved device.
• Class III: High-risk devices. These devices must successfully undergo clinical trials that demonstrate the device’s safety and efficacy.

In Europe, the CE-marking system also relies on a risk-based approach. It determines the risk of medical devices based on a host of factors, including the duration of body contact, invasive character, the energy source, effects on the circulation or nervous systems, and diagnostic impact.

In fact, the most fundamental change in approval processes for medical devices over the past decade has been the adoption of formal risk management. Until now, for example, the FDA only recommends that manufacturers voluntarily follow ISO 14971, a standard on risk management and medical devices. That’s about to change for many medical manufacturers.

IEC 60601-1: The new approach
Today’s trends in medical-device regulations favor risk categorization and management and quality systems. And this is what the new edition of IEC 60601-1 mandates. The IEC first published technical standards for the safety and effectiveness of medical electrical equipment in 1977. Since then, they have been updated to include the general standard, about 10 collateral standards, and about 60 specific standards.

Complying with IEC 60601-1 will be no easy matter. It requires a shift to applying risk management to product design and development, aligning the standard with the industry’s broad regulatory trends over the past decade. Manufacturers of all types of electrical medical equipment will experience this shift in several ways. For example:

• A product’s essential performance characteristics must be examined in relation to criteria needed to avoid unacceptable risk.
• The manufacturer’s process for complying with IEC 60601-1 must comply with risk-management principles found in ISO 14971.
• Every device will need a risk-management file.

In addition to adopting risk management to device development, the new standard also revises technical requirements in areas ranging from mechanical hazards such as crushing and instability to the use of alarms.

Connectors and cables
As an example, let’s look at one niche area: cables and connectors for medical devices. Despite the fact that these components tend to be well engineered and proven, when it comes to cables and connectors, virtually every section of the standard contains important changes.

For instance, the standard changes the definition and requirements for creepage and air clearance (subsection 8.9). Both of these are critical for identifying how a device reduces risk to patients and operators. So device manufacturers will need to assess how a connectors’ creepage and air clearance increase or decrease the risks associated with their devices. To do this, they must first know how creepage and air clearance are defined and measured. Here are the new definitions:

• Creepage: the shortest distance on the surface of an insulating material between two conductive elements.
• Air clearance: the shortest distance through the air between two conductive elements.

Creepage and air-clearance values can be complicated, therefore developers should work closely with suppliers to ensure they are designing for function and the design complies with this new standard. (The nearby illustration, Creepage and clearance, gives some instructions on how to measure them.)

But even if suppliers work with developers to make sure they have the proper specifications for connectors and cables, it is still the device manufacturer’s responsibility to define essential performance requirements and related technical specifications so that the risk-assessment profile is accurate.

In today’s increasingly IT-enabled and interoperable world of medical devices, electrical connectors play a vital role in delivering features and functions. They must also be evaluated when manufacturers develop a risk-assessment profile for new or updated devices.

Developers should understand the rules in IEC 60601 so they can specify connectors that comply with technical requirements, satisfy performance characteristics required for their device, and eliminate unacceptable risks related to the use of the device. Working with qualified suppliers can makes these tasks simpler.

A checklist of connector specs Here is a list of the technical information manufacturers provide to connector and assembly suppliers. Having this info ready — even before contacting the supplier — can speed up connector and cabling design and selection, which should accelerate the manufacturer’s development schedule.
1. Number of contacts needed
2. Voltage and current ratings of each contact
3. Known creepage and air clearance requirements for each contact
4. Environmental requirements
5. Material requirements and use (metal, plastic, reusable versus disposable, etc.)
6. Tests to be performed on the completed assembly
7. Cable requirements for signal or power(twisted pairs, coax, etc.

Browsing IEC 60601’s index
IEC 60601 Series — Medical Electrical Equipment — Part 1: General Requirements for Basic Safety and Essential Performance (IEC 60601-1: 2005) — applies to the basic safety and performance of electric medical equipment (ME) and systems. Here are some of the standard’s major sections:
1. Scope, object, and related standards
2. Normative references
3. Terminology and definitions
4. General requirements
5. General requirements for testing ME
6. Classification of ME and systems
7. ME identification, marking, and documents
8. Protection against electrical hazards from ME
9. Protection against mechanical hazards of ME and systems
10. Protection against unwanted and excessive radiation hazards
11. Protection against excessive temperatures and other hazards
12. Accuracy of controls and instruments and protection against hazardous outputs
13. Hazardous situations and fault conditions
14. Programmable electrical medical systems
15. Construction of ME
16. ME systems
17. Electromagnetic compatibility of ME and systems

© 2013 Penton Media, Inc.

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