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Design control application

Design controls may be applied to any product development process. The FDA example shown illustrates the influence of design controls on a design process.

About

Design controls are good quality assurance practices are used for the design of medical devices and that they are consistent with quality system requirements worldwide, the Food and Drug Administration revised the Current Good Manufacturing Practice (CGMP) requirements by incorporating them into the Quality System Regulation, 21 CFR Part 820.

Because design controls must apply to a wide variety of devices, the regulation does not prescribe the practices that must be used. Instead, it establishes a framework that manufacturers must use when developing and implementing design controls. The framework provides manufacturers with the flexibility needed to develop design controls that both comply with the regulation and are most appropriate for their own design and development processes. This guidance is intended to assist manufacturers in understanding the intent of the regulation. Design controls are based upon quality assurance and engineering principles.

Design controls are a component of a comprehensive quality system that covers the life of a device. The assurance process is a total systems approach that extends from the development of device requirements through design, production, distribution, use, maintenance, and eventually, obsolescence. Design control begins with development and approval of design inputs, and includes the design of a device and the associated manufacturing processes. Design control does not end with the transfer of a design to production. Design control applies to all changes to the device or manufacturing process design, including those occurring long after a device has been introduced to the market. This includes evolutionary changes such as performance enhancements as well as revolutionary changes such as corrective actions resulting from the analysis of failed product. The changes are part of a continuous, ongoing effort to design and develop a device that meets the needs of the user and/or patient. Thus, the design control process is revisited many times during the life of a product.

Quality System

In addition to procedures and work instructions necessary for the implementation of design controls, policies and procedures may also be needed for other determinants of device quality that should be considered during the design process. The need for policies and procedures for these factors is dependent upon the types of devices manufactured by a company and the risks associated with their use. Management with executive responsibility has the responsibility for determining what is needed.

Example of topics for which policies and procedures may be appropriate for the device are:

  • risk management
  • reliability
  • maintainability
  • serviceability
  • human factors engineering
  • software engineering
  • use of standards
  • configuration management
  • compliance with regulatory requirements
  • device evaluation (which may include third party product certification or approval)
  • clinical evaluations
  • document controls
  • use of consultants
  • use of subcontractors
  • use of company historical data[1]

Talking Points

Clinical engineers and OEMs evaluate the degree of compliance of a design control system, including identification of noncompliance issues, and be prepared to implement the improvements needed to meet both regulatory and business requirements.

Senior management needs to decide how the design function is to be managed and by whom. Senior management should also ensure that internal policies are established for design issues such as:

  • assessing new product ideas
  • training and retraining of design managers and design staff
  • use of consultants
  • evaluation of the design process
  • product evaluation, including third party product certification and approvals
  • patenting or other means of design protection

It is for senior management to ensure that adequate resources are available to carry out the design in the required time. This may involve reinforcing the skills and equipment available internally and/or obtaining external resources.

DESIGN AND DEVELOPMENT PLANNING

Design and development planning is needed to ensure that the design process is appropriately controlled and that device quality objectives are met. The plans must be consistent with the remainder of the design control requirements. Planning enables management to exercise greater control over the design and development process by clearly communicating policies, procedures, and goals to members of the design and development team, and providing a basis for measuring conformance to quality system objectives.

Design activities should be specified at the level of detail necessary for carrying out the design process. The extent of design and development planning is dependent on the size of the developing organization and the size and complexity of the product to be developed. Some manufacturers may have documented policies and procedures which apply to all design and development activities. For each specific development program, such manufacturers may also prepare a plan which spells out the project-dependent elements in detail, and incorporates the general policies and procedures by reference. Other manufacturers may develop a comprehensive design and development plan which is specifically tailored to each individual project.[2]

DESIGN INPUT

Design input is the starting point for product design. The requirements which form the design input establish a basis for performing subsequent design tasks and validating the design. Therefore, development of a solid foundation of requirements is the single most important design control activity.

Many medical device manufacturers have experience with the adverse effects that incomplete requirements can have on the design process. A frequent complaint of developers is that "there's never time to do it right, but there's always time to do it over." If essential requirements are not identified until validation, expensive redesign and rework may be necessary before a design can be released to production.

By comparison, the experience of companies that have designed devices using clear-cut, comprehensive sets of requirements is that rework and redesign are significantly reduced and product quality is improved. They know that the development of requirements for a medical device of even moderate complexity is a formidable, time-consuming task. They accept the investment in time and resources required to develop the requirements because they know the advantages to be gained in the long run.

Unfortunately, there are a number of common misconceptions regarding the meaning and practical application of the quality system requirements for design input. Many seem to arise from interpreting the requirements as a literal prescription, rather than a set of principles to be followed. In this guidance document, the focus is on explaining the principles and providing examples of how they may be applied in typical situations.[3]

DESIGN OUTPUT

he quality system requirements for design output can be separated into two elements: Design output should be expressed in terms that allow adequate assessment of conformance to design input requirements and should identify the characteristics of the design that are crucial to the safety and proper functioning of the device. This raises two fundamental issues for developers:

  • What constitutes design output?
  • Are the form and content of the design output suitable?

The first issue is important because the typical development project produces voluminous records, some of which may not be categorized as design output. On the other hand, design output must be reasonably comprehensive to be effective. As a general rule, an item is design output if it is a work product, or deliverable item, of a design task listed in the design and development plan, and the item defines, describes, or elaborates an element of the design implementation. Examples include block diagrams, flow charts, software high-level code, and system or subsystem design specifications. The design output in one stage is often part of the design input in subsequent stages.

Design output includes production specifications as well as descriptive materials which define and characterize the design.

Additionally, specifications are to include drawings and documents used to procure components, fabricate, test, inspect, install, maintain, and service the device, such as the following:

  • assembly drawings
  • component and material specifications
  • production and process specifications
  • software machine code (e.g., diskette or master EPROM)
  • work instructions
  • quality assurance specifications and procedures
  • installation and servicing procedures
  • packaging and labeling specifications, including methods and processes used[4]

DESIGN REVIEW

Many types of reviews occur during the course of developing a product. Reviews may have both an internal and external focus. The internal focus is on the feasibility of the design and the produceability of the design with respect to manufacturing and support capabilities. The external focus is on the user requirements; that is, the device design is viewed from the perspective of the user.

The nature of reviews changes and the persons expertise as the design progresses is of utmost importance. During the initial stages, issues related to design input requirements will predominate. Next, the main function of the reviews may be to evaluate or confirm the choice of solutions being offered by the design team. Then, issues such as the choice of materials and the methods of manufacture become more important. During the final stages, issues related to the verification, validation, and production may predominate. The term "review" is commonly used by manufacturers to describe a variety of design assessment activities.[5]

DESIGN VERIFICATION

Verification and validation are associated concepts with very important differences. Various organizations have different definitions for these terms. Medical device manufacturers are encouraged to use the terminology of the quality system requirements in their internal procedures.

To illustrate the concepts, consider a building design analogy. In a typical scenario, the senior architect establishes the design input requirements and sketches the general appearance and construction of the building, but associates or contractors typically elaborate the details of the various mechanical systems. Verification is the process of checking at each stage whether the output conforms to requirements for that stage. For example: does the air conditioning system deliver the specified cooling capacity to each room? Is the roof rated to withstand so many newtons per square meter of wind loading? Is a fire alarm located within 50 meters of each location in the building?

At the same time, the architect has to keep in mind the broader question of whether the results are consistent with the ultimate user requirements. Does the air conditioning system keep the occupants comfortable throughout the building? Will the roof withstand weather extremes expected at the building site? Can the fire alarm be heard throughout the building? Those broader concerns are the essence of validation.

In the initial stages of design, verification is a key quality assurance technique. As the design effort progresses, verification activities become progressively more comprehensive. For example, heat or cooling delivery can be calculated and verified by the air conditioning designer, but the resultant air temperature can only be estimated. Occupant comfort is a function not only of delivered air temperature, but also humidity, heat radiation to or from nearby thermal masses, heat gain or loss through adjacent windows, etc. During the latter design phases, the interaction of these complex factors may be considered during verification of the design.

Validation follows successful verification, and ensures that each requirement for a particular use is fulfilled. Validation of user needs is possible only after the building is built. The air conditioning and fire alarm performance may be validated by testing and inspection, while the strength of the roof will probably be validated by some sort of analysis linked to building codes which are accepted as meeting the needs of the user-subject to possible confirmation during a subsequent severe storm.[6]

DESIGN VALIDATION

Whereas verification is a detailed examination of aspects of a design at various stages in the development, design validation is a cumulative summation of all efforts to assure that the design will conform with user needs and intended use(s), given expected variations in components, materials, manufacturing processes, and the use environment.

1. Validation means confirmation by examination and provision of objective evidence that the particular requirements for a specific intended use can be consistently fulfilled. For example, Fault insertion testing, Failure Modes and Effects Analysis 2. Process Validation means establishing by objective evidence that a process consistently produces a result or product meeting its predetermined specifications. Design Validation means establishing by objective evidence that device specifications conform with user needs and intended use(s).[7]

DESIGN TRANSFER

No design team can anticipate all factors bearing on the success of the design, but procedures for design transfer should address at least the following basic elements. First, the design and development procedures should include a qualitative assessment of the completeness and adequacy of the production specifications. Second, the procedures should ensure that all documents and articles which constitute the production specifications are reviewed and approved. Third, the procedures should ensure that only approved specifications are used to manufacture production devices.

The first item in the preceding list may be addressed during design transfer. The second and third elements are among the basic principles of document control and configuration management. As long as the production specifications are traditional paper documents, there is ample information available to guide manufacturers in implementing suitable procedures. When the production specifications include non-traditional means, flexibility and creativity may be needed to achieve comparable rigor.[8]

DESIGN CHANGES

he design control system has to be concerned with the creation and revision of documents, as well as the management of finished documents. Additional mechanisms are required to provide needed flexibility while preserving the integrity of design documentation. These additional mechanisms are embodied in the procedures for review and approval of various documents. It is important that the design change procedures always include re-verifying and re-validating the design. Fortunately, most design changes occur early in the design process, prior to extensive design validation. Thus, for most design changes, a simple inspection is all that is required. The later in the development cycle that the change occurs, the more important the validation review becomes. There are numerous cases when seemingly innocuous design changes made late in the design phase or following release of the design to market have had disastrous consequences.[9]

DESIGN HISTORY FILE

Design history file (DHF) means a compilation of records which describes the design history of a finished device. The DHF shall contain or reference the records necessary to demonstrate that the design was developed in accordance with the approved design plan and the requirements of this part. Each manufacturer shall establish and maintain a DHF for each type of device.[10]


Reference

  1. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997
  2. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997
  3. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997
  4. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997
  5. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997
  6. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997
  7. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997
  8. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997
  9. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997
  10. FDA. Design Control Guidance For Medical Device Manufacturers. This Guidance relates to FDA 21 CFR 820.30 and Sub-clause 4.4 of ISO 9001. March 11, 1997

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