Medical device validation is a critical aspect of healthcare, but it’s rarely discussed outside of design and manufacturing circles. The Food and Drug Administration (FDA) is responsible for oversight, but by and large, they’ve delegated that role to individual manufacturers. The FDA’s Design Control Guidance for Medical Device Manufacturers policy specifically states:
“Each manufacturer shall establish and maintain procedures for validating the device design.”
Validation is a critical step in a product’s lifecycle. While it is sometimes confused with verification, these two stages are fundamentally different and are focused on distinct measurements and outcomes. Verification should be performed at numerous stages throughout the design, development and manufacturing processes. It is primarily concerned with evaluating whether each component is functioning correctly. Conversely, validation is something that, by definition, can only occur once the entire device is assembled and ready for use. Its goal is to evaluate whether the device actually meets the patient’s needs.
It’s possible for a machine to pass every single verification test and that each mechanical, electrical and software component operates flawlessly. The engineers are satisfied with the system, the project manager is happy with the process and the manufacturing department is confident it can put everything together according to the design specs. Validation is structured to ensure that, even when this is the case, the device delivers the desired result to the patient.
The Two Processes of Validation
Two separate processes make up this critical evaluation stage: process validation and design validation. Process validation is essentially the transition point between verification and validation: it ensures that a device, as a cohesive unit, consistently produces a result or product that meets design specifications.
When a piece of medical technology is first conceived, doctors and engineers work together to define what it’s supposed to do. Is it passive, simply measuring a patient’s temperature? Is it active, and having it in place is critical to keep a patient’s heart beating? Once the essential function is outlined, the team must define how this is to be measured and evaluated with precise specifications and fault tolerances. Process validation confirms that a device can not only meet these specs, but it can do so consistently.
Design validation is structured to confirm that those specifications are the right ones in a real-world scenario. Once the product is designed, prototyped, manufactured, delivered and placed in operation, does it accomplish what doctors needed it to do in the first place?
The Four Stages of Validation
The FDA defines four specific processes that make up validation: planning, review, methods and documentation. Effectively executing all four of these will produce one of two outcomes: either it will definitively confirm that a device is consistently achieving what it was designed to do and it’s medically useful, or it will show that it isn’t. If the latter is the case, these stages will uncover precisely where and why that is the case.
Although validation primarily occurs at the end of the process, planning for it begins in the earliest design stages. As the engineers and medical staff define what the device should accomplish and how it should perform, part of that process is outlining how that performance will be measured. The team needs to take it only one step further to draft the basic outline for how validation should proceed.
Validation review focuses on exposing any deficiencies in the original assumptions about patient needs and intended uses. Perhaps the device ends up being too large for its designed purpose, or the buttons are too difficult to press. Any problems are classified as either insignificant or erroneous; if the deficiency is substantial enough, corrective action may be required to fix the situation.
When the FDA defines validation methods, it states that although not all devices need clinical trials, all of them “require clinical validation and should be tested in the actual or simulated use environment…” Critical attention is paid to every detail because any deviation could result in problems down the line. For example, any device being evaluated must come off the line as part of the normal manufacturing process without any special attention paid to it — it cannot be a prototype, and it cannot be designed as a test unit. The FDA even specifies that it should be mailed or delivered in the same way it usually would in order to reveal any problems with packaging, such as electrostatic packing material that might interfere with electrical component operation. This is real-world testing at its finest.
Once the validation process is complete, the final stage is documentation. Every step along the way must be recorded and stored for future reference. This includes things like device master records, comprehensive specification definitions, procedural checklists, work instructions, research and technical proposals. Starting from planning and design, research and technical proposals documentation and comprehensive specification definitions records must be maintained for regulatory compliance and system continuity. In development, specific work instructions and procedural checklists that outline the exact steps needed to configure the prototype or proof of concept must be captured and stored to ensure that once in production, medical device products are properly configured, free from defects and right every time.
Validation is an indispensable cornerstone of a medical device’s lifecycle. Without it, we would undoubtedly have a host of functioning products that simply missed the mark.