Medical

CAD Nerds has over 8+ years experience in 3D for Medical Devices with multiple leading medical device manufacturers.

60601-1 3rd Edition and Design Controls: Good Idea

If you ever worked in medical device engineering (or generally for a medical device company in virtually any capacity), you know that surviving audits is a revolving part of the game. As a design engineer, this can sometimes seem rather frustrating, as you almost get the mindset that you are dedicating too much time to designing a product to pass an audit (aka paperwork) as opposed to optimizing the design for its use (much more fun).

The consequences of failing an audit could be disastrous for a company. They range anywhere from an official warning to the dreaded recall or even worse, an injunction on product sales. A lot of the responsibility towards convincing a regulatory body that you’re offering a safe and reliable device lies with the development team. For this reason I’ve come to look at auditors as an important extension of the review team, as opposed to bureaucrats looking to ruin your day. Sometimes, you may feel they come across as arrogant (i.e. who is this fellow that just waltzed in here and thinks he understands my design better than I do???). However, the sooner you accept that they are critiquing a system and not your acumen the sooner you realize that a good system ultimately helps everyone.

The main role of IEC 60601-1 3rd edition is to make sure that medical device designers have evaluated their product and accounted for “unacceptable” risk. “Unacceptable” risk is determined based on a combination of the severity of a device failure to the operator and/or patient, as well as the frequency with which the failure can be expected to occur. Generally, it’s up to the product manufacturer to develop a well-thought out acceptable risk matrix based on the device’s use. Keep in mind that risk is not just limited to the engineering design, but also the entire process that the medical device company uses to produce and sell product. These, respectively, are defined as DFMEA (Design Failure Mode Effect Analysis) and PFMEA (Process Failure Mode Effect Analysis).

Of course, regulatory bodies like the FDA are not unrealistic. They understand that medical devices are complicated and it is impossible to predict every failure mode, especially so the more sophisticated a device is. However, a medical device manufacturer is required to have a system in place to identify, monitor, document and deal with issues whenever they occur. Really, these are good guidelines to follow even if your industry doesn’t fall under the purview of the FDA. Here’s why:

Essential Performance:

Most of the time, if you are part of the engineering development team of a product, you are so familiar with the device’s workings that you may not realize someone outside of your team may not as readily understand what the key aspects of even the most basic design features are.

For instance, one of the first projects I worked on as an engineer was ensuring the internal structure of a device was IP64 ingress protected, while the outside case covers were present to provide a nice aesthetic look and feel to the device. However, everyone outside that mechanical engineering team just simply knew the whole device had IP64 ingress protection. Once the product was in market, a particular customer tended to handle the device in a very rough fashion, resulting in a number of the devices getting their covers fractured. This set off a panic in the company’s quality department, because there was an assumption that these fractures compromised the device’s ingress resistance integrity, which would be a big deal if it were the case. At this point, we (mechanical engineering design team) realized that either we had done a poor job communicating the design strategy to the other departments, in no small part due to a very compartmentalized company structure.

IEC 60601-1 3rd edition stresses the importance of identifying and documenting essential performance in medical device development. Key strategies can be documented in design specifications and / or explicit requirements. Additionally, a verification or validation protocol must exist for what is identified as an essential performance component. This ties in with the risk management aspect as an essential performance component must also be evaluated for acceptable risk. In my ingress design example above, implementation of proper design controls based on essential performance would have gone a long way in avoiding all the misinformation. In fact, after that debacle amongst a few others, product designs would undergo regular design reviews where the key development team would regularly update other department leaders on key design strategies.

Design Reviews:

Regulatory bodies are big on design reviews. You will NOT get a CE marking and be allowed to sell your product in the EU marketplace if you cannot show your organization has a system in place to conduct regular design reviews. These reviews should have 4 things:

1) Agenda
2) Discussion and action items
3) Follow-up, implementation and closure of action items
4) Signatures

Design reviews that follow the above criteria should be a no brainer to any design firm. The number of times I’ve been part of discussions where every person left the meeting thinking they were on the same page, only to later discover that everyone was talking past each other are too many to count. Putting it in writing eliminates problems, and should be included as part of a design history file.

​ All in all, having clear design requirements, essential performance components and strategies, risk analysis, verification and/or validation protocols (for each requirement, essential component and risk), and documented design reviews. If you keep this mindset, your confidence in your design will be tip top!