FAQ for Medical Standards

The following Frequently Asked Questions were compiled during the 2010 IDSA Medical Section Regional Reviews of ANSI/AAMI HE 75:2009 in California, Pennsylvania, Rhode Island and Ohio. The questions are from the attendees who represented a broad spectrum of disciplines where industrial design was in the minority. The answers are those given by the presenters and members of the AAMI HE75 committee – Mary Beth Privitera, Steve Wilcox, Michael Wiklund and Sean Hägen. The answers are not official responses by AAMI.

Q: Does HE 75 replace HE74?

A: No, HE75 replaces HE48; HE74 is all about process for QSR – It covers what to do…HE 75 is about designing – How to do it.

Q: Is this huge document comprehensive?

A: Unfortunately no, it’s an excellent starting place, but it is not intended to be a prescriptive recipe book. It was written as a reference to guide HF design decisions and compromises in addition to providing design rationales for those choices.

Q: What is FDA’s focus on this standard?

A: The FDA will look for references in your user requirements to the standard but they will pay particular attention to section 5 on risk analysis. All standards are voluntary and as such, they can be ignored.  The intent of HE 75 is to promote awareness of ergonomic considerations; it’s up to the design team to implement.

Q: Is it [HE75] a living document?

A: I don’t think this is the intention- if we need to make revisions, I think there will be HE 76…..

Q: Does environmental section cover stress risers?

A: No, stress risers come from multiple elements and would change based on the users and the conditions of usage; the environment section covers physical measures which are to be taken into consideration when selecting HF parameters such as an audible alarm.

Q: Testing instructions-development-where is the standard? 

A: HE75 does not directly address this- I think it’s touched on in the labeling section but honestly this is not a strong section.

Q: In-service/training guidelines where is this covered? 

A: Section 9.3.6.7 mentions this type of training. 

Q: How does FDA refer to the standard and use it?

A: FDA recognizes HE75 by giving manufactures another method to demonstrate their compliance – e.g. device manufacturers should reference compliance with ANSI/AAMI HE 75 Section 8.3.2.4.3 noise limits….

Q: Is there anthro data on the “growing” (fat people) population?

A: Not specifically but Section 7.3.3.2 mentions the following:

“Therefore, the data referenced in this section are arguably the best available to date for use in designing for medical instrumentation users. It should be noted, however, that because height and weight for human populations have increased since 2000, designers should consider these proportions during the design specification phase.”

Q: Is there consideration for gloves & repetitive actions? 

A: Yes, Section 4.4.5, mentions the external factors that influence task performance, Section 22.4.5.9, mentions testing the device in as a realistic situation, Section 22.4.7.6.8, mentions increasing time for performing a task.

Q: Is there an emotional outline in the standard?

A: No- emotional response is based on specific user groups and should be evaluated in contextual enquiry study (formative)

Q: Just noticeable differences covered in standard? 

A: Yes- see the anthropometry & biomechanics section…HE 75 replace HE 48, which provided only very general guidance on the design of displays, controls, consoles, and equipment based on the body of knowledge accumulated from aerospace, defense, and other industries. HE 75 focuses on the unique use interface challenges of the medical industry, and provides general good practices for the design of human–machine interfaces.

Q: Is the Just Noticeable Differences user group specific?

A: Where possible it’s listed not in terms of specific user group rather in gender and percentile.

Q: When do you use the standard in the iterative design process?

A: Immediately and/or just after concept generation.  During the onset of a design project, general standards and principles are helpful guidelines, once a design concept has been flushed out; specific standards can be applied, providing the engineering team with ergonomic limits/guidance.

Q: Controls – for example button size: are they too prescriptive? 

A: HE 75 presents best practices, often there are conflicting design requirements which need to be negotiated under prioritization.

Q: When a client wants to deviate from standard how do you use standard?

A: Deviation with good justification will happen as a result of the natural consequences/trade-offs within product development.  All standards are voluntary as such are subject to being ignored.  The intent of HE 75 is to promote awareness of ergonomic considerations, it is up to the design team to implement.

Q: How do you provide rationale for a deviation? 

A: Provide good documentation of the trade-off – rationalize any compromises with user inputs.

Q: Are there training courses [for HE75]? 

A: Yes, only Bob North’s course [Through the AAMI]

Q: Should we have some [standards training courses] for ID? 

A: We could do a webinar through IDSA…

Q: How is the standard assimilated?

A: Painfully…depends on the organization. Many organizations are now adding sections into the Quality Control Process to cover usability testing.

Q: How do you get on a committee? 

A: Become a member of the AAMI

Q: Is there information on auditory diminish rate?

A: That information may be found in the alarm section and/or the biomechanics section

Q: Are environmental conditions making standards tougher?

A: Sustainability and environmental issues are not covered in the standard

Q: Are touch screen errors statistics (like a list of gotchas) in the standard?

A: No, those were not really available at the time of publishing…I would bet money that Mike Wiklund has some…perhaps they will appear in the companion HE75 book

Q: Is there information on gestural inputs?

A: No, same as touch screen

Q: What is a good sample size for contextual observation and usability studies?

A: That’s always the big question…testing behavior allows for a relatively small N based on studies that show patterns in behavior becoming significant in samples as small as 7 +/-2…so assuming a study is based on behavior and not static opinion and your sample is homogeneous you can have such small samples…but the FDA is likely to red-flag anything below an N=16; especially summative testing (or an N=25 if the test only involves a single user population).

Q: Does it [HE75] tell you how to define homogeneous sample – in reference to market and user sample?

A: No, nor does it prescribe the appropriate sample size – that’s a case by case requirement

Q:  FDA isn’t interested in Quantitative analysis for what the risks are, but how do they compare devices with a predecessor device

A: FDA wants to know ratings for use error of the devices, but won’t accept a certain kind of argument for why the device is safe.  Example, if the error only happened 1 out of 30 uses they would not accept it.

Q: Does the FDA regulate the root analysis for process of design.

A:  There are no general principles; it’s really a device by device issue.