Medical Equipment in Simulated Animal Enclosures

[Roland chung]

Hi forum,

Test laboratory just declined our CB application for a home use nebulizer shaped like a panda.

The reason is that IEC 60335-1 (household appliance) does not allow the equipment to shape the enclosure like a toy. Although, the IEC 60601-1-11 does not address cases where the device is designed to look like a toy. It is not convincing that the "children playing" is an unacceptable risk for household appliance, but an acceptable risk for home use medical device.

Should be grateful for your advice, if any.

 

[Peter Selvey]

The test lab's concern sounds reasonable.

Technically, the manufacturer should have documented the issue in the risk management file. If was not in the file, that's already a bit of a red flag since since it is a fairly obvious misuse.

Regardless, once it is in the file, the manufacturer will have to look at the various possible event sequences, assign probability and severity numbers, and judge if the risk is acceptable. As it is a critical point, these details (both sequences and numbers) would need to be plausible and realistic.

A nebulizer is a lower risk device than most household appliances, so there is a faint possibility that it works out OK (acceptable risk). But the high probability of misuse makes it hard to justify even low severity events.

 

[Roland chung]

Thanks, peter.
It would be difficult to assign plausible probability and severity numbers. If the conclusion of usability validation in a simulated use or actual use environment is positive, can the risk be considered acceptable?

 

[Peter Selvey]

For usability, real user testing is a actually a weak verification tool as mentioned in the rationale of IEC 62366. It's hard to get enough data to be statistically relevant. Instead usability is mostly about adding common sense usability related specifications like on a touch screen having user buttons with a minimum size and space from other buttons, touch gives user feedback within 0.1s; verification then just checks these usability related specifications have been implemented.

Following that thinking, a common sense usability specification might simply be "don't make it look toy"

Apart from the possible damage if a child mistakes it for a toy (e.g. playing somehow influences the effective delivery of medication), to prove it is safe a manufacturer would also need to study the standards for toys as they will raise a lot of special issues e.g. small parts, toxicity and so on.

I think it is a big task and there is a high chance the end result is that some problem is raised that clearly kills the idea (risk is unacceptable).

That's why IEC 60335 applied a "blanket rule" to ban appliances looking like toys.

 

[Roland chung]

I agree with your points. But the team said neither IEC 60601-1 nor IEC 60601-1-11 bans this design. The Philips "Sami the Seal" nebulizer is shaped like a seal to attract children.