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93/42/EEC Class I Medical Device Weigh Scale - Class A under EN 62304?

Personally I agree that a set of scales to weight a patient is a medical device, but to use your previous example, a set of pharmacy scales to weigh a cytotoxic chemotherapy treatment is not a medical device according to the MDD!



ok, thanks
good angle... i can use that point

it does not make a diagnosis but is used to make a diagnosis...

after reading the definition in the mdd again this makes sense
one of the discussions we had was on yes or no some device makes a diagnosis, it does not have to, if it is intended to be used to make a diagnosis that makes it a medical device

Cressel - 2010

The MDD 93/42/EEC,as amended by Directive 2007/47/EEC, defines a medical device as follows (see Article 1, Section 2a):
(a) " medical device” means any instrument, apparatus, appliance, software, material or other article, whether used alone or in combination, including the software intended by its manufacturer to be used specifically for diagnostic and/or therapeutic purposes and necessary for its proper application, intended by the manufacturer to be used for human beings for the purpose of:
- diagnosis, prevention, monitoring, treatment or alleviation of disease,
- diagnosis, monitoring, treatment, alleviation of or compensation for an injury
or handicap,
- investigation, replacement or modification of the anatomy or of a
physiological process,
- control of conception,
and which does not achieve its principal intended action in or on the human body by pharmacological, immunological or metabolic means, but which may be assisted in its function by such means.

According to my understanding, a weight scale is NOT within the above defintion of a "medical device".

I have a question. I am new to this forum, and am getting mixed messages from the regulatory affairs people I have been dealing with. My company makes a universal dose counting scales for asthma inhalers (pMDIs) In Canada (where I am from) Health Canada has ruled that it is not a medical device. I am told that in the US it will be considered a Class II device by FDA because it is used in conjunction with a Class II device. Is this true? My device merely informs the user of how many dose they have remaining, so that they can decide to replenish the medicine. I have an "opinion" from MHRA in UK that it is not a device, and in Australia they basically said "you decide" Any direction you can give me would be greatly appreciated.

Thank you, Cressel


Involved In Discussions
We had an audit and the auditor asked us to check if the EN62304 was even applicable if the medical device is a STAND ALONE device.

Now not having looked at this for such a long time... it has given me cause to have a brainache!

1) the weight scale is sold by itself; it is not connected to a pc, there is no connecter for RS232, bluetooth, usb, wireless, etc. There is no communicaiton to an external database.

2) the device uses a microcontroller (thus FIRMWARE / EMBEDDED Software).
The software itself cannot be modified by the customer, albeit some performance criteria could be changed (calibration, gravity setting, on-time, etc.). This would fall under 60601-1-4 (PEMS).

Knowing the above do you think that EN62304 is NOT required and that the weigh system can be justified as a STAND ALONE system?

also, does anyone know where the formal definition of STAND ALONE device originated?

thank you for your time
Looking through the post (going back to the 2009 comments), one point to make about weigh scales being a medical device or not it that it is entirely dependent on the claim made by the manufacturer (in the labelling, instruction manual, advertising), not actual use.

Example: a scale is bought from K-Mart, the manual makes no claim of diagnostic purpose, but nevertheless used in a medical clinic. This is not a medical device. The same is true of many things used in the medical environment which affect the clinical outcome but were never designed (or claimed) specifically to be for a medical purpose.

As for the application of 62304:
If the scales are advertised or claimed to be for a medical purpose, then yes, 62304 is technically applicable even if it is just a embedded PIC which samples the data from the sensor, applies some filtering, adds calculations such as non-linear compensation, temperature compensation etc and then displays the result. It's still software.

Class A controls are fairly weak so it would not be much work for compliance. They essentially treat the "software system" as a black box anyway.

You could also argue that the device is so simple that complete system testing (the complete device, hardware, software, mechanical) is sufficient, no need to pull the software out as a separate component with special controls.

Depending on the regulation, this latter approach may require some formal documentation to justify non-application of 62304. In Europe, "alternate solutions" are required by law to be documented if a harmonized standard is not applied. EN 62304 is harmonized.

If you follow this process correctly (i.e. first recognizing the standard is harmonized and applicable, and then justifying why your alternate solution still meets the related essential requirements), an auditor cannot write a non-compliance for not applying a harmonized standard. The auditor is then obliged to find objective evidence why your alternate solution does not meet the essential requirement, which can be difficult.


Quite Involved in Discussions
Hello Qu1nn,

Preamble: there is NO direct link between 62304 software class A,B,C and FDA class I, II, III.

Your device design should be designed according 60601-1. 60601-1 3rd edition is a recognized standard by FDA. Section 14 of this standard is about software embedded in an electro-mechanical system (your case). Section 14 of 60601-1 quotes 62304.
Given your intended use, my opinion is that your software falls into class A of 62304 (no injury). So you can implement a very light process, where the testing phase of software in well documented. Proofs that software works are enough.

By the way, I haven't found a definition of stand-alone, neither in FDA, nor in EC guidances.


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