Regarding the definition of "pneumatic" in relation to IEC 60601-1

[milagre]

Hello everyone,

In 60601-1, subclause 9.7 is applicable to "Pneumatic and hydraulic parts." I am trying to determine how the standard defines pneumatic.

Definitions for the word pneumatic can vary significantly from "containing gas under pressure," to "using air pressure to move or work."

My device is a neonatal CPAP. The "pneumatic" system in our device mixes air and oxygen together and then gives it to the patient. "Pneumatics" do not assist in the motion or support of our device (although I guess you could make the arguement the gas does some "work" in the lungs).

The easiest and perhaps intended way to define pneumatic is to go off of the 9.7.1 ("General") contents. Here, it says:

The requirements of this subclause apply to vessels and parts of ME EQUIPMENT subject to pressure, the rupture of
which could result in an unacceptable RISK.​

You could use this statement to define "pneumatic" as any part subject to pressure that would result in unacceptable risk if it ruptured.

Of course, my CPAP device would have an unacceptable risk if tubing ruptured, as the device would lose essential performance of providing air to the patient.

My question:

Should my path forward be to show that the tubing cannot rupture in normal or single fault conditions? This is true, but the phrasing of 9.7.1 seemed to imply that any rupture, even beyond single fault conditions, would have to be considered. Maybe that is only my inexperience talking.


I looking forward to hearing opinions on this matter.

 

[Pads38]

Re: Regarding the definition of "pneumatic" in relation to 60601-1

Is your CPAP device pneumatic? - No.

Could you use other parts of clause 9.7 (pressure vessels) to inform your Risk Analysis? - Yes.

 

[milagre]

Re: Regarding the definition of "pneumatic" in relation to 60601-1

I would just as soon declare our CPAP device as not pneumatic as well. I definitely don't think that it falls under pneumatic as the standard seems to define it. I just wasn't clear on if I had to prove it wasn't pneumatic per the standard's definition of that term.

That is a good point on informing the Risk Analysis.

 

[Ronen E]

Re: Regarding the definition of "pneumatic" in relation to 60601-1

Is your CPAP device pneumatic? - No.

I would be a bit more cautious about it. Every CPAP device has some form of air compressor and pipework to handle air at pressures higher than the ambient.

On the other hand, I don't know 60601's nitty gritty. I was going to suggest "consult an experienced accredited test lab", but I'm not sure whether this is something "new" from the 3rd edition, and I feel that at the moment nobody is really very experienced with the 3rd edition, enough to make close calls in grey areas.

Cheers,
Ronen.

 

[Pads38]

The "Pressure Vessel" section of 60601 (Clause 9.7) is not very detailed and leaves much to "Risk Management".

For more detailed guidance it might be worth looking at a standard such as 60601-2-12 - Critical Care Ventilators. Don't try and say that you are in compliance with that - it will have some detailed requirements that are applicable due to the criticality of use. Instead say you are "using it to inform your design process".

I am not familiar with it, but it is likely to have suitable tests detailed for the pressurised parts and gas delivery systems.

Beyond that, there may be something useful in the standards for medical gas delivery though I am not familiar with those ones.

EDIT
Just checked - 60601-2-12 has been withdrawn!
That's a pity - it had requirements for pressure vessels and for bio-compatibility, although it did explicitly exclude CPAP.
I don't know what has replaced it.

 

[Pads38]

Update to the post above:

IEC 60601-2-12 has been replaced by ISO 80601-2-12 and ISO 60601-2-13 covers anaesthetic workstations.

 

[milagre]

Cheers Pads. I'll request a copy and look into how ISO 80601-2-12 can help us.

 

[Ronen E]

Hi,

I'm starting to sound like a broken record... BUT... I would be cautious about using standards written for ventilators / anaesthesia devices for CPAP devices. IMO it might prove as a black hole that will suck up lots of resources.

It's been a few years since I last worked on a CPAP device so my best advice re. standards is go over the EC MDD harmonized std list - you'll find a few that are applicable to respiratory devices. Stay away from ventilators / anaesthesia devices on that list.

Cheers,
Ronen.

 

[Pads38]

Thanks for your caution Ronen.

The list of harmonised standards would be a sensible place to seek out a suitable alternative. From the preview of the ventilator standard the full requirements would be very onerous.

To be clear, I was suggesting using the standard only as a source of a suitable test for, perhaps, the pressurised parts. We have done this in other areas, but you do have to be careful to be very clear that you are not claiming compliance with that standard, only using it "for design and test input".

 

[Peter Selvey]

Just to throw some experience in the fire: the clause is an update from the 2nd ed which was obviously written for equipment using MPa rather cmH20. Examples are equipment that has high pressure gas inlets (e.g. infant incubator) or use hydraulics for lifting (chairs, tables). This clause is not really intended for CPAPs.

For completeness, a report covering a CPAP might use a verdict of "N/A" (not applicable), but in the remarks it would state that loss of pressure or excess pressure can only result in clinical/physiological risks which are covered separately (by the particular standard). Or you could use a verdict of "Pass", but in that case, concrete links to the risk evaluation would be required.