EBME Forums Forums Management Medical Equipment Management Electric Beds - PAT or Medical Safety Testing

Here at my hospital in the US we've traded in out electric chair in favor of lethal injection which requires not electrical safety test. Do they still do site prep and use clean needles? not being a clinician I couldn't say.
There seems to be a question everywhere as to what to test, how to test and when to test just about everything. If anything a patient could contact is an applied part, what's not an applied part. I test the beds at our facility, maintenance (estates) did test beds untill we upgraded to beds with built in scales and other electronics. We check all the movement controls, lock outs, scale and alarms and do an electrical safety test. Is this the right thing to do? I certainly hope so.

Are we all (still) agreed (?) that hospital electrical beds get PAT tested (rather than 601 tested)?

Perhaps of more concern is that, in my experience, the majority of electrical patient connected devices in Doctors' surgeries are routinely PAT tested by local electrical contractors rather than tested to a medical electrical spec.

Barney

No, Barney, that's a lesser concern. Patients lie on hospital beds, and can't easily escape. The risk is greater.

But, with regards to your point, it's my understanding that those contractors are paid per equipment tested, regardless of whether it's a 'fridge or an ECG recorder. So we can see the motivation. But what are you suggesting, that there should be no electrical safety testing in doctors' surgeries? Or they should be carried out by medical engineers ... or what?

Has anybody seen any evidence of a medical bit of kit damaged by the scatter-gun approach to PAT testing, I wonder?

I suppose I'm suggesting that a PAT label stating the item has passed all its electrical tests in according to the IEE (IET) recommendations is all fine. However if the item is a medical device with patient connections I would be interested to see what patient leakage currents were measured!

Barney

Exactly Barney. What's important is the ass-covering printout so no-one can criticise us afterwards if there's a problem.

The bed is a medical device used in the patient environment so if it's an active device, i.e. powered, it needs to be tested using a medical grade safety tester - that establishes the limits we're working to.

If you consider the top of the bed around the mattress and guard rails is applied parts then the patient leakage must be limited to a maximum of 100uA a.c. & 10uA d.c. under NC and 500uA a.c. & 50uA d.c. under SFC (2nd Ed 60601-1 Std).

A mistake I made earlier in this thread, when considering a class 1B device in particular, is that a B applied part would likely fail a mains on applied parts test for beds whose enclosure and applied parts are earthed.

Of course, the MOAP test is only applicable for accessible signal inputs and outputs, not applied parts and certainly not applicable for testing earthed applied parts (the test will fail S/C to Earth).

I've learned from this thread if nobody else has. On reflection, having thought about what an applied part is defined as, according to the standard(s), I wouldn't disagree with Ged Dean's posts earlier.

Except to say that actually in the field the distinction between enclosure and applied parts and the number of applied parts to test (seperate and in contact with the patient) is blurred if individuals encounter an unfamiliar bed.

I don't think a standard PAT test is appropriate nor, considering the point you raised about tests in the community, Barney, is an operator who isn't competent in the use of a medical grade safety tester, if one is actually used.

Anyhow the best safety test is one where physical and visual inspection is thourough and the electrical one just confirms what we can't possibly see.

Just to stir things up a bit - how would IEC62353 test methods fare if applied to testing of a typical electric bed I wonder? Hopefully a pass or fail should be produced on either a 60601-1 test or a 62353 test, eh?

Don't get me wrong, guys, I'm no great fan of (what I call) the "scatter gun" approach to PAT testing ... but isn't legislation involved here?

And no, those blokes don't carry two electrical safety testers (eg, an industrial PAT tester and a 601-tester). Everything gets the full blast!

But I also believe that in most NHS hospitals, electric hospital beds are looked after by the Estates Department, and are PAT tested just like the kettles, toasters and all the rest.

It's easy to get portable medical grade safety testers with additional safety test standards built-in for other types of device; including PAT.

There's no getting away from the fact that electric beds are active medical devices covered by the MDD and not portable appliances used in a domestic, industrial or commercial environment.

So, if you consider the application, the equipment used around the bed and the environment it's used in, ideally we should have electricians using a medical tester to test electric beds - preferably without patients still in them.

If I remember correctly the HSE guidelines on electrical safety testing say that the environment where the devices are used must be considered and appropriate level of testing performed.

The risk of electrical safety issues on electric beds, particularly applied parts, are likely to be negligible (since I don't hear much talk of adverse incidents involving patients receiving an electric shock).

Testing to manufacturing standards is probably only an issue for manufacturers and regulatory processes at the design/development/construction stage or those involved in device evaluation & acceptance testing.

This means PAT testing of electric beds is probably sufficient in practice but this is not testing to an applicable general or particular medical device standard.

So PAT testing is not really appropriate but obviously goes most of the way to ensure the bed is safe. Is this good enough? is the question then.

If PAT testing ensures an acceptable level of risk, even if it does not assure the equivalent level of safety testing to medical or any other specific device standards, then perhaps it's use is justified? I suppose the argument for PAT testing goes somthing like this:

PAT is sufficient to ensure safety to an acceptable level of risk and it gets us away from the complexities of testing to medical manufacturing standards plus it allows the employer to meet HSE requirements.

Thereby ensuring an acceptable degree of safety of electric beds without having to repeat relatively complicated and time consuming manufacturing based tests for conditions whose probability of occurring is probably negligible in practice.

I guess this is why we need a test standard, like IEC 62353, for routine testing of medical devices used healthcare in much the same way as employers & HSE need a PAT standard for domestic, commercial and industrial appliance testing in the general workplace.

Also to save time and effort when we know that the medical safety tests of electric beds in particular, probably are in excess of what's required for routine safety checks.

Regarding PAT testers virsus Medical Electrical tester.
(Thanks to Mike IET)

In my considered opinion, if these items were tested with a conventional appliance tester, then inadequate testing would have been carried out.
The basis for this is that Medical Electrical Testers resolve leakage currents down to below 10uA and use a RC network to simulate human tissue. So, the tests carried out by a 'PAT' tester are probably inappropriate.

I agree with the above conclusion.

Barney

Yes, but what is the legal requirement for PAT testing in doctors' surgeries, dental surgeries, veterinary clinics et al ... and what does it say?

And, on the issue of beds, I've recently seen hospital beds that come fitted with "Schuko"-type mains plugs (why?), with adaptor cables used to plug them into the UK 13A mains outlet. When I enquired about this, I was given to believe that to fit UK plugs would constitute a "modification" to the bed. How does this contribute to electrical safety, I wonder?