|
|
|
|
Hi all,
I am getting confused by EST again,
We always test any DVD players, laptops etc which patients want to use while on dialysis. So far so good.
Today we had a DVD player, Class 2 (double insulation symbol on back), which just failed Enclosure/Touch current in normal conditions when the probe was connected to the aerial socket or the headphone socket. We got 105mA reading - limit is 100mA for a no fault condition.
I have told the patient she cannot use the equipment while on dialysis.
Am I right or am I doing the wrong tests ?
I remember on the Liverpool course many years ago, being told that Classification is not an absolute method of deciding which tests should be carried out; in other words if it is possible to perform a test then do it whatever class it is.
Chris
|
|
|
You mean micro rather than milliamps don't you. As in 62353 equipment leakage direct method 100uA for class 2 equipment. The problem is you are testing a DVD player as if it were a medical device because it's going to be used by someone connected to another medical device, but it isn't designed to meet these standards. It would pass PAT leakage touch current for class 2 as it's under 250uA.
|
|
|
Hi Fraser,
Yes I did mean uA.
I understand that the limits are higher for non-med equipment but, as you say it is being used by someone on a dialysis machine, so shouldn't it be considered as part of a medical equipment system ?
The patient has a central line which I suppose makes things worse in theory.
If the patient was at home it might be different as we can't necessarily control what they use at home; but in the dialysis unit we have to take extra precautions. We have never had similar equipment fail the medical device limits before.
Regards
Chris
|
|
|
Hi Chris,
we had the same thing when we installed new TV's, leakage current was above the limit at the headphone socket so we put some isolation in place. That was easy enough for a fixed installation but you're not going to be able to do that in your case. Do you test all the non medical equipment that patients use a part of a program or is it just a one off check when it's reported to you?
I'm not sure about differentiating between lines and fistulas, the current path could still be across the heart when the patient touches something with their mobile arm.
Fraser
|
|
|
Hi again Fraser,
The unit staff are supposed to bring us anything like DVD players, laptops, heated pillows that they see patients using, for us to EST. Never had a problem before.
Chris
|
|
|
Hi Chris,
I'm shocked (!) that a class 2 device failed touch current limits. Our entire unit only has isolated supply so in theory is there any need to test for this on anything other than medical devices?
Gerry
|
|
|
why are you are surprised? it's well within the touch current limit it was designed to meet
|
|
|
Hi Chris, Do we need to test domestic equipment that requires PAT testing to the stringent EST that applies to medical equipment? Is this a topic that might be worth while expanding on? I suppose that it might be relevant to discuss from a patient safety perspective and seek the views of technical managers throughout UK. Would you be OK with that? Gerry
|
|
|
Hi Gerry,
Indeed that's why I started the thread - I am not sure what we should be doing.
Someone, years ago, suggested that a DVD player/laptop used by a patient on dialysis is part of a system, which includes the machine, the chair and any additional monitoring equipment.
Chris
|
|
|
Hi Chris,
I know that is the case if the manufacturer supplies the kit,we were asked to supply a TV and DVD system with a Digiterm chair for a private satellite unit and the power supply had to be medical grade with 12v TV & DVD so the cost was extortionate.
My understanding is that anything within touching range of the patient on the chair should be low leakage,clearly in a home HD set up thats going to be difficult to police unless you put special 240v sockets in.
www.healthtec.co.uk
|
|
|
Hi Chris,
It is a difficult one; from patient safety perspective we should test to 1B or 1BF, from an equipment perspective we should test according to the specification the device was manufactured to. I can't help but think it's a bit like testing dialysis machines to 1BF or 1CF just in case a neck line is used (though I think it makes little difference to the patient applied part) even though the machine is manufacturered to spec 1B. As part of Med Physics in Dumfries we test any equipment that is on our register and under our ownership. I agree with your point that we should look from a patient safety perspective and accept the implications of increased workload. Maybe all dialysis installations should be supplied from an isolation transformer and that takes the problem away....I think.
Gerry
|
|
|
Hi Gerry
I was Just looking through the posts and found yours.
Indeed HD machines are manufactured to class1 type B Spec however, they MUST comply with CF patient applied part leakages.
That means in any single fault condition applied part leakage must be <50micoamps to allow catheter use.
Based on this anyone dialysing with a catheter absolutely must have a redundant earth connected. This is typically performed as you know with an equipotential connector.
Ian Morgan did once raise the question about patient micro shocks when using CVC's at an ART meeting.
I do sometime witness machine use without the EP connectors used (or other redundant earth).
Andrew
|
|
|
Hello Andrew,
After much consultation the requirement for electrical testing is to test any device to the standard to which is was built. If a device is built as a Class 1 type B the that is what it must be tested to. Using a Class 1 Type B as a Type CF
is another matter! However there are some manufacturers that specifically state that if you dialyse using a dual lumen catheter for access then you must have the equipotential earth connected to an earth independent of the mains supply earth.
It won’t be a problem until it is a problem :)
Regards,
Gerry
On 8 Aug 2016, at 17:08, Andrew Gardner [via ART Forum] < [hidden email]> wrote:
Hi Gerry
I was Just looking through the posts and found yours.
Indeed HD machines are manufactured to class1 type B Spec however, they MUST comply with CF patient applied part leakages.
That means in any single fault condition applied part leakage must be <50micoamps to allow catheter use.
Based on this anyone dialysing with a catheter absolutely must have a redundant earth connected. This is typically performed as you know with an equipotential connector.
Ian Morgan did once raise the question about patient micro shocks when using CVC's at an ART meeting.
I do sometime witness machine use without the EP connectors used (or other redundant earth).
Andrew
To unsubscribe from Electrical Safety of patient's own entertainment equipment,
click here.
NAML
|
|
Locked
