There is no requirement in IEC 60601-2-2 for the part to be defibrillator proof. Although the test is modified by IEC 60601-2-2, the applicability of the test remains based on the general standard which is optional based on classifications as determined by the manufacturer.
There is a possibility that the test lab is thinking it is mandatory based on the TRF (test report form) provided by the IECEE CB scheme. These forms can often use cryptic or abbreviated text for the requirement which imply something is mandatory when it is not, especially for particular standards (which are often read independent from the 601-1 TRF). Or, the test lab may be policing outside of the standard, knowing that most (all?) ESUs are classified as defib proof, so it makes sense that an accessory should also be defib proof.
Thank you for the hint. That might explain their way of thinking, sounds reasonable.
In one sense, I agree with the lab. A good risk analysis should find that the probability of the neutral electrode and cable remaining on the patient and connected to the ESU during defibrillation will be "possible"; the potential harm due to insulation breakdown to be medium severity (burns) and therefore the risk should be unacceptable without a risk control measure, and the obvious risk control measure is verifying the insulation is OK for the expected defib voltages.
Agree.
However, it's not really a practical concern. The issue is not the electrode itself but the insulation on the cable that connects between NE and the ESU. In practice the insulation on the cable will be easily able to handle 2kV pulse of 2-3ms, which is very light stress in terms of dielectric strength due to the short duration. If a cable really failed the 2kV pulse test, the insulation would have to be so thin (say 50µm or less) that it would be useless mechanically. So, yes, theoretically applicable from risk management but practically a waste of time.
I think the requirement in 60601-2-2 clause 201.15.101.4 * NE cord insulation should cover any defib proof concerns when talking about cable insulation, or does it not? Especially 3rd dash of 201.15.101.4 with 2.1 kV dielectric strength test.
Another thing is the insulation of the electrode (backing side - not patient side) itself. Usually a thin plastic layer (e.g. PET) with a foam or some kind of medical tape (PE, PP,...). So all in all about 1 to 2 mm of plastic insulation. Additionally, the electrode is mostly covered with drapes during surgeries. I agree that there is no practical concern, but the only part with can be argued at, would be the electrode itself in this perspective, not the cable. For the cable exists at least a dielectric testing in 60601-2-2 I can refer to.
The situation for the NE electrode being connected with a cable, but the non-patient side connector is removed from the ESU should not be an issue. Medical operators should be trained to know that if a part with an accessory is classified as defib proof, the connector at the equipment side should remain connected. This is not only for safety during defibrillation but also being able quickly restart the medical procedure after defibrillation is performed. There is no requirement in other standards (in particular, patient monitors, IBP, Temp, ECG etc) to defib test an accessory with the accessory disconnected from the equipment.
Thank you for the hint, I did not think of that.
