What is a Class II laptop?
Of course this refers to the electrical isolation class of 90% of all laptop power supply 'bricks'.
Some laptops have a Switch Mode Power Supply that is referenced to earth, and have a three core mains lead, so that it is not Class II.
Almost
all laptop power supplies are class II (and switch mode based), even those with 3 wires! The earth connection is for EMC purposes and has no effect on the isolation between the input (mains) and the output. Look at the marking on the PSU and you will see the double insulation symbol. In fact I have only ever seen one (very old) laptop PSU that was not class II (so the earth was connected to the output -ve connection).
A SMPS using a two core mains lead will deliver the DC output that is floating at about half the mains voltage. The leakage current is low, as has been said about 100 microamps, but this will put the patient at increased risk if used during an interventional procedure.
Why will it put the patient at an increased risk? The interventional patient will be connected by CF applied parts. The laptop (PSU) will be medical rated, if used within the patient environment, so poses no more danger than the enclosure of other medical devices, which are allowed a touch leakage of 100uA. A non-medical PSU should not be used within the patient environment but still presents a low risk as the leakage is well below the single fault value of 500uA.
A tablet would be safe as it is normally run on its batteries, but my Ipad has just under 100 microamps when running on a genuine Apple power supply. It is not acceptable to simply warn users of the danger of plugging the tablet into the charger when using it in a medical location. Such warning are too easy to ignore.
The only common place a non-medical device, such as an iPad or laptop, gets used while connected to the mains, is by a patient during haemodialysis. Again when normal dialysis is being performed (B type applied part) a leakage up to 500uA (SFC) is acceptable, since this could be expected if the patient touch the dialysis machine when the earth was broken and is in line with 60601-1. If CVC dialysis is being performed then only a haemodialysis machine with CF (applied part) rating should be used, so there is no chance of the touch leakage from a medical device flowing via the catheter, in the event the patient touches the machine, another medical device or their iPad!
Use the wrong machine for CVC dialysis and the patient is put at risk, from other electrical devices including medical ones!
