I work as a HEMS paramedic here in the UK on a Bolkow 105 and we carry a Medtronic (Physio Control) Lifepack 12 defibrillator which can be used in flight.
Although the Bolkow is not EFIS, many of our colleagues across the country use EC135's and use similar equiment.
The pilot would abviously be informed if shocks were going to be delivered, oxygen is supposed to be turned off (whenever you shock) and other common sense precautions taken.
Hope this helps somewhat.
(I'm new to this site and was trailing through past threads as I'm bored on nights!!!)