Reference: Regulation (EU) No 965/2012 on Air Operations, Annex V (Part SPA)
It is not the medical equipment itself that has to be approved in accordance with Regulation (EU) No 748/2012, but its installation on the helicopter. Therefore, if it is a fixed installed equipment, it has to be approved; if it is removable, the housing or any other part which is installed has to be approved. In general terms, the principle applied here is that no kind of equipment (medical or not, installed or not) shall affect the airworthiness or the safe operation of the aircraft even in the case of failures or malfunctions.
This means, for example, that if the equipment is powered by a power source of the aircraft, there shall be no adverse effect on the power source itself or on other systems or parts of the aircraft, or that the equipment is checked and cleared against electromagnetic interference.