IMO, it must not be too problemental, or the parents would not be wishing to leave her while they go out, no?
I agree with the first poster, get educated on Pediatric CPR.
They may have shared this information with you just in passing, or it may be problematic. The only way to know for sure is to talk to her parents, or have her parents and your parents get together and make sure it's a good match.
I mean, my grandmother is 89 and has congestive heart failure
, and now that she's stable, it's not problematic in the least.
Best of luck!