I'd be curious as to how we could lawfully define whether someone "can" render assistance.
I might be misremembering from my own CPR classes, but I was under the impression that anybody with a CPR certification (and I have to assume the nurses
would be CPR-certified) was legally obligated to help someone in need. You might not be able to get in trouble if you don't help, but you're supposed to help if you've been trained to do so. Otherwise why bother getting the certification at all?