WHO is a child? - Xtianty and Islam please

[System of Solace]

What if the surgery involves, say, cutting a hole into the child's throat to form an airway, and without this procedure the child will die?

What if a child suffers from something like gangrene, and refuses to have their leg amputated, endangering their life? As a parent, wouldn't I be obligated to intervene in my child's decision?

You're playing the what-if game again, Clive.
It goes without saying this is an ignorant question.
First of all, what person would choose to die of gangrene?
Second, how does that have anything to do with his original statement? This is a life or death situation, not an unneeded and potentially life-threatening surgery that is done because a book says so.