I've done a quick search of these forums and Google, and although there's lots of brilliantly helpful information about anaesthesia, I haven't been able to find much about a rather specific situation that I'm considering.

If someone is rushed into hospital and requires immediate surgery but is already unconscious, what is the protocol regarding anaesthesia? Do doctors have to wait until the patient regains consciousness or can they proceed to surgery and administer an anaesthetic? Is the situation any different if there is a relative/companion with them that can tell doctors about any allergies, reactions, etc? I can't really imagine doctors/surgeons wanting to operate on someone who is unconscious of their own accord and might wake up at any point, but administering an anaesthetic to someone who is already unconscious strikes me as unsafe.

I'm not an anaesthetist and I've never had a general anaesthetic so I'm unfamiliar with the general protocols beyond internet research. If anyone has experience or more information, I would greatly appreciate it. Thanks in advance!