I would suggest that in those circumstances you attempt to foind a sober driver for the trip.
But, ther again, your scenario is too limited to make a valid assessment.
Where are you?
How do you know the ambulance cannot arrive in time?
What has happened to the person who needs the ambulance that dictates the time limit?
etc etc etc!
Let's say you are not "pissed out of your skull" but definitely over the limit. You're at a pub out in the sticks. It's at least 10 minutes for an ambulance to get to you and your partner has collapsed and will die if they don't get to the hospital within 15 minutes. You drive them to the hospital and just before you get there, somebody dressed all in black steps out into the road in front of you. Had you been sober, you would have reacted in time not to hit them, but you aren't sober, so you kill them.
These are, in my opinion, mitigating circumstances. It doesn't mean you are not guilty and it doesn't mean you should not be punished in some way, but when you chose to drive drunk, it was either that or watch your partner die in front of your eyes. Don't you think some leniency should be applied in those circumstances? Would you risk the possibility of accidentally killing a stranger and losing your licence against the certainty of your partner's death? Would you blame somebody else who chose to try to save their partner?