I've lost two deer to this over the last 7 or 8 years. Things I've learned from my losses and talking to others. First pull the feed. I darted lots in emergencies without pulling feed, but when possible it always helps. It's also good to pull water, just like us when we get sedated we are told to not eat or drink for 12 hours before surgery.
Put as little stress on the animal. If you dart a deer and it dosen't go down after two darts, and is getting worked up and nervous, it is best to quit while your ahead, dart it some reverser and try a different day. You will lose the animal to myopathy or regurgitation related pneumonia if you push it too hard. A few years ago, I pushed the limits and lost a buck because I ran him hard and darted him three times til he finally went down, all because the preserve said they HAD to have him that day. Well he made it to the preserve, then died a week later from pneumonia. I would have been better off just selling to a different preserve and not rush.
When an animal is down, prop the animal up in a natural bedded position, tuck the legs in under the body, lay the head flat out in front and pull the animals tounge out and off to one side of the mouth. The tongue can relax, and cause problems with breathing and swallowing while they are under sedation.
I hope others can add on more, and I hope this helps you.
