I'm still a nursing student and I haven't had any experience with critical situations where blood products are urgently needed (I've transfused blood but it wasn't where the patient was actively bleeding out, hemoglobin dropped low enough to warrant it).
Per textbook, you should infuse the blood slowly at say 50ml/hour for the first 15 mins and watch for a reaction and then increase the rate if there is no reaction. However, if the patient is critical/bleeding out, do you suspend that rule and just "pour" that blood in as fast as it will go and hope they don't react? I'm guessing that the pros (getting the hemoglobin and BP back up) outweigh the cons (possible chance of a reaction) in such a situation. Is that right?