Stupid question

Okay, here is a dumb question that I have recently become confused about as i am in clinicals. if my pt. has a low BP, what can i do respiratory wise to raise it? (i know i would do many other things first, but this is like a last ditch thing before pressors) would increasing my resp. rate on my vent. raise the bp? (due to neg. pressure of each respiration 'pulling' blood from lower body to increase return to heart) or would it lower my bp due to blowing off too much co2? I know, i know, a simple and probrably stupid question, but i can't remember and can't seem to find it in my literature. any ideas? (and please don't tell me 'look it up' - it is not something someone has asked, it just popped into my head today and i couldn't remember and can't seem to find the answer) thanks for any responses.