Will I feel pain under intravenous sedation?

I'm having root c therapy under conscious sedation, but am getting scared after reading that the drugs don't kill the pain, only make you relaxed etc. I know I will also have local anaesthetic (needles) but they didn't work on this tooth as it has an inflamed nerve (the dentist tried already and 4 needles didn't work). I don't want to be in pain and trapped in the chair unable to speak up.