I'm a little nervous about getting this procedure done. Some advise please?

I hate I.V.'s and I'm told they hurt and that if they don't stick it in right the first time they'll keep sticking you until they get it right. Is that true? And my nose is stuffed up because of infection and the surgury is in my mouth so since I can't breath out of my nose does that mean I could suffocate? I know these are silly questions I'm just a little scared so sorry about that. Thank you for your help.