Sounds like something out of a sci-fi movie, but this is done commonly now with certain nutrients. B12 most commonly. There's some buzz about intravenous magnesium sulfate injections as well to increase serum magnesium.
http://www.patientsmedical.com/treatments/ivtherapy/ivtherapy.aspx
However, now people are able to get a full spectrum of vitamins and minerals into their bloodstream at once. Part of me thinks this is a bit too wild to be used, but in reality it could be considered safe because of the few side-effects of simply having a higher level of certain nutrients in the blood. As long as someone has functional kidneys, it sounds like it's not a high risk medical procedure.
Although it's routine sometimes to receive IV doses of certain nutrients, it's not common for us to simply go in for a nutritional boost in "that way." It might be a good alternative to taking supplements, especially if it's shown to have significant enough benefits.
IV Magnesium sulfate Intravenous magnesium as an adjuvant in acute bronchospasm: a meta-analysis. http://www.ncbi.nlm.nih.gov/pubmed/10969219
