Ok first let me clearly state i am not a doctor nor do i play one on tv. I have never "vaped" caffeine BUT let me tell you a little story and you can judge from there. Back not to long ago i was a smoker. If it burned i would smoke it (not that skunk weed i know what your thinking). anyway among the many forms of smoke (pipe, cig, cigar) i really enjoyed a hookah.
Now there is a entire line of shesha (hookah tobacco) that has caffeine in it. I tried it and MAN WHAT A BUZZ i could not sleep for days and was all jittery. It certainly worked on me.
That being said i would say the hookah works somewhat like vaping. the tobacco does not really burn but you heat it up and smoke the steam/vapor off of it. So while i dont know for sure that vaping it would work i can make a logical deduction that if the caff levels were high enough in the juice it would.
It has been stated that it was not known if the lining of the lungs could absorb through to the blood stream. Well i would say how do you think toxin would get into your blood from breathing. Just saying but keep in mind i am not a doctor, just some crazy old guy who has smoked caffeine once upon a time
