I've worked as an xray tech for over 7 years (in a couple different hospitals) and we NEVER had patients prep for a SBFT. I've just had to not eat or drink for 8 hours prior to the test. Within that time, food is out of your small intestines and in your large, so it doesn't interfere with the test. It makes me wonder why they have you prep.
Aside from that thought...40 minutes isn't that fast a time for barium to reach the end of your small intestines....I had a patient once who literally within 10 minutes had barium reach her rectum...now that's fast!! The average time for a SBFT is 45-60 minutes. You have to remember that your body doesn't use barium like food, so it just runs through, and doesn't take time to break down or anything.
I'm guessing that you didn't hear from your GI yet with the results??
32 yr old female-dx with Crohn's in '97 after emergency resection and appendectomy, 2nd resection '05, Bilateral pulmonary emboli 10/09
Currently on Humira, Omeprazole, Effexor, Seroquel, Calcium, Vit D
Coumadin stopped 3/15/10!!!!