I work at an FMC clinic and that blood flow does seem too high if you are using 15g needles. I have floated to several of our clinics and it depends on the medical director as to how fast the bfr can be run on any size of needles. We don't go over 550 with 14g needles but this is his preference. As long as you have a valid order and it doesnt harm the patient you should be ok. I would think with BFR that high you risk more recirculation, and possibly damaging the RBC's if run through too small a needle.