Ok so i have been a medical assistant/lpn:mad: for a couple of months now. I work for the most anal primary care group. when i take a blood pressure sometimes i can get 120/80 and some how when the dr checks it again on ther "md recheck" they can sometimes come out with a reading of 150/90! how can that be? Can a persons blood pressure change so drastically within a 5-10 time span? if not then what am i doing wrong. I use the right size cuff. I place it right where the artery sign is over artery and i sometimes get way off readings and sometimes cant hear anything at all. is that also normal.. and my biggest concern is taking a blood pressure on a overweight person waying over 300lbs...taking their blood pressure with a thigh cuff, first of all i can get the cuff over ther arm cuz th cuff is so wide and their arms are so large and short. one of the other medical assistants said its normal to but scethescop under cuff but i cant hear a thing. I do not want to give false readings and i want to be a pro at taking blood pressures. can someone help?