Apparently many places are not scrupulously careful of your position as they test your BP... And it matters a lot.
"The latest clinical practice guidelines from the American Heart Association emphasize several key steps for an?¡ª¾±²Ô³¦±ô³Ü»å¾±²Ô²µ?, back support, feet flat on the floor with legs uncrossed, and an appropriate arm position, in which the middle of an adjustable BP cuff is positioned at mid-heart level on an arm supported on a desk or table."
