My Omron HEM-712C digital blood pressure monitor
First, I do not believe there is any accurate way to measure blood pressure without having a valve installed; not a practical alternative.
The standard method using an arm-cuff and stethoscope is highly dependent on the person doing the measurement. Once my hearing started to fail, I had to go to a digital meter and found after three of these which failed and comparing my current Samsung to three different methods; manual, an elaborate 'calibrated' digital on a stand and another 'calibrated' cuff-type during an examination by a professional, none of these agreed better than 10-15 mm and the worst was 25-30 mm apart.
Using the average of those 'profis,' my current wrist-type digital measures about 10 points low on both systolic and diastolic so I just ignore the absolute numbers and use it only to determine relative deviations.
For that, mine is repeatable enough.
on Sep 16, 2010