You measure the pressure you need to apply, to stop the blood going through the cuff.
It’s probably not possible to measure blood pressure perfectly. +- 5mmHg seems to be a completely normal error, probably even more. But it seems to be good enough.
It’s probably not possible to measure blood pressure perfectly. +- 5mmHg seems to be a completely normal error, probably even more. But it seems to be good enough.
For a device to be approved as a Class 1 medical device for blood pressure measurement, the FDA wants +/- 3mmHg to an established BP measuring method.
I still think though, that in a common setup the +-3mm is impossible to reach. People don’t sit perfectly still, may flex their muscles during the measurement, etc