When measuring the blood pressure nurses often say numbers like”120 on 80″. What exactly do those numbers mean and why do you die when they coincide?

Question

When measuring the blood pressure nurses often say numbers like”120 on 80″. What exactly do those numbers mean and why do you die when they coincide?

In: Biology

Answer 1

No one has stated what the numbers actually mean. 120/80 refers to the distance a column of mercury will be pushed up (in millimetres). They used mercury because its denser and you could read the movement easier. They used a tube of it and the high number pushed it up 120mm. Then they allow it to drop to the lower number, which only pushed it up to 80mm.

That why they initially squeeze the cuff hard (to see how high it reaches) and slowly release the pressure until the lower number is reached.

Edit: the chemical sign for mercury is Hg, so the unit for blood pressure (at least in Canada) is mmHg