The torr is a unit of pressure. Its symbol is Torr. One torr was originally defined as the pressure exerted by a depth of one millimeter of mercury (mmHg), and then as 1/760 of a standard atmosphere.
Because the standard atmosphere is now a defined quantity in the SI system of units, the torr is hence defined as exactly 101325 / 760 = 2533.125 / 19 ≈ 133.3223684 pascals. Although the torr is still in common use in low-pressure engineering, the pascal is now the recommended unit of pressure.
This unit (usually under the millimeter of mercury name) remains the most common unit for the measurement of blood pressure in much of the world.
Normal atmospheric pressure can support around 760 mm of mercury; hence 1/760 of an atmosphere, or 1 mm of mercury (mmHg), has been a convenient measure of pressure for a long time, and is sometimes also called a torr.
Because the standard atmosphere has been precisely defined (10th CGPM, 1954), and the standard atmosphere had previously been defined as 760 mmHg exactly, those two definitions are now combined to define the torr as exactly 101325/760 ≈ 133.3223684 pascals.
Although they are synonyms in practice, the torr and millimetre of mercury are very slightly different by virtue of their definitions in British Standard BS 2520 ([1], [2]).
Isolated systolic hypertension (ISH) is defined as systolic BP >= 140 mmHg and diastolic BP <= 90 mmHg.
When BP is 115/75 to 185/115 mmHg, each increase of 20 mmHg in systolic BP or 10 mmHg in diastolic BP doubles the risk of cardiovascular disease for people between ages 40 and 70.
People with systolic BP 120 to 139 mmHg or diastolic BP 80 to 89 mmHg are also at increased risk of these diseases and are considered to be prehypertensive; such people are candidates for lifestyle modifications to reduce risk.
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