Many people have digital blood pressure measuring devices in their homes today.
These devices have become relatively inexpensive.
A cuff is put onto the arm and inflated.
As it deflates, the blood pressure (and usually heart rate as well) are measured.
The results are usually displayed on an LCD screen.
Many of these digital measuring devices even come equipped with memory so that users can keep track of blood pressure readings on different days and at different times of the day for comparison purposes.
You will see these digital measuring devices in many doctor's offices, as well, but there are also many doctors who prefer having blood pressure measured the old-fashioned way, using a cuff, a column of mercury, and a stethoscope, because they believe that it is more accurate.
When this method is used, the person who is taking the blood pressure listens for Karotoff sounds.
After the cuff has been inflated, they place the stethoscope on the brachial pulse.
Then they slowly deflate the cuff and listen.
While watching the mercury lower, they note the pressure when they first hear the Karotoff sounds (systolic pressure) and the pressure when they can no longer hear the Karotoff sounds (diastolic pressure).
Blood pressure is determined by the pressure in the veins and vessels when the heart beats, versus the pressure in the veins and vessels when the heart rests between beats.
Readings are expressed as systolic pressure (when the heart beats) over diastolic pressure (when the heart rests between beats).
If a reading is 120 systolic and 80 diastolic, the reading is expressed verbally as "120 over 80" and written as 120/80.
A reading of 120/80 is considered optimal for people under the age of 55.
Any reading that is above 140/90 indicates a blood pressure reading that is too high, and the patient should see the doctor.