Reference:

Blood Pressure: Highs, Lows & What's Normal

blood-pressure-generic-101007-02
Credit: Marius Scarlat | Dreamstime

Blood pressure is one of the vital signs that doctors measure to assess general health. Blood pressure is the measurement of the force of blood as it hits the walls of the arteries. It is expressed as two numbers: the systolic pressure, which is the pressure as the heart beats, and the diastolic pressure, which is the measurement as the heart relaxes between beats. Blood pressure is recorded as systolic over diastolic (120/80).

People confuse high blood pressure with a high heart rate or pulse rate, which is the number of times your heart beats per minute. There is no direct connection between the two, and high blood pressure does not necessarily result in a high pulse rate, and vice versa. A vigorous workout may only modestly increase blood pressure while significantly raising your heart rate.

Checking your blood pressure

A manual or digital blood pressure monitor (sphygmomanometer) typically comes with instructions that should be followed carefully to get the most accurate results.

The first step is to find your pulse by pressing your index finger on the brachial artery, which is at the bend of your elbow, slightly to the inside center. On a manual monitor, place the head of the stethoscope in the general area, or for a digital monitor, place the cuff in this area.

For a manual monitor, you have to hold the pressure gauge in one hand (your weaker hand) and the bulb in the other hand. Inflate the cuff until it reads about 30 points above your normal systolic pressure. At this point, you should not hear your pulse in the stethoscope. When you hear the first heart beat, this is the systolic pressure. As you deflate the cuff, keep listening for a heart beat. When you can no longer hear it, that is your diastolic pressure.

A digital monitor does the inflation and deflation and recording of the systolic and diastolic heart rates.

 

What is normal blood pressure?

A normal systolic blood pressure is classified as below 120, but a desirable rate is between 90 and 119. A normal diastolic blood pressure is below 80, but a desirable rate is between 60 and 79.

Those who are fit — including those who regularly exercise and professional athletes — tend to have lower blood pressures and heart rates, as do those who do not smoke and are a healthy weight.

The Journal of the American Medical Association (JAMA) recently published an article recommending changes in the guidelines for blood pressure levels for certain patients. Adults age 60 or older should only take blood pressure medication if their blood pressure exceeds 150/90, higher than current guideline of 140/90, according to the new recommendations.

The panel that compiled the guidelines also recommended that diabetes and kidney patients younger than 60 be treated when their blood pressure exceeds 140/90, which is the same for patients without kidney disease or diabetes. People with those chronic conditions have previously been prescribed medication when their blood pressure went above 130/80.

High blood pressure, low blood pressure

Both low and high blood pressure are more common in older patients in part due to normal changes during aging. In addition, plaque buildup related to age can decrease the blood flow to the heart muscle and the brain.

Hypertension is medically defined as any blood pressure over 120/80. Prehypertension is classified as 120-139 over 80-89. Stage 1 high blood pressure is 140-159 over 90-99, and Stage 2 is 160 and above over 100 and above.

The dangers of high blood pressure include hardening of the arteries, or atherosclerosis, stroke, and the development of heart disease.

Low blood pressure, known as hypotension, can also cause health problems such as fainting and dizziness. Quick, dramatic drops in blood pressure can reduce the adequate blood supply to the brain. Most of the time, hypotension goes undetected and is typically not dangerous unless it produces symptoms.

What causes high blood pressure?

A number of factors can raise blood pressure, including stress, smoking, caffeine, certain over-the-counter and prescribed medications and even cold temperatures. Some people are especially susceptible to a spike in their blood pressure when they visit a doctor, a situation known as white coat hypertension or white coat syndrome.

You will get a more accurate reading if you try to avoid as many of these factors as you can when taking your blood pressure and by taking your blood pressure at about the same time each day.

More from LiveScience