Blood pressure changes throughout the day and varies from person to person. Various factors affect blood pressure, including your body position, breathing rhythm, stress level, physical activity, medications, what you eat or drink, and the time of the day (blood pressure is usually lowest at night when you sleep and rises when you wake up). In healthy individuals, your body responds and adapts to these changes to keep your blood pressure within a normal range. This ensures that vital organs, such as your brain and kidneys, receive a constant blood flow and nutrient supply.
Even occasional dizziness or lightheadedness may be a relatively minor problem — the result of mild dehydration from too much time in the sun or a hot tub, for example. Still, it's important to see your doctor if you have signs or symptoms of hypotension because they can point to more-serious problems. It can be helpful to keep a record of your symptoms, when they occur and what you're doing at the time.
"Blood pressure guidelines are not updated at regular intervals. Instead, they are changed when sufficient new evidence suggests the old ones weren't accurate or relevant anymore," says Dr. Paul Conlin, an endocrinologist with Harvard-affiliated VA Boston Healthcare System and Brigham and Women's Hospital. "The goal now with the new guidelines is to help people address high blood pressure — and the problems that may accompany it like heart attack and stroke — much earlier."
Some people have low blood pressure all the time. They have no symptoms and their low readings are normal for them. In other people, blood pressure drops below normal because of a medical condition or certain medicines. Some people may have symptoms of low blood pressure when standing up too quickly. Low blood pressure is a problem only if it causes dizziness, fainting or in extreme cases, shock.
Pulmonary hypertension is caused by changes in the cells that line the pulmonary arteries. These changes cause the walls of the arteries to become stiff and thick, extra tissue may also form. This can reduce or block blood flow through the blood vessels. Increased blood pressure is then caused because it is harder for blood to flow. Pulmonary hypertension can be an associated condition with scleroderma, sarcoidosis, pulmonary embolism, and dermatomyositis.
Many kids and teens with high blood pressure have an unhealthy lifestyle — a bad diet, excess weight, stress, and too little physical activity. So the health care provider might recommend weight loss, exercise, reduced screen time (time spent watching TV, or using a computer or mobile devices), dietary changes, and even relaxation techniques. Teens with hypertension should not smoke because it can make the long-term associated heart problems worse.
Wear a blood pressure monitor. This monitor is attached to you. You will be asked to wear it for 24 hours. The monitor is usually programmed to take blood pressure readings every 15 to 30 minutes all day and night while you go about your normal activities. The doctor will evaluate the results. In some cases, home blood pressure monitors may also be used to evaluate the effectiveness of your treatment.
The new guidelines stem from the 2017 results of the Systolic Blood Pressure Intervention Trial (SPRINT), which studied more than 9,000 adults ages 50 and older who had systolic blood pressure (the top number in a reading) of 130 mm Hg or higher and at least one risk factor for cardiovascular disease. The study's aim was to find out whether treating blood pressure to lower the systolic number to 120 mm Hg or less was superior to the standard target of 140 mm Hg or less. The results found that targeting a systolic pressure of no more than 120 mm Hg reduced the chance of heart attacks, heart failure, or stroke over a three-year period.
For a normal reading, your blood pressure needs to show a top number (systolic pressure) that’s between 90 and less than 120 and a bottom number (diastolic pressure) that’s between 60 and less than 80. The American Heart Association (AHA) considers blood pressure to be within the normal range when both your systolic and diastolic numbers are in these ranges.
Right after exercise is stopped, blood pressure decreases — often to levels a bit lower than normal resting blood pressure, and this effect can last for hours. Also, people who exercise regularly usually experience permanent improvements in resting blood pressure levels, as exercise strengthens the heart, helps with weight loss, improves circulation and lessens peripheral resistance — all factors that benefit blood pressure.
The cause for hypertension is not always known, although it can develop as a result of other health conditions including: sleep apnea, kidney problems, and thyroid issues. Beyond chronic health conditions, risk factors for hypertension include age, the amount of salt you eat, being overweight or obese, using tobacco, drinking excessively, not exercising, and having too little potassium in your diet.
Not only the degree of obesity is important, but also the manner in which the body accumulates extra fat. Some people gain weight around their belly (central obesity or "apple-shaped" people), while others store fat around their hips and thighs ("pear-shaped" people). "Apple-shaped" people tend to have greater health risks for high blood pressure than "pear-shaped" people.
Understanding the normal BP range with age can help the doctor and you to estimate your cardiovascular health. Blood pressure levels can fluctuate significantly from one reading to the next and it is important to remember that just one abnormally high reading does not signify that you have high blood pressure. Doctors usually use an average of multiple blood pressure readings taken over a period of several days to arrive at a diagnosis of high blood pressure.
The range of systolic blood pressure for most healthy adults falls between 90 and 120 millimeters of mercury (mm Hg). Normal diastolic blood pressure ranges between 60 and 80 mm Hg. Current guidelines define normal blood pressure range as lower than 120/80. Blood pressures over 130/80 are considered high. High blood pressure increases the risk of damaging the arteries, which leads to the development of:
Blood pressure is measured with a blood pressure cuff (sphygmomanometer). This may be done using a stethoscope and a cuff and gauge or by an automatic machine. It is a routine part of the physical examination and one of the vital signs often recorded for a patient visit. Other vital signs include pulse rate, respiratory rate (breathing rate), temperature, and weight.
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
The findings mean that an additional 14 percent of U.S. adults, or about 30 million people, will now be diagnosed as having high blood pressure, compared with the number diagnosed before the new guidelines. This will bring the total percentage of U.S. adults with high blood pressure to 46 percent, up from 32 percent previously. [9 New Ways to Keep Your Heart Healthy]
The kidney can respond to changes in blood pressure by increasing or decreasing the amount of urine that is produced. Urine is primarily water that is removed from the blood. When the kidney makes more urine, the amount (volume) of blood that fills the arteries and veins decreases, and this lowers blood pressure. If the kidneys make less urine, the amount of blood that fills the arteries and veins increases and this increases blood pressure. Compared with the other mechanisms for adjusting blood pressure, changes in the production of urine affect blood pressure slowly over hours and days. (The other mechanisms are effective in seconds.)
Low blood pressure is also known as hypotension. This is usually defined in an adult as a systolic recording of less than 90 mmHg, although it has been suggested that for elderly people, below 110 mmHg is a more appropriate definition. Blood pressure and heart rate are controlled by the autonomic nervous system (the nervous system that controls bodily functions that we do not have to think about).
Blood pressure readings fall into four general categories, ranging from normal to stage 2 high blood pressure (hypertension). The level of your blood pressure determines what kind of treatment you may need. To get an accurate blood pressure measurement, your doctor should evaluate your readings based on the average of two or more blood pressure readings at three or more office visits.