Blood Pressure: How to Control High Blood Pressure

Blood pressure Classification

Systemic arterial pressure

The risk of cardiovascular disease increases progressively above 115/75 mmHg, below this level there is limited evidence.

Observational studies demonstrate that people who maintain arterial pressures at the low end of these pressure ranges have much better long-term cardiovascular health. There is an ongoing medical debate over what is the optimal level of BP to target when using drugs to lower BP with hypertension, particularly in older people.

Fluctuation of Blood pressure

BP fluctuates from minute to minute and normally shows a circadian rhythm over a 24-hour period, with the highest readings in the early morning and evenings and the lowest readings at night. Loss of the normal fall in BP at night is associated with a greater future risk of cardiovascular disease and there is evidence that night-time BP is a stronger predictor of cardiovascular events than day-time BP. Blood pressure varies over longer time periods (months to years) and this variability predicts adverse outcomes.

BP also changes in response to temperature, noise, emotional stress, consumption of food or liquid, dietary factors, physical activity, and changes in posture, such as standing up, drugs, and disease. The variability in BP and the better predictive value of ambulatory BP measurements have led some authorities, such as the National Institute for Health and Care Excellence (NICE) in the UK, to advocate for the use of ambulatory blood pressure as the preferred method for the diagnosis of hypertension.

Other factors of fluctuation

Various other factors, such as age and sex, also influence a person’s BP. Differences between left and right arm BP measurements tend to be small. However, occasionally there is a consistent difference greater than 10 mmHg which may need further investigation, e.g. for peripheral arterial disease or obstructive arterial disease.

There is no accepted diagnostic standard for hypotension, although pressures less than 90/60 are commonly regarded as hypotensive. In practice, blood pressure is considered too low only if symptoms are present.

Systemic arterial pressure and age

Fetal blood pressure

In pregnancy, it is the fetal heart and not the mother’s heart that builds up the fetal BP to drive blood through fetal circulation. The BP in the fetal aorta is approximately 30 mmHg at 20 weeks of gestation and increases to approximately 45 mmHg at 40 weeks of gestation.

The average BP for full-term infants:

• Systolic 65–95 mmHg
• Diastolic 30–60 mmHg

Childhood

Reference ranges for BP in children

Stage	Approximate age	Systolic BP, mmHg	Diastolic BP, mmHg
Infants	0 to 12 months	75–100	50–70
Toddlers and Preschoolers	1 to 5 years	80–110	50–80
School-age	6 to 12 years	85–120	50–80
Adolescents	13 to 18 years	95–140	60–90

In children, the normal ranges for BP are lower than for adults and depend on height. Reference BP values have been developed for children in different countries, based on the distribution of BP in children of these countries.

Aging adults

In adults in most societies, systolic BP tends to rise from early adulthood onward, up to at least age 70; diastolic pressure tends to begin to rise at the same time but starts to fall earlier in mid-life, at approximately age 55. Mean blood pressure rises from early adulthood, plateauing in mid-life, while pulse pressure rises quite markedly after the age of 40.

Consequently, in many older people, systolic BP often exceeds the normal adult range, if the diastolic pressure is in the normal range this is termed isolated systolic hypertension. The rise in pulse pressure with age is attributed to increased stiffness of the arteries. An age-related rise in BP is not considered healthy and is not observed in some isolated unacculturated communities.

Systemic venous pressure

Site		Normal pressure range (in mmHg)
Central venous pressure		3–8
Right ventricular pressure	systolic	15–30
	diastolic	3–8
Pulmonary artery pressure	systolic	15–30
	diastolic	4–12
Pulmonary vein/ Pulmonary capillary wedge pressure		2–15
Left ventricular pressure	systolic	100–140
	diastolic	3–12

BP generally refers to the arterial pressure in the systemic circulation. However, measurement of pressures in the venous system and the pulmonary vessels plays an important role in intensive care medicine but requires invasive measurement of pressure using a catheter.

Variants of venous pressure

Variants of venous pressure include:

• Central venous pressure, which is a good approximation of right atrial pressure, is a major determinant of right ventricular end-diastolic volume. (However, there can be exceptions in some cases.)
• The jugular venous pressure (JVP) is indirectly observed pressure over the venous system. It can be useful in the differentiation of different forms of heart and lung disease.
• The portal venous pressure is the BP in the portal vein. It is normally 5–10 mmHg

Pulmonary pressure

Normally, the pressure in the pulmonary artery is about 15 mmHg at rest.

Increased BP in the capillaries of the lung causes pulmonary hypertension, leading to interstitial edema if the pressure increases to above 20 mmHg, and to pulmonary edema at pressures above 25 mmHg.

Mean systemic pressure

If the heart is stopped, BP falls, but it does not fall to zero. The remaining pressure measured after cessation of the heartbeat and redistribution of blood throughout the circulation is termed the mean systemic pressure or mean circulatory filling pressure; typically this is of the order of ~7mm Hg.

Disorders of blood pressure

Disorders of BP control include high blood pressure, low blood pressure, and blood pressure that shows excessive or maladaptive fluctuation.

High blood pressure

Hypertensive emergency

Arterial hypertension can be an indicator of other problems and may have long-term adverse effects. Sometimes it can be an acute problem, for example, a hypertensive emergency.

Mechanical stress

Levels of arterial pressure put mechanical stress on the arterial walls. Higher pressures increase heart workload and progression of unhealthy tissue growth (atheroma) that develops within the walls of arteries.

The higher the pressure, the more stress that is present and the more atheroma tends to progress and the heart muscle tends to thicken, enlarge and become weaker over time.

Shortened life expectancy

Persistent hypertension is one of the risk factors for strokes, heart attacks, heart failure, and arterial aneurysms, and is the leading cause of chronic kidney failure.

Even moderate elevation of arterial pressure leads to shortened life expectancy. At severely high pressures, mean arterial pressures 50% or more above average, a person can expect to live no more than a few years unless appropriately treated.

Isolated systolic hypertension

In the past, most attention was paid to diastolic pressure; but nowadays it is recognized that both high systolic pressure and high pulse pressure (the numerical difference between systolic and diastolic pressures) are also risk factors.

In some cases, it appears that a decrease in excessive diastolic pressure can actually increase risk, due probably to the increased difference between systolic and diastolic pressures. 

Heart valve regurgitation

For those with heart valve regurgitation, a change in its severity may be associated with a change in diastolic pressure. In a study of people with heart valve regurgitation that compared measurements 2 weeks apart for each person, there was an increased severity of aortic and mitral regurgitation when diastolic BP increased, whereas when diastolic BP decreased, there was a decreased severity.

Low blood pressure

BP that is too low is known as hypotension. This is a medical concern if it causes signs or symptoms, such as dizziness, fainting, or in extreme cases, circulatory shock.

Causes of low arterial pressure include:

• Sepsis,
• Hemorrhage – blood loss,
• Cardiogenic shock,
• Neurally mediated hypotension (or reflex syncope),
• Toxins including toxic doses of BP medicine,
• Hormonal abnormalities, such as Addison’s disease, and
• Eating disorders, particularly anorexia nervosa and bulimia.

Orthostatic hypotension

A large fall in BP upon standing (persistent systolic/diastolic BP decrease of >20/10 mm Hg) is termed orthostatic hypotension (postural hypotension) and represents a failure of the body to compensate for the effect of gravity on circulation.

Standing results in increased hydrostatic pressure in the blood vessels of the lower limbs. The consequent distension of the veins below the diaphragm (venous pooling) causes ~500 ml of blood to be relocated from the chest and upper body. This results in a rapid decrease in central blood volume and a reduction of ventricular preload which in turn reduces stroke volume, and mean arterial pressure.

Normally this is compensated for by multiple mechanisms, including activation of the autonomic nervous system which increases heart rate, myocardial contractility, and systemic arterial vasoconstriction to preserve BP and elicits venous vasoconstriction to decrease venous compliance.

If compensatory mechanisms fail and arterial pressure and blood flow decrease beyond a certain point, the perfusion of the brain becomes critically compromised (i.e., the blood supply is not sufficient), causing lightheadedness, dizziness, weakness, or fainting.

Fluctuating blood pressure

Normal fluctuation in BP is adaptive and necessary. Fluctuations in pressure that are significantly greater than the norm are associated with greater white matter hyperintensity, a finding consistent with reduced local cerebral blood flow and a heightened risk of cerebrovascular disease.

Within both high and low blood pressure groups, a greater degree of fluctuation was found to correlate with an increase in cerebrovascular disease compared to those with less variability.

Blood pressure Measurement

Arterial pressure is most commonly measured via a sphygmomanometer, which uses the height of a column of mercury, or an aneroid gauge, to reflect the BP by auscultation. The most common automated BP measurement technique is based on the oscillometric method.

A fully automated oscillometric measurement has been available since 1981. This principle has recently been used to measure BP with a smartphone. Measuring pressure invasively, by penetrating the arterial wall to take the measurement, is much less common and usually restricted to a hospital setting. Novel methods to measure BP without penetrating the arterial wall, and without applying any pressure on a patient’s body are currently being explored. 

How to control high blood pressure without medication

If you have high blood pressure, you may wonder if medication is necessary to bring the numbers down. But lifestyle plays a vital role in treating high blood pressure. Controlling blood pressure with a healthy lifestyle might prevent, delay or reduce the need for medication.

Here are 10 lifestyle changes that can lower blood pressure and keep it down:

Lose extra pounds and watch your waistline

Blood pressure often increases as weight increases. Being overweight also can cause disrupted breathing while you sleep (sleep apnea), which further raises blood pressure.

Weight loss is one of the most effective lifestyle changes for controlling blood pressure. If you’re overweight or have obesity, losing even a small amount of weight can help reduce blood pressure. In general, blood pressure might go down by about 1 millimeter of mercury (mm Hg) with each kilogram (about 2.2 pounds) of weight lost.

Also, the size of the waistline is important. Carrying too much weight around the waist can increase the risk of high blood pressure.

In general:

• Men are at risk if their waist measurement is greater than 40 inches (102 centimeters).
• Women are at risk if their waist measurement is greater than 35 inches (89 centimeters).

These numbers vary among ethnic groups. Ask your health care provider about a healthy waist measurement for you.

Exercise regularly

Regular physical activity can lower high blood pressure by about 5 to 8 mm Hg. It’s important to keep exercising to keep blood pressure from rising again. As a general goal, aim for at least 30 minutes of moderate physical activity every day.

Exercise can also help keep elevated blood pressure from turning into high blood pressure (hypertension). For those who have hypertension, regular physical activity can bring blood pressure down to safer levels.

Some examples of aerobic exercise that can help lower blood pressure include walking, jogging, cycling, swimming, or dancing. Another possibility is high-intensity interval training. This type of training involves alternating short bursts of intense activity with periods of lighter activity.

Strength training also can help reduce blood pressure. Aim to include strength training exercises at least two days a week. Talk to a health care provider about developing an exercise program.

Eat a healthy diet

Eating a diet rich in whole grains, fruits, vegetables, and low-fat dairy products and low in saturated fat and cholesterol can lower high blood pressure by up to 11 mm Hg. Examples of eating plans that can help control blood pressure are the Dietary Approaches to Stop Hypertension (DASH) diet and the Mediterranean diet.

Potassium in the diet can lessen the effects of salt (sodium) on blood pressure. The best sources of potassium are foods, such as fruits and vegetables, rather than supplements. Aim for 3,500 to 5,000 mg a day, which might lower blood pressure by 4 to 5 mm Hg.

Ask your care provider how much potassium you should have.

Reduce salt (sodium) in your diet

Even a small reduction of sodium in the diet can improve heart health and reduce high blood pressure by about 5 to 6 mm Hg.

The effect of sodium intake on blood pressure varies among groups of people. In general, limit sodium to 2,300 milligrams (mg) a day or less. However, a lower sodium intake — 1,500 mg a day or less — is ideal for most adults.

To reduce sodium in the diet:

• Read food labels. Look for low-sodium versions of foods and beverages.
• Eat fewer processed foods. Only a small amount of sodium occurs naturally in foods. Most sodium is added during processing.
• Don’t add salt. Use herbs or spices to add flavor to food.
• Cook. Cooking lets you control the amount of sodium in the food.

Limit alcohol

Limiting alcohol to less than one drink a day for women or two drinks a day for men can help lower blood pressure by about 4 mm Hg. One drink equals 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of 80-proof liquor.

But drinking too much alcohol can raise blood pressure by several points. It can also reduce the effectiveness of blood pressure medications.

Quit smoking

Smoking increases blood pressure. Stopping smoking helps lower blood pressure. It can also reduce the risk of heart disease and improve overall health, possibly leading to a longer life.

Get a good night’s sleep

Poor sleep quality — getting fewer than six hours of sleep every night for several weeks — can contribute to hypertension. A number of issues can disrupt sleep, including sleep apnea, restless leg syndrome, and general sleeplessness (insomnia).

Let your health care provider know if you often have trouble sleeping. Finding and treating the cause can help improve sleep. However, if you don’t have sleep apnea or restless leg syndrome, follow these simple tips for getting more restful sleep:

• Stick to a sleep schedule. Go to bed and wake up at the same time each day. Try to keep the same schedule on weeknights and on weekends.
• Create a restful space. That means keeping the sleeping space cool, quiet, and dark. Do something relaxing in the hour before bedtime. That might include taking a warm bath or doing relaxation exercises. Avoid bright light, such as from a TV or computer screen.
• Watch what you eat and drink. Don’t go to bed hungry or stuffed. Avoid large meals close to bedtime. Limit or avoid nicotine, caffeine, and alcohol close to bedtime, as well.
• Limit naps. For those who find napping during the day helpful, limiting naps to 30 minutes earlier in the day might help nighttime sleep.

Reduce stress

Long-term (chronic) emotional stress may contribute to high blood pressure. More research is needed on the effects of stress reduction techniques to find out whether they can reduce blood pressure.

However, it can’t hurt to determine what causes stress, such as work, family, finances, or illness, and find ways to reduce stress. Try the following:

• Avoid trying to do too much. Plan your day and focus on your priorities. Learn to say no. Allow enough time to get what needs to be done.
• Focus on issues you can control and make plans to solve them. For an issue at work, talk to a supervisor. For conflict with kids or spouse, find ways to resolve it.
• Avoid stress triggers. For example, if rush-hour traffic causes stress, travel at a different time or take public transportation. Avoid people who cause stress if possible.
• Make time to relax. Take time each day to sit quietly and breathe deeply. Make time for enjoyable activities or hobbies, such as taking a walk, cooking, or volunteering.
• Practice gratitude. Expressing gratitude to others can help reduce stress.

Monitor your blood pressure at home

Home monitoring can help you keep tabs on your blood pressure. It can make certain your medications and lifestyle changes are working.

Home blood pressure monitors are available widely and without a prescription. Talk to a health care provider about home monitoring before you get started.

Get support

Supportive family and friends are important to good health. They may encourage you to take care of yourself, drive you to the care provider’s office or start an exercise program with you to keep your blood pressure low.

Blood pressure in other animals

Blood pressure in non-human mammals is similar to human blood pressure. In contrast, heart rate differs markedly, largely depending on the size of the animal (larger animals have slower heart rates). As in humans, blood pressure in animals differs by age, sex, time of day, and circumstances: measurements made in laboratories or anesthesia may not be representative of values under free-living conditions.

Rats, mice, dogs, and rabbits have been used extensively to study the causes of high blood pressure.

Blood pressure and heart rate of various mammals (modified from)

Species	Blood pressure mm Hg		Heart rate beats per minute
	Systolic	Diastolic
Calves	140	70	75–146
Cats	155	68	100–259
Dogs	161	51	62–170
Goats	140	90	80–120
Guinea-pigs	140	90	240–300
Mice	120	75	580–680
Pigs	169	55	74–116
Rabbits	118	67	205–306
Rats	153	51	305–500
Rhesus monkeys	160	125	180–210
Sheep	140	80	63–210

Hypertension in cats and dogs

Hypertension in cats and dogs has been diagnosed if the blood pressure is greater than 150 mm Hg (systolic) and/or 95 mm Hg (diastolic).