What is blood pressure?
The heart pumps blood through the blood vessels in our bodies. This is important for delivering oxygen and other nutrients to our tissues, and also for removing waste. The pumping action is caused by the heart muscle relaxing and contracting. When the heart muscle relaxes (called diastole) the heart is filled with blood. Subsequent contraction of the heart muscle (called systole) forces the blood from the heart into the blood vessels to circulate around the body. Blood pressure (BP) refers to the pressure created in the arteries by blood as the heart contracts and relaxes.
How do we measure blood pressure?
The most accurate, non-invasive method of measuring BP is the mercury sphygmomanometer used by your trained health professional. However, due to environmental concerns regarding heavy metal contamination, these may be phased out in the future. The accuracy of other devices varies widely. Digital devices should be checked and validated every 6 months.
What Is “Normal” Blood Pressure?
A blood pressure reading has a top number (systolic) and bottom number (diastolic). The ranges are:
- Normal: Less than 120 over 80 (120/80)
- Prehypertension: 120-139 over 80-89
- Stage 1 high blood pressure: 140-159 over 90-99
- Stage 2 high blood pressure: 160 and above over 100 and above
- High blood pressure in people over age 60: 150 and above over 90 and above
People whose blood pressure is above the normal range should consult their doctor about steps to take to lower it.
What Causes High Blood Pressure?
Blood pressure is the measure of the force of blood pushing against blood vessel walls. The heart pumps blood into the arteries (blood vessels), which carry the blood throughout the body. High blood pressure, also called hypertension, is dangerous because it makes the heart work harder to pump blood out to the body and contributes to hardening of the arteries, or atherosclerosis, to stroke, kidney disease, and to the development of heart failure. The exact causes of high blood pressure are not known, but several factors and conditions may play a role in its development, including:
- Being overweight or obese
- Lack of physical activity
- Too much salt in the diet
- Too much alcohol consumption (more than 1 to 2 drinks per day)
- Older age
- Family history of high blood pressure
- Chronic kidney disease
- Adrenal and thyroid disorders
- Sleep apnea
- Essential Hypertension
Essential hypertension is also greatly influenced by diet and lifestyle. The link between salt and high blood pressure is especially compelling. People living on the northern islands of Japan eat more salt per capita than anyone else in the world and have the highest incidence of essential hypertension. By contrast, people who add no salt to their food show virtually no traces of essential hypertension. The majority of all people with high blood pressure are “salt sensitive,” meaning that anything more than the minimal bodily need for salt is too much for them and increases their blood pressure. Other factors that can raise the risk of having essential hypertension include obesity; diabetes; stress; insufficient intake of potassium, calcium, and magnesium; lack of physical activity; and chronic alcohol consumption.
When a direct cause for high blood pressure can be identified, the condition is described as secondary hypertension. Among the known causes of secondary hypertension, kidney disease ranks highest. Hypertension can also be triggered by tumors or other abnormalities that cause the adrenal glands (small glands that sit atop the kidneys) to secrete excess amounts of the hormones that elevate blood pressure. Birth control pills — specifically those containing estrogen — and pregnancy can boost blood pressure, as can medications that constrict blood vessels.
What are the signs and symptoms of high blood pressure?
High blood pressure usually has no signs or symptoms, so the only way to know if you have high blood pressure is to have yours measured. However, a single high reading does not necessarily mean you have high blood pressure. Many things can affect your blood pressure through the day, so your doctor will take a number of blood pressure readings to see that it stays high over time.
Controlling high blood pressure
- Lifestyle changes
- keep taking the medicines regularly, often for the rest of your life.
- Monitoring blood pressure
- Manage heart disease risk factors
- High blood pressure is a risk factor for heart disease.
Types of blood pressure medicine:-
There is a wide range of high blood pressure medicines. You can take more than one type of medicine because they each lower your blood pressure in different ways. There are four main types of medicine that doctors use to treat high blood pressure:
- ACE inhibitors: these medicines help to control hormones that affect blood pressure. Most of these medicines have names that end in “pril”
- Angiotensin receptor blockers (or ARBs): these also control hormones that affect blood pressure. Most of these medicines have names that end in “artan”
- Calcium channel blockers: these medicines make the artery walls relax, making them wider, which lowers blood pressure. Most of these medicines have names that in “pine”
- Thiazide diuretics: these medicines remove unwanted fluid from the body, which helps lower blood pressure. Most of these medicines have names that end in “ide”.
What is low blood pressure?
Many people worry about low blood pressure (hypotension), but probably don’t need to. Some people have a blood pressure level that is lower than normal. In general this may be good news – because the lower your blood pressure is, the lower your risk of stroke or heart disease. However, in a few cases, having low blood pressure can cause problems, so you might need to speak to your doctor or nurse.
What is a low blood pressure reading?
A low blood pressure reading is having a level that is 90/60 mm Hg, or lower. Only one of the numbers has to be lower than it should be to count as low blood pressure. In other words:
- if the top number is 90 or less (regardless of the bottom number) this may be low blood pressure
- if the bottom number is 60 or less (regardless of the top number) this may be low blood pressure.
What causes low blood pressure?
Some people have a blood pressure level that is naturally low. That is, there is no specific cause or reason why. However, some health conditions or medicines can cause you to develop low blood pressure.
Is low blood pressure dangerous?
Usually, having low blood pressure is not a cause for concern. However, sometimes your blood pressure can drop to a point where you may feel faint. If you find that your blood pressure is suddenly much lower than usual, there may be a reason for this. Speak to your doctor or nurse.
How is low blood pressure treated?
Most people with low blood pressure will not need treatment. Proper diet will help low blood pressure.
Can you give blood if you have high blood pressure?
Blood Pressure, High. Acceptable as long as your blood pressure is below 180 systolic (first number) and below 100 diastolic (second number) at the time of donation. Medications for high blood pressure do not disqualify you from donating.
Can you give blood if you have low blood pressure?
Acceptable as long as you feel well when you come to donate, and your blood pressure is at least 80/50 (systolic/diastolic).
Preparing for blood pressure measurement:-
For at least two hours before getting your BP measured, you should avoid caffeine and tobacco smoke. These may cause your BP to rise, especially if they are taken together. Try to relax in the waiting area, and seat yourself comfortably.
Conditions associated with a change in blood pressure:-
There are several conditions associated with changes in BP.
Hypertension (or high blood pressure) is associated with a greater risk of:-
- Coronary heart disease
- Chronic kidney disease
- Heart failure
Hypotension (or low blood pressure) is seen in cases of:-
- Orthostatic hypotension
- Exposure to toxins
- Hormonal abnormalities (e.g. Addison’s disease)