First Aid Handbook: Blood Pressure

A doctor checks a woman's blood pressure with a device
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What is blood pressure?

Blood pressure is a measure of the force of your blood pushing against the walls of your arteries and is measured both as the heart contracts (systole) and as is relaxes (diastole).  Your blood pressure is expressed in millimeters of mercury, usually stated as “_____ (first number) over _____ (second number).” The first number is the pressure when your heart beats and is pumping the blood; the second is the pressure when your heart is at rest, between beats. A normal blood pressure reading for adults is lower than 120/80 and higher than 90/60.

What factors affect blood pressure?

Blood pressure has a daily pattern, so the time it is taken will affect the readings. Normally it is lowest at night during sleep and begins to rise a few hours before you wake up. It usually continues to rise a bit during the day with the peak occurring in mid-afternoon. As evening approaches, it typically lowers again.

Cold weather and seasonal changes in weather may also affect blood pressure. In general, blood pressure tends to be higher in winter (“cold weather”) and lower in summer due to a constriction of blood vessels resulting in increased pressure. Blood pressure may also be affected by a sudden change in weather patterns, such as a weather front or a storm. Your body — and blood vessels — may react to abrupt changes in humidity, atmospheric pressure, cloud cover or wind in much the same way it reacts to cold. These weather-related variations in blood pressure are more common in people age 65 and older.

In general, aging has some effect on vital signs, including blood pressure. Older people may become dizzy or light-headed when standing up too quickly due to a sudden drop in blood pressure. The risk of high blood pressure also increases in older adults. Some medications can affect blood pressure, such as diuretics (water pills) which can cause low blood pressure.

What does it mean if the numbers are high or low?

Blood pressure that is too high or too low can cause problems. And, abnormal blood pressure patterns may indicate certain disease conditions including poorly controlled high blood pressure, obstructive sleep apnea, kidney disease, thyroid problems, diabetes, nervous system problems, and cardiovascular disease.

You have high blood pressure if your readings show that the systolic (first number) is 140 or higher OR the diastolic (second number) is 90 or higher. If you have other risk factors, numbers lower than these may also cause you to be considered to have high blood pressure. Untreated high blood pressure can cause damage to body organs and increase the likelihood of a stroke.

High blood pressure is what we hear about most often, but low blood pressure can also cause problems. If your blood pressure is 90/60 or lower, you have low blood pressure. Some people have low blood pressure all the time and it is normal for them. In other people, blood pressure drops below normal because of a medical condition or certain medicines. Most doctors will only consider chronically low blood pressure a problem only if it causes noticeable symptoms such as dizziness, fainting, lack of concentration, or rapid, shallow breathing.

Are there ways to prevent high blood pressure?

Because high blood pressure increases your risk for both heart disease and stroke, you want to pay attention to those numbers! If left untreated, high blood pressure can damage important organs, such as the brain or kidneys. The best ways to prevent it from developing are to practice a healthy lifestyle and try to prevent and/or treat any conditions you are aware of.

Certain lifestyle factors may increase your risk for high blood pressure including night-shift work; high levels of stress or anxiety; and tobacco use. High blood pressure is often called the “silent killer” because there are often no signs or symptoms and many people are unaware they have it. That makes it even more important to have it checked regularly.

As an urgent care facility, Integrity Urgent Care is here for you when you or a family member are sick or injured. We also want to help you stay healthy and are here to answer questions you might have about blood pressure – or any other medical topic. Call or visit any one of our four convenient locations daily from 8 am to 8 pm. Let our family take care of your family.

A.D.A.M. Medical Encyclopedia.  Aging changes in vital signs. [online]. Last revised 31 Jul 2019 [accessed 13 Aug s019].

A.D.A.M. Medical Encyclopedia. Blood pressure. [online]. Last reviewed 10 May 2019 [accessed 12 Aug 2019].

National Library of Medicine. Low blood pressure. [online]. Last updated 25 Jul 2019 [accessed 13 Aug 2019].
Sheps S. Blood pressure: does it have a daily pattern? [online]. 9 Jan 2019 [accessed 13 Aug 2019].

Sheps S. Blood pressure: Is it affected by cold weather? [online]. 9 Jan 2019 [accessed 13 Aug 2019].

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