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Blood pressure is one of the four major vital signs, the others being heart rate, breathing rate, and body temperature. These vital signs can help give a general idea of how well the body and its organs are performing.
Changes in a person’s vital signs can indicate an underlying health problem or a need to make lifestyle changes.
Blood pressure is typically measured using a blood pressure cuff. People who do not have the proper equipment may still want to measure their blood pressure, but this is difficult to do accurately. In most cases, it is better to buy a blood pressure machine or visit a doctor or pharmacy for testing.
Blood pressure measures the amount of force blood places on the blood vessels in the body. A blood pressure reading includes two numbers that indicate the pressure inside the arteries as the blood flows through the body.
The upper number, called the systolic pressure, measures the pressure inside the arteries as the heart contracts to pump blood. The lower number, called the diastolic pressure, is the pressure inside the artery as the heart rests between each beat.
According to the American Heart Association, normal blood pressure is anything below 120/80 mm Hg. If these numbers go higher than 120/80 mm Hg, it is often an indication that the heart is working too hard to pump blood through the arteries.
High blood pressure can be caused by many factors, including:
Accurate blood pressure readings are important, as high blood pressure may not cause any symptoms until it is dangerously high.
Doctors use either electronic or mechanical machines to measure blood pressure in a clinic. In some cases, they may recommend monitoring and recording the blood pressure at home.
Monitoring blood pressure at home usually requires a machine that insurance may or may not cover. Reasons a doctor may recommend monitoring blood pressure at home include needing to know the blood pressure at certain times of the day or after taking certain medications.
It is possible, however, to take blood pressure without using a machine.
To check the blood pressure without the aid of an automated machine, a person will need several medical items. These are:
- a stethoscope
- a blood pressure cuff with a squeezable balloon
- an aneroid monitor, which has a numbered dial to read measurements
To check the blood pressure manually, sit in a relaxed position with the arm at rest on a table. Secure the cuff on the bicep and squeeze the balloon to increase the pressure.
Watch the aneroid monitor and increase the pressure to about 30 mm Hg over the normal blood pressure, or to 180 mm Hg if this is not known. When the cuff is inflated, place the stethoscope just inside the elbow crease under the cuff.
Slowly deflate the balloon and listen through the stethoscope. When the first beats hit, note the number on the aneroid monitor. This is the systolic pressure.
Continue listening until the steady heartbeat sound stops and record the number from the aneroid monitor again. This is the diastolic pressure. These two numbers are the blood pressure reading.
When checking blood pressure at home, it is important to remember:
- Manual cuffs come in different sizes depending on the size of the arm. Using the right size ensures the most accurate reading.
- The cuff should always sit directly on the bare skin.
- Take a few deep breaths and relax for up to 5 minutes before measuring blood pressure.
- Avoid talking during the test.
- Place the feet flat on the floor and sit up straight while measuring the blood pressure.
- Avoid checking blood pressure in a cold room.
- Support the arm as close to heart level as possible.
- Measure the blood pressure at a few different times during the day.
- Avoid smoking, drinking, and exercise for 30 minutes before taking blood pressure.
- Empty the bladder before taking a blood pressure test. A full bladder may give an incorrect blood pressure reading.
The easiest and most accurate way to measure the blood pressure at home is to buy an automated blood pressure monitor with an upper arm cuff.
The instructions for use may vary with each machine, and a person should follow them carefully to ensure proper operation. If the instructions are difficult to understand, a local pharmacy or doctor’s office will be able to show a person how to operate the machine correctly.
Doctors may ask a person to bring their at-home machine to the office during their next visit to test the accuracy compared to the doctor’s reading.
Using a high-quality machine is important, as inaccurate readings may cause unnecessary or harmful changes in medications or treatments.
A variety of blood pressure monitors are available for purchase online and in most drug stores. A person may wish to speak to a doctor about which brand they recommend.
There are apps and wrist devices that claim to measure the blood pressure, but these results are frequently inaccurate and are not a reliable way to monitor a person’s health.
Apps that log blood pressure results may be helpful for people who need to take regular blood pressure tests, however.
Recording a set of readings into these apps may help doctors identify trends in blood pressure and recommend treatments.
Blood pressure readings fall into the following categories:
|Blood pressure status||Systolic mm Hg||Diastolic mm Hg|
|Normal||Less than 120||Less than 80|
|Elevated||120–129||Less than 80|
|Stage 1 high blood pressure (hypertension)||130–139||80–89|
|Stage 2 high blood pressure||140 or higher||90 or higher|
|Hypertensive crisis (seek immediate medical attention)||180 or higher||120 or higher|
Normal blood pressure is considered anything below 120/80 mm Hg. However, a healthy number may vary from person to person.
The numbers may change based on factors such as:
- physical activity
- underlying medical conditions
Anyone uncertain about their target blood pressure should visit a doctor for guidance.
If an at-home reading is higher than usual, it is important to do another reading 5 minutes later to ensure it is accurate.
Anyone who experiences a systolic pressure over 180 mm Hg or a diastolic pressure over 120 mm Hg should seek emergency medical care, as this is a sign of a hypertensive crisis.
Blood pressure can vary based on a range of factors, so it is essential to take more than one reading for accuracy.
Tests taken at home may not be as accurate as those offered at the doctor’s office, but automated blood pressure monitors are often just as precise.
Anyone concerned about their blood pressure readings should consult a doctor for the best way to monitor and manage their blood pressure.
Lifestyle changes are often necessary and may include things such as reducing salt intake and exercising regularly.
Medications may also be recommended in some cases. Monitoring blood pressure at home can help a doctor determine if the dose is sufficient or needs changing.