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How Does Blood Pressure Cuff Work

Systolic Vs Diastolic Blood Pressure

How Blood Pressure Readings Work

Systolic BP is the amount of pressure exerted against your artery walls as your heart contracts, pushing blood into the arteries. Diastolic BP measures the lowest pressure in your arteries as your heart maximally relaxes.

Blood pressure readings for adults fall into five categories:

Blood Pressure Stages
Higher than 120

Are The Readings Different Between An Upper Arm Blood Pressure Monitor And A Wrist Blood Pressure Monitor

It is quite possible that your readings may be different from your upper arm to your wrist as blood pressure varies throughout the human body. All Omron blood pressure monitors, whether upper arm or wrist, are validated in the same manner and have the same accuracy specifications. In terms of which type of blood pressure monitor is best for you, we recommend that you discuss this with your doctor, based on your individual needs.

For more information on Omrons line of upper arm and wrist home blood pressure monitors, click below:

Choose Arm Cuffs Over Wrist Cuffs

You can purchase a blood pressure monitor at any drugstore or online. No matter where you buy yours, Dr. Laffin recommends getting a monitor with an automatic cuff that wraps around your upper arm. Its called a brachial blood pressure monitor.

Dont get one where you need a stethoscope, he says. An automatic cuff is best. And if youre over age 50, avoid cuffs that go around your wrist.

Wrist cuffs are likely fine if youre under 50, he says.

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How Blood Pressure Is Tested

A device called a sphygmomanometer will be used to measure your blood pressure.

This usually consists of a stethoscope, arm cuff, pump and dial, although automatic devices that use sensors and have a digital display are also commonly used nowadays.

Its best to sit down with your back supported and legs uncrossed for the test. Youll usually need to roll up your sleeves or remove any long-sleeved clothing, so the cuff can be placed around your upper arm. Try to relax and avoid talking while the test is carried out.

During the test:

  • you hold out one of your arms so its at the same level as your heart, and the cuff is placed around it your arm should be supported in this position, such as with a cushion or arm of a chair
  • the cuff is pumped up to restrict the blood flow in your arm this squeezing may feel a bit uncomfortable, but only lasts a few seconds
  • the pressure in the cuff is slowly released while a stethoscope is used to listen to your pulse
  • the pressure in the cuff is recorded at 2 points as the blood flow starts to return to your arm these measurements are used to give your blood pressure reading

You can usually find out your result straight away, either from the healthcare professional carrying out the test or on the digital display.

Youve Incorrectly Positioned Your Patients Body

HOW STUFF WORKS??: How does a sphygmomanometer (blood pressure gauge) work?

The second most common error in BP measurement is incorrect limb position. To accurately assess blood flow in an extremity, influences of gravity must be eliminated.

The standard reference level for measurement of blood pressure by any technique direct or indirect is at the level of the heart. When using a cuff, the arm where the cuff is applied must be at mid-heart level. Measuring BP in an extremity positioned above heart level will provide a falsely low BP whereas falsely high readings will be obtained whenever a limb is positioned below heart level. Errors can be significant typically 2 mmHg for each inch the extremity is above or below heart level.

A seated upright position provides the most accurate blood pressure, as long as the arm in which the pressure is taken remains at the patients side. Patients lying on their side, or in other positions, can pose problems for accurate pressure measurement. To correctly assess BP in a side lying patient, hold the BP cuff extremity at mid heart level while taking the pressure. In seated patients, be certain to leave the arm at the patients side.

Arterial pressure transducers are subject to similar inaccuracies when the transducer is not positioned at mid-heart level. This location, referred to as the phlebostatic axis, is located at the intersection of the fourth intercostal space and mid-chest level (halfway between the anterior and posterior chest surfaces.

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Indirect Measurement Of Blood Pressure

The most common method of measurement is the blood pressure cuff. This measurement has become established for personal use as well as for examination by a doctor because it is easy to carry out and, compared to direct measurement, is non-invasive.

Blood pressure cuffs for the upper arm or wrist are available for this measurement method. Both work in a similar way: the cuff is inflated until the blood flow is stopped. The measurement can then take place.

Omron Bp Cuff Sizes And Their Monitors

1. Omron 10 Series Home Blood Pressure Monitor

The blood pressure cuff that comes with the Omron 10 Series:

  • Pre-formed Easy-Wrap Comfit Cuff: Fits upper arms 9 to 17 in circumference

Other blood pressure cuff sizes compatible with the Omron 10 Series:

2. Omron Platinum Home Blood Pressure Monitor

The blood pressure cuff that comes with the Omron Platinum:

  • Wide Range Cuff: Fits upper arms 9 to 17 in circumference

Other blood pressure cuff sizes compatible with the Omron Platinum:

  • Small Cuff: Fits upper arms 7 to 9 in circumference

3. Omron Gold Home Blood Pressure Monitor

The Blood Pressure Cuff that comes with the Omron Gold:

  • Wide Range Cuff: Fits upper arms 9 to 17 in circumference

Other blood pressure cuff sizes compatible with the Omron Gold:

  • Small Cuff: Fits upper arms 7 to 9 in circumference

4. Omron 7 Series Home Blood Pressure Monitor

The blood pressure cuff that comes with the Omron 7 Series:

  • Pre-formed Easy-Wrap Comfit Cuff: Fits upper arms 9 to 17 in circumference

Other blood pressure cuff sizes compatible with the Omron 7 Series:

Theres seven more Omron home monitors available, check out all the blood pressure cuff sizes included with them in this article I wrote recently, Omron Home Blood Pressure Cuff Sizes.

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Measuring Blood Pressure With A Sphygmomanometer

A sphygmomanometer has three parts:

  • a cuff that can be inflated with air,
  • a pressure meter for measuring air pressure in the cuff, and
  • a stethoscope for listening to the sound the blood makes as it flows through the brachial artery .

The scale of the pressure meter ranges from 0 to 300 mmHg. The pressure meter has a rubber pump on it for inflating the cuff and a button for letting the air out.

To measure blood pressure, the cuff is placed around the bare and stretched out upper arm, and inflated until no blood can flow through the brachial artery. Then the air is slowly let out of the cuff.

As soon as the air pressure in the cuff falls below the systolic blood pressure in the brachial artery, blood will start to flow through the arm once again. This creates a pounding sound when the arteries close again and the walls of the vessels hit each other after a heart beat. The sound can be heard by placing the stethoscope close to the elbow. Right when you start to hear this pounding for the first time you can read your systolic blood pressure off the pressure meter.

The pounding sound stops when the air pressure in the cuff falls below the diastolic blood pressure in the brachial artery. Then the blood vessels remain open. Right when the pounding stops, you can read the diastolic blood pressure off the pressure meter.

Will I See Differences Between My Readings At Home Compared To Readings In My Doctor’s Office

How blood pressure monitors work?

Yes, you will see some differences. This is normal and can occur for many reasons. Some of the more common reasons are:

  • A persons blood pressure varies throughout the day, so at any given moment your blood pressure can change.
  • In terms of the amount of change there are published studies that show a given persons blood pressure can change by up to 20 mm within a day, based on activity levels, food/drink intake, stress, etc.
  • You may have a condition known as White Coat Hypertension. This is a condition in which a blood persons blood pressure rises above its usual level when it is measured in a doctors office or clinical setting.
  • You may have a condition known as Masked Hypertension. This is a situation in which a persons blood pressure falls below its usual level when it measure in a doctors office or clinical setting.
  • So do not be alarmed when you see differences between your readings at home compared to your readings in your doctors office. Discuss it with your doctor to get the best overall picture of your heart health.

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    Who Are Wireless Blood Pressure Monitors For

    The American Heart Association and other health organizations recommend that people with high blood pressure measure it at home, a practice known as self-measured blood pressure monitoring or home blood pressure monitoring .

    Blood pressure naturally rises and falls throughout the day but chronically high readings can be a sign that your heart is strained and working too hard, a condition known as hypertension. High blood pressure often has no obvious signs or symptoms, which is why it’s known as the “silent killer.” Over time it can increase your risk of heart attack, stroke and heart and kidney failure.

    SMBP can help rule out “white coat hypertension,” in which a person’s blood pressure is high in the doctor’s office but normal in daily life, and masked hypertension, in which a person’s blood pressure is normal in the doctor’s office but elevated in daily life.

    “Taking blood pressure as part of every routine office visit is, at best, not necessary, and at worst, may lead to inferences about a person’s hypertension status that are incorrect,” says Yale Medicine cardiologist Erica S. Spatz, MD. “Ideally we would be using home blood pressure readings to screen for and monitor hypertension. These readings are more indicative of a person’s true hypertension status and better associated with the outcomes we care about, namely heart disease, stroke and kidney disease.”

    Extra Large Blood Pressure Cuff Sizes

    1. LifeSource Home Blood Pressure Monitor

    The LifeSource monitor comes with an extra large cuff only, but the medium and large cuffs can be purchased separately. The following extra large cuff is included:

    • LifeSource Extra Large Cuff: 16.5 23.6

    This monitor only comes with the extra large size cuff 10. The extra large cuff can only be used with this monitor. Therefore, you cannot purchase a less expensive LifeSource monitor and use the extra large cuff with it.

    2. Welch Allyn Home 1700 Series Blood Pressure Monitor

    The 1700 series comes with the standard size cuff, but the extra large cuff can be ordered separately 11. The cuffs can be changed easily within seconds.

    The following are the standard and extra large blood pressure cuff sizes:

    • Welch Allyn 1700 Standard Size BP Cuff: 8.75 16.5
    • Welch Allyn 1700 Extra Large Size BP Cuff: 15.75 21.25

    3. Omron Professional Intellisense Blood Pressure Monitor

    This monitor comes with the following four blood pressure cuffs including an extra large:

    • Omron Extra Large Blood Pressure Cuff: 17 20
    • Large Cuff: 13 17
    • Medium Cuff: 9 13
    • Small Cuff: 7 9

    This monitor is marketed towards the professional but is operated automatically like other home monitors and can be used in the home too 12.

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    What If I Don’t Have High Or Low Blood Pressure

    High blood pressure is one symptom of preeclampsia, a condition that affects 5% to 8% of pregnancies.

    People who are otherwise healthy but at an increased risk of developing hypertension and cardiovascular disease, such as people with a family history of early hypertension or women with a history of preeclampsia during pregnancy, can also benefit from SMBP tests. “Monitoring home blood pressure from time to time can provide an early window into elevated blood pressures, giving higher-risk people the feedback they need to avert the onset of hypertension,” says Spatz.

    Totally healthy? Occasional SMBP can still be helpful. “Knowing how your blood pressure responds to periods of stress or lack of sleep can provide important mind-body connections, and may motivate you to take a more holistic approach to your cardiovascular health,” says Spatz.

    Just one caveat: Some people are unable to get an accurate blood pressure reading using these devices because of illness, birth defects or conditions such as an irregular heartbeat, so talk to your doctor about whether SMBP is right for you.

    Errors Using A Wrist Blood Pressure Cuff

    How To Take Blood Pressure On Wrist Cuff

    Its easier to make an error using a wrist cuff over a standard upper arm cuff. Its because people arent used to them and the cuff is smaller allowing more movement away from heart level. The following are errors when using a wrist blood pressure cuff:

    • Not keeping the wrist cuff at heart level.
    • Not supporting the upper arm properly. The elbow should be supported on a comfortable surface.
    • Wrapping the cuff around the protruding wrist bone.
    • Wrapping the cuff too loose. There shouldnt be any space between the cuff and the skin.
    • Using the wrong wrist.

    Learn more details to the instructions above in my article, How To Use a Wrist Blood Pressure Cuff.

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    High Or Low Blood Pressure

    Hypertension is when your BP is above normal. When BP is too high for too long, it can slowly and significantly harm your health. Often, people with hypertension have no symptoms, and thus may be unaware they have high BP.

    Hypotension is when your BP is too low or below normal. It can cause fainting, dizziness, and fatigue. Low BP typically only presents a problem when it’s linked to symptoms.

    According to the American Heart Association, there is no specific number at which day-to-day BP is considered too low. Within certain limits, it is ideal to keep your BP on the low side, as long as you aren’t experiencing symptoms of low BP.

    How Is High Blood Pressure Treated

    Treatment for hypertension depends on how high your blood pressure is, as well as your lifestyle and risk factors.

    For elevated blood pressure, the goal is to keep your blood pressure from developing into clinical hypertension. No medications are necessary at this stage. Your doctor may recommend:

    For stage 1 hypertension, your doctor may recommend lifestyle changes as mentioned above, as well as:

    • reducing your sodium intake
    • finding healthy ways to manage your stress
    • medication, if your blood pressure doesnt improve after 1 month of lifestyle changes

    For stage 2 hypertension, the typical treatment, in addition to a healthier lifestyle, is medication. Your doctor may prescribe one or more of the following medications to help lower your blood pressure:

    A hypertensive crisis requires immediate treatment. Medications may be given orally or intravenously .

    The most for a hypertensive crisis include:

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    Blood Pressure Cuff Too Big For Arm

    A blood pressure cuff too big for the arm will cut the blood flow faster resulting in a lower blood pressure measurement. What is the blood pressure cuff size rule?

    It is recommended the blood pressure cuff bladder length should be 75-100% of the upper arm circumference. The width should be 37-50% of the upper arm circumference.

    Its important to use a monitor with an arm circumference range fitting the upper arm. Lets say a monitor comes with a standard size cuff range between 8.75-16.5. If the arm measures 15, typically this size cuff and inside bladder would be appropriate for measuring blood pressure 4.

    The cuff bladder is located inside the the blood pressure cuff material. The bladder is what fills up with air when the monitor is turned on. The air supply tube connects inside to the bladder and provides air from the monitor.

    My article, Blood Pressure Cuff Too Large, contains three studies which informs you how much blood pressure was lower when using a cuff too large. In addition, it has tips on avoiding the problem.

    What Do The Numbers Mean

    How Blood Pressure Works Animation – Understanding Blood Pressure Measurement Monitor Readings Video

    When a healthcare professional takes your blood pressure, its expressed as a measurement with two numbers, one number on top and one on the bottom , like a fraction. For example, 120/80 mm Hg.

    Blood pressure is measured in millimeters of mercury. Thats what the mm/Hg stands for. Heres what the numbers mean:

    • Your systolic pressure is the pressure of the blood in your arteries when your heart contracts or beats.
    • Your diastolic pressure is the pressure of the blood in your arteries between beats, when your heart relaxes.

    Both numbers are important in determining the state of your heart health.

    Numbers greater than the ideal range may be a sign that your heart is working too hard to pump blood to the rest of your body.

    For a normal reading, your blood pressure needs to show:

    • a systolic pressure thats above 90 mm Hg and less than 120 mm Hg, and
    • a diastolic pressure thats between 60 mm Hg and less than 80 mm Hg

    The American Heart Association considers blood pressure to be within the normal range when both your systolic and diastolic numbers are in these ranges.

    If youre in the normal range, no medical intervention is needed. However, its important to maintain a healthy lifestyle and moderate weight to help prevent high blood pressure from developing.

    You may need to be even more mindful of your lifestyle if high blood pressure runs in your family.

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