How tight blood pressure cuff?

5 errors that are giving you incorrect blood pressure readings

Nurses and physicians often argue over differences between arterial line and non-invasive blood pressure (NIBP) cuff readings. Revised guidelines for management of high blood pressure increased thresholds for diagnosing and treating hypertension, causing further debate and controvery .

To make the best use of blood pressure monitoring equipment, it is helpful to have an insight into how the equipment works and the likely sources of error that can affect readings.

Here’s what many of us do wrong, and how to take a blood pressure reading:

The most common error when using indirect blood pressure monitoring equipment is using an incorrectly sized BP cuff

1. You’re using the wrong-sized cuff

The most common error when using indirect blood pressure measuring equipment is using an incorrectly sized cuff. A BP cuff that is too large will give falsely low readings, while an overly small cuff will provide readings that are falsely high. The American Heart Association publishes guidelines for blood pressure measurement . recommending that the bladder length and width (the inflatable portion of the cuff) should be 80 percent and 40 percent respectively, of arm circumference. Most practitioners find measuring bladder and arm circumference to be overly time consuming, so they don’t do it.

The most practical way to quickly and properly size a BP cuff is to pick a cuff that covers two-thirds of the distance between your patient’s elbow and shoulder. Carrying at least three cuff sizes (large adult, regular adult, and pediatric) will fit the majority of the adult population. Multiple smaller sizes are needed if you frequently treat pediatric patients.

Korotkoff sounds are the noises heard through a stethoscope during cuff deflation. They occur in 5 phases:

  • I – first detectable sounds, corresponding to appearance of a palpable pulse
  • II – sounds become softer, longer and may occasionally transiently disappear
  • III – change in sounds to a thumping quality (loudest)
  • IV – pitch intensity changes and sounds become muffled
  • V – sounds disappear

In their 1967 guidelines, the AHA recommended that clinicians record the systolic BP at the start of phase I and the diastolic BP at start of phase IV Korotkoff sounds. In their 1981 guidelines, the diastolic BP recommendation changed to the start of phase V .

2. You’ve incorrectly positioned your patient’s body

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 (or leg) 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 patient’s 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 patient’s 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.

Note that the mid-axillary line is often not at mid-chest level in patients with kyphosis or COPD, and therefore should not be used as a landmark. Incorrect leveling is the primary source of error in direct pressure measurement with each inch the transducer is misleveled causing a 1.86 mmHg measurement error. When above the phlebostatic axis, reported values will be lower than actual; when below the phlebostatic axis, reported values will be higher than actual.

3. You’ve placed the cuff incorrectly

The standard for blood pressure cuff placement is the upper arm using a cuff on bare skin with a stethoscope placed at the elbow fold over the brachial artery.

The patient should be sitting, with the arm supported at mid heart level, legs uncrossed, and not talking. Measurements can be made at other locations such as the wrist, fingers, feet, and calves but will produce varied readings depending on distance from the heart.

The mean pressure, interestingly, varies little between the aorta and peripheral arteries, while the systolic pressure increases and the diastolic decreases in the more distal vessels.

Crossing the legs increases systolic blood pressure by 2 to 8 mm Hg. About 20 percent of the population has differences of more than 10 mmHg pressure between the right and left arms. In cases where significant differences are observed, treatment decisions should be based on the higher of the two pressures.

4. Your readings exhibit ‘prejudice’

Prejudice for normal readings significantly contributes to inaccuracies in blood pressure measurement. No doubt, you’d be suspicious if a fellow EMT reported blood pressures of 120/80 on three patients in a row. As creatures of habit, human beings expect to hear sounds at certain times and when extraneous interference makes a blood pressure difficult to obtain, there is considerable tendency to “hear” a normal blood pressure.

Orthostatic hypotension is defined as a decrease in systolic blood pressure of 20 mm Hg or more, or diastolic blood pressure decrease of 10 mm Hg or more measured after three minutes of standing quietly.

There are circumstances when BP measurement is simply not possible. For many years, trauma resuscitation guidelines taught that rough estimates of systolic BP (SBP) could be made by assessing pulses. Presence of a radial pulse was thought to correlate with an SBP of at least 80 mm Hg, a femoral pulse with an SBP of at least 70, and a palpable carotid pulse with an SBP over 60. In recent years, vascular surgery and trauma studies have shown this method to be poorly predictive of actual blood pressure .

Noise is a factor that can also interfere with BP measurement. Many ALS units carry doppler units that measure blood flow with ultrasound waves. Doppler units amplify sound and are useful in high noise environments.

BP by palpation or obtaining the systolic value by palpating a distal pulse while deflating the blood pressure cuff generally comes within 10 – 20 mmHg of an auscultated reading. A pulse oximeter waveform can also be used to measure return of blood flow while deflating a BP cuff, and is as accurate as pressures obtained by palpation.

In patients with circulatory assist devices that produce non-pulsatile flow such as left ventricular assist devices (LVADs), the only indirect means of measuring flow requires use of a doppler.

The return of flow signals over the brachial artery during deflation of a blood pressure cuff in an LVAD patient signifies the mean arterial pressure (MAP). While a normal MAP in adults ranges from 70 to 105 mmHg, LVADs do not function optimally against higher afterload, so mean pressures of less than 90 are often desirable.

Clothing, patient access, and cuff size are obstacles that frequently interfere with conventional BP measurement. Consider using alternate sites such as placing the BP cuff on your patient’s lower arm above the wrist while auscultating or palpating their radial artery. This is particularly useful in bariatric patients when an appropriately sized cuff is not available for the upper arm. The thigh or lower leg can be used in a similar fashion (in conjunction with a pulse point distal to the cuff).

All of these locations are routinely used to monitor BP in hospital settings and generally provide results only slightly different from traditional measurements in the upper arm.

5. You’re not factoring in electronic units correctly

Electronic blood pressure units also called Non Invasive Blood Pressure (NIBP) machines, sense air pressure changes in the cuff caused by blood flowing through the BP cuff extremity. Sensors estimate the Mean Arterial Pressure (MAP) and the patient’s pulse rate. Software in the machine uses these two values to calculate the systolic and diastolic BP.

To assure accuracy from electronic units, it is important to verify the displayed pulse with an actual patient pulse. Differences of more than 10 percent will seriously alter the unit’s calculations and produce incorrect systolic and diastolic values on the display screen.

Given that MAP is the only pressure actually measured by an NIBP, and since MAP varies little throughout the body, it makes sense to use this number for treatment decisions.

A normal adult MAP ranges from 70 to 105 mmHg. As the organ most sensitive to pressure, the kidneys typically require an MAP above 60 to stay alive, and sustain irreversible damage beyond 20 minutes below that in most adults. Because individual requirements vary, most clinicians consider a MAP of 70 as a reasonable lower limit for their adult patients.

Increased use of NIBP devices, coupled with recognition that their displayed systolic and diastolic values are calculated while only the mean is actually measured, have led clinicians to pay much more attention to MAPs than in the past. Many progressive hospitals order sets and prehospital BLS and ALS protocols have begun to treat MAPs rather than systolic blood pressures.

Finally, and especially in the critical care transport environment, providers will encounter patients with significant variations between NIBP (indirect) and arterial line (direct) measured blood pressure values.

In the past, depending on patient condition, providers have elected to use one measuring device over another, often without clear rationale besides a belief that the selected device was providing more accurate blood pressure information.

In 2013, a group of ICU researchers published an analysis of 27,022 simultaneous art line and NIBP measurements obtained in 852 patients . When comparing the a-line and NIBP readings, the researchers were able to determine that, in hypotensive states, the NIBP significant overestimated the systolic blood pressure when compared to the arterial line, and this difference increased as patients became more hypotensive.

At the same time, the mean arterial pressures (MAPs) consistently correlated between the a-line and NIBP devices, regardless of pressure. The authors suggested that MAP is the most accurate value to trend and treat, regardless of whether BP is being measured with an arterial line or an NIBP. Additionally, supporting previously believed parameters for acute kidney injury (AKI) and mortality, the authors noted that a MAP below 60 mmHg was consistently associated with both AKI and increased mortality.

Since 1930, blood pressure measurement has been a widely accepted tool for cardiovascular assessment. Even under the often adverse conditions encountered in the prehospital or transport environment, providers can accurately measure blood pressure if they understand the principles of blood flow and common sources that introduce error into the measurement process.

Keep learning about blood pressure assessment by reading how to mitigate NIBP and auscultating innacuracies by watching the plethysmography waveform on your pulse oximeter and noting the mean arterial pressure. Learn how to read a MAP.

4. Lehman LH, Saeed M, Talmor D, Mark R, Malhotra A. Methods of blood pressure measurement in the ICU. Crit Care Med. 2013;41:34-40.

This article, originally posted Apr. 9, 2014, has been updated.

For people with high blood pressure or a high risk of the disease, monitoring their blood pressure may become a daily requirement.

As more advanced blood pressure readers have been made, it is quite easy to check blood pressure at home.

However, high technology is not enough to ensure an accurate blood pressure reading. Some commons things we do can cause the numbers falsely high.

According to American Heart Association, there are seven common mistakes people make when measuring their blood pressure:

Talking. When people measures blood pressure, they should keep still and silent and not talk on the phone or answer questions. Why? because talking can add 10 points to the reading.

Sitting with crossed legs – Crossing legs when sitting is polite. But this can increase the blood pressure reading 2-8 points. The best way is to uncross your legs while ensuring your feet are supported.

Unsupported arm – during a blood pressure measurement, your measured arm should be relaxed and supported. If you have to hold it, the blood pressure numbers may go up to 10 points higher than it should be.

The best way is to position your arm on a chair or counter, so that the measurement cuff is level with your heart.

Unsupported back/feet – Like unsupported arms, this can also add 6-10 points to your blood pressure reading. The best way is to sit on a chair with your back supported and put your feet on the floor or a footstool.

Wrapping the cuff over clothing – This common error can add 5-50 points to your reading. Instead, be sure the cuff is placed on a bare arm.

The cuff is too tight – a very tight cuff not only makes you uncomfortable, but also may add 2-10 points to your blood pressure. So you should ensure a proper fit.

Having a full bladder – this common mistake can add 10-15 points to your blood pressure reading. Always empty your bladder before your measure your blood pressure.

All the seven mistakes are common things we do in daily life, but they can make a difference in whether or not a person is classified as having high blood pressure.

A false diagnosis can bring unnecessary treatments that harm your health.

“Knowing how to measure blood pressure accurately at home, and recognizing mistakes in the physician’s office, can help you manage your pressure and avoid unnecessary medication changes.” One researcher said.

New AHA Recommendations for Blood Pressure Measurement

In-Clinic Measurement

In the standard clinic procedure (mercury sphygmomanometer with the Korotkoff ’s sound technique), accurate measurement of blood pressure depends on the person doing the reading, or the “observer.” Proper training; use of an accurate, well-maintained device; correct selection and positioning of the cuff; appropriate positioning of the patient; and recognition of factors that may skew the measurement are critical. One of the most common observer errors is terminal digit bias (e.g., excessive recording of “zero” as the last digit, or fitting the measurement to a specific recognized threshold). Guidelines for in-clinic measurement are summarized in Table 2.

TABLE 2

American Heart Association Guidelines for In-Clinic Blood Pressure Measurement

Recommendation

Patient should be seated comfortably, with back supported, legs uncrossed, and upper arm bared.

Diastolic pressure is higher in the seated position, whereas systolic pressure is higher in the supine position.

An unsupported back may increase diastolic pressure; crossing the legs may increase systolic pressure.

Patient’s arm should be supported at heart level.

If the upper arm is below the level of the right atrium, the readings will be too high; if the upper arm is above heart level, the readings will be too low.

If the arm is unsupported and held up by the patient, pressure will be higher.

Cuff bladder should encircle 80 percent or more of the patient’s arm circumference.

An undersized cuff increases errors in measurement.

Mercury column should be deflated at 2 to3 mm per second.

Deflation rates greater than 2 mm per second can cause the systolic pressure to appear lower and the diastolic pressure to appear higher.

The first and last audible sounds should be recorded as systolic and diastolic pressure, respectively. Measurements should be given to the nearest 2 mm Hg.

Neither the patient nor the person taking the measurement should talk during the procedure.

Talking during the procedure may cause deviations in the measurement.

Information from Pickering TG, Hall JE, Appel LJ, Falkner BE, Graves J, Hill MN, et al.; Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Recommendations for blood pressure measurement in humans and experimental animals. Part 1: blood pressure measurement in humans. Hypertension 2005;45:142–61.

TABLE 2

Recommendation

Patient should be seated comfortably, with back supported, legs uncrossed, and upper arm bared.

Diastolic pressure is higher in the seated position, whereas systolic pressure is higher in the supine position.

An unsupported back may increase diastolic pressure; crossing the legs may increase systolic pressure.

Patient’s arm should be supported at heart level.

If the upper arm is below the level of the right atrium, the readings will be too high; if the upper arm is above heart level, the readings will be too low.

If the arm is unsupported and held up by the patient, pressure will be higher.

Cuff bladder should encircle 80 percent or more of the patient’s arm circumference.

An undersized cuff increases errors in measurement.

Mercury column should be deflated at 2 to3 mm per second.

Deflation rates greater than 2 mm per second can cause the systolic pressure to appear lower and the diastolic pressure to appear higher.

The first and last audible sounds should be recorded as systolic and diastolic pressure, respectively. Measurements should be given to the nearest 2 mm Hg.

Neither the patient nor the person taking the measurement should talk during the procedure.

Talking during the procedure may cause deviations in the measurement.

Information from Pickering TG, Hall JE, Appel LJ, Falkner BE, Graves J, Hill MN, et al.; Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Recommendations for blood pressure measurement in humans and experimental animals. Part 1: blood pressure measurement in humans. Hypertension 2005;45:142–61.

Observers should be assessed for physical and cognitive competency to perform the procedure, including vision, hearing, and eye/hand/ear coordination. Retraining of all health care professionals is strongly recommended by the AHA. Training methods using audiovisual tapes to test and retest accuracy are extremely effective. Online resources that may be useful include a guide to accurate blood pressure measurement athttp://www.igan.ca/id57.htm, and an instructional video from BMJ Books atwww.abdn.ac.uk/medical/bhs/tutorial/tutorial.htm.

DEVICE

According to the AHA, mercury sphygmomanometers still are the preferred device and should be used if available and properly maintained, although they are being removed from clinical practice for environmental reasons. The tubing between the device and the cuff should be 27.5 inches (70 cm) or more in the office setting. The system must be airtight, so the tubing and release valve should be inspected regularly.

Other devices, such as aneroid and hybrid sphygmomanometers, may be used as a substitute or a supplement, but there is no widely accepted replacement. Mercury sphygmomanometers still are necessary for evaluating the accuracy of other devices.

Automated oscillometric devices may be useful for an increased number of readings and to avoid expensive training. Devices with linear deflation rates may be more accurate than those with stepwise deflation. Measurements with automated devices typically are lower than those taken by a physician, perhaps because of the white coat effect; correct patient position and cuff selection still are required. Some automated devices have been validated for use during pregnancy and may be useful as an alternative to mercury devices in the future. Automated devices are acceptable in newborn and young infants and in the intensive care setting, although their reliability is unclear.

PATIENT POSITION

The position of the patient can have a sizable impact on blood pressure measurements. For the most accurate measurement, the AHA recommends that the patient be relaxed and seated with legs uncrossed and back and arm supported. Children should have their feet on the floor rather than dangling above it. If possible, the patient should be seated five minutes before the reading. All clothing covering the cuff location should be removed (rolled-up sleeves, if tight, may create a tourniquet effect above the cuff).

The middle of the cuff on the upper arm should be level with the right atrium, at the midpoint of the sternum. If the upper arm is below the level of the right atrium, the readings will be too high; if the upper arm is above heart level, the readings will be too low In the supine position, the arm should be supported on a pillow to raise it above the level of the heart, which is situated about halfway between the bed and the sternum. In women who are pregnant, the left lateral recumbency position can be used, with measurement on the left arm.

TABLE 3

Recommended Cuff Sizes for Accurate Measurement of Blood Pressure

Patient Recommended cuff size

Adults (by arm circumference)

22 to 26 cm

12 × 22 cm (small adult)

27 to 34 cm

16 × 30 cm (adult)

35 to 44 cm

16 × 36 cm (large adult)

45 to 52 cm

16 × 42 cm (adult thigh)

Children (by age)*

Newborns and premature infants

4 × 8 cm

Infants

6 × 12 cm

Older children

9 × 18 cm

*—A standard adult cuff, large adult cuff, and thigh cuff should be available for use in measuring a child’s leg blood pressure and for children with larger arms

Information from Pickering TG, Hall JE, Appel LJ, Falkner BE, Graves J, Hill MN, et al.; Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Recommendations for blood pressure measurement in humans and experimental animals. Part 1: blood pressure measurement in humans. Hypertension 2005;45:142–61.

TABLE 3

Patient Recommended cuff size

Adults (by arm circumference)

22 to 26 cm

12 × 22 cm (small adult)

27 to 34 cm

16 × 30 cm (adult)

35 to 44 cm

16 × 36 cm (large adult)

45 to 52 cm

16 × 42 cm (adult thigh)

Children (by age)*

Newborns and premature infants

4 × 8 cm

Infants

6 × 12 cm

Older children

9 × 18 cm

*—A standard adult cuff, large adult cuff, and thigh cuff should be available for use in measuring a child’s leg blood pressure and for children with larger arms

Information from Pickering TG, Hall JE, Appel LJ, Falkner BE, Graves J, Hill MN, et al.; Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research. Recommendations for blood pressure measurement in humans and experimental animals. Part 1: blood pressure measurement in humans. Hypertension 2005;45:142–61.

The patient should not talk during the procedure, because this may cause deviations in the measurement. Other factors that can affect the measurement include exercise, smoking, alcohol consumption, muscle tension, bladder distension, room temperature, and background noise.

In older patients, blood pressure should be measured routinely in the standing and seated positions to screen for postural hypotension

CUFF SIZE AND PLACEMENT

The most common error in blood pressure measurement is use of inappropriate cuff size. Considerable overestimation can occur if the cuff is too small. The bladder length recommended by the AHA is 80 percent of the patient’s arm circumference, and the ideal width is at least 40 percent. Error is minimized when the cuff width is 46 percent of the arm circumference, although for large adult and thigh cuffs this is not practical. In obese patients, longer, wider cuffs are needed to compress the brachial artery adequately. In children, cuff bladder width should be at least 40 percent of the arm circumference halfway between the olecranon and acromion; the cuff should then cover 80 percent or more of the arm circumference. Recommended cuff sizes are listed in Table 3.

For correct cuff placement, the midline of the cuff bladder should be positioned over the arterial pulsation in the patient’s upper arm following palpation of the brachial artery in the antecubital fossa. There should be a 2– to 3–cm space for the stethoscope between the lower end of the cuff and the antecubital fossa, unless this would require an undersized cuff. In patients with an arm circumference greater than 50 cm, the cuff should be wrapped around the forearm, supported at heart level, and the radial pulse felt at the wrist

INFLATION AND DEFLATION

The rate of deflation in indirect blood pressure measurement significantly impacts the reading. The AHA recommends that the cuff be inflated to at least 30 mm Hg above the point at which the radial pulse disappears. The cuff should then be deflated at a rate of 2 to 3 mm Hg per second (or per pulse when the heart rate is slow). Deflation rates greater than 2 mm Hg per second can cause the systolic pressure to appear lower and the diastolic pressure to appear higher. In pregnant women, the fifth Korotkoff ’s sound has been recommended as the diastolic measurement, although the fourth Korotkoff ’s sound should be used when sounds are audible with the cuff deflated.

For a child, overinflation of the cuff may cause discomfort. One technique to avoid this is to estimate the systolic pressure by inflating the cuff while palpating the pulse, and then inflate the cuff to 30 mm Hg above the estimated level when the pressure is auscultated.

TAKING READINGS

The AHA recommends that at least two readings be taken, with a one-minute interval between them, and the average of the measurements recorded. The first reading in a series is usually the highest. Additional readings should be taken if the difference between the first two is greater than 5 mm Hg

At the first visit, blood pressure should be measured in both arms, which may be useful for identifying coarctation of the aorta and upper-extremity arterial obstruction. If there is a consistent difference in measurement between the arms, the highest pressure should be recorded. In children, the right arm is always preferable for consistency and comparison with reference tables.

HYPERTENSION IN CHILDREN

Children should not be diagnosed with hypertension without confirmation from repeated visits unless they are symptomatic or have profoundly elevated levels. The most precise measurement is the average of multiple readings taken over weeks or months, because this allows for reduction of anxiety. In children, a difference of several millimeters of mercury often is found between the fourth and fifth Korotkoff’s sounds. Children with repeatedly elevated measurements should have leg blood pressure measured to screen for coarctation of the aorta. This can be done by auscultation over the popliteal fossa, with use of a thigh cuff or oversized arm cuff. A systolic thigh blood pressure that is more than 10 mm Hg lower than the systolic arm pressure is cause for additional coarctation testing.

Avoid these common blood pressure measuring mistakes

This checklist can help ensure accurate readings both at the doctor’s office and at home.

Updated: May 3, 2019Published: October, 2018


Image: © Maica/Getty Images

Blood pressure is a key indicator of cardiovascular health. So it’s vitally important to make sure that you check yours regularly — and accurately. But according to the American Heart Association (AHA), health care professionals don’t always follow the proper techniques when measuring a person’s blood pressure. The AHA cites seven common errors (detailed below) that can lead to an artificially high blood pressure reading.

Plus, there’s one additional step that may be overlooked after you get a blood pressure reading of 130/80 mm Hg or higher, a level that defines high blood pressure, says endocrinologist Dr. Naomi Fisher, director of the Hypertension Service and Hypertension Innovation at Brigham and Women’s Hospital.

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Your Step-by-Step Guide to Monitoring Your Blood Pressure at Home

Your doctor may want you to monitor your blood pressure at home to get an accurate picture of your health, especially if your blood pressure spikes at the doctor’s office or if you take medications for your hypertension. “One blood pressure reading is only one moment in time,” says Madeleine Lloyd, RN, MS, program director of New York University’s College of Nursing. “Several readings are needed to obtain an accurate blood pressure long term.” To better manage blood pressure, you want the readings you take at home to be as accurate as possible. This step-by-step guide for using a home blood pressure monitor can help.

Choosing a Monitor

You have the choice of a manual home blood pressure monitor or a digital one. Each has pros and cons, although digital blood pressure monitors are easier to use and to read because readings for both your systolic (when your heart is pumping) and diastolic (when it is at rest) levels flash on the screen. If you own a manual monitor with a manometer (the blood pressure gauge) and stethoscope, practice with a member of your medical team first. If you have a digital monitor, take it to your doctor’s office to make sure it’s calibrated properly.

Step 1: Relax

If you have hypertension, you may need to take your blood pressure at home twice a day — and you’ll want to be relaxed when you do it. Try to take your reading around the same time every day — an hour after you wake up and an hour before bed, for example. Just avoid any stimulants, such as caffeine, tobacco, or alcohol, for at least 30 minutes before a reading. You should also wait 30 minutes after exercising. Finally, empty your bladder before you begin.

Step 2: Take a Seat

Sit down in a comfortable chair next to a desk or table where you can place your home blood pressure monitor. Rest quietly, without talking, for 5 to 10 minutes before you start. Make sure your back is supported, and that your feet are comfortably on the floor with your legs uncrossed. Take your pressure on your nondominant arm. Lift that forearm to heart level and support it on the desk so it stays comfortably elevated. Open your palm and face it up.

Step 3: Find Your Pulse

Locate your pulse by gently placing your index and middle fingers on the inside of the crease in your elbow. Press down gently and slide your fingers slowly over the area until you feel rhythmic pulsing. This is your brachial artery, the artery that runs from your shoulder to the bend in your elbow. Some digital home blood pressure monitors will tell actually you your pulse rate. If yours does, skip this step.

Step 4: Put on the Cuff

Wrap the cuff around your arm so it’s snug but not too tight. As a rule of thumb, you should be able to slip one finger under the cuff. Place the cuff against your skin, not over your clothing. Lloyd notes not to just push your sleeve up to the top of your arm — doing so forms a tight bend around the upper arm. The bottom of the cuff should be about one inch above the bend, or crease, in your elbow. Look for an arrow or line on the cuff that should be lined up with (or point to) the pulse from your brachial artery.

Step 5: Take Your Pressure

Hold the manometer, in your nondominant hand. Most models have a built-in stethoscope, but if you’re using a detached one, place it over the spot where you located your pulse. With your dominant hand, hold the bulb and close the valve by turning the screw in a clockwise direction, then squeeze the bulb quickly to inflate the cuff until the indicator in the manometer is about 30 points higher than your expected systolic number — you shouldn’t be able to hear your heartbeat through the stethoscope at this point. Watch the gauge carefully as you slowly open the valve, and remember the number it reads when you hear your first beat; this is the systolic, or top, number of your blood pressure. As you continue to slowly let out the air, look for the number on the gauge at the moment when you no longer hear the beat; this is the diastolic, or bottom, number of your blood pressure. Finish deflating the cuff. A digital blood pressure monitor can be semiautomatic (you pump up the cuff with a bulb) or fully automatic (you press a button to inflate the cuff instead of using a bulb). Follow the manufacturer’s instructions to start the reading. A digital blood pressure monitor will usually beep when it reads your pressure and display the two numbers, your systolic and diastolic pressures, on its screen.

Step 6: Record Your Blood Pressure Numbers

To help you better manage your daily blood pressure readings, write down both your systolic and diastolic pressures and the date and time in a log. Organize your records so both you and your doctor can use them to treat and manage your condition. If a reading seems unusual, you may want to repeat it to be sure. Wait at least a minute, then take off the cuff and start over — don’t just reinflate it. Some doctors recommend taking two to three readings each time.

Step 7: Store Your Monitor

Keep your home blood pressure monitor in a safe, dry, and cool place, and store it so the tubing isn’t twisted. Check your home blood pressure monitor periodically for cracks or leaks in the tubing. Once a year, take it to your health care provider to see if it needs recalibrating. With guidance and a little practice, you’ll learn how to use your home blood pressure monitor, making this part of managing your hypertension one of the easiest.

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It’s a familiar scenario: You find yourself at the doctor’s office, sitting on the edge of an exam table with your feet dangling inches above the floor. The nurse or medical assistant who seconds ago instructed you to sit now asks you questions about the reason for your visit – all while taking your blood pressure.

That measurement, however, could come back dangerously high – and flat wrong.

Together, the dangling feet, the unsupported back, even the chit chat are more than enough to throw off a blood pressure reading and classify a patient as having high blood pressure when they don’t.

And if that measurement was taken with the blood pressure cuff on top of a shirt sleeve instead of a bare arm? It could push a patient’s reading high enough to qualify for medication that might not be needed.

Until recently, high blood pressure, or hypertension, was defined by any measurements with 140 or higher as the top number, and 90 or greater as the bottom.

Last November, the American Heart Association updated its high blood pressure guidelines and established a new threshold for diagnosing high blood pressure at 130/80. That change of 10 mmHg (millimeters of mercury) was enough to classify nearly half of all Americans as having high blood pressure.

It also has served as a reminder about the importance of getting blood pressure measured properly.

Yet, for a procedure performed millions of times every day across the country, very few medical professionals – even nurses and doctors – nail the routine correctly, said Dr. Michael Rakotz, a family physician and the vice president of health outcomes for the American Medical Association.

An ongoing AMA campaign has tried to raise awareness about how to correct the most common errors people make when measuring blood pressure, whether at the doctor’s office or at home.

“Every time we go out and conduct blood pressure measurement trainings, people tell us afterward that they’ve been doing it wrong for years,” Rakotz said.

Posters tacked inside exam rooms and vital stations are aimed just as much at patients as they are at clinical staff because “once the patients learn how their blood pressure should be measured, they aren’t going to let anybody measure it incorrectly again,” he said.

When getting blood pressure measured, both feet need to rest on the ground or a stool. The back needs to be supported, as well as the arm, which should be propped at heart level. Many times, these procedures fail to be observed.

Other common mistakes include:

  • Failing to rest before a measurement. Sitting quietly for about five minutes can help relax the body.
  • Placing a cuff over clothing. Depending on the thickness of the sleeve, clothing can add up to 50 mmHg to a reading. The blood pressure cuff needs to be placed on a bare arm – so roll up your sleeve or come wearing short sleeves.
  • Using the wrong sized cuff. Squeezing an arm into a cuff that’s too small can add anywhere between 2 mmHg and 10 mmHg to a measurement.
  • Engaging in conversation. Avoid the small talk. Even active listening can add 10 mmHg.

With just one or two simple errors in measurement techniques, a patient could suddenly find himself classified as having high blood pressure, said Dr. Raymond Townsend, a nephrologist.

“Suddenly, they have a disease that they didn’t have yesterday,” said Townsend, director of the hypertension program at the University of Pennsylvania Hospital. “When you label someone as having hypertension, you actually have given them a chronic disease label. That can be a downer in our outlook on life so getting it right is important.”

Townsend worked with Rakotz on a study where they implemented a “blood pressure check challenge” to nearly 160 medical students during the 2015 AMA annual meeting.

Only one student performed all 11 measurement elements correctly.

“It didn’t matter if you were a guy or a gal, whether you were a first-year medical student or fourth-year, whether you were going into internal medicine or obstetrics. They just didn’t know what they were doing,” Townsend said. “Out of 11 possible things to do right, the average they got was four.”

Townsend knows that doctors have a lot of information to balance in their minds when seeing patients.

“But of all the things that we do in clinical medicine, what is the single most important difference we can make to help someone live longer and live free of target organ damage? There’s only one answer,” he said. “It’s to measure and treat blood pressure correctly.”

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10 Factors That Can Affect Blood Pressure Readings

Have you ever visited the doctor’s office and discovered your blood pressure was higher than you expected? Most people do not realize their blood pressure is constantly changing minute by minute in response to mood, activity, body position, etc. In fact, simple changes can cause blood pressure to fluctuate between 5 and 40 mmHg. Here is a list of 10 factors that can temporarily cause significant deviations in your blood pressure measurements.

  1. Blood Pressure Cuff is too Small1,3,4 – It is extremely important to make sure the proper size blood pressure cuff is used on your upper arm when taking a measurement. In fact, most blood pressure measurement errors occur by not taking the time to determine if the patient’s arm circumference falls within the Range indicators on the cuff. Studies have shown that using too small of a blood pressure cuff can cause a patient’s systolic blood pressure measurement to increase 10 to 40 mmHg.
  2. Blood Pressure Cuff Used Over Clothing1,3,4 – When having your blood pressure measured, the cuff should always be placed directly on your arm. Studies have shown that clothing can impact a systolic blood pressure from 10 to 50 mmHg.
  3. Not Resting 3-5 minutes3,4- To obtain an accurate blood pressure measurement, it is important that you relax and rest quietly in a comfortable chair for 3 to 5 minutes before a reading is taken. Any activities such as exercise or eating can affect your systolic blood pressure measurement 10 to 20 mmHg.
  4. Arm/Back/Feet Unsupported1,3,4 – When having your blood pressure measured, you should always be seated in a comfortable chair, legs uncrossed, with your back and arm supported. If your back is not supported, your diastolic blood pressure measurement may be increased by 6 mmHg. Crossing your legs has shown to raise your systolic blood pressure by 2 to 8 mmHg. The positioning of your upper arm below your heart level will also result in higher measurements, whereas positioning your upper arm above your heart level will give you lower measurements. These differences can increase/decrease your systolic blood pressure 2mmHg for every inch above/below your heart level.
  5. Emotional State5,6- Stress or anxiety can cause large increases in blood pressure. If you are having your blood pressure taken while thinking about something that causes you to tense up or become stressed, your blood pressure levels could significantly increase.
  6. Talking1,2,3,4 – If you are talking to the nurse/doctor while having your blood pressure taken, studies have shown that your systolic blood pressure measurement may increase 10 to 15mmHg.
  7. Smoking1,5,6- Tobacco products (cigarettes, cigars, smokeless tobacco) all contain nicotine which will temporarily increase your blood pressure, so refrain from smoking at least 30 minutes before having a blood pressure measurement taken.
  8. Alcohol/Caffeine4,5,6 – Alcohol and caffeine (sodas, coffee, tea, etc) consumption causes blood pressure levels to spike so stay away from alcohol/caffeine at least 30 minutes before having a blood pressure measurement taken.
  9. Temperature4,5 – Blood pressure tends to increase when you are cold. Therefore, if you are at the doctor’s office and the room temperature is “chilly” to you, be aware that your blood pressure readings may be higher than expected.
  10. Full bladder1,3,4 – Your blood pressure is lower when your bladder is empty. As your bladder gradually fills, your blood pressure increases. Studies have shown that your systolic blood pressure measurements could increase 10 to 15mmHg when you have a full bladder.

From the list above, you can see that small changes in your body, environment, and activities all have a significant impact on your blood pressure measurements. Since there are several factors that influence blood pressure, it is important that medical professionals follow the AHA guidelines for taking blood pressure measurements to avoid misdiagnosis of hypertension and inappropriate prescription of anti-hypertension medications.

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B. Place the stethoscope in your ears. Tilt the earpiece slightly forward to get the best sound.

3. Inflate and deflate the cuff

If you are using a manual monitor:

A. Hold the pressure gauge in your left hand and the bulb in your right.

B. Close the airflow valve on the bulb by turning the screw clockwise.

C. Inflate the cuff by squeezing the bulb with your right hand. You may hear your pulse in the stethoscope.

D. Watch the gauge. Keep inflating the cuff until the gauge reads about 30 points (mm Hg) above your expected systolic pressure. At this point, you should not hear your pulse in the stethoscope.

E. Keeping your eyes on the gauge, slowly release the pressure in the cuff by opening the airflow valve counter clockwise. The gauge should fall only two to three points with each heartbeat. (You may need to practice turning the valve slowly.)

F. Listen carefully for the first pulse beat. As soon as you hear it, note the reading on the gauge. This reading is your systolic pressure.

G. Continue to slowly deflate the cuff.

H. Listen carefully until the sound disappears. As soon as you can no longer hear your pulse beat, note the reading on the gauge. This reading is your diastolic pressure.

I. Allow the cuff to completely deflate.

IMPORTANT: If you released the pressure too quickly or could not hear your pulse DO NOT inflate the cuff right away. Wait one minute before repeating the measurement. Start by reapplying the cuff.

If you are using a digital monitor:

A. Hold the bulb in your right hand.

B. Press the power button. All display symbols should appear briefly, followed by a zero. This indicates that the monitor is ready.

C. Inflate the cuff by squeezing the bulb with your right hand. If you have a monitor with automatic cuff inflation, press the start button.

D. Watch the gauge. Keep inflating the cuff until the gauge reads about 30 points (mm Hg) above your expected systolic pressure.

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