TRANSCRIBED BY: FRED, GEORGE, RON, BILL, GINNY

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Alfredo Guzman, M.D.

People find it far easier to forgive others for being wrong than being right. Albus Dumbledore, Harry Potter & The Half-Blood Prince Paulo Coelho

Blood pressure measurement

1.2 9 June

2014

BP MEASUREMENT

Proper measurement & interpretation - essential in the dx & management of HPN

Home BP & average 24-hr ambulatory BP are generally lower than clinic-taken BP

BP tends to be higher in the early morning, soon after walking, than any other time of the day

Night time BP is generally 10-20% lower than day time BP White Coat HPN

Px manifests a higher BP in a hospital/clinical setting. They are at risk of developing sustained HPN.

FACTORS AFFECTING BP MEASUREMENTS

Instrumentation o BP Apparatus: Mercury, Aneroid, Digital o BP cuff size

Area of arm covered

Technique of BP Measurement

Patient Factor

Environment

BP APPARATUS / SPHYGMOMANOMETER MERCURY MANOMETER

Standard for all BP measurements

Large tube for rapid & in pressure

2mm graduated markings on tube

Mylar-wrapped glass or plastic tube preferred

Mercury is at zero and column rises and falls rapidly

TESTING THE MERCURY MANOMETER

Check the 0. Top of meniscus should rest at the zero mark

Inflate to 200 mmHg. Wait 1 min. Record Pressure.

o If

TRANSCRIBED BY: FRED, GEORGE, RON, BILL, GINNY

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Blood pressure

measurement

Can be used on either right or left arm,

THE STETHOSCOPE

Earpiece should face forward in the ear canal

Must have thick tubing 12-15 inches long

Bell for low pitched sounds

o Used to detect low frequency Korotkoff sounds

Diaphragm for high pitched sounds

5 PHASES OF KOROTKOFF SOUNDS

Korotkoff Sounds produced by the flowing of blood as the cuff

is released

Phase Description Remarks

I 1st appearance of clear,

tapping sound

Represents Systolic P

(SBP)

II Soft murmurs that

replace Phase I sounds

-

III

Loud murmurs that

replace Phase II

sounds

Due to blood flow

through constricted artery

IV

Sudden muffling of

Phase III sounds

Due to constriction of

the artery; arterial

diastolic P is

approached

V

Disappearance of

Korotkoff sounds

Represents Diastolic BP

(DBP) in most pxs is

normally w/n 10mmHg

from Phase IV

(abnormal if >10mmHg

difference; Phase IV is

abruptly muffled)

The usual BP reading involves Phase I and Phase V Korotkoff

sounds for SBP and DBP, respectively.

If there is a significant difference (>10mmHg) between Phase IV

and V, both pressures should be recorded (e.g. 130/70/10

mmHg); seen in anemia, aortic regurgitation, thyrotoxicosis.

In chronic, severe aortic regurgitation or a large arteriovenous

fistula, where the disappearance point may reach 0 mmHg, Phase

IV is much closer to the intraarterial diastolic pressure than Phase

V. All 3 pressures should be noted (e.g. 140/60/0 mmHg).

Difficulty in Hearing Korotkoff Sounds

Condition Pathology

Severe aortic stenosis Arterial P rises at a slow rate

Shock Markedly constricted arteries

Severe heart failure Markedly constricted arteries

Opening and closing the fist repeatedly can help dilate blood

vessels of the arms and make Korotkoff sounds more audible.

Korotkoff sounds represented during BP measurement. Note the

auscultatory gap.

TECHNIQUES IN BP MEASUREMENT 1. Support arm at the level of the heart

2. Inflate cuff 30 mmHg above the palpatory BP

3. Release pressure at a rate of 2-3 mmHg/s

Initially, measure BP on both arms

Use arm w/ higher BP on subsequent measurements

Measure BP at least twice per visit; allow 1-2 minutes in between measurements

If there is >5 mmHg difference between 2 consecutive measurements, additional or continued measurements should be made

Take the average of the last 2 BP measurements and record

TECHNIQUE OF BP MEASUREMENT IN THE DX OF HPN I. TIMING OF BP MEASUREMENT

For Dx: Multiple readings taken at various times throughout

waking hours

For Monitoring: Measure prior to intake of anti-hypertensive

medication to determine trough or nadir effect

II. PATIENT POSITION

Usually taken while sitting slouched on the chair

o Supine position SBP & DBP by 2-3 mmHg

Allow patient to rest and sit quietly for 5 minutes

o Apprehension increases BP

Measure both sitting and standing BP to detect postural hypotension (sudden drop in BP upon standing; in elderly, DM)

III. PATIENT & PHYSICIAN POSITION

Sitting; feet flat on the floor

Arm supported at heart level

Confirm viability of brachial pulse by palpation

Use bell (detection of low-pitched sounds)

TRANSCRIBED BY: FRED, GEORGE, RON, BILL, GINNY

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Blood pressure

measurement

OBSERVERS SKILL IN BP MEASUREMENT

The brain must be programmed to follow the proper guidelines

every time the P is measured.

Must be able to store the systolic and diastolic P & recall them

accurately.

Must be able to hear the Korotkoff sounds and knowhow to

interpret them.

Must be able to recall and write down correctly & legibly the sounds

heard.

Must be able to find & feel the pulses needed for BP measurement.

UNEQUAL BP IN BOTH ARMS

STEPS IN MEASURING THE BP

STEPS TO ENSURE ACCURATE BP MEASUREMENT

Instruct px to avoid smoking/drinking caffeinated drinks 30 mins

prior to BP measurement

Make the examining room as quiet & comfy as possible

Arm should be supported at heart level. Ask px to sit quietly for 5

mins on chair

Make sure the arm is free of clothing. There should be NO

arteriovenous fistulas for dialysis, scarring from prior brachial

artery cutdowns, or signs of lymphedema

Palpate the arm so that the brachial artery (located at the

antecubital crease) is at heart level (roughly level w/ the 4th

interspace at its junction w/ the sternum

If the px is seated, rest the arm on a table a little above the pxs

waist, if standing, try to support the pxs arm at the mid-chest level

STEPS IN MEASURING THE BP

Center the inflatable bladder over the brachial artery. Lower border

of cuff should be 2.5cm above the antecubital crease. Secure

the cuff snugly. Position arm so that it is slightly flexed at the

elbow,

To determine how high to raise the cuff P, 1st estimate the systolic

pressure by palpation. As you feel the radial artery w/ the fingers

of one hand, inflate the cuff until the radial pulse disappears. Read

this P on the manometer & add 30 mmHg to it. Use of this sum as

the target for the next inflation prevents discomfort from

unnecessary high cuff P. This also avoids the occasional error

caused by an auscultatory gap (a silent interval that may be

present between the systolic & diastolic pressure)

Deflate cuff promptly & completely & wait 15-30 seconds

Next, place the bell of a stethoscope lightly over the brachial artery,

taking care to make an air seal w/ its full rim. Because the sounds

to be heard, the Korotkoff sounds, are relatively low pitched,

they are better heard w/ the bell.

Inflate the cuff rapidly again to the level determined, then deflate it

slowly (2-3mmHg/sec), Note the level at w/c you hear the sounds

of at least 2 consecutive beats. This is the Systolic Pressure.

Continue to lower the P slowly until the sounds become muffled &

then disappear. To confirm the disappearance of sounds, listen as

the P falls another 10-20mmHg. Then deflate the cuff rapidly to

zero. The disappearance point, w/c is usually only a few mmHg

below the muffling pt, provides the best estimate of true diastolic P

in adults.

Read both the systolic & diastolic levels to the nearest 2mmHg.

Wait 2 mins & repeat. Average your findings. If the 1st 2 readings

differ by 5mmHg, take additional readings,

Avoid slow/ repetitive inflations of the cuff, because the resulting

venous congestion can cause false readings.

BP should be taken in both arms at least once. Normally, there

may be a difference in P of 5mmHg & sometimes up to 10mmHg.

Subsequent readings should be made on the arm w/ the higher

pressure.

o Loose cuff/bladder = false high readings

o Earpiece should face forward in the ear canal.

o Bell of the stethoscope is used for low-frequency sounds

o Auscultatory gaps are associated w/ arterial stiffness &

atherosclerotic disease

o P difference of >10-15mmHg seen in subclavian steal syndrome

& aortic dissection

o BP of 110/70 is usually normal, but could indicate significant

hypotension if previous readings are high

DEFINITIONS OF NORMAL & ABNORMAL LEVELS

CATEGORY SBP

(mmHg) DBP

(mmHg)

Normal < 120 and < 80

Prehypertension 120 - 139 or 80 - 89

Hypertension

Stage 1

Stage 2

140 159

160

or

or

90 99

100

BP goal for pxs w/ HPN, DM, or renal disease is

TRANSCRIBED BY: FRED, GEORGE, RON, BILL, GINNY

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Blood pressure

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o A femoral pulse that is smaller & later than the radial pulse

suggests coarctation of the aorta or occlusive aortic disease.

BP is lower in the legs than in the arms in these conditions.

THE APPREHENSIVE PATIENT

Try to relax the px

Repeat the measurement later in the encounter

Some px will say their BP is only elevated in the office (White Coat

HPN) & may need to have their BP measured several times at

home or in a community setting.

THE OBESE OR VERY THIN

For the obese, the a wide cuff (15cm)

If arm circumference exceeds 41cm, us a thigh cuff (18cm wide)

For the very thin arm, use a pediatric cuff

WEAK/ INAUDIBLE KOROTKOFF SOUNDS

To rule out Coartation of the aorta, consider: Technical problems: wrong placement of stethoscope, failure to

make full skin contact w/ bell venous engorgement of the arm from

repeated inflations of the cuff

Consider shock

WHEN KOROTKOFF SOUNDS CANT BE HEARD AT ALL Estimate systolic P via palpation. Alternative methods such as

Doppler techniques or direct arterial pressure tracings may be necessary.

To intensify the Korotkoff sounds, these may be done: o Raise the arm before & while you inflate the cuff. Then lower the

arm & determine the BP. o Inflate the cuff. Ask the px to make a fist several times. Then take

the BP.

ARRHYTHMIAS

Irregular rhythms produce variations in Pand therefore unreliable measurements.

Ignore the effects of an occasional premature contraction.

W/ frequent premature contractions or atrial fibrillation, determine the average of several observations and note that your measurements are approximate.

THE HYPERTENSIVE PX W/ UNEQUAL BP IN BOTH ARMS

To detect coarctation of the aorta, make 2 further BP measurements at least once in every hypertensive px:

Compare BP in the arms and legs.

Compare the volume and timing of the radial and femoral pulses. Normally, volume is equal and the pulses occur simultaneously.

Coarctation of the aorta arises from narrowing of the thoracic aorta, usually proximal but sometimes distal to the left subclavian artery.

Coarctation of the aorta & occlusive aortic disease are distinguished by hypertension in the upper extremities & low BP in the legs and by diminished or delayed femoral pulse.