YouTube Transcript:
How to Measure Blood Pressure

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hello I'm Eric strong from Stanford

University today I'll be talking to you

about blood pressure focusing on how to

this video will cover a lot of ground by

the end you'll be able to define blood

pressure including the difference

between the systolic and diastolic

pressure next you'll be able to define

the chord cough sounds and the Oscar

story gap to choose an appropriate sized

blood pressure cuff for patients of

different sizes to demonstrate proper

technique when manually measuring a

patient's blood pressure to list common

pitfalls with blood pressure measurement

to list indications for blood pressure

measurement and last to define

hypertension and hypotension you can

summarize these objectives as the what

how and why of measuring blood pressure

so first what is blood pressure blood

pressure is simply the pressure exerted

by circulating blood on the walls of the

arteries it is one of the most important

physiological parameters of the body

which is why it's included in the five

vital signs along with temperature heart

rate respiratory rate and oxygen

saturation the physics of blood pressure

is remarkably complex but the basic

factors which determine it include the

heart rate myocardial contractility

which refers to how hard the heart is

squeezing vascular tone which refers to

how much the arteries are constricted or

relaxed blood volume blood viscosity and

last arterial compliance which refers to

how much give or elasticity the arteries

have as a consequence of the cardiac

cycle blood pressure is cyclical

myocardial contraction is also called

systole so the high point of the blood

pressure which occurs during contraction

is called the systolic blood pressure

relaxation of the heart is called

diastole and thus the low point of the

blood pressure occurring at the very end

of diastole is called the diastolic

blood pressure whenever you hear blood

pressure reported as two numbers such as

150 over 80

that's the systolic and diastolic

pressure we use archaic units for

measuring blood pressure called

millimeters of mercury which refers back

to the days when mercury manometers with

a principle measuring tool we don't use

mercury containing devices

anymore due to concerns about their

toxicity but their associated units

still persist before we get to the

actual procedure of measuring blood

pressure there are two phenomena of

which you need to be aware the quart

cough sounds and the escola Tori gap the

cord cough sounds are rhythmic noises

heard using a stethoscope that are

produced by turbulent blood flow in an

artery usually the brachial artery that

is being partially compressed by a blood

pressure cuff it occurs when such

compressive pressure is between the

person's systolic and diastolic pressures

pressures

that pressure is higher than systolic

blood flow is cut off all together and

that pressures lower than diastolic

there is no compression of the artery at

any point in the cardiac cycle but when

the pressure is in between the systolic

and diastolic pressure the artery

alternates between compressed and open

creating turbulence and the cord cough

sounds something called an auscultate or

a gap occurs in a small minority of

patients it is present when there is a

range of blood pressures in between the

systolic and the diastolic in which

there are no cord cough sounds it's

observed primarily in older patients

with a wide pulse pressure that is a

relatively large difference between the

systolic and diastolic pressures the

escola tory gap is important because a

failure to recognize its presence can

result in a significant underestimation

of the systolic pressure or an

the equipment for blood pressure

measurements is very simple a standard

stethoscope and something called a sphygmomanometer

sphygmomanometer

most people colloquially call this thing

a blood pressure cuff which is a

misnomer since the cuff is only part of

it specifically the part that goes

around the patient's arm the other parts

of the sphygmomanometer include the

pressure gauge the inflation bulb used

to inflate the cuff and a one-way valve

which can be twisted to regulate the

flow of air from the cuff controlling

its rate of deflation depending on your

equipment the gauge may be either

mounted on the wall attached to a small

rolling stand or be small enough to be

hooked directly onto the cuff itself

regarding the best timing as to when

blood pressure should be measured keep

in mind that blood pressure varies

throughout the day and can be

temporarily impacted by exercise or

caffeine consumption within the prior 30

minutes also for patients taking

antihypertensive medication consider the

timing of the meds relative to the blood

pressure measurement in general it's

preferable to measure blood pressure

immediately before the meds

are usually taken but this is often not

practical if a patient's clinic visit is

relatively late in the day in addition

there may be specific situations in

which measurement shortly after meds are

taken is instead preferred for example

if a patient has been complaining of

lightheadedness which could be due to

excessive medication so now what's the

actual procedure first although this is

often omitted in practice it's

recommended that the patient first empty

his or her bladder as a full bladder may

slightly elevate the pressure also it's

important that the patient be resting in

a quiet room for at least five minutes

beforehand but once the patient has been

resting and calm for a few minutes and

you've washed or otherwise sanitized

your hands you can begin next the

patient should be properly positioned

for ambulatory patients this means

seated with back supported both feet

flat on the floor and with their arms

supported at approximately the level of

the heart if there is not a tray or

table on which the patient can rest

their arm you will need to support it

for them while performing the

measurement failure to properly position

the patient may result in an elevated

reading which does not represent their

true resting blood pressure in most

cases it does not matter which arm you

choose however there are some

circumstances in which it does the most

common of these situations is with a

patient who is on hemodialysis for whom

you should avoid measurement of blood

pressure in the same arm as the dialysis

access be sure that the upper arm can be

exposed without constricting it by a

tightly rolled up sleeve if this cannot

be done the patient will need to remove

their outer layer of clothing you want

to be sure to have selected the proper

sized cuff there is some variability

between different manufacturers but most

have about five sizes of arm cuffs

ranging from infant to a large adult

with a sixth extra-large size labeled

thigh guidelines recommend that the

length of the bladder inside the cuff

which is the chamber in which the air is

contained should be 80 to 100 percent

the circumference of the arm I honestly

don't know anyone who man you

léa checks this with a tape measure but

luckily many cups have a helpful guide

printed on your inside aspect you can

see here a range in which the opposite

edge should lie when the cuff is wrapped

snugly around the patient's arm if it

falls within the range the cuff is good

if it doesn't you need to look for a

different size in the rare occasion in

which a patient's arm is too large for

the large adult size you may need to use

an adult thigh cuff on the arm wrap the

cuff around the arm such that the bottom

edge is about two to three centimeters

above the crease of the elbow the cuff

will have a marking usually an arrow

which should be aligned to rest over the

approximate location of the brachial

artery in order to avoid problems with

the oskol Tottori gap the systolic

pressure should first be estimated from

the pulse obliteration pressure this

will also help to prevent an

unnecessarily excessive cuff inflation

that will be uncomfortable for the

patient to do this ignore your

stethoscope just for a moment and

instead place one or two fingers over

the radial pulse once you are confident

that you can feel it turn the valve to

the closed position and slowly inflate

the cuff until the pulse disappears

completely the pressure which that

occurs is approximately the systolic

pressure once you have an estimate for

the systolic pressure place the

stethoscope over the brachial artery

which can be aided by tucking in one

edge under the cuff inflate the cuff to

thirty millimeters of mercury above the

pulse obliteration pressure and turn the

valve to the open position just enough

to decrease the pressure by about two to

three millimeters of mercury for each

heartbeat at one point you'll begin to

hear the cord coughs sounds even though

the sounds may not initially be constant

the pressure at which you hear the very

first thump is the systolic pressure

continues to slowly lower the pressure

at some point the sounds will abruptly

become muffled and just a little bit

below that they'll disappear altogether

although in the past some experts

recommended using the muffling pressure

as a dice

pressure general consensus is currently

that the pressure at which these sounds

disappear completely should be used

instead as it's easier to identify and

thus is more reproducible continue to

lower the pressure for at least 10

millimeters of mercury below the

disappearance of sounds to ensure that

you have accurately identified the

diastolic pressure the procedure should

be performed at least twice the final

recorded blood pressure should be the

average of all readings taken in the

same sitting rounded off to the nearest

two millimeters of mercury you may

observe the gauge needle beating within

the same range of pressure as when the

chord cough sounds are present and it

may be tempting to use this visual

observation as a surrogate for

auscultate at blood pressure however

this is not advised since there may not

be complete agreements between the

needles oscillations and the chord cough

sounds after measurements is complete

don't forget to tell the patient the

result as they will likely be anxious to

know it there are five common mistakes

that both novices and experienced

professionals alike make when measuring

blood pressure first not allowing the

patient to rest quietly before

measurement measurements of the blood

pressure in a patient immediately after

they've rushed in the clinic because

they are running late and are stressed

out from the drive and from having

trouble finding parking is unlikely to

be accurate second not bothering to

change the cuff from the default size

already attached to the gauge even if

not appropriate for the patient the

usual situations in which this might

occur is when a so-called regular sized

cuff is the only one in the room but you

are either seeing a small child or

seeing a morbidly obese adult if the

cuff is not the right size it will not

give you an accurate reading and

inaccurate data is more dangerous than

in absence of data so familiarize

yourself with where the clinic or

hospital keeps different sized cuffs and

use the correct size third knot first

checking the pulse obliteration pressure

giving the patient preventable

discomfort and also risking an unrest

of the systolic pressure due to the

presence of an obstacle to Tory gap

fourth allowing the patient to support

his or her own arm which will lead to a

false elevation of pressure and last

lowering the cuff pressure to fast which

can lead to either a falsely low

systolic pressure a falsely high

diastolic pressure or both so far I've

discussed what blood pressure is and how

its measured I'm going to spend the last

few minutes talking about why we would

want to measure blood pressure in the

first place specifically what are its

indications well fortunately they are

simple to summarize if you are a

healthcare professional evaluating a

patient you should be checking the

patient's blood pressure irrespective of

the patient's age reason for evaluation

the presence or absence of symptoms and

location of care the one exception to

this is healthy children under the age

of three being seen for a well-child

visit in whom the rates of blood

pressure abnormalities are exceptionally

low and what are the abnormalities of

blood pressure that you're looking for

first there's hypertension which refers

to blood pressure that is too high

although in practice no one uses this

precise terminology you can think of

there being two broad categories of

hypertension chronic and acute chronic

hypertension the overwhelming majority

of which is primary hypertension is

defined as either a systolic pressure of

140 or greater or a diastolic of 90 or

greater as measured at two separate

visits primary hypertension is important

to identify with routinely screening the

blood pressure because it's asymptomatic

but if left untreated it will increase

the risk of heart disease stroke kidney

failure and vision loss acute

hypertension which in practice is

referred to as a hypertensive crisis is

further subcategorized as hypertensive

emergency if the patient has evidence of

end organ damage such as confusion

shortness of breath or kidney failure or

hypertensive urgency if the blood

pressure is acutely high but the patient

is otherwise doing okay

although some clinicians teach specific

cut-offs for how high blood pressure

should be in diagnosing an acute

hypertensive crisis I don't recommend

using such cut-offs instead I consider

the patient's baseline blood pressure

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YouTube Transcript:How to Measure Blood Pressure

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YouTube Transcript:
How to Measure Blood Pressure