every nurse and doctor in the world
needs to build a record blood pressures
using manual devices using the
auscultate aura method by listening with
a stethoscope and originally we used to
use these sphygmomanometer
sphygmomanometer the name of the guy
that developed it manometer is a
pressure gauge and this one uses
millimeters of mercury in a column this
one's analog and uses a dial is the same
thing and what they're both doing is
we're going to wrap this cuff around the
patient's arm and as we blow that cuff
up and let it down the pressure in the
cuff is going to be the same as the
pressure that is recorded on that dial
that's how we know it works and what
we're listening for is is sounds called
quartic offs sounds after Nikolai
quartic off the well known Russian
surgeon who first published in 1905 and
what we do is we put the cuff on and we
pump it up above the systolic pressure
that is above the pressure at which the
heart is contracting during systole when
the left ventricle is contracting and as
we let the pressure down when there's
just sufficient pressure for the blood
to get past the cuff on the top of the
arm we can hear that in the brachial
artery
now we used to think that the sounds
were caused by the turbulence of the
blood in the arterial vessel but the
physicists have now told us that that
would generate lower frequency sounds
than this
and the sounds that were actually
hearing are caused by resonance is set
up by the arterial wall itself but there
doesn't matter it's the same thing
in practical terms the sounds are the
same thing the sounds represent the same
pressures so when we start to let the
pressure down there's a point you can
hear some odd sounds when you let in the
pressure down so I suppose the blood
pressure 120 over 80 when you're letting
the pressure down from say 160 180 do
get on sounds but when you get to 120
which is the blood pressure in this case
you start getting a regular sound and
those regular sounds are the pulse just
coming through the the cuff and the
systolic pressure the first pressure is
when we hear and the first sound so that
very first sound is usually fairly faint
but then it gets progressively louder it
gets progressively louder now the very
first sound is the systolic blood
pressure the first pressure in this case
hundred twenty then typically it gets
progressively louder there is a bit of
variation in these sounds but it will
get progressively louder then you'll
have one bead that you here which is the
loudest one that you hear then after
that the beat will become muffled and
then after that it will die away
fairly soon after that well it can be a
millimeter or two of mercury after the
the muffled sound or it can be as much
as 10 millimeters of mercury after the
muffled sound but it will die away and
the last sound that you can hear with
your ears is the diastolic pressure now
we used to teach that the first muffled
sound was the diastolic pressure we now
know this does not represent accurately
the physiological situation so what used
to be called the diastolic dilemma is
now over the very last sound that you
can hear is the diastolic pressure so
typically we start off quiet very first
sound that your systolic pressure
then first of all full sound and that
very last faint sound you hear is the
diastolic pressure so let's see this
donut practice now bill you never been
keeping an eye on your blood pressure
lately I'd like to check it now is that
okay with you that's fine okay so I'm
going to put this cuff on to bills arm
now we can see there's a line there that
says artery that's going to go over
Bill's brachial artery and I'm just
going to palpate bills brachial artery
times okay but now the brachial artery
is medial it's two-thirds of the way
across to the inside this is the medial
this is the lateral surface and the
brachial artery is just here I can feels
break that I can feel Bill's brachial
artery pulsating there can you feel that
bill in a press never press it quite
hard
yeah dormant yeah so I can feel the
brachial pulse there quite nicely and
with a bit of practice you get to know
exactly where the brachial artery is and
it's very consistent between individuals
usually just go put a scope on now well
you've had this done right and it's nice
and easy with these velcro ones we're
now going to connect up to the pressure
gauge the manometer and as we see that's
calibrated in millimeters of mercury now
I'm going to do is I'm going to tighten
that up like that and when I screw that
that means I can start pumping up and
you'll feel the pressure there would you
feel that pressure going on yeah and
then to let the pressure down I'm going
to turn it that way again with a bit of
practice you can control this really
quite precisely
now the other thing I'm going to do is
I'm going to listen with a stethoscope
I'm going to listen with the diaphragm
side which is that side so just make
sure I'm open to the diaphragm so when
is that's now open to the Bell side turn
it that way it's now open to the
diaphragm slide so I'm going to put that
over yours brachial artery apply a
little bit of pressure now I'm going to
put this up and we're going to pump it
up till I can't hear any pulses coming
through Bill's brachial artery so they
hear no sounds now I'm going to
gradually down listening for the first
sound
and there we have it now got bills blood
pressure and all that you listen to that
to see what you think it is
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you
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now the units of blood pressure are
millimeters of mercury and this is
because originally blood pressure was
measured measured in just that
millimeters of mercury
so in this old-style sphygmomanometer
blood pressure machine we've got a
reservoir of mercury in there and from
reporting the mercury up this reflects
the pressure in the cuff around about
Bill's arm
so we can see it exactly in millimeters
of mercury so again we'll pump up till
we can't hear it
and then we'll let it down and as we
listened for the sounds we'll work out
what bills blood pressure is and this is
actually the most accurate way to do it
because the specific gravity and the
density of mercury of course is never
going to Barry
so have a listen to build blood pressure
when we take you with mercury and see
what you can hear in terms of the sounds
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