29
Non-Invasive Blood Pressure (NIBP) Measurement
Non-Invasive Pressure Measurement Principles
Oscillometric method
The
b
eat in the p
u
lsation generated
b
y the contraction of the heart is capt
u
red as the press
u
re inside the c
u
ff to
meas
u
re the
b
lood press
u
re. If the c
u
ff
w
rapped aro
u
nd the
u
pper arm is press
u
rized s
u
fficiently, the
b
lood flo
w
stops,
bu
t the
b
eat of the p
u
lsation is present and the press
u
re inside the c
u
ff recei
v
es this and oscillates.
N
ext, as the
press
u
re inside the c
u
ff grad
u
ally decreases, the oscillation of the press
u
re
w
ithin the c
u
ff grad
u
ally increases and
reaches a peak. As the press
u
re
w
ithin the c
u
ff decreases f
u
rther, the oscillation decreases from its peak.
The press
u
re
w
ithin the c
u
ff and the relationship
w
ith the increase and decrease of the oscillation
w
ithin the c
u
ff in this
series of processes are stored into memory, calc
u
lations are carried o
u
t, and the
b
lood press
u
re
v
al
u
e is determined.
The press
u
re
w
ithin the c
u
ff
w
hen the oscillation increases drastically is the systolic press
u
re and the press
u
re
w
ithin
the c
u
ff
w
hen the oscillation decreases drastically is the diastolic press
u
re. Also, the press
u
re
w
ithin the c
u
ff
w
hen the
oscillation peaks is taken as the a
v
erage p
u
lsation press
u
re.
The oscillometric method does not determine the
b
lood press
u
re
v
al
u
e instantly like a microphone type a
u
tomatic
b
lood
press
u
re ga
u
ge
w
ith the a
u
sc
u
ltation method,
bu
t rather determines it from the series of change c
u
r
v
es as explained
a
b
o
v
e. Therefore, it is not easily affected
b
y external noise, an electric scalpel or other electro s
u
rgical instr
u
ments.
KOROTKOV SOUNDS
RADIAL PULSE
HEM-907-C3_D_M.fm Page 29 Wednesday, July 4, 2018 12:11 PM
