Non-Invasive Blood Pressure Machines - Basics
| Abbreviation / other names What
does |
N.I.B.P
Non = not |
| What does it do? |
It measures the pressure of the blood in the arteries Some NIBP Machines also display Pulse (Heart) Rate. |
| Physiology |
When the heart beats it pumps blood to the body through the
arteries. The pumping of the heart, the volume of the blood
and the diameter of the blood vessels all determine the pressure
inside the vessels. When the heart contracts the pressure increases
to the “systolic” pressure and in between heart
beats the pressure falls to the “diastolic” pressure.
The average pressure (mean pressure) is calculated. |
| How it works |
A cuff is placed around the arm or leg and is inflated with
air until the blood flow in the limb is stopped. The monitor
then lets the air out of the cuff, slowly decreasing the pressure.
When the pressure in the cuff decreases to the systolic pressure
the blood starts to spurt through the artery causing oscillations
in the cuff pressure. This noise is picked up by a microphone
or pressure transducer. When the pressure is reduced to the
diastolic pressure the oscillation noise stops. The systolic
and diastolic pressures are recorded as the pressures in the
cuff where the oscillations start and finish. The Blood spurting
through the artery (between the Systolic and Diastolic Pressures)
coincides with a Heart ‘beat’ The time interval
between 4 - 6 Beats is measured and Pulse Rate is then calculated. |
| Units of measurement |
mmHg |
| Typical values |
Systolic: 120 mmHg Diastolic: 80 mmHg Mean arterial: 100 mmHg |
| Picture of equipment |
|
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Criticare NIBP & Pulse Oximeter