Masimo Rad-87, Operator'S Manual

Page: 15 / 101

Rad-87 Pulse CO-Oximeter Operator’s Manual 1-5 1-5
1
o v e r v i e w
PRINCIPLE OF OPERATION
Pulse CO-Oximetry is governed by the following principles:
1. Oxyhemoglobin (oxygenated blood), deoxyhemoglobin (non-oxygenated blood),
carboxyhemoglobin (blood with carbon monoxide content), methemoglobin (blood
with oxidized hemoglobin) and blood plasma constituents differ in their absorption of
visible and infrared light (using spectrophotometry, see fi gure below).
Carboxyhemoglobin
Oxyhemoglobin
Methemoglobin
Deoxyhemoglobin
Absorption Spectra
Plasma
Absorption (1/mm)
0
0.5
600 800
1.0
1.5
2.0
2.5
3.0
3.5
4.0
1000 1200 1400 1600
Wavelength (nm)
2. The amount of arterial blood in tissue changes with your pulse (photoplethysography).
Therefore, the amount of light absorbed by the varying quantities of arterial blood
changes as well.
The Rad-87 Pulse CO-Oximeter uses a multi-wavelength sensor to distinguish between
oxygenated blood, deoxygenated blood, blood with carbon monoxide, oxidized blood and
blood plasma. The Rad-87 utilizes a sensor with various light-emitting diodes (LEDs) that
pass light through the site to a photodiode (detector). See fi gure below. Signal data is
obtained by passing various visible and infrared lights (LED’s, 500 to 1400nm) through a
capillary bed (for example, a fi ngertip, a hand, a foot) and measuring changes in light ab-
sorption during the blood pulsatile cycle. This information may be useful to clinicians. The
maximum radiant power of the strongest light is rated at
≤
25mW. The detector receives
the light, converts it into an electronic signal and sends it to the Rad-87 for calculation.
2
1
1. Light Emitting Diodes (LEDs)
( 7+ wavelengths )
2. Detector