Smiths Medical 1850, Operation Manual

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Chapter 2: Monitor Features
Oximeter Clinician’s Operation Manual 2-1
Chapter 2: Monitor Features
About the Manuals
The Clinician’s Operation Manual provides installation, operation, and
maintenance instructions for the health-care professional trained in
monitoring respiratory and cardiovascular activity.
The Home-Use Instruction Book provides operation and maintenance
instructions for the home-use caregiver. The home-use caregiver is
assumed to be trained in oximeter use by a doctor or other health-care
professional. The Home-Use Instruction Book supplements, and does
not replace, training provided by a health-care professional in oximeter
use.
Theory of Operation
The oximeter determines SpO
2
and pulse rate by passing two wave-
lengths of light, one red and one infrared, through body tissue to a pho-
todetector. During measurement, the signal strength resulting from
each light source depends on the color and thickness of the body tissue,
the sensor placement, the intensity of the light sources, and the absorp-
tion of the arterial and venous blood (including the time varying effects
of the pulse) in the body tissues.
Figure 2-1: Theory of Operation
The oximeter processes these signals, separating the time invariant
parameters (tissue thickness, skin color, light intensity, and venous
blood) from the time variant parameters (arterial volume and SpO
2
) to
identify the pulse rate and calculate oxygen saturation. Oxygen satura-
tion calculations can be performed because oxygen saturated blood
predictably absorbs less red light than oxygen depleted blood.