Nellcor N-395 Operator's Manual page 11

Bone, tissue, pigmentation, and venous vessels normally absorb a
constant amount of light over time. The arteriolar bed normally
pulsates and absorbs variable amounts of light during the
pulsations. The ratio of light absorbed is translated into a
measurement of functional oxygen saturation (Sp02).
Note: For an explanation of functional versus fractional
saturation, refer to Principles of Operation.
Because a measurement of Sp02 is dependent upon light from the
sensor, excessive ambient light can interfere with this
measurement.
Specific inforination about ambient environmental conditions,
sensor application, and patient conditions is contained throughout
tlii s manual.