Spectros Medical Devices Inc.
Page 10 of 44
Rev B
T-STAT 2.0 User Manual
Table 1
Normal Range of Oxygenation Values for pulse oximetry, central venous
sampling, and VLS tissue oximetry
Value
Normal
Range
Description
SaO
2
%
95-100%
i,ii
Arterial hemoglobin saturation. Commonly
estimated by Pulse Oximetry.
SvO
2
%
65-75%
iii,iv
Venous hemoglobin saturation. Commonly
estimated by Central Venous Catheter
sampling.
StO
2
%
65-77%*
Tissue optical hemoglobin saturation. A
capillary-weighted value that is typically
much closer to venous saturation than to
arterial saturation.
*Normal values, as read by the T-Stat ® Tissue Oximeter, for liver and the small intestine have not yet been
established, as these readings are affected by organ pigments, and surface bile (respectively).
Sensitive to Hypoxemia
During hypoxemia (low arterial saturation), when oxygen delivery to the tissue is reduced,
both pulse oximetry and tissue optical oximetry report low values.
Sensitive to low-flow or no-flow Ischemia
Reduced blood flow ischemic states are detected by tissue oxygen saturation (StO
2
%) but are
not detected by pulse oximetry. During reduced blood flow ischemia (such as from tissue
ablation, thrombosis, or cardiac failure), the arterial saturation remains unchanged, but the
reduced blood flow results in a lowered tissue oxygenation due to a higher fractional
extraction of delivered oxygen to the capillaries.
Estimates Blood Content
T-Stat
®
estimates and displays the relative hemoglobin of the tissue (rHemoglobin) in
μ
mol/L.
Pulse oximetry is insensitive to this value, registering only the changes in blood content during
arterial pressure changes between systole and asystole rather than the total blood signal. This
signal may vary with depth of the measurement, and therefore is dependent upon the sensor
used, as well as has a high noise induced by scattering. rHemoglobin values are +/- 20% and
include total hemoglobin plus myoglobin.
