Spectros Medical Devices Inc.
Page 31 of 44
Rev B
T-STAT 2.0 User Manual
3.
T-Stat
®
Values During Ischemic Hypoxia (Low blood flow):
During local ischemia in human colon polyps, induced by either epinephrine injection or suture
ligation, the following values have been measured.
5
Table A.2.
Human Colon Polyp Tissue Oxygenation During Ischemia
Polyp Intervention
Oxygenation
(Mean +/- SD)
No. of Tests
(n)
Normal
70% +/- 5%
(n=26)
Vascular Tie-Off
15% +/- 6%
(n=14)
Epinephrine Injection
13% +/- 5%
(n=16)
Control (Saline Injection)
75% +/- 4%
(n=5)
Note that during hypoxemia, with a normal pulse oximetry reading of 90-94%, the difference
between SaO
2
% and StO
2
% in muscle raises to as high as 77% (well above the hypoxemia
range of 15-35%). Thus, the difference between the pulse oximetry estimate of SaO2% and the
tissue oximetry measure of StO2% may allow for discrimination of ischemia from pure
hypoxemia.
4.
Discriminating Between Ischemia, Hypoxemia, or mixed Hypoxia-Ischemia:
The predictive value of this feature has not been tested in prospective clinical trials. In animal
and human studies, a difference between the pulse oximeter saturation (SaO2%) and tissue
oximeter (StO2%) of <30% suggests hypoxemia, while a difference >35% suggests ischemia
or mixed hypoxemia-ischemia.