Both probes have been used in various studies with varying results [9-12].The relative www.selleckchem.com/products/BAY-73-4506.html optical attenuation of the backscattered light at four wavelengths (680 nm, 720 nm, 760 nm, and 800 nm) is measured to calculate two second-derivative attenuation values, one centered at 720 nm and the other at 760 nm [15]. The ratio of the 720 nm to 760 nm second-derivative values is directly extrapolated to StO2, defined as [HbO2]/([Hb] + [HbO2]), via a calibration table. The calibration table relating StO2 to the second-derivative attenuation ratio is stored permanently within the NIRS device and is common to each device and probe used [15]. The NIRS devices were calibrated before the first measurement in each subject using a light-scatter calibrator.

Vascular occlusion testOne NIRS probe was placed on the skin of the thenar eminence and another NIRS probe was placed on the lateral side of the anterior surface of the forearm for simultaneous measurement of thenar StO2 and forearm StO2 during the VOTs. Both the hand and the forearm were kept at heart level with the palms up. The subjects were instructed not to move their hand or arm, or to change their sitting position during measurements.Baseline arterial pressure was measured using a manual sphygmomanometer. After a 3-minute stabilization period (baseline measurement), stagnant ischemia was induced for 3 minutes by rapidly inflating a pneumatic cuff (within 5 seconds), placed around the upper arm, to 50 mmHg above systolic blood pressure. The cuff was subsequently deflated (within 1 second) and StO2 measurements were continued up to 5 minutes post ischemia.

StO2 curve characteristicsStO2 data from the two devices were continuously saved (one sample every 3.5 seconds) on two computers and were retrospectively analyzed using InSpectra Analysis V3.3 software (Hutchinson Technology). The VOT-derived StO2 traces were divided into four phases: baseline, ischemia, reperfusion, Carfilzomib and hyperemia (Figure (Figure11).Figure 1Vascular occlusion test-derived tissue oxygen saturation phases and parameters. The vascular occlusion test-derived tissue oxygen saturation (StO2) traces were divided into four phases (baseline, ischemia, reperfusion, and hyperemia) and were analyzed …The ischemic phase was analyzed for StO2 downslope (%/minute), minimum StO2 after 3 minutes of ischemia (%), and ��StO2 (%; that is, the difference between baseline and minimum StO2). The StO2 downslope is generally considered to reflect muscle metabolism and the minimum StO2 is considered to indicate the extent of ischemia.The reperfusion phase was analyzed for two parameters: upslope (%/minute) and rise time (minutes), both StO2 measured over the interval from minimum StO2 to baseline (Figure (Figure1).1).