<qa>  What is the effect of an arterial line in the radial artery supplying this muscleMeasuring tissue oxygen saturation St02 in the thenar eminence is emerging as a measurement of resuscitation. However, no study to our knowledge has evaluated the effects of an arterial line in the radial artery supplying this muscle bed on St02. This study will attempt to address the interaction between an arterial line and St02 monitoring in the thenar eminence. As most patients who require aggressive resuscitation will have an arterial line, it is important to understand what if any impact this will have on St02 in the same extremity. 