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Thenar Measurement Site

The shunting of blood to vital organs during hypovolemia is a well-recognized physiologic phenomenon.1 It follows that the ideal measurement site of StO2 in trauma patients would be a sensitive indicator of oxygenation in peripheral muscle.

After studying the viability of several potential anatomic sites, Hutchinson Technology found the thenar eminence to be the optimal solution. Not only is the thenar eminence easily accessible, it provides consistent results between patients.

1 Thorén O. Blood flow patterns of the forearm of critically ill post-traumatic patients. A plethysmographic study, Acta Chir Scand Suppl. 1974;443:1-59.

StO2 measurements on the thenar eminence of 707 healthy volunteers resulted in a tight distribution of results.
Crookes BA, Cohn SM, Bloch S, et al. Can near-infrared spectroscopy identify the severity of shock in trauma patients? J Trauma. April 2005; 58(4):806-813; discussion 813-816.


The InSpectra™ StO2 Tissue Oxygenation Monitor provides a direct, absolute measurement of hemoglobin oxygen saturation in tissue (StO2), providing trauma teams the ability to measure tissue oxygenation and monitor it during resuscitation. It is the only tissue oxygenation monitor designed for trauma environments. The InSpectra StO2 Tissue Oxygenation Monitor uses near infrared light to illuminate tissue, and then analyzes the returned light to produce a quantitative measurement of oxygen saturation in the tissue's microcirculation.

The StO2 Trauma Study researched the role that tissue oxygen saturation monitoring could play in hemorrhagic shock and resuscitation. Study results demonstrate that StO2 measurements less than 75% may indicate serious hypoperfusion in trauma patients and that StO2 functions as well as base deficit in indicating hypoperfusion in trauma patients.