Journal of Trauma & Treatment

Depth Penetration of Near Infrared Spectroscopy in the Obese

Abstract

Johnson A, Roskosky M, Freedman B and Shuler MS

Near-Infrared Spectroscopy (NIRS) measures to a depth of 2 to 3 cm below the skin, raising concern over the utility of NIRS in the obese patient. The purpose of this prospective study is to investigate the effect of overlying adipose tissue thickness (ATT) on NIRS oxygenation measurements of skeletal muscle. ATT was measured by ultrasound. NIRS sensors were placed over the anterior and superficial posterior compartments of one leg during exercise and the change in regional oxygen saturation was calculated for each compartment. There was a decreasing trend in change of rSO2 from baseline with increasing ATT. Extremely obese patients (BMI >40) had significantly smaller changes in rSO2 from baseline as compared to otherwise similar patients in both the compartments (p<0.01). As ATT increased, the change of the NIRS values from baseline decreased. There was not a specific BMI or ATT determined to be incapable of being monitored.