Thenar oxygen saturation measured by near infrared spectroscopy as a noninvasive predictor of low central venous oxygen saturation in septic patients

Objective  To validate thenar oxygen saturation (StO₂) measured by near-infrared spectroscopy (NIRS) as a noninvasive estimation of central venous saturation (ScvO₂) in septic patients. Design  Prospective observational study. Setting  A 26-bed medical–surgical intensive care unit at a university-affiliated hospital. Patients  Patients consecutively admitted to the ICU in the early phase of severe sepsis and septic shock, after normalization of blood pressure with fluids and/or vasoactive drugs. Measurements  We recorded demographic data, severity score, hemodynamic data, and blood lactate, as well as ScvO₂, and StO₂ measured simultaneously on inclusion. Patients were divided into two groups according to ScvO₂ values: group A, with ScvO₂ < 70%, and group B, with ScvO₂ ≥ 70%. Results  Forty patients were studied. StO₂ was significantly lower in group A than in group B (74.7 ± 13.0 vs. 83.3 ± 6.2, P 0.018). No differences in age, severity score, hemodynamics, vasoactive drugs, or lactate were found between groups. Simultaneously measured ScvO₂ and StO₂ showed a significant Pearson correlation (r = 0.39, P 0.017). For a StO₂ value of 75%, sensitivity was 0.44, specificity 0.93, positive predictive value 0.92, and negative predictive value 0.52 for detecting ScvO₂ values lower than 70%. Conclusions  StO₂ correlates with ScvO₂ in normotensive patients with severe sepsis or septic shock. We propose a StO₂ cut-off value of 75% as a specific, rapid, noninvasive first step for detecting patients with low ScvO₂ values. Further studies are necessary to analyze the role of noninvasive StO₂ measurement in future resuscitation algorithms. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.