Tissue-oxygenation assessment using near-infrared spectroscopy during severe sepsis: confounding effects of tissue edema on StO₂ values

Excerpt

Measurement of tissue oxygen saturation (StO₂) in critically ill septic patients may be able to detect occult hemodynamic abnormalities that cannot be detected using standard monitoring techniques [1]. Near-infrared spectroscopy (NIRS) has been developed after studies indicating that biological tissues are transparent to light in the near-infrared region and that oxyhemoglobin (HbO₂) and deoxyhemoglobin (Hb) have significantly different spectra [2]. The use of near-infrared light to measure tissue oxygenation in healthy human subjects has been extensively validated [3, 4]. Several studies have indicated that disturbances in tissue oxygenation are related to the development of multiple organ failure in critically ill trauma patients [5]. Girardis et al. demonstrated that oxygenation at the brachioradialis muscle is disturbed in septic patients compared with healthy controls [6]. However, to our knowledge, no data on the validity of measuring tissue oxygenation using NIRS in patients with severe sepsis and septic shock have been reported so far. …