Muscle StO2 in critically ill patients

PURPOSE OF REVIEW: Tissue hypoperfusion is a common pathophysiologic process leading to multiple-organ dysfunction and death. An important goal of hemodynamic monitoring is the early detection of inadequate tissue perfusion and oxygenation. The use of simple, noninvasive monitoring techniques has the advantage of facilitating earlier initiation of therapy. Near-infrared spectroscopy has emerged in recent years as a tool for monitoring peripheral oxygenation (StO2) in various tissues, including muscle. Here, we review our current knowledge about the applicability, usefulness, and limitations of near-infrared spectroscopy as a technique to evaluate muscle oxygenation in acutely ill patients. RECENT FINDINGS: StO2 may be an appropriate measure for early resuscitation of critically ill patients, especially in those with low cardiac output states or after severe trauma. Its usefulness in sepsis is less well established. However, by inducing an occlusion stress, a variety of dynamic variables can be measured to assess local metabolic demand and microvascular reactivity. Several recent studies have shown that profound alterations of these near-infrared-spectroscopy-derived dynamic variables are frequent in patients with severe sepsis and these alterations are associated with a poor outcome. SUMMARY: Near-infrared spectroscopy provides a noninvasive measure of muscle oxygen metabolism and microvascular dysfunction in critically ill patients. It may be useful to guide the management of critically ill patients.