Oxygen extraction and perfusion markers in severe sepsis and septic shock: diagnostic, therapeutic and outcome implications.

PURPOSE OF REVIEW: The purpose of this study is to review the recent literature examining the clinical utility of markers of systemic oxygen extraction and perfusion in the diagnosis, treatment and prognosis of severe sepsis and septic shock. RECENT
FINDINGS: When sepsis is accompanied by conditions in which systemic oxygen delivery does not meet tissue oxygen demands, tissue hypoperfusion begins. Tissue hypoperfusion leads to oxygen debt, cellular injury, organ dysfunction and death. Tissue hypoperfusion can be characterized using markers of tissue perfusion (central venous oxygen saturation and lactate), which reflect the interaction between systemic oxygen delivery and demands. For the last two decades, studies and quality initiatives incorporating the early detection and interruption of tissue hypoperfusion have been shown to improve mortality and altered sepsis care. Three recent trials, while confirming an all-time improvement in sepsis mortality, challenged the concept that rapid normalization of markers of perfusion confers outcome benefit. By defining and comparing haemodynamic phenotypes using markers of tissue perfusion, we may better understand which patients are more likely to benefit from early goal-directed haemodynamic optimization.
SUMMARY: The phenotypic haemodynamic characterization of patients using perfusion markers has diagnostic, therapeutic and outcome implications in severe sepsis and septic shock. However, irrespective of haemodynamic phenotype, the outcome reflects the quality of care provided at the point of presentation. Utilizing these principles may allow more objective interpretation of resuscitation trials and translate these findings into current practice.