Out of hospital cardiac arrest is a major health problem. Prognosis is still poor even after return to spontaneous circulation. The pathophysiology of cardiac arrest implies ischemia-reperfusion and sepsis like syndrome. These phenomenons can lead to microvascular dysfunction explaining probably multi-organ failure after cardiac arrest. Few means allow the exploration of microvascular function in human. Muscle StO2 is a technique allowing the assessment of microvascular function non-invasively. The aim of this study is to evaluate muscle StO2 as a prognostic factor after out of hospital cardiac arrest.

Out of hospital cardiac arrest is a major health problem accounting for 375000 deaths each year in Europe. Even after return to spontaneous circulation, survival is poor because of complications such as post-anoxic encephalopathy and multi-organ failure. The pathophysiology of cardiac arrest implies ischemia-reperfusion and sepsis like syndrome. These conditions are frequently associated with microvascular dysfunction that can be the "motor" of multi-organ failure. Few means allow the exploration of microvascular function in human. Recently, StO2, a non-invasive technique assessing microvascular function has been described. This technique measures the tissular saturation of a muscle using the near-infrared spectroscopy technique. It has been described to be a good prognostic factor during haemorrhagic shock state. Dynamic parameters such as reperfusion slope allow discriminating between survivors and survivors after severe sepsis. This dynamic test assesses the microvasculature recruitment that could be a marker of better prognosis. The aim of this study is to evaluate muscle StO2 as a prognostic factor after out of hospital cardiac arrest.

Inclusion Criteria:

• Out of hospital cardiac arrest
• Patient aged between 18 and 80 years
• Having a Social Security System

Exclusion Criteria:

• Pregnant women, lack of appropriate consent