Severe sepsis and septic shock remain the leading causes of child mortality worldwide. Sepsis is a complex process that ultimately leads to circulation disorders, organ perfusion abnormalities, capillary leakage, tissue hypoxia, and organ failure. The difficulty of clinical treatment is microcirculation and mitochondrial dysfunction in septic shock. Once shock enters the stage of microcirculation failure, conventional treatment is ineffective. ECMO can effectively support the circulatory system and provide good oxygen delivery, but there are many controversies in clinical treatment. 1) whether ECMO can effectively improve the clinical prognosis of children with septic shock; 2) appropriate timing for ECMO intervention; 3) which key clinical factors affect the effect of ECMO treatment. This study intends to adopt a multi-center, prospective, non-randomized controlled trial design, and the main research hypothesis is whether ECMO treatment can improve the success of discharge survival of children with septic shock.

In this study, a variety of statistical analysis methods will be used to screen the clinical indicators and truncation values suitable for starting ECMO, and to construct a comprehensive prediction model, so as to determine the basis for the optimal timing of ECMO treatment in the future. The efficacy of ScVO2, lactic acid, and vasoactive inotrope score (VIS) on the ECMO treatment timing will also be evaluated. This study aims to evaluate and improve the clinical application of ECMO in the treatment of sepsis in children

Inclusion Criteria:

• Children with septic shock and refractory septic shock admitted to the PICU of all the study centers

Exclusion Criteria:

• Fatal chromosomal abnormalities (e.g., trisomy 13 or 18)
• Uncontrolled bleeding
• Irreversible brain damage
• After allogeneic bone marrow transplantation
• Weight less than 2.5kg or severe malnutrition

Children with septic shock and refractory septic shock admitted to the pediatric intensive care unit（PICU） of all the study centers