Severe Sepsis

1\. To research the current situation of severe infection in children in China, and to investigate the incidence, prognosis and disease burden of severe infection in children in different regions of China. 2. Establish the risk prediction model and diagnosi model of severe infection in children, and verify the accuracy of the model in multi-center; 3. To study the effectiveness and safety of different treatments in real diagnosis and treatment, and to evaluate the efficacy of subgroups under different ages and high risk factors.

This is an observational study to understand the changes in alveolar dead space in medical critically ill patients with severe infection (severe sepsis) requiring mechanical ventilation and the possibility to predict multi-organ failure. The measurement of alveolar dead space used to require sophisticated equipment and time. New ventilators have microprocessors that allow rapid mathematical calculation with minimal intervention.

Subjects previously enrolled / randomized in the ReActIF-ICE (Recovery from acute immune failure in septic shock by immune cell extracorporeal terapy - immune competence enhancement) study received either standard sepsis treatment (control group) or standard sepsis treatment and additionally the ARTICE treatment (treatment group) during their index hospitalization. All subjects are followed up for 90 days after enrollment. In this long term follow up study, the enrolled subjects shall be followed up beyond 90 days for up to 5 years.