Caspofungin is an anti-fungal drug mainly metabolized by the liver. The pathophysiological status of children with severe infection will affect the metabolism of caspofungin in the body especially in the case of liver dysfunction. There is little metabolism of caspofungin through the kidney and continuous renal replacement therapy and renal function have little influence on the pharmacokinetics of caspofungin. The study aim to investigate PK/PD of caspofungin in children with specific pathophysiological conditions, such as liver insufficiency, hypoproteinemia, ECMO treatment, or sepsis.

The current international recommended dose of caspofungin is 70 mg per square metre for load for children who is older than three months of age, followed by 50 mg per square metre for maintenance. For newborns and infants younger than 3 months of age，25 mg per square metre is also recommended.

Whether such a recommended dose can achieve an ideal PK/PD target in children with liver insufficiency, hypoproteinemia, ECMO treatment, or severe infection is still lacking in sufficient clinical data.

The objective of this study is to investigate PK/PD of caspofungin in children with specific pathophysiological conditions, such as liver insufficiency, hypoproteinemia, ECMO treatment, or sepsis.

Blood sampling time points of caspofungin are listed as follow:

Before administration (0 min); 1 h, 2 h, 4 h, 8 h , 12 h and 24 h after administration.

The concentration of caspofungin in whole blood will be analyzed at Huashan Hospital of Fudan University.

Inclusion Criteria:

• Children receiving caspofungin in pediatric intensive care unit

Exclusion Criteria:

• No Informed Consent signed Participate in other clinical trials

Children receiving caspofungin in pediatric intensive care unit including but not limited to children with liver insufficiency, hypoproteinemia, ECMO treatment, CRRT treatment or sepsis.