The objective of this study is to describe the pharmacokinetics of standard doses of caspofungin in critically ill patients.

This is a prospective observational study performed on critically ill patients. Inclusion criteria are: severe sepsis on admission requiring broad-spectrum antibiotics. Both medical and surgical patients will be included. Any type of infections will be included (pulmonary, abdominal, urinary tract, etc.) Antibiotics regimen includes: broad spectrum anti-bacterial antibiotics plus caspofungin (70 mg i.v. on the first day day, and 50 mg i.v. on the consecutive days, once daily.

Blood samples (3 mL) will be collected 2, 4, 8,12 and 24 hours after each dose of caspofungin for 3 consecutive days. The standard arterial canula will be used to obtain samples.

30 minutes after each sample collection, blood will be centrifuged for 10 minutes at 3,000 rpms. Subsequently, supernatant will be collected and frozen.

Serum caspofungin concentration will be measured with high performance liquid chromatography.

Each patient's hemodynamics parameters will be recorded with the use of transpulmonary thermodilution technique (PICCO). Other therapies i.e.: ventilatory support, sedation, an antifungal agent will be given as required.

Inclusion Criteria:

• Patients who require ICU treatment due to severe sepsis age
• 18-80 years
• an eligible consent obtained from the patient or his/her attendant

Exclusion Criteria:

• allergy to caspofungin
• lack of consent to participate in the study
• age of patients below 18 or above 80 years

Patients admitted to ICU due to severer sepsis recognition. Both medical and surgical patients will be included. Any site of infection will be treated in the manner.