The study will evaluate the benefit of early initiation of CRRT in the initial phase of severe sepsis in patients admitted to the ICU. Primary evaluated end-point is 28-day mortality. Secondarily evaluated end-point is length of ICU-stay, length of stay in hospital, duration of mechanical ventilation. There are two groups. One group of participants with early CRRT initiation and another group with late CRRT initiation. Reference group no CRRT.

The aim is to determine the optimal timing of initiation of CRRT with respect to the degree and duration of acute kidney injury (AKI) in ICU patients. The CRRT parameters and the duration of therapy will be monitored, depending on initial biochemical and clinical values of the patient. Part of the study is the follow-up of patients with a 3-month delay.

Inclusion Criteria:

• reaching criteria of severe sepsis, ICU admission

Exclusion Criteria:

• pregnant women, younger than 18 years, reaching contraindications for initiation of renal replacement therapy

Patient in severe sepsis (reaching criteria for severe sepsis), both gender, age over 18 years old, admisset in ICU.