The aim of this prospective study is to assess the prognostic value of bioactive plasma adrenomedullin (ADM) in 600 patients with severe sepsis or septic shock in an international multicenter study and to validate the findings concerning the association of ADM concentration and the use of vasopressor therapy, organ failure and outcome.

Sepsis involves an overactive inflammatory response to severe bacterial infection that can compromise vascular integrity and cause tissue edema, organ dysfunction and death. Adrenomedullin (ADM) has attracted the interest of researchers because of its powerful physiological functions. An anti-ADM antibody reduced the norepinephrine infusion rates required to achieve hemodynamic targets, increased urine flow and improved creatinine clearance, which ultimately resulted in attenuated systemic inflammation and tissue apoptosis, during resuscitated cecal ligation and puncture (CLP)-induced septic shock in mice.

In humans, plasma ADM has been determined only in a small number of sepsis patients, and - except from one study - the assays used did not selectively measure the bioactive ADM form and have been considered not reliable. Therefore, the potential value of determining plasma ADM in such patients cannot yet be ascertained and the optimal cut off needs to be validated in future studies

Inclusion Criteria:

• Age >18 years
• Patients admitted in intensive care unit for severe sepsis or septic shock according to international, standardized criteria,transferred from another intensive care unit less than 24 hours after the primary admission, or being treated with vasopressors for less than 24 hours in the prior ICU
• Signed Consent form

Exclusion Criteria:

• Age < 18 years
• Severe sepsis or septic shock patients transferred from another intensive care unit later than 24 hours after the primary admission or being treated with vasopressors for more than 24 hours in the prior ICU
• Pregnant women
• Vegetative coma
• Participation in an interventional clinical trial in the preceding month

600 patients admitted in intensive care unit of 26 hospitals, in 5 countries, with diagnosis of severe sepsis or septic shock, will be included in this study.