Cardiac surgery patients have a high risk to suffer from postoperative infections. Some studies have shown, that humoral and cellular factors are associated with perioperative immunodysfunction and can increase the risk of postoperative infections. Monocytes in the blood and, especially alveolar macrophages are important for an adequate host defence. In studies the investigators have shown that hemodynamic parameters have a significant influence on the probability to develop postoperative infections. The aim of the study is to investigate, whether cardiac surgery patients have an altered immune function after surgery that is predictive for the latter development of subsequent infections and whether they benefit from a goal-directed volume and hemodynamic therapy.

Inclusion Criteria:

• elective cardiac surgery patient undergoing cardiopulmonary bypass
• signed informed consent

Exclusion Criteria:

• pregnant or breast feeding women
• Age <18 years
• pulmonary disease with an oxygenation index <300mmHg
• liver disease (>Child B)
• HIV-Infection
• Therapy with corticosteroids
• Condition after transplantation
• preexisting infection before operation