Preoperative examination will monitor apart from basic data such as age, diagnosis, co-morbidity score ASA, BMI, level of inflammatory parameters (CRP, blood count, other biochemistry examination). Patient must fulfill criteria SIRS to be enrolled in the study and display signs of peritonitis. Precise indication to surgery will be recorded. After introduction of anesthesia the investigators will perform examination of arterial blood (ASTRUP) and will calculate APACHE