Evaluation of Intestinal Brush Border Enzyme Function in Critically Ill Patients

Septic Shock: Recruitment and inclusion criteria * 15 mechanically ventilated critically ill patients fulfilling criteria of SIRS (2 symptoms: RR \> 20/min, HR \> 90/min, Temp. \> 38°/\< 36°, 12G/l\< WBC \< 4G/l; assumed or proven infection, persistent hypotension refractory to fluid therapy and need for vasopressors. * Time window for inclusion: up to 72h after onset of symptoms Exclusion criteria * PLT \< 50G/l, * PT \< 50%, * Continuous therapeutic anticoagulation, * DIC, st. p. MCI within 14 days, * Gastrointestinal perforation, * Age \< 18 years, * Age \> 80 Years SIRS: Recruitment and inclusion criteria * 15 mechanically ventilated critically ill patients fulfilling criteria of SIRS (2 symptoms: RR \> 20/min, HR \> 90/min, Temp. \> 38°/\< 36°, 12G/l \< WBC \< 4G/l; assumed or proven infection * Time window for inclusion: up to 72h after onset of symptoms Exclusion criteria: * PLT \< 50G/l, * PT \< 50%, continuous therapeutic anticoagulation, * DIC, st. p. MCI within 14 days, * Gastrointestinal perforation, * Age \< 18 years, * Age \> 80 Years Healthy/controls: * 15 control subjects will be recruited from the outpatient ward referred to the endoscopy of the Department of Medicine III - Division of Gastroenterology and Hepatology for upper GI-endoscopy because of epigastric pain or reflux symptoms. Inclusion criteria: * Signed informed consent Exclusion criteria: * Patients with diarrhea of unknown origin, IBD or known celiac disease * Age \< 18 years * Age \> 80 Years * PLT \< 50G/l, PT \< 50% * Therapeutic oral anticoagulation