Sepsis, cardiac arrest and multiple trauma are potentially life-threatening conditions and common reasons for intensive care unit (ICU) admission. The aim of this study is to investigate the role of the signaling substance serotonin in blood in these conditions.

ICU-PATIENTS

Inclusion criteria:

• Active treatment of sepsis, septic shock, cardiac arrest with ROSC or severe multiple trauma.
• Age over 18 years
• Written consent from the patient or preliminary consent from the next of kin.
• Receiving mechanical ventilator treatment upon inclusion.
• Arterial and central venous cannulas present.

Exclusion criteria:

• Withdrawal of consent
• Serotonergic carcinoid syndrome, short bowel or other considerable comorbidity altering serotonin content in blood.
• Intoxication prior to ICU admission.

HEALTHY CONTROLS

Inclusion criteria:

• Age over 18 years and signed written consent.
• Conformed to diet and activity restrictions.

Exclusion criteria:

• Any acute illness or injury
• Ongoing autoimmune, malignant, infectious, or other inflammatory disease.
• Severe psychiatric disease or drug abuse.
• Use of any medication except oral contraceptives last two weeks.
• Withdrawal of consent.

ICU CONTROLS

Inclusion criteria:

• Status epilepticus, encephalitis, stroke, or other localized neurological disease.
• Age over 18 years
• Written consent from the patient or preliminary consent from the next of kin.
• Receiving mechanical ventilator treatment upon inclusion.
• Arterial and central venous cannulas present.

Exclusion criteria:

• Withdrawal of consent
• Clinical signs of infection with focal symptoms or temperature over 38,0°C.
• Biochemical signs of infection or inflammation with leukocytes > 11 x 10^9/l, CRP > 15 mg/l, or PCT > 0,10 μg/l.
• Respiratory failure with PaO2/FiO2 ratio < 40 kPa.
• Circulatory failure with MAP < 60 or need for pressor treatment prior to sedation.
• Thrombocytopenia or thrombocytosis with platelets < 100 or > 400 x 10^9/l.
• Serotonergic carcinoid syndrome, short bowel or other considerable comorbidity altering serotonin content in blood.
• Extracranial autoimmune or malignant disease.
• Severe psychiatric disease or drug abuse.
• Intoxication or physical trauma prior to ICU admission.

Patients with sepsis or septic shock, cardiac arrest with ROSC or severe multiple trauma, admitted to ICU and receiving mechanical ventilation will be screened for inclusion. A group of healthy controls will also be included.