The routine application of an arterial thermal-dye-dilution technique (so called COLD-Monitoring) offers new perspectives in the hemodynamic management of critically ill patients using a small invasive technique. COLD-Monitoring employs a computerized analysis of a double-indicator (temperature and dye) dilution technique which requires only a central venous catheter and a special fibre optic catheter with a temperature probe applied to the femoral artery. Especially in critically ill patients with septic course or multiple organ failure (MOF) COLD-monitoring serves to exactly measure volume and therefore distribution, to objectify capillary leakage by extravascular lung water index, to check the excretoric liver-function by plasma-deviation-rate of ICG and to perform a well controlled epinephrine therapy by measuring cardiac function index and systemic vascular resistance index.