SMOOCH - Small Volume Challenges to Predict Volume Responsiveness: Prospective Interventional Study

Inclusion Criteria: * Patients are equipped with PiCCO monitoring independently to the study. * One criteria of decreased usefulness of the parameters of preload/volume responsiveness available using the PiCCO device: 1. Femoral access of the central venous catheter precluding application of the normal ranges of global enddiastolic volume index and central venous pressure. 2. Absence of sinus rhythm and/or controlled ventilation precluding the use of stroke volume variation. 3. Evidence of increased intraabdominal pressure which is known to further reduce the usefulness of central venous pressure. 4. Contradictory suggestions by stroke volume variation and global enddiastolic volume index. 5. Intolerance of passive leg raising. 6. Absence of therapeutic alternatives to volume resuscitation. Exclusion Criteria: * Extravascular volume-over plus: global enddiastolic volume index \> 1000ml/sqm * Pulmonary edema: extravascular lungwater index \> 20ml/kg * Cardiogenic shock without volume deficiency (cardiac index \<2L/min; global enddiastolic volume index \> 850ml/sqm)