PiCCO has become a widely used haemodynamic monitoring device in the management of shock patients in ICU patients nowadays. But the effects on outcome of use of Picco, such as hospital mortality, vasoactive agents-free days, intensive care unit, and mechanical ventilation-free days and change of lactate and BNP in shock patients has not been determined. Patients will be randomly assigned to a Picco group or the control group, hospital mortality, vasoactive agents-free days, intensive care unit, and mechanical ventilation-free days and change of lactate and BNP will be observed. The conclusion will supply evidence for the clinical effectiveness of Picco in shock patients.

Inclusion Criteria:

• critically ill patients with shock: Mean arterial pressure (MAP) < 65 mmHg (< 8,7 kPa) or systolic arterial pressure (SAP) < 90 mmHg (< 12 kPa) or the need for vasopressor (Norepinephrine <0.05µg/kg/min) to support the MAP ≥ 65 mmHg (≥ 8,7 kPa) or the SAP ≥ 90 mmHg ≥ 12 kPa), when one of these criteria has lasted for 4 hours or longer

Exclusion Criteria:

• Age < 18 years
• Age > 85 years
• Pregnancy (positive pregnancy test in women of child bearing age)