Inclusion Criteria:  Age more than 18 years Diagnosis of shock defined by systolic blood pressure < 90 mmHg or mean arterial blood pressure < 65 mmHg and/or clinical hypoperfusion Mechanically ventilated without ventilator dyssynchrony and no ventilator triggering Present of central venous cather or arterial catheter  Exclusion Criteria:  Age < 18 years Frankly hypovolemic shock or hemorrhagic shock Suspicious of cardiogenic shock Suspicious of acute decompensated heart failure Suspicious of acute coronary syndrome Denied participation or denied inform consent