 2. Early norepinephrine group. The patient will receive fluid therapy together with low dose of norepinephrine 0.05 mcgkgmin. If after titrate intravenous fluid therapy until achieve goal CVP or PCWP or other fluid responsive test, but the mean blood pressure still lower than 65 mmHg, then additional titrate dose of norepinephrine will be given to the patient according to standard septic shock guideline. 