Current septic shock guideline recommends fluid resuscitation as the first treatment. Vasopressors, including norepinephrine is recommended to start after achieve adequate fluid therapy. This can cause a certain duration of systemic hypotension before vasopressor is commenced. Initiation of norepinephrine together with fluid therapy soon after diagnosis of septic shock may increase blood pressure quicker than start treatment with intravenous fluid alone. The rapid restoration of perfusion pressure may improve septic shock outcome.

We will include severe infection patient who had evidence of organ dysfunction and hypotension and randomize into 2 groups as following:

1. Control group. The patient will receive treatment according to septic shock guideline 2013, which start with intravenous fluid replacement until achieve target central venous pressure (CVP) or pulmonary capillary wedge pressure (PCWP) or other fluid responsive test goal. If the patient's mean arterial blood pressure still lower than 65 mmHg, then norepinephrine or dopamine will initiate to rise blood pressure. The patient will receive 5% dextrose water as the placebo of norepinephrine.
2. Early norepinephrine group. The patient will receive fluid therapy together with low dose of norepinephrine (0.05 mcg/kg/min). 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.

Inclusion Criteria:

• Age > or = 18 years old
• Diagnosed severe sepsis or septic shock according to survival sepsis campaign 2013
• Mean arterial pressure < 65 mmHg

Exclusion Criteria:

• Pregnancy
• Severe underlying condition that unexpected to survive more than 48 hours
• Severe peripheral vascular disease
• Patient who required major surgery within 24 hours