Efficacy and Safety of Methylene Blue in the Treatment of Severe Septic Shock

In addition to standard treatment, patients will receive methylene blue intervention. The method is as follows: a loading dose of 2.5 mg/kg administered via micro-pump over 15 minutes, followed by a continuous infusion at a rate of 0.25 mg/kg/hour for 12 hours or until norepinephrine has been continuously discontinued for 4 hours, whichever comes first. If norepinephrine needs to be increased to 0.1 μg/kg/min before the 12-hour period ends, continue using methylene blue until the 12-hour infusion is completed.

In addition to standard treatment, patients will receive a placebo control with normal saline, administered for the same duration as the intervention group.