MEthylene Blue use in the ED

​Methylene Blue Summary 

• Uses include methemeglobinemia and vasoplegia. There is also some evidence supporting its use in angioedema.  

• Dose for methemeglobinemia is 1.5mg/kg over 1-2min 
• Dose for vasoplegia is 1-2mg/kg over 1-2min, then option infusion of 1-2mg/kg/hr over a maximum of 1-2hrs. 

• Mechanism of action: lots of biochemistry involved, but it breaks down to methylene blue inhibiting soluble cGMP to prevent NO endothelium-dependent relaxation in vascular smooth muscle to halt NO induced vasodilation.  

• Adverse effects of methylene blue administration include pain/burning at the injection site, nausea, HA 
• Avoid use in patients with G6PD deficiency, and use with caution in patients on multiple serotonergic agents (SSRIs, SNRIs, TCAs) as methylene blue can induce serotonin syndrome. This last point is especially important when using the drug as an infusion as there is high risk for serotonin syndrome with prolonged use.  
• Don’t forget to warn you nursing/support staff that the pulse ox reading may be artificially low while the methylene blue is being infused, however this reaction is transient.