Hypotension is a common complication of intermittent renal replacement therapy. Methylene blue, an inhibitor of nitric oxide synthesis, has been suggested to improve hemodynamics during renal replacement therapy in ambulatory patients, but evidence is lacking for critically ill patients.

This trial will assess whether methylene blue can improve hemodynamics and blood pressure for patients with shock requiring renal replacement therapy.

BLUE is a randomized, multicenter, open-label trial. Patients with high risk of hypotension during RRT will be randomized to receive either methylene blue infusion at a dose of 1 mg/kg as a bolus, followed by continuous infusion of 0.1 mg/kg of body weight in a total of 200 mL of saline solution throughout the dialysis session, or to usual care. The usual care group will not receive any intervention. A total of 260 patients are expected to be randomized in a 1:1 ratio.

Inclusion Criteria:

• Patients over 18 years old
• Acute kidney injury or acute-on-chronic kidney disease requiring intermittent renal replacement therapy hemodialysis
• Systolic blood pressure lower than 100 mmHg or use of vasopressor
• Signed informed consent

Exclusion Criteria:

• Pregnancy
• Life expectancy less than 24 hours
• Exclusive palliative or end-of-life care
• RRT due to hypertensive crisis
• Known allergy to methylene blue
• Known Glucose-6-phosphate dehydrogenase (G6PD) deficiency
• Prior participation in the study
• Acute coronary syndrome
• Chronic nitrate oral use

Data will be shared upon reasonable request

6 months after trial is published

After aproval by the executive comittee

Blinding of healthcare professionals is not feasible due to the distinct visual of methylene blue. However, outcome assessors and statisticians will remain blinded to group allocation to minimize bias.