Early Methylene Blue in the Microhemodynamics of Septic Patients

Inclusion Criteria: * Adult patients with a diagnosis of sepsis and persistent hemodynamic dysfunction despite adequate fluid resuscitation, requiring escalation of noradrenaline dose to maintain mean arterial pressure ≥65 mmHg, with prolonged capillary refill time or septic shock according to Sepsis-3 definition, within less than 6 hours of the diagnosis, will be eligible for the study. Exclusion Criteria: * Pregnant or breastfeeding patients; * Patients with any withdrawal or withholding life-sustaining intervention; * Cardiac surgery patients in the immediate postoperative period; * Refractory septic shock, with a high propability of death within 24 hours; * Personal or familiar history of glucose-6-phosphate dehydrogenase (G6PD) deficiency; * Allergy to methylene blue, phenothiazines, or food dyes; * Recent administration of linezolid (less than 14 days ago); * Recent intake of serotonergic psychiatric medications (less than 2 weeks ago - with the exception of fluoxetine, which must be less than 5 weeks ago), * Recent intake (less than 2 weeks ago) of monoamine oxidase inhibitors (MAOIs), such as rasagiline and selegiline.