Methylene blue treatment of pediatric patients in the cardiovascular intensive care unit

Background: In both adults and children, hypotension related to a vasoplegic state has multiple etiologies, including septic shock, burn injury or cardiopulmonary bypass-induced vasoplegic syndrome likely due to an increase in nitric oxide (NO) within the vasculature. Methylene blue is used at times to treat this condition, but its use in pediatric cardiac patients has not been described previously in the literature. Objective: 1) Analyze the mean arterial blood pressures and vasoactive-inotropic scores of pediatric patients whose hypotension was treated with methylene blue compared to hypotensive controls; 2) Describe the dose administered and the pathologies of hypotension cited for methylene blue use; 3) Compare the morbidity and mortality of pediatric patients treated with methylene blue versus controls. Design: A retrospective chart review. Setting: Cardiac ICU in a quaternary care free-standing children’s hospital. Patients: Thirty-two patients with congenital heart disease who received methylene blue as treatment for hypotension, fifty patients with congenital heart disease identified as controls. Interventions: None. Measurements and Main Results: Demographic and vital sign data was collected for all pediatric patients treated with methylene blue during a three-year study period. Mixed effects linear regression models analyzed mean arterial blood pressure trends for twelve hours post methylene blue treatment and vasoactive-inotropic scores for twenty-four hours post treatment. Methylene blue use correlated with an increase in mean arterial blood pressure of 10.8mm Hg over a twelve-hour period (p< 0.001). Mean arterial blood pressure trends of patients older than one year did not differ significantly from controls (p=1.00), but patients less than or equal to one year of age had increasing mean arterial blood pressures that were significantly different from controls (p=0.02). Mixed effects linear regression modeling found a statistically significant decrease in vasoactive-inotropic scores over a twenty-four-hour period in the group treated with methylene blue (p< 0.001). This difference remained significant comparted to controls (p=0.003). Survival estimates did not detect a difference between the two groups (p=0.39). Conclusion: Methylene blue may be associated with a decreased need for vasoactive-inotropic support and may correlate with an increase in mean arterial blood pressure in patients who are less than or equal to one year of age.