Role of methylene blue in the maintenance of postinduction hemodynamic status in patients with perforation peritonitis: A pilot study

Context: Methylene blue is an inhibitor of guanylate cyclase and hence prevents vasoplegia mediated by nitric oxide in patients with sepsis. Aims: This study aimed to analyze the effect of methylene blue on blood pressure maintenance following induction of anesthesia in patients presenting with peritonitis. Subjects and Methods: Thirty patients diagnosed to have perforation peritonitis were randomized into two groups (Group MB, Group NS). Patients in Group MB were given injection methylene blue 2 mg/kg over 20 min and patients in Group NS were given 50 ml of normal saline over 20 min, before induction. Heart rate, mean arterial pressure (MAP), cardiac output, and systemic vascular resistance (SVR) were recorded every 5 min for 1 h after infusion. Statistical Analysis: Hemodynamic parameters were analyzed using repeated-measures analysis of variance with Bonferroni's test. Blood gas analysis was analyzed using independent Student's t-test, and P < 0.05 was considered statistically significant. Results: MAP was lower at all-time points in Group NS than Group MB; however, it was statistically significant immediately, and 5 min the following induction. MAP fell from 94.8 ± 11.8 mmHg to 89.2 ± 16.0 mmHg immediate postinduction in Group MB and from 92.1 ± 9.8 mmHg to 74.1 ± 12.6 mmHg in Group NS. MAP and SVR were significantly higher in Group MB, 5 min following induction. No adverse events attributable to methylene blue were noted. Conclusions: Methylene blue contributes to the maintenance of postinduction hemodynamic stability in patients with perforation peritonitis.