Microcirculatory Effects of Methylene Blue

Microcirculatory Effects of Methylene Blue in Vasoplegic Shock After Cardiopulmonary Bypass: a Pilot Study

International guidelines recommend Methylene Blue (MB) as a second-line drug in the treatment of norepinephrine refractory vasoplegic shock (VS) after Cardiopulmonary Bypass CPB. Macrocirculatory effects of MB in this setting are now well established but microcirculatory effects of MB remain unknown.

The purpose of this study is to assess the micro vascular effects of a single administration of methylene blue (1.5 mg/kg over 30 minutes) for norepinephrine-refractory VS post CPB.

Microcirculatory effect will be monitored before and one hour after MB infusion through cutaneous refill time, video microscopy measurements of the sublingual microcirculation and tissue oxygen saturation combined with vascular occlusion test (VOT).

Inclusion Criteria:

• patients receiving methylene blue prescribed by the clinician in charge of the patient
• patient receiving a dose of norepinephrine > 0.5µg/kg/min
• normal or increase cardiac (> 2 L.min-1.m-2) at the time of inclusion
• vasoplegic syndrome post cardiopulmonary bypass for cardiac surgery

Exclusion Criteria:

• the need for hemodynamic intervention during the time of study (fluid resuscitation, introduction of inotropic or vasopressor support, change in inotropic support dose)
• age under 18 years