Vasoplegic Shock Treated with Methylene Blue Complicated by Severe Serotonin Syndrome

Management of severe vasoplegic shock in overdose can be very challenging. We describe a case of severe refractory vasodilatory shock in poisoning where methylene blue (MB) was used with success. However, the patient subsequently developed severe Serotonin Syndrome (SS) as a result of an interaction between serotonergic drugs and MB.

A 15-year-old male developed severe vasoplegic shock 1.5 hours after overdosing on several different medications including quetiapine slow release, quetiapine immediate release, desvenlafaxine slow release, venlafaxine, amlodipine, ramipril, fluoxetine, promethazine and lithium. His vasoplegic shock was resistant to high doses of noradrenaline and vasopressin. MB was administered 6.5 hours post ingestion and within 1 hour there was an improvement in his hemodynamic status and reduction of catecholamine requirements. Twelve hours post ingestion, he developed severe Serotonin Syndrome that lasted 5 days as a result of interaction between MB, a reversible monoamine oxidase inhibitor (MAO-I), and the antidepressants taken in overdose. MB had a calculated half-life of 38 hours.

MB is a useful additional strategy for severe drug induced vasodilatory shock and may be potentially life-saving. Clinicians should be aware that it can interact with other drugs and cause life-threatening Serotonin Syndrome. Lower doses or shorter durations may be wise in patients at risk of this interaction.