Serotonin Syndrome

Know the serotonergic anesthetic drugs - Meperidine, tramadol, methylene blue, and interactions with MAOIs and SSRIs/SNRIs can precipitate it; review the medication list and avoid additive serotonergic agents.

Recognize the triad - Clonus and hyperreflexia, autonomic instability, and altered mental status, often with hyperthermia — distinguish it from malignant hyperthermia and neuroleptic malignant syndrome.

Stop the offending drugs and support - Discontinue serotonergic agents, control agitation (benzodiazepines), cool actively for hyperthermia, and support hemodynamics.

Manage hyperthermia and rigidity - Severe hyperthermia is the killer; use aggressive cooling and sedation, with paralysis and intubation in extreme cases.

Autonomic lability - Expect labile blood pressure and heart rate; use short-acting, titratable agents.

Serotonin syndrome is a potentially life-threatening state of excess serotonergic activity, caused by serotonergic drugs alone or, classically, in combination.

It's a clinical triad of neuromuscular excitation (clonus, hyperreflexia, rigidity), autonomic instability (hyperthermia, tachycardia, labile blood pressure), and altered mental status. It matters in anesthesia because several of our drugs are serotonergic and can precipitate or worsen it — notably meperidine, tramadol, methylene blue, and, with MAOIs, certain agents.