The prevalence of serotonin syndrome in an intensive care unit: A prospective observational study

In spite of life-threatening nature of serotonin syndrome (SS), it remains an under-diagnosed condition. The availability of epidemiological data about SS, especially in the ICU setting, may help physicians make early diagnoses and interventions.

This was a 6-month prospective study in a medical ICU of a tertiary hospital to find out the prevalence of SS. All consecutive adult patients admitted to the medical ICU were evaluated to see if they fulfilled the Hunter criteria of SS. Patients who met the Hunter criteria were evaluated further for other details.

Overall, 309 patients were identified of which 24 (7.8%) met the Hunter criteria. The mean age was 52.4 years, and 75% were male. Most patients received two or more serotonergic drugs. Ondansetron was the most common serotonergic drug (58%), followed by tramadol (38%), and cough syrup (dextromethorphan or chlorpheniramine, 21%). None of the patients received a diagnosis of SS by the treating physicians. Chronic obstructive pulmonary disease exacerbation with respiratory failure and metabolic encephalopathy were the two most common admission diagnoses (17% each). Twenty-two patients received cyproheptadine. There were no fatalities.

SS is not uncommon in the ICU setting. There is a need to increase awareness among physicians.