RESUMEN
OBJECTIVE: To determine the incidence of withdrawal syndrome after prolonged infusion of fentanyl and midazolam in children, and the associated risk factors. DESIGN: Historic or retrospective cohort study. SETTING: Pediatric Intensive Care Unit in an academic center. PATIENTS: Forty-eight pediatric patients who received sedation and analgesia only with fentanyl and midazolam through continuous infusion for at least 48 hours. INTERVENTIONS: None. MAIN VARIABLES OF INTEREST: Collected data included demographic and clinical parameters, dose and duration of sedation received, and incidence, severity and treatment of withdrawal syndrome. RESULTS: Fifty percent of the patients developed withdrawal syndrome. There were significant differences between the patients who developed withdrawal syndrome and those who did not, in terms of the duration of infusion and the cumulative doses of both drugs. A cumulative fentanyl dose of 0.48 mg/kg, a cumulative midazolam dose of 40 mg/kg, and a duration of infusion of both drugs of 5.75 days were risk factors for the development of withdrawal syndrome. Most children developed mild or moderate disease, beginning about 12-36 hours after weaning from infusion. Methadone was used in most cases for treating withdrawal. CONCLUSIONS: There is a high incidence of withdrawal syndrome in children following the continuous infusion of midazolam and fentanyl. The duration of infusion of both drugs and higher cumulative doses are associated with the development of withdrawal syndrome.