Relationship between rate of fentanyl infusion and time to achieve sedation in nonobese and obese critically ill children.

PURPOSE: The relationship between initial fentanyl infusion dosage and time to goal sedation in nonobese and obese critically ill children was examined.

METHODS: A retrospective cohort study of 75 fentanyl infusions initiated in mechanically ventilated children age 2-17 years with an inpatient admission between January 1, 2012, and May 31, 2014, who subsequently received a fentanyl infusion was conducted. The primary outcomes of the study included the time to goal sedation and fentanyl dosage characteristics (i.e., underdosage, optimal dosage, or overdosage). Sedation scores were assessed by the State Behavioral Scale, a validated instrument to assess sedation in children. Key independent (predictor) variables were collected, including baseline demographics and admission diagnoses. Multivariable regression models were used to examine the association between initial fentanyl infusion dosage and time to goal sedation or dosing characteristics while controlling for obesity status and other modifying or confounding factors.

RESULTS: A total of 75 infusions met the study's inclusion criteria, representing 74 patients. The majority of patients (52%) were boys, and the median age was 8.1 years. Eighteen children (24%) were obese. The median time to goal sedation was 10.9 hours. Among nonobese children, every 10-μg/hr increase in initial fentanyl dosage was associated with a 19% lower probability of achieving goal sedation at any point in time. Initial fentanyl dosage was not associated with time to goal sedation in obese children.

CONCLUSION: Fentanyl infusion rates in obese and nonobese children varied widely in the time needed to achieve goal sedation. At any given time, initial fentanyl infusion rates were less likely to result in goal sedation in nonobese than in obese children.