Hemodynamic response to fluid management in children undergoing dexmedetomidine sedation for MRI

Dexmedetomidine is administered for pediatric sedation for MRI studies. It has the advantage of preserving respiratory function and producing a sedation state identical to that of natural sleep. It can, however, cause a dose-dependent decrease in systemic blood pressure in children. The purpose of this study was to investigate whether i.v. fluid loading with normal saline solution before the initiation of dexmedetomidine administration would affect the frequency of hypotension.

Quality assurance data on consecutively registered children who were sedated with dexmedetomidine for MRI were reviewed. All children received a bolus of 3 μg/kg dexmedetomidine followed by a continuous infusion of 2 mg/ kg/h. A normal saline fluid bolus consisting of 0, 10, or 20 mL/kg was administered to each child within 1 hour before initiation of dexmedetomidine administration. Hypotension was defined as a greater than 20% decrease in mean arterial blood pressure from baseline.

Sedation was administered to 1692 children. Data on fluid administration were missing in three cases. In the other cases, 252 (14.9%) children received 0 mL/kg of normal saline solution, 598 (35.3%) received 10 mL/kg, and 839 (49.6%) received 20 mL/kg. In a multiple logistic regression model controlled for confounding variables, the odds of development of hypotension with 10 mL/kg of fluid decreased 53% (odds ratio, 0.47; 95% CI, 0.28-0.79; p = 0.004) compared with 0 mL/kg.

Administration of 10 mL/kg of normal saline solution before the initiation of dexmedetomidine administration for pediatric MRI sedation is effective in decreasing the incidence of observed hypotension.