Intraocular pressure and hemodynamic changes following tracheal intubation in children

Study Objective: To determine the optimal time in which to make intraocular pressure (IOP) measurements in children following tracheal intubation. Design: Randomized, controlled trial. Setting: Operating rooms of a tertiary-care children's hospital. Patients: Thirteen healthy children undergoing elective strabismus correction surgery under halothane and nitrous oxide (N₂O) endotracheal anesthesia. Interventions: Following induction of anesthesia, patients were randomly assigned to receive stable end-tidal halothane concentrations of 0.5% or 1.0% in 66% N₂O. Measurements and Main Results: Baseline (preintubation) IOP, heart rate (HR), and mean arterial pressure (MAP) were recorded after 10 minutes of steady-state end-tidal concentrations. These measurements were repeated at 1-minute intervals following tracheal intubation, which was facilitated with atracurium. HR and MAP changes were found to be good predictors of IOP changes. IOP returned to baseline (preintubation) values when HR and MAP returned to preintubation levels. However, IOP measurements under anesthesia may not reflect awake values. Conclusions: We recommend that IOP be measured only after HR and MAP have returned to preintubation levels in children who have undergone tracheal intubation during halothane and N₂O anesthesia.