Effects of halothane on intraocular pressure in anesthetized children

Intraocular pressure (IOP) measurements in children are usually performed under nitrous oxide and halothane anesthesia. We studied the effects of both time and end-tidal halothane concentration on IOP in 80 children (mean age ± SD = 4.5 ± 2.9 yr), to determine the most optimal time to make such measurements in anesthetized children. In 30 children the end-tidal halothane and nitrous oxide concentrations were kept constant while IOP was measured at 1-min intervals after the induction of anesthesia. Intraocular pressure did not change with time. In another 50 children IOP was measured immediatly after induction, after 10 min of steady-state end-tidal halothane concentrations of both 0.5% and 1.0% in 66% nitrous oxide, and immediately after tracheal intubation. Intraocular pressure did not differ significantly at either halothane concentration but increased after tracheal intubation. We conclude that in patients anesthetized with halothane and nitrous oxide, IOP after induction remains constant over time and is not affected by end-tidal halothane concentrations up to 1.0% but is affected by tracheal intubation. Thus, the optimal time to measure IOP in children receiving up to 1% halothane in 66% nitrous oxide is during the first 10 min after induction, but before tracheal intubation.