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Effects of halothane on intraocular pressure in anesthetized children
M F Watcha1, F C Chu, J L Stevens
1Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri.
Insights
Intraocular pressure (IOP) measurements in children under halothane and nitrous oxide anesthesia are stable for 10 minutes post-induction. Avoid measuring IOP immediately after tracheal intubation for accurate results.
Area of Science:
- Anesthesiology
- Ophthalmology
- Pediatric Medicine
Background:
- Intraocular pressure (IOP) measurement in children typically requires anesthesia.
- Nitrous oxide and halothane are common anesthetic agents used for pediatric IOP measurement.
Purpose of the Study:
- To determine the optimal timing for IOP measurement in anesthetized children.
- To evaluate the impact of anesthetic duration and halothane concentration on IOP.
- To assess IOP changes related to tracheal intubation.
Main Methods:
- Studied 80 children (mean age 4.5 years) undergoing anesthesia.
- Measured IOP at 1-minute intervals after induction in 30 children with constant anesthetic levels.
- Assessed IOP at various time points and halothane concentrations (0.5%, 1.0%) in 50 children, including post-intubation.
Main Results:
- IOP remained stable over time when anesthetic concentrations were constant.
- IOP did not significantly change with end-tidal halothane concentrations up to 1.0%.
- IOP significantly increased immediately following tracheal intubation.
Conclusions:
- Pediatric IOP measurements are reliable within the first 10 minutes after induction with halothane and nitrous oxide.
- Tracheal intubation causes a significant increase in IOP, making this time point unsuitable for measurement.
- Optimal IOP assessment in this pediatric population occurs before tracheal intubation.
Abstract:
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 immediately 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.