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Effective concentration (EC50) of sevoflurane for intraocular pressure measurement in anaesthetised children with
Elayavel Ravichandran1, Nitika Goel1, Babita Ghai1
1Department of Anaesthesia, PGIMER, Chandigarh, India.
Insights
Determining optimal sevoflurane concentrations for pediatric intraocular pressure (IOP) measurement is crucial. This study found that younger infants (1-12 months) require higher sevoflurane levels (1.98%) than older children (12-36 months, 0.55%) to prevent movement during IOP assessment.
Area of Science:
- Anesthesiology
- Pediatric Ophthalmology
- Pharmacology
Background:
- Sevoflurane is a common anesthetic for pediatric procedures.
- It reduces intraocular pressure (IOP) in a dose-dependent manner.
- Optimal sevoflurane concentration for safe IOP measurement in children is not established.
Purpose of the Study:
- To determine the optimal end-tidal sevoflurane concentration for accurate IOP measurement in pediatric patients.
- To identify concentrations that prevent patient movement during IOP assessment under anesthesia.
Main Methods:
- Two pediatric glaucoma patient groups (1-12 months and 12-36 months) were studied.
- Inhalational induction with sevoflurane was used.
- The Dixon and Massey method was employed to determine effective sevoflurane concentrations for 'no movement' during IOP measurement.
Main Results:
- The 50% effective concentration (EC50) for no movement during IOP measurement was 1.98% for the 1-12 months group and 0.55% for the 12-36 months group.
- The 95% effective concentration (EC95) values were 2.47% for the 1-12 months group and 0.94% for the 12-36 months group.
- Statistical significance was observed in both age groups (P < 0.05).
Conclusions:
- A higher end-tidal sevoflurane concentration (approximately 2%) is required for IOP measurement in infants aged 1-12 months compared to those aged 12-36 months (approximately 0.5%).
- These concentrations achieve successful IOP measurement without movement in 50% of the respective pediatric populations.
- Age-specific sevoflurane dosing is essential for reliable IOP assessment in pediatric patients.
Background And Aim:
Sevoflurane, a preferred anaesthetic for children, exhibits a dose-dependent reduction in intraocular pressure (IOP). However, consensus is lacking regarding optimal end-tidal sevoflurane concentration for safe IOP measurement. This study aimed to identify the concentration at which IOP measurement could be attempted without inducing movements in paediatric patients after inhalational induction.
Methods:
Two paediatric groups (1-12 months and 12-36 months) with glaucoma undergoing examination under anaesthesia were recruited. After induction with 8% sevoflurane and 100% oxygen, the first child had an end-tidal sevoflurane concentration maintained at 2% for 4 min, followed by IOP measurement. Success was defined as 'no movement', and subsequent concentrations (adjusted in 0.2% steps) were determined using the Dixon and Massey method based on the previous patient's responses.
Results:
The study included 75 children. The effective concentration of sevoflurane causing 'no movement' during IOP measurement in 50% of the study population for successful IOP measurement was 1.98% (95% confidence interval [CI] 1.63, 2.17, P = 0.017) for 1-12 months group and 0.55% (95% CI 0.39, 0.66, P = 0.002) for 12-36 months group. Probit regression analysis yielded effective concentration of sevoflurane causing 'no movement' during IOP measurement in 95% of the study population values of 2.47% (95% CI 2.24, 4.58, P = 0.017) for 1-12 months group and 0.94% (95% CI 0.78, 1.57, P = 0.002) for 12-36 months group.
Conclusion:
In paediatric patients, a higher end-tidal sevoflurane concentration of 2% is needed for IOP measurement in 1-12 months age group compared to 0.5% required in 12-36 months age group, achieving success in 50% of the study population.
