Abstract
Purpose: :
Examination under anesthesia (EUA) is needed to measure intraocular pressure (IOP) in children, but little information exists on the effect of modern anesthetic agents on IOP, including time course and mechanism of action.
Methods: :
This randomized trial compared IOP after inhaled sevoflurane gas (S) to that after intramuscular ketamine hydrochloride (K) in children undergoing EUA. IOP was measured with Tonopen XL as soon as possible after anesthesia induction and 2,4,6, and 8 minutes thereafter. At the same times, we recorded systolic and diastolic blood pressure (SBP, DBP) and heart rate (HR).
Results: :
Among 30 subjects (S=15, K=15, mean age =62 months) age, gender, diagnosis, medication use and surgical history did not differ significantly by assignment group. Decrease in IOP between the first measurement and that at 4 minutes was significant for S (mean 19%, maximum 38%, p=0.0003), but not for K (mean = 3.9%, max =26%, p=0.33). Mean IOP for S diverged rapidly from that for K: by 2 minutes, IOP for S =20.4 mmHg, IOP for K =28.7 mmHg (p=0.04). DBP (p=0.03) and HR (p=0.006) were significantly lower for S than K at 6 minutes.
Conclusions: :
Pre–anesthesia IOP could not be determined, but we found a declining IOP in subjects with S, but not with K. The rapidity of effect suggests artificially low measured IOP with S may be difficult to avoid clinically. The speed of IOP lowering and concomitant changes in blood pressure and heart rate suggest hemodynamic changes underlie the effect of S on IOP.
Keywords: intraocular pressure • drug toxicity/drug effects