The Effect of Different Concentrations of Sevoflorane on Intraocular Pressure in Children Undergoing Ocular Surgery Under General Anesthesia

Introduction One important goal in anesthetic management during ocular surgery is to provide adequate control of intraocular pressure (IOP). An increase in IOP may be catastrophic in patients with glaucoma or a penetrating open-eye injury. Accurate assessment of IOP is particularly important in infants and children with definite or suspected glaucoma undergoing examination under anesthesia (EUA).

There is an ongoing debate over the effect of anesthetic agents on the IOP. Anesthetic regimens in this surgical field commonly consist of short-acting anesthetic agents, such as propofol and sevoflurane, usually combined with short-acting analgesics, such as remifentanil [1-3].

Both propofol and sevoflurane are known to reduce the IOP [4-7]. Previous studies have compared these two anesthetics protocols in order to determine which provides superior control of the IOP. Propofol produced significantly lower IOP measurements compared to sevoflurane (both combined with remifentanil), in cataract surgery [8], whereas in non-ophthalmic surgery propofol and sevoflurane caused a comparable decrease in IOP [9].

Sevoflurane, an inhalational anesthetic, has a rapid onset of action, faster recovery time and lower incidence of reported side effects in pediatric patients [10], and is also suitable for inhalation induction because it does not irritate the airway [3].

During pediatric ocular surgery, the inspired sevoflurane concentration is normally maximal at induction of anesthesia (approximately end-tidal concentration of 7%), and it is thereafter reduced or discontinued to achieve an end-tidal sevoflurane concentration of <0.1% by the completion of skin closure. In between these time points the inhaled end-tidal concentration gradually decreases and may have an impact over the IOP that could affect the conduct of surgery. A prospective randomized clinical trial compared the effects of ketamine and sevoflurane on IOP during the eight minutes after induction of anesthesia (in 2-minute intervals) in children with suspected or diagnosed glaucoma undergoing EUA [5]. During these 8 minutes the IOP decreased significantly only in the sevoflurane group. This finding contradicted claims that measurements immediately after induction are relatively unaffected by anesthetics, and suggested that variations in sevoflurane concentration do affect the IOP. To this end there is no data in the literature to support or disprove this finding.