Changes in intraocular pressure during prone spine surgery under propofol and sevoflurane anesthesia.

Background: Intraocular pressure (IOP) has been shown to increase during prone spine surgery. Although propofol and sevoflurane have been widely used during such surgery, there have been no data to compare the IOP changes under propofol and sevoflurane anesthesia. The present study was therefore conducted to investigate IOP changes under propofol and sevoflurane anesthesia during prone spine surgery.

Method: After institutional approval and informed consent, 24 patients undergoing prone spine surgery were studied. Patients were randomly allocated to 1 of 2 groups: the propofol or sevoflurane group. Propofol or sevoflurane was administered to maintain the bispectral index between 40 and 60. The IOP was measured using a Tonopen XL hand-held tonometer 10 minutes after induction of anesthesia in the supine position (baseline), 10, 60, and 120 minutes after positioning in the prone position, and 10 minutes after returning to the supine position.

Results: There were no significant differences in IOP values at baseline between the 2 groups. IOP values after positioning in the prone position were significantly higher than those at baseline in both groups (propofol group: from 8.9±3.5 to 21.9±5.0 mm Hg; sevoflurane group: from 11.6±3.9 to 24.8±3.4 mm Hg; P<0.05). Although IOP values were higher in the sevoflurane group than in the propofol group, the differences in IOP values were not statistically significant.

Conclusions: The results indicated that the choice of anesthetic agent, sevoflurane or propofol, did not have significant effects on IOP changes during a relatively short interval of prone spine surgery.