The Effect of Retrobulbar Block on Bi-Hemispheric Cerebral Oxygen Saturation and Early Period Postoperative Cognitive Function with Lidocaine and Levobupivacaine in Elderly Patients Undergoing Ophthalmic Surgery: A Randomised Controlled Trial

Abstract

Objectives: To measure the changes in cerebral oxygen saturation (rSO(2)) and Mini-Mental State Examination (MMSE) test scores after a retrobulbar block Design: A prospective double-blinded randomised controlled trial Setting: Medical faculty hospital, Department of Ophthalmology, Ondokuz Mayis University, Samsun, Turkey Subjects: Sixty-six patients (age >60 years) undergoing vitreoretinal surgery (duration <1 hour) Interventions: The retrobulbar block was performed with lidocaine and levobupivacaine. Main outcome measures: Bilateral rSO(2) measurements were performed before and after the retrobulbar block and during the postoperative period. The MMSE was performed preoperatively and postoperatively to evaluate the short-term cognitive function. Sensory and motor block durations, pain, akinesia and conjunctival feeling scores, patient-surgeon satisfaction and complications were also recorded. Results: The rSO(2) was higher in both hemispheres (for both the intraoperative and postoperative periods) in group L (lidocaine) compared to group LB (levobupivacaine). There were no differences between the groups regarding the short-term MMSE scores. The L group showed a faster sensory block onset than the LB group, but the difference was not statistically significant. However, the motor block onset/end times and the sensory block end times were significantly greater in group LB. Moreover, the surgeon and patient satisfaction scores were higher in group LB. Conclusions: Higher rSO(2) values were observed in patients with a lidocaine-induced retrobulbar block than those with levobupivacaine. No effect on the MMSE scores was seen. Overall, further studies that investigate long-term MMSE scores are necessary to demonstrate that the elevation in rSO(2) does not affect the MMSE score.