[Racemic bupivacaine, levobupi vacaine and ropivacaine in regional anesthesia for ophthalmology -- a comparative study].

BACKGROUND AND OBJECTIVE: Racemic bupivacaine, used in peribulbar anesthesia owing to its high potential to promote motor blockade, presents a smaller safety margin for cardiotoxicity in relation to ropivacaine and levobupivacaine. The objective of this study was to compare the degree of motor blockade and alteration of intraocular pressure (IOP) produced by racemic bupivacaine, levobupivacaine and ropivacaine in peribulbar block.

METHOD: Ninety seven patients, ASA physical status I and II, submitted to peribulbar anesthesia, were randomly allocated into three groups: group A-(n=16) receiving racemic bupivacaine 0.75% with epinephrine 1:200.000; group B -(n=16) levobupivacaine 0.75% with epinephrine 1:200.000; group C -(n=15) ropivacaine 0.75%. A single inferior injection peribulbar anesthesia was performed with 7 ml of the anesthetic solution plus 280 UI of hyaluronidase. The IOP and the degree of motor blockade were registered five minutes before injection and 1,2,3,4,5 and 10 minutes after it. The motor blockade was evaluated according to Nicoll's scale. For statistical analysis, Wilcoxon's test, simple frequency analysis, and Student-t test were used. p<0.05 was considered significant.

RESULTS: There were no significant differences between groups with respect to the degree of motor blockade. The IOP variation between the groups was not clinically significant.

CONCLUSIONS: Considering the advanced age of most of these patients and the high concentrations of local anesthetics used in peribulbar blockade, the use of ropivacaine and levobupivacaine produces motor blockade as effective as racemic bupivacaine while minimising risks for cardiotoxicity.