Lidocaine-pancuronium bromide retrobulbar injection: experimental studies of simultaneous neural and myoneural blockage for profound akinesia.

The akinesia of the superior rectus muscle after retrobulbar administration of lidocaine was quantitatively compared to the akinesia after retrobulbar administration of a mixture of lidocaine and pancuronium bromide. Adult cats were given halothane general anesthesia and a limited orbitotomy was performed to facilitate exposure of the superior rectus muscle and its branch of the superior division of the oculomotor nerve. The superior rectus muscle was disinserted and connected to a myograph. A suprathreshold stimulus of 3 volts was then applied to the branch of the oculomotor nerve innervating the superior rectus muscle. The strength, measured in grams, of the superior rectus muscle contraction was then quantitated with the myograph. Subsequently, retrobulbar administration of the drug was given and at 10 minute intervals thereafter the suprathreshold electrical stimulus of 3 volts was reapplied to the nerve innervating the superior rectus muscle, and the strength of the contraction was recorded with the myograph. Retrobulbar administration of 0.5 cc of 2% lidocaine was compared with retrobulbar administration of a mixture of 0.5 cc of lidocaine 2% and 0.2 mg of pancuronium bromide at a dosage of 0.04 mg per kilogram. For the first 30 minutes of the experiment, each retrobulbar administration provided profound akinesia with a total absence of measurable muscular contraction, despite suprathreshold stimulation of the nerve. From 40 to 120 minutes following the retrobulbar administration, the combination of lidocaine 2% and pancuronium bromide was associated with persistent absence of measurable superior rectus contraction.(ABSTRACT TRUNCATED AT 250 WORDS)