Comparison of methohexital and alfentanil on movement during placement of retrobulbar nerve block.

We compared the use of methohexital (0.5 mg/kg) with alfentanil (20 micrograms/kg) as a drug for limiting movement and pain during the placement of a retrobulbar block (RBB). Thirty patients (ASA class I-III) were randomly assigned to receive either methohexital or alfentanil (15 patients in each group). All but two patients (87%) treated with alfentanil were awake and responsive to command. All of the patients given methohexital were unresponsive at the time of block placement. However, less movement was observed when patients were treated with alfentanil compared to methohexital (P < 0.0002). None of the patients treated with alfentanil complained of pain during placement of the RBB. No difference was detected in the incidence of respiratory depression. However, one patient who received alfentanil had a prolonged period of apnea (approximately 30 s) with a significant decrease in oxygen saturation. The incidence of nausea and vomiting and the time to discharge from the outpatient department were similar in the two groups. The results of this study suggest that alfentanil may be used as a single drug to limit movement during placement of retrobulbar block for ophthalmic surgery.