The effect of intraoperative retrobulbar block on anesthetic management of enucleation under general anesthesia

This case chronicles the effect of a retrobulbar block on a coincident general anesthetic for enucleation in an elderly man. This ASA II patient had a medical history of insulin-dependent diabetes with few apparent cardiovascular complications and mild chronic obstructive pulmonary disease. Induction of anesthesia was accomplished with small doses of midazolam, droperidol, and alfentanil followed by thiamylal. The patient was intubated and maintained on isoflurane and nitrous oxide. A retrobulbar block was administered according to the surgeon's instructions without immediate, untoward consequences. Within 10 minutes the patient suffered a profound decrease in blood pressure and pulse requiring repeated doses of glycopyrrolate, phenylephrine, and ephedrine to maintain effective perfusion. These effects do not appear to have resulted from direct elicitation of the oculocardiac reflex, but rather from the loss of surgical stimuli from the block that essentially resulted in inadequate sympathetic tone. The author concludes that anesthetists in similar circumstances should anticipate the possibility of hypotension and lessened anesthetic requirements following retrobulbar block when coincident general anesthesia is planned.