Sedaçåo com midazolam ou com a associaçåo midazolam-fentanil em cirurgia oftálmica sob bloqueio retrobulbar / Midazolam or midazolam-fentanyl for sedation during ophthlamic surgery under retrioobulbar blockade

RESUMO

Background and objectives - Absoolute immobility, low intraocular pressure, reduction of bleeding in the operative field and abolition of the coculocardiac reflex are the main goals of anesthesia for ophthalmic surgery. It is possible to achieve such goals with regional techniques, although it is difficult to keep the patient immobile and comfortable during the performance of the block as well as during the surgical procedure. The fulfill the ideal conditions, we have been using clinical results we decided to study both regimens regarding the patients' reaction during the performance of the block, their behavior transoperatively and their degree of amnesia. Methods - Forty patients with physical status ASA I, II and III were studied, randomly allocated into groups A and B. Patients in group A were sedated with midazolam 1 to 4 mg (0.03 to 0.06 mg.kg)(less one) and patients in group B received 1 to 4 ml of solution containing 5 mg of midazolam and 50 mg of fentanyl diluted to 5 ml of Ringer-lactate solution (0.02 to 0.06 ml.kg)(less one). In both groups enough drug was injected until we could have a calm and cooperative patient, without ventilatory depression. After sedation, patients were submitted to retrobulbar block associated with akinesia of the orbicularis muscle (O'Brien technique), Patients' reaction during the performance of the blocks and their recall of the procedure 30 minutes later were registered. Patients were also evaluated regarding their cooperation and calmness, reaction, agitation or depression. Results - In both groups it was observed only mild reaction during the performance of blocks, with almost no recallof the procedure and calmness and cooperation during surgery. No case of agitation or respiratory depression was observed. There were no statistically significant differences between groups A and B regarding the studied variables. Conclusions - Midazolam and midazolam-fentanyl, in small doses, have proven efficient for sedation of patients during ophthalmic surgeries under retobulbar block. However, it should be stressed that the use of either technique does not absolutely guarantee a calm and cooperative patient. A successful operation on the eye under regional anesthesia and sedation depends on adequate patient selection, surgeon's ability and permanent vigilance of the anesthesiologist