Objectives: To determine if adding ketamine to propofol provides better sedation than propofol alone for patients receiving a retrobulbar block for eye surgery.
Material and methods: Randomized double-blind trial enrolling 50 patients receiving a retrobulbar nerve block for eye surgery. Patients were randomly assigned to 2 groups. In the propofol group sedation was induced with 0.45 mg x kg(-1) of propofol. In the ketamine plus propofol group sedation was induced with 0.45 mg x kg(-1) of propofol plus 0.25 mg x kg(-1) of ketamine. We recorded patient characteristics (age, weight, ASA class, height, sex), hemodynamic variables (blood pressure, heart rate), puncture conditions, sedation (score on the Observer's Assessment of Alertness/Sedation [OAA/S] scale), ventilation (end-tidal carbon dioxide pressure, apneas, need for reanimation maneuvers, pulse oximetry), time until onset of effect, duration of effect, and amnesia.
Results: No significant differences were observed in time to onset, duration of effect, patient characteristics, hemodynamic or respiratory variables, or amnesia. Sedation assessed on the OAA/S-scale was lower in the propofol group and the puncture conditions were significantly better in the ketamine plus propofol group. The only adverse psychomimetic reaction was transient agitation, observed in 2 propofol group patients.
Conclusions: Low doses of ketamine associated with propofol improve puncture conditions for performing a retrobulbar block without increasing unwanted side effects.