Intravenous sedation prior to peribulbar anesthesia for cataract surgery in elderly patients

ABSTRACT

Cataract surgery, a common operation in the elderly, is frequently performed under regional anesthesia. Dexmedetomidine, a sedativeanalgesic, is devoid of respiratory depressant effects. This study was to compare the effects of dexmedetomidine sedation with those of midazolam sedation in patients undergoing cataract surgery under peribulbar anesthesia and to assess if iv sedation [using dexmedetomidine or midazolam] prior to peribulbar anesthesia minimizes the pain or discomfort, when compared with placebo [saline]. 60 patients were undergoing elective cataract surgeries under local anesthesia randomized into three equal groups to receive one of the following dexmedetomidine Group D, midazolam Group M and saline Group S. Sedation was titrated to a Ramsay sedation score of 3. Mean arterial pressure [MAP], heart rate [HR], readiness for recovery room discharge [time to Aldrete score of 10], and patients' and surgeons' satisfaction [on a scale of 1-7] were determined. The three groups were similar in age, sex, ASA physical status and mean axial length of the globe. 10 minutes post block the MAP decreased in Group D compared to Group M and S where there was a highly significant difference [P < 0.01] [between Group D and M] and a Very highly significant difference [P < 0.0001] [between Group S and D]. The heart rate also decreased in Group D compared to Group M and S where there was a significant difference [P < 0.01] [between Group D and M] and a Very highly significant difference [P < 0.0001] [between Group S and D]. As regard SpO2 there was no significant difference between the Groups throughout the operation. There were no differences in HR between treatment groups in the recovery period; however, MAP was significantly lower throughout the period of recovery in the dexmedetomidine group. There was no difference between treatment groups in the time to achieve an Aldrete score of 10 and the time to eligibility for PACU discharge. In conclusion, this study demonstrates that iv dexmedetomidine or midazolam appears to be a suitable agent for sedation in patients undergoing cataract surgery, reduced the perception of pain associated with the performance of peribulbar anesthesia and attenuated haemodynamic responses. In the recovery room, dexmedetomidine was associated with an analgesia-sparing effect, slightly increased sedation, but no compromise of respiratory function or psychomotor responses