Dexmedetomidine vs midazolam for monitored anaesthesia care during cataract surgery

Cataract surgery is commonly performed under local anaesthesia with midazolam sedation. Dexmedetomidine, a sedative-analgesic, is devoid of respiratory depressant effects, and its use in cataract surgery has not been reported. This double-blind study compared the use of dexmedetomidine and midazolam in patients undergoing cataract surgery.

Forty-four patients undergoing cataract surgery under peribulbar anaesthesia randomly received either i.v. dexmedetomidine 1 microg kg(-1) over 10 min; followed by 0.1-0.7 microg kg(-1) h(-1) i.v. infusion (Group D), or midazolam 20 microg kg(-1) i.v.; followed by 0.5 mg i.v. boluses as required (Group M). 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.

MAP and HR were lower in Group D compared with Group M [86 (se 3) vs 102 (3) mm Hg and 65 (2) vs 72 (2) beats min(-1), respectively] (P<0.05). Group D patients had slightly higher satisfaction with sedation [median (IQR): 6 (6-7) vs 6 (5-7), P<0.05], but delayed readiness for discharge [45 (36-54) vs 21 (10-32) min, P<0.01] compared with patients in Group M. Surgeons' satisfaction was comparable in both groups [5 (4-6) vs 5 (4-6)].

Compared with midazolam, dexmedetomidine does not appear to be suitable for sedation in patients undergoing cataract surgery. While there was a slightly better subjective patient satisfaction, it was accompanied by relative cardiovascular depression and delayed recovery room discharge.