Comparison of two dosing schedules of intravenous dexmedetomidine in elderly patients during spinal anesthesia

BACKGROUND: As the number of elder patients grows, spinal anesthesia for such patients are increasing significantly. Any effort is needed to use the least anesthetic drug for maintaining the anesthesia while avoiding hazards of cardio-pulmonary complications. METHODS: American Society of Anesthesiologists physical status classification I and II, Forty five elderly patients (≥ 60 years) who received transurethral resection of the prostate or transurethral resection of the bladder tumor were allocated randomly into three treatment groups. The DMT 0.5 group was designed as with dexmedetomidine 0.5 µg/kg while the DMT 1.0 group has a 1 µg/kg intravenous injection over 10 min before anesthetic induction. The Control group was designed to get a normal saline. Each group was compared regarding the maximum sensory block level, extension of anesthesia, degree of motor block, level of sedation, VAS score and complications. RESULTS: There were no significant differences among the 3 treatment groups regarding the maximum level of sensory block and motor block. However, the duration of sensory block was significantly longer in DMT 1.0 group than in the control group (P = 0.045). Both DMT 1.0 group (median = 3, range = 2-6) and DMT 0.5 group (median = 3, range = 1-6) showed a mean value of 3-4 Ramsay sedation score, which resulted in more excessive sedation and significantly greater incidence of bradycardia compared to the control group. No complications such as hypotension, nausea, tremor, and hypoxia were found during this investigation. CONCLUSIONS: In elder patients, the DMT 1.0 group is effective in duration of sensory block and is superior in the aspect of prolonged duration of sensory block compared to the DMT 0.5 group.