Fig. 4

Cumulative PCIA sufentanil consumption and supplementary meperidine doses. (a) There is significantly differences in cumulative PCIA sufentanil consumption at 48 h between in the control group and the dexmedetomidine group (Values represent means with 95% confidence interval, cumulative dose at 48 h for 196.6 ± 22.2 vs. 154.3 ± 17.5 μg, P = 0.034). Sufentanil consumption in the dexmedetomidine group was required 22% less than the control group. (b) Cumulative of meperidine supplementary doses at each time intervals after surgery was significantly lesser in the dexmedetomidine gourp than the control group (P = 0.002). PCIA, patient-controlled intravenous analgesia; SD, standard deviation