Effect of Dexmedetomidine on the ED50 and ED95 of Sufentanil in Patient-Controlled Intravenous Analgesia After Cesarean Section: A Randomized, Controlled, Double-Blind Trial.

To determine the effect of dexmedetomidine on the ED50 and ED95 of sufentanil in patient-controlled intravenous analgesia (PCIA) after cesarean section. Parturients who underwent elective cesarean section (n = 80) were randomly assigned to either the sufentanil group (S group) or the dexmedetomidine-sufentanil combination group (DS group). Patients in the S group received a combination of sufentanil, 5 mg of tropisetron, and saline, whereas patients in the DS group were administered 1.5µg/kg of dexmedetomidine in addition to sufentanil, 5 mg of tropisetron, and saline. The ED50 and ED95 of sufentanil were determined by Dixon sequential method. We used probit regression to calculate the ED50, ED95, and 95% confidence intervals for sufentanil in each group. The ED50 and ED95 for sufentanil in the S group were 1.634 (95% CI: 1.476-1.810)µg/kg and 2.035 (95% CI: 1.841-3.312)µg/kg, respectively. The ED50 and ED95 for sufentanil in the DS group were 1.275 (95% CI: 1.187-1.353)µg/kg and 1.503 (95% CI: 1.406-1.824)µg/kg. The VAS scores with rest at t5 and with movement at t4- t5 were lower in the DS group (P< 0.05). The t2-t5 Ramsay scores in the DS group were higher than those in the S group (P< 0.05). The doses of sufentanil and tramadol were markedly reduced in the DS group, while the onset of first lactation occurred significantly earlier in the DS group (P< 0.05). Compared with the S group, the DS group had a lower incidence of nausea, vomiting, and skin itching (P< 0.05), and lower frequency of patient-controlled analgesia (PCA) episodes (P< 0.05), and better postoperative pain satisfaction (P< 0.05). The 1.5µg/kg dexmedetomidine can significantly decrease the ED50 and ED95 of sufentanil in patient-controlled intravenous analgesia after cesarean section, provide good postoperative analgesia and sedation, and promote the earlier occurrence of first lactation.