Remifentanil for labour analgesia: a double-blinded, randomised controlled trial of maternal and neonatal effects of patient-controlled analgesia versus continuous infusion.

This trial aimed to compare the maternal and neonatal effects of remifentanil given by patient-controlled analgesia (PCA) or continuous infusion for labour analgesia. Patient controlled analgesia was administered using increasing stepwise boluses from 0.1 to 0.4 μg.kg(-1) (0.1 μg.kg(-1) increment, 2 min lockout, n = 30). Continuous infusion used rates from 0.05 to 0.2 μg.kg(-1) .min(-1) (0.05 μg.kg(-1) .min(-1) increment, n = 30). Dose increments were given on request. Women reported lowest pain scores (median (IQR [range]) of 3 (2-4 [2-5]) for PCA and 4 (3-5.25 [3-7]) for continuous infusion (p = 0.004) at 60 min after the beginning of analgesia. The mean (SD) remifentanil umbilical vein/maternal artery ratio in the PCA and infusion groups were 0.74 (0.45) vs 0.70 (0.52), respectively (p = 0.776). The mean (SD) umbilical artery/umbilical vein ratios were 0.31 (0.12) vs 0.26 (0.07), respectively (p = 0.088). Maternal and neonatal adverse reactions of remifentanil were similar between the two groups. The total remifentanil consumption (median (IQR [range]) during PCA administration was lower than continuous infusion, 1.34 (1.22-1.48 [0.89-1.69]) mg vs 1.49 (1.35-1.61 [1.12-1.70] mg; p = 0.011). The results suggest that remifentanil PCA provides better pain relief and similar placental transfer compared with continuous infusion.