Addition of dextrose 3.5% to intrathecal sufentanil for labour analgesia reduces pruritus

Purpose: To determine whether the addition of a low concentration (3.5%) of dextrose would minimize pruritus while maintaining the quality of analgesia. Methods: In a double blind study 48 parturients in early labour were randomized to one of two study groups: dextrose (Dex, n = 24; 10 μg sufentanil in dextrose 3.5%), or normal saline (NS, n = 24; 10 μg sufentanil in normal saline). Parturients received the study drug as the intrathecal injection of the combined spinal-epidural (CSE) technique for labour analgesia. Duration and degree of analgesia were measured until epidural analgesia was initiated or delivery of the baby. The intensity and distribution (above T₆, T₆-L₁, and below L₁) of pruritus were measured at five minute intervals during first 25 min after injection. Results: Quality and duration of analgesia did not differ between groups, but the overall incidence of pruritus was less in the Dex group (88% vs 42%, P = 0.001). Within each region, the incidence of pruritus was less in the Dex group. In patients who had pruritus, for the Dex group, the incidence of pruritus in the upper region (>T6) was lower than the NS group. There was no difference in the lower regions. Conclusion: The addition of dextrose 3.5% to intrathecal sufentanil reduced the incidence of pruritus without affecting the duration or quality of analgesia in parturients in early labour. The distribution of pruritus in the Dex group was limited to below T₆ suggesting that pruritus to intrathecal sufentanil is mediated at the spinal level.