Background and Objectives In our clinical experience, sufentanil is more effective when administered intrathecally than intravenously. To test this hypothesis, we compared the analgesic characteristics of 7.5 μg of intrathecal or intravenous sufentanil for pain relief after total-hip replacement.

Methods A randomized, double-blind study was conducted of 40 patients older than 75 years who experienced total-hip arthroplasty in which continuous spinal anesthesia was administered. In the recovery room, as soon as a pain score higher than 3 on a scale of 10 on a visual analog scale was reported, either 7.5 μg intrathecal or 7.5 μg intravenous sufentanil were given. If the pain score remained higher than 3 at 20 minutes after sufentanil administration,1.25 mg of “rescue” intrathecal bupivacaine were given.

Results During the first 20 minutes after intrathecal or intravenous injection, a significantly faster relief of pain was observed for the intrathecal group from 2.5 until 20 minutes. Significantly, more patients needed rescue bupivacaine in the intravenous group (7 of 20 v 0 of 20, P < .008), whereas significantly more patients in the intrathecal group reached a pain score of 0 (20 of 20 v 9 of 20, P < .001). The time to the first analgesic intervention for a pain score greater than 3 was significantly longer in the intrathecal group (224 ± 100 v 98 ± 60 minutes, P < .001). Pruritus was observed only in 5 patients of the intrathecal group (P < .047), whereas peripheral oxygen saturation under 95% was observed only in 6 patients in the intravenous group (P < .045).

Conclusions After total-hip replacement, intrathecal route of sufentanil administration rapidly offers excellent analgesia of better quality and longer duration when compared with the intravenous route.