This randomized, double-blinded, placebo-controlled trial investigated the effect of continuous epidural
butorphanol on intrathecal
morphine-related
pruritus in patients undergoing
cesarean section. Eighty-three patients undergoing elective
cesarean section under
spinal anesthesia (1.5 mL of isobaric
bupivacaine 0.5 % and 0.1 mg of preservative-free
morphine) were enrolled in this study. Subjects were randomized to receive epidural
butorphanol (n = 43) or
normal saline combined
bupivacaine (n = 40). In the study group, after the umbilical cord was clamped, patients were administered an epidural loading dose of 1 mg followed by a 48-h infusion of 0.004 %
butorphanol with 0.1 %
bupivacaine at a rate of 2 mL/h. In the
normal saline group, saline was used for the loading dose and the infusion 0.1 %
bupivacaine at a same rate. Postoperatively, a blinded observer recorded the incidence/severity of
pruritus, visual analog
pain scores and sedation level at 1, 3, 6, 9, 12, 24 and 48 h. The 48-h consumption of breakthrough
analgesic (
tramadol) was also noted. The primary outcome was the incidence of
pruritus at 48 h. At 48 h, the incidence of
pruritus was significantly lower in the
butorphanol group (16.3 vs. 52.5 %; P < 0.001). Furthermore, compared with the
normal saline group, the intensity of
pruritus was also decreased with epidural
butorphanol at 3, 6 and 9 h (all P ≤ 0.008). The
pain scores were significantly lower at 12, 24 and 48 h (all P < 0.05) in the
butorphanol groups. Patients only receiving
bupivacaine required a higher cumulative dose of
tramadol (37.5 ± 62.8 vs. 9.3 ± 36.6; P = 0.014). In patients undergoing elective
cesarean section, continuous epidural
butorphanol with
bupivacaine decreases the incidence and severity of intrathecal
morphine-related
pruritus without adversely affecting the quality of postoperative
analgesia.