Efficacy and side effect profile of varying doses of intrathecal fentanyl added to bupivacaine for labor analgesia.

The purpose of this randomized, double blinded and controlled study was to determine the optimal dose of intrathecal fentanyl when combined with bupivacaine 2.5 mg for initiation of labor analgesia. Parous parturients with cervical dilation between 3 and 5 cm were randomized to receive intrathecal fentanyl 0 (control), 5, 10, 15, 20 or 25 micrograms, combined with bupivacaine 2.5 mg, followed by a lidocaine/epinephrine epidural test dose. Visual analog pain scores (VAPS) and the presence of side effects were determined every 15 min until the parturient requested additional analgesia. Fetal heart rate (FHR) tracings were compared between groups. All parturients who received fentanyl >/= 15 micrograms had VAPS < 20 mm and duration of analgesia > 15 min, but this was not true for all parturients with fentanyl doses < 15 micrograms. Duration of analgesia was shorter for fentanyl groups 0, 5 and 10 micrograms, compared to groups 15, 20 and 25 micrograms, but there was no difference between the 15, 20 and 25 micrograms groups. There was no difference in the incidence of nausea and vomiting, or in FHR tracing changes. The incidence of pruritus was greater in all fentanyl groups compared to control. These data suggest that, when combined with intrathecal bupivacaine 2.5 mg, fentanyl 15 micrograms provides satisfactory analgesia to all parturients. Higher fentanyl doses produced no additional benefit in duration or quality of analgesia.

The dose-response of intrathecal sufentanil added to bupivacaine for labor analgesia.

BACKGROUND: Regional analgesia for labor often is initiated with an intrathecal injection of a local anesthetic and opioid. The purpose of this prospective, randomized, blinded study was to determine the optimal dose of intrathecal sufentanil when combined with 2.5 mg bupivacaine for labor analgesia. METHODS: One hundred seventy parous parturients with cervical dilation between 3-5 cm were randomized to receive intrathecal 0 (control), 2.5, 5.0, 7.5, or 10.0 microg sufentanil combined with 2.5 mg bupivacaine, followed by a lidocaine epidural test dose, for initiation of analgesia (34 patients in each group). Visual analog scores and the presence of nausea, vomiting, and pruritus were determined every 15 min until the patient requested additional analgesia. Fetal heart rate tracings were compared between groups. RESULTS: Groups were similar for age, height, weight, oxytocin dose, duration of labor, and baseline visual analog scores. Duration of action was significantly shorter for control patients (39 +/- 25 min [mean +/- SD]) compared with those administered sufentanil, all doses (93 +/- 32, 93 +/- 47, 94 +/- 33, 97 +/- 39 min), but was not different among groups administered 2.5, 5.0, 7.5, or 10.0 microg sufentanil. More patients who received 10 microg sufentanil reported nausea and vomiting than did control patients. The severity of pruritus increased with administration of 7.5 and 10.0 microg sufentanil. There was no difference in fetal heart rate changes among groups. CONCLUSIONS: Intrathecal bupivacaine (2.5 mg) without sufentanil did not provide satisfactory analgesia for parous patients. However, bupivacaine combined with 2.5 microg sufentanil provided analgesia comparable to higher doses, with a lower incidence of nausea and vomiting and less severe pruritus.