The dose-response of intrathecal sufentanil added to bupivacaine for laboranalgesia

Background: Regional analgesia for labor often is initiated with an intrath ecal injection of a local anesthetic and opioid. The purpose of this prospe ctive, randomized, blinded study was to determine the optimal dose of intra thecal sufentanil when combined with 2.5 mg bupivacaine for labor analgesia . Methods: One hundred seventy parous parturients with cervical dilation betw een 3-5 cm were randomized to receive intrathecal 0 (control), 2.5, 5.0, 7. 5, or 10.0 mu g sufentanil combined with 2.5 mg bupivacaine, followed by a lidocaine epidural test dose, for initiation of analgesia (34 patients in e ach group). Visual analog scores and the presence of nausea, vomiting, and pruritus were determined every 15 min until the patient requested additiona l analgesia. Fetal heart rate tracings were compared between groups. Results: Groups were similar for age, height, weight, oxytocin dose, durati on of labor, and baseline visual analog scores. Duration of action was sign ificantly shorter for control patients (39 +/- 25 min [mean +/- SD]) compar ed 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 mu g sufentanil. More patients who received 10.0 mu g s ufentanil reported nausea and vomiting than did control patients. The sever ity of pruritus increased with administration of 7.5 and 10.0 pg sufentanil . There was no difference in fetal heart rate changes among groups. Conclusions Intrathecal bupivacaine (2.5 mg) without sufentanil did not pro vide satisfactory analgesia for parous patients. However, bupivacaine combi ned with 2.5 mu g sufentanil provided analgesia comparable to higher doses, with a lower Incidence of nac-sea and vomiting and less severe pruritus.