The Effects of Adding Isoproterenol to 0.125% Bupivacaine on the Quality and Duration of Epidural Analgesia in Laboring Parturients

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Abstract
This study was conducted to determine the effects of adding isoproterenol to epidural bupivacaine and sufentanil on the quality and duration of analgesia during labor.In a double blind, randomized study, 80 women were divided into two groups, receiving three doses of 0.125% bupivacaine with 7.5 [micro sign]g of sufentanil and either 12.5 [micro sign]g of epinephrine (EPI group) or 5 [micro sign]g of isoproterenol (ISO group). Contraction pain was measured using a 100-mm visual analog scale (VAS) before epidural analgesia, at 5-min intervals for 15 min after each epidural injection, and hourly thereafter. Overall, no significant differences were observed in VAS scores between the groups. However, in the ISO group, VAS scores at 10 and 15 min after the first and second administration were significantly lower than those in the EPI group. Analgesia after each administration lasted significantly longer in patients who received epinephrine. Because of the limited duration of analgesia in the ISO group, more patients in this group received a fourth epidural administration of 0.125% bupivacaine with epinephrine 1:800,000. In conclusion, the addition of isoproterenol to bupivacaine and sufentanil induces a faster onset of analgesia and reduces the duration of analgesia compared with bupivacaine with sufentanil and epinephrine. Therefore, it is preferable to use isoproterenol only once, as a test dose, after the placement of the epidural catheter. Implications: We analyzed the quality and duration of analgesia in laboring women after they received bupivacaine and sufentanil combined with isoproterenol or epinephrine epidurally. We found that the addition of isoproterenol to bupivacaine and sufentanil induces a faster onset of analgesia and reduces the duration of analgesia. (Anesth Analg 1998;86:749-52)