Continuous Epidural Infusions for Obstetric Analgesia

Abstract

A prospective study was conducted to assess the quality of analgesia provided by a continuous epidural infusion of 0.25% bupivacaine during labor and delivery. Ninety-seven consecutive parturients had a lumbar epidural catheter inserted, and 0.25% bupivacaine was infused by a volumetric infusion pump. The mean infusion rate was 25 mg/hr which produced a mean high sensory level of T8.7 (range T3 to T12). The bupivacaine infusion lasted a mean of 4.2 ± 0.3 hrs. (range 35 minutes to 16 hrs). Parturients rated the quality of epidural analgesia as satisfactory in 97% of the cases. No episodes of local anesthetic toxicity, tachyphylaxis, nor any neurological sequelae were noted. Twelve patients had transient hypotensive episodes during the course of the labor of which only one instance could be related to the bupivacaine infusion. In the series, 92 had 5 minute Apgar scores ⩾ 7. Plasma concentrations of the local anesthetic were determined at delivery in 13 parturients and in the newborns. The mean plasma concentrations were 0.76 μg/ml and 0.17 μg/ml, respectively, with a U/M ratio of 0.22. We conclude that the continuous epidural infusion technique utilizing a volumetric infusion pump is both technically feasible and practical for use in obstetrics. Furthermore, a marked saving in physicians9 time is accrued by elimination of the repetitive ‘top-up’ injections of local anesthetic.