BACKGROUND:A meta-analysis of studies comparing high doses of bupivacaine with ropivacaine for labor pain found a higher incidence of forceps deliveries, motor block, and poorer neonatal outcome with bupivacaine. The purpose of this study was to determine if there is a difference in these outcomes when a low concentration of patient-controlled epidural bupivacaine combined with fentanyl is compared with ropivacaine combined with fentanyl.METHODS:This was a multicenter, randomized, controlled trial, including term, nulliparous women undergoing induction of labor. For the initiation of analgesia, patients were randomized to receive either 15 ml bupivacaine, 0.1%, or 15 ml ropivacaine, 0.1%, each with 5 microg/ml fentanyl. Analgesia was maintained with patient-controlled analgesia with either local anesthetic, 0.08%, with 2 microg/ml fentanyl. The primary outcome was the incidence of operative delivery. We also examined other obstetric, neonatal, and analgesic outcomes.RESULTS:There was no difference in the incidence of operative delivery between the two groups (148 of 276 bupivacaine recipients vs. 135 of 279 ropivacaine recipients; P = 0.25) or any obstetric or neonatal outcome. The incidence of motor block was significantly increased in the bupivacaine group compared with the ropivacaine group at 6 h (47 of 93 vs. 29 of 93, respectively; P = 0.006) and 10 h (29 of 47 vs. 16 of 41, respectively; P = 0.03) after injection. Satisfaction with mobility was higher with ropivacaine than with bupivacaine (mean +/- SD: 76 +/- 23 vs. 72 +/- 23, respectively; P = 0.013). Satisfaction for analgesia at delivery was higher for bupivacaine than for ropivacaine (mean +/- SD: 71 +/- 25 vs. 66 +/- 26, respectively; P = 0.037).CONCLUSIONS:There was no difference in the incidence of operative delivery or neonatal outcome among nulliparous patients who received low concentrations of bupivacaine or ropivacaine for labor analgesia.

Anesthesiologists have ever increasing access to electronic information about anesthesia and obstetric outcomes. Information is placed on databases for many reasons including: (1) generation of administrative reports, (2) quality improvement review, (3) research projects, (4) hypothesis generation, and (5) as a source of pilot data to support a grant application or research proposal. Institutional Review Board (IRB) approved randomized controlled trials provide valid causation data concerning the questions explored in studies. Studies based on database information collected for another purpose are retrospective and subject to all the limitations of retrospective studies. In particular, retrospective studies can show association but cannot support, or refute, causation. The main research value of retrospective studies is as a source of pilot data for hypothesis generation. To highlight these points, let us examine the use of databases in two of the major obstetric anesthesia controversies of the last decade and then explore how databases might be used in the future.

A randomized, double-blind study was undertaken comparing an epidural test dose of lidocaine followed by 100 mu g fentanyl (E-LE, n = 19) to combined spinal epidural sufentanil 10 mu g (CSE-S, n = 21) in low risk women in early labour. The primary outcome measured was the duration of analgesia; secondary outcomes included the quality of analgesia, incidence and severity of pruritus, lower limb motor blockade, and the ability to ambulate. A P <0.05 was considered statistically significant, Baseline demographic characteristics, including parity, were similar between groups. CSE-S provided analgesia of longer duration than E-LF (126 +/- 61 min versus 83 +/- 37 min, P <0.01). Visual analog scores (VAS) for pain were higher with E-LF throughout the study period (P <0.05) although patients in both groups had clinically acceptable analgesia. The VAS for pruritus were higher ill the CSE-S group (P <0.05) but no patient requested treatment for pruritus. Mild motor weakness was more frequent in the E-LF group (5/19 versus 0/21, P <0.05) and fewer patients in the E-LF group met criteria for ambulation (13/19 versus 20/21, P <0.05). While both E-LF and CSE-S provide effective analgesia for women in early labour, the more rapid onset of analgesia, lower VAS pain scores, longer duration of action and lesser impact on ability to ambulate suggest advantages of CSE-S over E-LE (C) 1999 Harcourt Publishers Ltd.

Magnesium sulphate is not an effective tocolytic. Magnesium sulphate therapy was also linked to preterm neonatal deaths in one study, which was stopped before completion. Other studies suggest a possible neuroprotective effect of magnesium. Both of these issues require further study. Magnesium sulphate is clearly the drug of choice to prevent recurrent eclampsia and to treat severe pre-eclampsia.

Previous studies have shown that bolus doses of fentanyl (50 and 100 micro gram) with epidural bupivacaine delay gastric emptying by up to 45 min.We studied the effect of the addition of small-dose fentanyl to epidural bupivacaine infusions on gastric emptying during labor. The acetaminophen absorption technique was used to infer gastric emptying. Twenty-eight patients in established labor consented to participate in the study. They were randomized to receive either 1) 10 mL bupivacaine 0.125% followed by an infusion of 0.125% bupivacaine at 10 mL/h or 2) 10 mL bupivacaine 0.125% with 50 micro gram fentanyl followed by an infusion of 0.125% bupivacaine and 0.0002% fentanyl at 10 mL/h. Two hours after initiation of epidural analgesia, each patient ingested 20 mg/kg acetaminophen in a suspension of 150 mL water. Venous blood samples were drawn for a baseline and then every 15 min for 2 1/2 h. There were no significant demographic differences between the groups. There were no differences detected between groups in the peak plasma concentrations of acetaminophen, the time to achieve the peak plasma concentrations, or the area under the curve at 45 and 90 min. Our results indicate that epidural infusions for labor analgesia using 0.125% bupivacaine and 0.0002% fentanyl do not delay gastric emptying compared to infusions of bupivacaine 0.125% alone. (Anesth Analg 1996;82:612-6)

Natural History of Postpartum Back Pain and Its Relationship with Epidural Anesthesia P. Groves;T. Breen;B. Ransil;N. Oriol; Anesthesiology