Adding fentanyl 0.0002% to epidural bupivacaine 0.125% does not delay gastric emptying in laboring parturients

Previous studies have shown that bolus doses of fentanyl (50 and 100 micrograms) 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 micrograms 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.