The Effects of Epidural Opioids on Fetal Heart Rate Variability when Coadministered with 0.25% Bupivacaine for Labor Analgesia

ABSTRACT

Assessment of fetal heart rate (FHR) variability provides important information regarding fetal well-being. Normal FHR variability is generally associated with fetal normoxia. Opioids are frequently coadministered with local anesthetics to provide epidural analgesia for labor. Epidural opioid effects on FHR variability have not been extensively studied. In a double-blind, randomized study, 109 parturients had their epidural catheter injected with either butorphanol (2 mg), fentanyl (50 μg), sufentanil (15 μg) or saline and bupivacaine (0.25%). FHR tracings of 30 min duration were obtained both before and after epidural analgesia. Each of the 218 tracings was randomly numbered and later graded by the same individual for short- and long-term variability. The two 30-min tracings for each patient were then paired but not ordered as to which tracing was “pre-epidural” or “postepidural” and again compared for change in short-and long-term variability between the paired tracings. The paired tracings were then ordered as “pre-epidural” or “postepidural.” A designation was made whether long-term variability was increased, decreased, or stayed the same after induction of epidural analgesia. Short-term variability was initially present in all patients. There were no changes in short-term variability after induction of epidural analgesia. There was no difference in long-term variability in any group receiving opioids as compared to control. There was no difference in the change in long-term variability after induction of epidural analgesia. The addition of butorphanol, fentanyl, or sufentanil to epidural bupivacaine (0.25%) does not change FHR short- or long-term variability.

Keywords

Anesthetic techniques - epidural - anesthesia - obstetric - analgesics - opioid - butorphanol - fentanyl - sufentanil