Does Intrathecal Sufentanil Really Cause More Episodes of Fetal Bradycardia?

In Response: We thank Dr. Lee for his interest and comments on our article. We acknowledge that epinephrine absorbed from the epidural and spinal space exerts inhibitory effects on the myometrium (1,2). Theoretically, this may have introduced bias in our study because no epinephrine was present in the intrathecal sufentanil alone group. However, we feel this is highly unlikely based on the doses of epinephrine used and the timeframe in which uterine hyperactivity occurred following intrathecal sufentanil. Especially in the group in which spinal sufentanil, bupivacaine, and epinephrine were combined, the epinephrine dose was only 2.5 μg. Vercauteren et al. (3) showed no effects on progress of labor and labor outcome in patients with intrathecal epinephrine in this dose. Moreover, most of the problems of uterine hyperactivity and nonreassuring fetal heart rate developed within the first 30 minutes (although we recorded for a longer period). This is also what has been described in the initial reports (4). We question that absorption from the spinal and epidural space occurred that rapidly to induce uterine relaxation in the two groups in which epinephrine was added. Sufentanil is only detected in maternal plasma after more then 30 minutes following an intrathecal injection (5). We chose these three groups for our study since they were also the drugs we were using in day-to-day clinical practice. We had retrospective data that intrathecal sufentanil caused more problems then both other combinations (6). So drug selection was partly based on our clinical experience. If indeed epinephrine absorption prevented uterine hypertonicity following spinal analgesia, this remains an important finding, as this is of clinical benefit to the patient. Epinephrine then protects uteroplacental blood flow and improves the quality of analgesia and the duration of spinal analgesia (3). Marc Van de Velde, MD, PhD Department of Anesthesiology University Hospital Leuven Leuven, Belgium [email protected]