Neonatal monitoring after maternal fentanyl analgesia in labor.

Objective: To characterize different methods of monitoring neonatal effects associated with maternal opioid analgesia. Special focus was on the static-charge-sensitive bed (SCSB), which could potentially serve as a non-invasive neonatal monitor.
Methods: 12 healthy, term newborns from normal pregnancies were included in this prospective, randomized, controlled study. Maternal labor analgesia was either intravenous fentanyl (n = 5) or paracervical bupivacaine blockade (n = 7). Neonatal recording from delivery to the age of 12 hours included continuous SCSB monitoring with ECG and oximeter for sleep states, respiration, oxygenation, heart rate, and body movements. In addition, umbilical blood pH, Apgar, Amiel-Tison's Neurologic and Adaptive Capacity Scoring (NACS), skin cyanosis scoring, blood pressure, rectal and skin temperatures, and skin blood flow measurements were performed.
Results: The study was interrupted, because one baby in the fentanyl group had a significant decrease in oxyhemoglobin saturation (SpO2) to 59%. This was considcred to be residual effect of fentanyl and was treated with naloxone. SpO2 was generally lower in the fentanyl group. Epochs with SpO2 < 90% were more frequent in the fentanyl group, especially during active sleep (mean +/- SD 11.9 +/- 10.7% vs. 2.0 +/- 1.7% of epochs, p = 0.034). Mean heart rate values were lower in the fentanyl group (121.1 +/- 6.4 vs. 132.6 +/- 6.8 beats per minute, p = 0.02), and this difference was seen during wake and all sleep states. Maximum heart rate values were lower in the fentanyl group, too. The opiate group had less quiet sleep than controls (9.6 +/- 2.8% vs. 18.3 +/- 8.3%, p = 0.05). NACS after birth was lower in the fentanyl group (median [range] 15 [13-26] vs. 22 [20-25], p = 0.004).
Conclusions: Several differences were seen between the fentanyl and the control group babies. The SCSB method proved sensitive enough to find neonatal effects of maternal analgesia. Together with ECG and SpO2 monitoring, SCSB gives plentiful information on neonatal well-being in a non-invasive way. Results of this study emphasize the importance of neonatal monitoring after maternal opiate use in labor.