Retrospective study of the effect of remifentanil use during labor on fetal heart rate patterns

Objective: To investigate possible associations between remifentanil and the appearance of sinusoidal heart rate patterns in fetuses, and neonatal outcomes.

Methods: The present retrospective cohort study included data from patients at over 37 weeks of singleton or multiple pregnancies attending Zuyderland Medical Center, Sittard, the Netherlands, in labor between June 1, and August 31, 2015. Patient data were stratified by whether remifentanil was administered during delivery (remifentanil group) or not (control group), and fetal heart rate tracings were reviewed to identify sinusoidal heart rate patterns. The neonatal outcomes compared were 5-minute Apgar scores and umbilical artery pH.

Results: There were 119 patients included in the study; 60 in the remifentanil group and 59 in the control group. Tracings from 20 (33%) patients in the remifentanil group exhibited a sinusoidal heart rate pattern after remifentanil administration, compared with 5 (8%) patients in the control group (P=0.001). The median time before the onset of sinusoidal patterns after remifentanil administration was 12 minutes. No adverse neonatal outcomes were recorded in either group.

Conclusion: Remifentanil use during labor was associated with the occurrence of sinusoidal heart rate patterns in the fetus; this was not associated with adverse neonatal outcomes.