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Updated: Aug 17, 2026

Instrumentation of Near-term Fetal Sheep for Multivariate Chronic Non-anesthetized Recordings
Published on: October 25, 2015
Predicting prolonged fetal heart rate deceleration following intrathecal fentanyl/bupivacaine
R R Gaiser1, M McHugh, T G Cheek
1Department of Anesthesia, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA. gaiserr@uphs.upenn.edu
Background:
Intrathecal opioids for labor analgesia are occasionally associated with fetal heart rate abnormalities. We wanted to identify risk factors for this occurrence.
Methods:
The fetal tracings of 151 consecutive patients were reviewed for the period including 30 min before and 60 min after combined spinal-epidural analgesia using intrathecal bupivacaine with fentanyl. Their progress of labor at injection was also recorded.
Results:
Lack of fetal head engagement (odds ratio 5.5, 95% CI 2.1-14.2) and the presence of variable fetal heart rate decelerations (odds ratio 3.6, 95% CI 1.6-8.4) were associated with prolonged fetal heart rate deceleration after combined spinal-epidural analgesia.
Conclusion:
This case-control study suggests that if the fetal head is not engaged or if the fetus is experiencing variable decelerations, there is an increased risk of prolonged fetal heart rate deceleration following intrathecal fentanyl/bupivacaine. This finding must now be confirmed in a cohort study.
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