Effects of Spinal Anesthesia on the Fetal Autonomic Nervous System

Evaluation of the Impact of Spinal Anesthesia on the Fetal Autonomic Nervous System During an Elective Caesarean Delivery

Elective cesarean deliveries account for over 10% of births in France and are often scheduled around 39 weeks of gestation. When feasible, spinal anesthesia is considered the gold standard in such a clinical situation. However, a well-known complication is maternal hypotension, which may lead to placental hypoperfusion and fetal acidosis. Heart rate variability (HRV) markers reflect autonomic nervous system (ANS) activity, which plays a key role in maintaining fetal homeostasis.

The Lille University Hospital has developed a technology to assess parasympathetic activity through HRV analysis. This technology has been adapted to obtain an HRV markers specific of the fetal autonomic nervous system assessment: the Fetal Stress Index (FSI). Preclinical studies have shown that FSI correlates with parasympathetic fluctuations and fetal acidosis.

This pilot study aims to evaluate the impact of spinal anesthesia on fetal ANS activity during elective cesarean delivery using a continuous beat-to-beat fetal heart rate recording device: the TOCONAUTE device. FSI will be retrospectively computed to assess fetal autonomic response. Maternal ANS activity will also be monitored using the Analgesia Nociception Index (ANI). A secondary objective is to explore the predictive value of ANI and FSI for maternal hypotension or fetal hypoxia.

Inclusion Criteria:

• Pregnant woman scheduled for elective cesarean delivery
• Age: over 18 and under 45 years
• Gestational age ≥ 37 weeks of amenorrhea
• Singleton pregnancy
• Proficient in the French language
• Participant has provided written informed consent to take part in the study
• Affiliated with a national health insurance scheme

Exclusion Criteria:

• Requirement for general anesthesia or combined epidural-spinal analgesia
• Fetal malformation
• Intrauterine fetal demise
• Maternal and/or fetal cardiac rhythm disorders
• History of heart transplantation
• Open wound in an area covered or enclosed by one of the study devices
• Risk of viral or infectious contamination of any component of the device
• Hospitalization for medical termination of pregnancy
• Sensory disorders resulting in lack of pain perception on the skin
• Ongoing treatment that may alter autonomic nervous system activity (e.g., beta-blockers, anticholinergics, atropine)
• Participant with an implanted medical device (e.g., pacemaker)
• Known allergy to any component of the devices: polyamide, polyester, elastane, silver, or other synthetic materials
• Participant whose anatomical area intended for ClearSight sensor placement is insufficient to allow proper application
• Concurrent participation in another interventional research study