Spinal anesthesia is the technique of choice for planned cesarean section. It is associated with a high frequency of maternal hypotension. Hyperactivity of the sympathetic system assessed with the LF/HF ratio (heart rate variability analysis) predicts the severity of maternal hypotension after spinal anesthesia. Increased LF/HF ratio may be explained by maternal stress that can be measured with salivary amylase. The goal of this study is to assess the relationship between salivary amylase and severity of maternal hypotension after spinal anesthesia for planned cesarean section.

Salivary amylase, heart rate variability, Spielberger state-trait inventory are assessed on the morning of surgery, on the surgical ward, and repeated in the operating room, before performing spinal anesthesia. Spinal anesthesia use hyperbaric bupivacaine (11 mg), sufentanil (5 µg) and morphine (100 µg). Prophylactic treatment of hypotension uses a continuous infusion of ephedrine (0.6 mg/ml) and phenylephrine (10 µg/ml). Rate of the continuous infusion is adapted to keep maternal systolic blood pressure between 95-105% of preinduction values. Total dose of ephedrine and phenylephrine infused from spinal anesthesia to delivery of the newborn is recorded (about 20 minutes for the estimated time frame). Association between stress markers and total dose of vasoactive drugs will be tested with the Spearman's correlation coefficient.

The study is observational. The subjects do receive a therapeutic intervention but the investigator does not assign patients to this intervention since this intervention is a routine care (spinal anesthesia for planned cesarian section) that would have been performed in the absence of the study.

Pregnant women undergoing planned cesarean section under spinal anesthesia

Pregnant women undergoing planned cesarean section