Salivary Substance P Levels During Cesarean Section Under Spinal versus General Anesthesia: A Prospective Study

Substance P is a key neuropeptide involved in the transmission of nociceptive (pain) signals. The choice of anesthesia for childbirth, particularly for cesarean section (CS), is a critical decision that directly impacts the mother's physiological response to the procedure. This study aims to compare the levels of salivary SP in pregnant women undergoing CS under spinal versus general anesthesia.

Eighty-three patients participated in this prospective comparative study. They were categorized into two groups: general and spinal anesthesia groups. The primary outcome was to measure the mean difference in salivary substance P level at three different time points of CS, and to compare these values between both groups. The secondary outcome was to assess the factors affecting the substance P levels in the mothers.

The study included 44 (53%) who received spinal anesthesia and 39 (47%) who received general anesthesia. Median substance P levels were significantly higher in the spinal anesthesia group (761 pg/mL [IQR 532-1335]) compared with the general anesthesia group (409 pg/mL [IQR 118-1094]; U = 1188.0, p = 0.0026). On multiple regression analysis, type of anesthesia was the independent variable influenced the levels of salivary substance P.

This study demonstrates that participants receiving spinal anesthesia have significantly higher salivary substance P levels compared to those undergoing general anesthesia for CS. Further research is needed to understand the mechanisms underlying this observation and to determine its clinical implications for maternal and neonatal outcomes.