Time-dependent placental transfer of sevoflurane during cesarean delivery under general anesthesia: a prospective observational study.

BACKGROUND

General anesthesia for cesarean delivery requires balancing adequate maternal anesthetic depth against fetal drug exposure. The relationship between induction-to-delivery time, maternal anesthetic concentration, and fetal sevoflurane exposure remains incompletely characterized.

METHODS

In this prospective observational study, 16 women undergoing elective cesarean delivery under general anesthesia were enrolled. Paired maternal and umbilical blood samples were analyzed by headspace gas chromatography-mass spectrometry at delivery. Our primary investigation was the correlation between induction-to-delivery time and feto-maternal ratio.

RESULTS

Mean induction-to-delivery time was 3.3 ± 1.1 min (range 1.5-5.3). Mean feto-maternal ratio was 0.2 ± 0.16. Induction-to-delivery time correlated with feto-maternal ratio (P < 0.001). Each additional minute increased fetal exposure by 52%. Neither end-tidal concentration nor maternal blood sevoflurane levels predicted fetal blood concentrations. In exploratory analysis, fetal sevoflurane concentration showed no evidence of large effects on Apgar scores (r = -0.06, P = 0.830) or umbilical pH (r = 0.41, P = 0.110). All neonates achieved an Apgar score of at least 8 at 10 min; no acidosis occurred.

CONCLUSIONS

Induction-to-delivery time was strongly associated with fetal sevoflurane exposure. End-tidal monitoring reflects maternal anesthetic depth but does not predict fetal drug levels. Given the limited sample size, the clinical implications for neonatal outcomes remain uncertain. Minimizing induction to delivery time may reduce fetal exposure, but this requires confirmation in larger studies.