Mode of anaesthesia on fetal acid-base status at caesarean section.

OBJECTIVE

To study fetal acid-base status and its implications under different modes of anaesthesia for caesarean sections.

METHODS

A prospective cohort study was conducted of 196 consecutive women with singleton non-anomalous fetuses who underwent either elective or emergency caesarean section after 36 completed weeks. Immediately after the baby was delivered, blood was drawn from the umbilical vein and one of the umbilical arteries and sent in ice for acid-base analysis. Maternal demographics, pre-existing medical conditions and antenatal complications were retrieved from antenatal records. Apgar scores and admissions to neonatal intensive care units (NICUs) were noted.

RESULTS

Six women were excluded from analysis because the umbilical venous blood was either not collected or clotted. Another two were excluded because of placental abruption. The number of subjects that received spinal, epidural and general anaesthesia were 134, 36 and 18, respectively. Apgar scores were higher in spinal anaesthesia and epidural anaesthesia group (P<0.01). General anaesthesia was associated with a higher incidence of fetal acidaemia, both in the umbilical artery and vein. Spinal anaesthesia was associated with the highest pH in umbilical venous blood. Base excess in umbilical venous samples was highest in the spinal anaesthesia group (P=0.006), although pH values were similar for the three groups. There was no difference in admissions to NICU.

CONCLUSIONS

This study provided evidence of the advantages of spinal anaesthesia over epidural and general anaesthesia. Our findings are in contrast with recent evidence in the literature.