Cardiac output changes with phenylephrine and ephedrine infusions during spinal anesthesia for cesarean section: A randomized, double-blind trial.

Hypotension is a common side effect of spinal anesthesia. Phenylephrine and ephedrine are the two most frequently used vasopressors to treat spinal hypotension during cesarean delivery. In this randomized double-blind study, we aimed to evaluate cardiac output (CO) changes with phenylephrine or ephedrine infusions titrated to maintain baseline systolic blood pressure (bSBP) during spinal anesthesia. Women (n = 40) scheduled for elective cesarean delivery received either phenylephrine 100 µg/min or ephedrine 5 mg/min infusions. Baseline hemodynamics (cardiac output, heart rate, systolic blood pressure) were recorded in the left lateral tilt position before fluid preload, and recorded every minute after spinal anesthesia until delivery. Umbilical cord blood gases were analyzed within 5 minutes of delivery. Good systolic blood pressure control was attained in both groups with minimal periods of hypotension (SBP <80% of bSBP) or hypertension (SBP >120% of bSBP). Cardiac output and heart rate increased over time with ephedrine, but decreased with phenylephrine. The maximum increase in CO from the baseline was 12%, in the ephedrine group, and this occurred 20 minutes after spinal injection. Cardiac output fell by more than 17% in the phenylephrine group, maximal at 10 minutes following spinal injection. Despite good systolic blood pressure control and increased cardiac output with ephedrine, administration of ephedrine was associated with significantly more fetal acidosis [Median (Interquartile range, IQR) UApH - phenylephrine = 7.33 (7.31-7.34) and ephedrine = 7.22 (7.16-7.27), P < .05].

Fetal effects of combined spinal-epidural vs epidural labour analgesia: a prospective, randomised double-blind study.

We have compared fetal heart rate patterns, Apgar scores and umbilical cord gas values following initiation of labour analgesia using either combined spinal-epidural or epidural. One hundred and fifteen healthy women requesting neuraxial analgesia in the first stage of labour were randomly assigned to receive either combined spinal-epidural (n = 62) or epidural analgesia (n = 53). Fetal heart rate traces, recorded for 30 min before and 60 min after neuraxial block, were categorised as normal, suspicious or pathological according to national guidelines. Sixty-one fetal heart rate tracings were analysed in the combined spinal-epidural group and 52 in the epidural group. No significant differences were found in fetal heart rate patterns, Apgar scores or umbilical artery and vein acid-base status between groups. However, in both combined spinal-epidural and epidural groups, there was a significant increase in the incidence of abnormal fetal heart rate patterns following neuraxial analgesia (p < 0.0001); two before compared with eight after analgesia in the combined spinal-epidural group and zero before compared with 11 after in the epidural group. These changes comprised increased decelerations (p = 0.0045) (combined spinal-epidural group nine before and 14 after analgesia, epidural group four before and 16 after), increased late decelerations (p < 0.0001) (combined spinal-epidural group zero before and seven after analgesia, epidural group zero before and eight after), and a reduction in acceleration rate (p = 0.034) (combined spinal-epidural group mean (SD) 12.2 (6.7) h(-1) before and 9.9 (6.1) h(-1) after analgesia, epidural group 11.0 (7.3) h(-1) before and 8.4 (5.9) h(-1) after). These fetal heart rate changes did not affect neonatal outcome in this healthy population.