Authors: Allison J. Lee, M.D. et
Anesthesiology 8 2017, Vol.127, 241-249
Background: Current recommendations for women undergoing cesarean delivery include 15° left tilt for uterine displacement to prevent aortocaval compression, although this degree of tilt is practically never achieved. We hypothesized that under contemporary clinical practice, including a crystalloid coload and phenylephrine infusion targeted at maintaining baseline systolic blood pressure, there would be no effect of maternal position on neonatal acid base status in women undergoing elective cesarean delivery with spinal anesthesia.
Methods: Healthy women undergoing elective cesarean delivery were randomized (nonblinded) to supine horizontal (supine, n = 50) or 15° left tilt of the surgical table (tilt, n = 50) after spinal anesthesia (hyperbaric bupivacaine 12 mg, fentanyl 15 μg, preservative-free morphine 150 μg). Lactated Ringer’s 10 ml/kg and a phenylephrine infusion titrated to 100% baseline systolic blood pressure were initiated with intrathecal injection. The primary outcome was umbilical artery base excess.
Results: There were no differences in umbilical artery base excess or pH between groups. The mean umbilical artery base excess (± SD) was −0.5 mM (± 1.6) in the supine group (n = 50) versus −0.6 mM (± 1.5) in the tilt group (n = 47) (P = 0.64). During 15 min after spinal anesthesia, mean phenylephrine requirement was greater (P = 0.002), and mean cardiac output was lower (P = 0.014) in the supine group.
Conclusions: Maternal supine position during elective cesarean delivery with spinal anesthesia in healthy term women does not impair neonatal acid–base status compared to 15° left tilt, when maternal systolic blood pressure is maintained with a coload and phenylephrine infusion. These findings may not be generalized to emergency situations or nonreassuring fetal status.
What We Already Know about This Topic
It is ubiquitous obstetric anesthesia practice to implement left lateral uterine displacement in all women during cesarean delivery
It is not known whether after spinal anesthesia in pregnant women, a fluid load, and a phenylephrine infusion to maintain baseline blood pressure can substitute for left lateral uterine displacement
What This Article Tells Us That Is New
In healthy term pregnant women undergoing elective cesarean delivery after spinal anesthesia, with a crystalloid coload and prophylactic phenylephrine infusion, supine horizontal position or 15° left tilt of the surgical table (in a randomized protocol) had no effect on umbilical artery base excess
When maternal systolic blood pressure was maintained with fluid and phenylephrine, there was no apparent benefit to left lateral uterine displacement during cesarean delivery