Regulation of maternal placental blood flow

Carter, Anthony Michael

doi:10.1016/s0143-4004(99)80021-6

Cited by 4 publications

(1 citation statement)

References 72 publications

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“…The concerns regarding hypotension raised by Papazova et al and van den Bosch et al are speculative and conflicting at best; the 'large body of evidence' for improved placental flow after EDA and for EDA being a treatment for placental insufficiency is hardly argumentative against the mechanism that we hypothesized. Placental perfusion is an understudied subject, but it is known that there is no physiological regulation for the lack of arteriolar vascular resistance 9 . The studies cited by these authors are of small populations, rather than large (randomized controlled) trials, and are beset by methodological issues, such as lack of correction for gestational age, maternal stature and body mass index, of which all affect maternal hemodynamics and warrant caution.…”

Section: Placental Perfusion and Hemodynamic Changesmentioning

confidence: 99%

Intrapartum epidural analgesia and emergency delivery for presumed fetal compromise: association or causation? Hypothesized mechanism explored

Heijtmeijer,

Damhuis,

Thilaganathan

et al. 2023

Ultrasound in Obstet & Gyne

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Section: Placental Perfusion and Hemodynamic Changesmentioning

confidence: 99%

Intrapartum epidural analgesia and emergency delivery for presumed fetal compromise: association or causation? Hypothesized mechanism explored

Heijtmeijer,

Damhuis,

Thilaganathan

et al. 2023

Ultrasound in Obstet & Gyne

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The Effects of Ephedrine and Phenylephrine on Placental Vascular Resistance During Cesarean Section Under Epidual Anesthesia

Guo

Qin

Qian

et al. 2015

Cell Biochem Biophys

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The purpose of this article is to study the effect of ephedrine and phenylephrine on placental vascular resistance during cesarean section under epidural anesthesia via Doppler ultrasonography. Sixty female subjects, scheduled for elective cesarean section and had an intrathecal injection of bupivacaine, were randomly divided into two groups to receive phenylephrine (50 μg/min) or ephedrine (4 mg/min) via titration to maintain systolic blood pressure at baseline. Doppler ultrasonography was used to measure baseline vascular resistance values prior to administration of anesthesia, and resistance index (RI) and systolic peak velocity/diastolic velocity (S/D) values of umbilical artery and uterine artery were measured at each time point within first 20 min following intrathecal injection. Blood samples were collected from umbilical artery and umbilical vein during delivery to assess the blood gas values. No significant differences in RI and S/D values of umbilical artery and uterine artery after intrathecal injection were found between two groups. RI and S/D values of uterine artery slightly increased in both groups at each time point after anesthesia, but remained within the normal range. No significant differences were observed in blood gas values and the total amount of vasoconstriction drugs between two groups. In contrast to previous reports that used animal models, our study did not show increased placental vascular resistance in patients following phenylephrine (50 μg/min) or ephedrine (4 mg/min) infusion, as well as no significant differences in the effect of either of these two. The discrepancy between the results of human and animal studies may be related to species differences and the mechanism of human placental vascular remodeling.

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