The effects of spinal anaesthesia for elective caesarean section on uterine and umbilical arterial pulsatility indexes in normotensive and chronic hypertensive pregnant women: a prospective, longitudinal study

Abstract

BackgroundDespite the known effects of neuraxial blockade on major vessel function and the rapid decrease in uterine vascular impedance, it is unclear how the blockade affects the utero-placental circulation in the near-term. We hypothesize that among women with chronic hypertension, a loss of sympathetic tonus consequent to spinal block may cause significant changes in the utero-placental haemodynamics than the changes typical in normal pregnant women. Therefore, the main study objective was to analyse the effect of spinal anaesthesia for caesarean section on uterine and umbilical arterial impedance in pregnant women at term diagnosed with stage-1 chronic hypertension.MethodsA prospective, longitudinal study was performed in singleton pregnant women (203 low-risk and 33 with hypertension) scheduled to undergo elective caesarean section. The mean arterial blood pressure and pulsatility indexes for the uterine and umbilical arteries were recorded before and after spinal anaesthesia was performed using 8–9 mg hyperbaric bupivacaine (5 mg/mL) and 2–2.5 μg sufentanil (5 μg/mL). Multiple linear regression models with errors capable of correlation or with unequal variances were fitted using the generalized least squares.ResultsIn normotensive women, the mean arterial blood pressure decreased after administering spinal anaesthesia (p < 0.05). The pulsatility index of the uterine and umbilical arteries did not change after spinal anaesthesia. In the hypertensive women, the mean arterial blood pressure (p < 0.05) and uterine artery pulsatility index (p < 0.05) decreased. In both groups, the umbilical artery pulsatility index did not change after spinal anaesthesia.ConclusionsIn stage-1 chronic hypertensive pregnant women at term, spinal anaesthesia for caesarean section reduces uterine artery impedance but not umbilical artery impedance.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2393-14-291) contains supplementary material, which is available to authorized users.

Blood pressure and cardiac output during caesarean delivery under spinal anaesthesia: a prospective cohort study

“…They found a decrease in MAP after spinal anaesthesia in both study groups, while the fetal circulatory parameters were unchanged. Their results are in contrast to our findings of a small increase in blood pressure, but may be explained by the fact that Guedes-Martins et al 16 did not infuse a vasoconstrictor to avoid spinal anaesthesia-induced hypotension. Their study supports that vasoconstrictor prophylaxis is necessary to avoid maternal hypotension.…”

“…It is not clear whether the participating women were positioned in a left lateral tilt position, the authors did not use invasive monitoring, and it is difficult to compare the results to our study. In line with the findings of Lato et al , 15 Guedes-Martins et al 16 found that spinal anaesthesia induced hypotension at caesarean section, but that hypotension was not associated with altered pulsatility indices in the uterine or umbilical arteries.…”

“…Guedes-Martins et al 16 examined blood pressure and uterine and umbilical artery pulsatility indices before and after spinal anaesthesia in normotensive and hypertensive women without pre-eclampsia. They found a decrease in MAP after spinal anaesthesia in both study groups, while the fetal circulatory parameters were unchanged.…”

Reference Curve for the Mean Uterine Artery Pulsatility Index in Singleton Pregnancies

“…In women with a low risk of developing preeclampsia, increased uterine artery PI with notching was the best predictor of overall risk (sensitivity 23 %, specificity 99 %, positive likelihood ratio Other factors apart from trophoblast invasion also influence uterine blood flow. Additional factors include physical activity [16], local anesthesia [17] but also the location of the placenta [18].…”

Comparison of efficacy and safety of preemptive infusion protocols of ephedrine and phenylephrine - prevention of hypotension and effects on hemodynamic parameters during spinal anesthesia for caesarean section

“…Hypotension occurs within approximately 70-80% of cases as a consequence of sympathetic blockade in the affected areas of anesthesia, which might cause organ and placental hypoperfusion. Acute hypotension reduces cerebral perfusion, which leads to transient ischemia and activates the vomiting center [3][4][5][6]. Fall in CO reduces oxygen delivery to organs and tissues, results in buildup of oxygen debt, causing complications after SA [7,8,9].…”