Cerebral Artery Pulsatility Index Ratio Research Articles

Perinatal and 2-year neurodevelopmental outcome in late preterm fetal compromise: the TRUFFLE 2 randomised trial protocol

IntroductionFollowing the detection of fetal growth restriction, there is no consensus about the criteria that should trigger delivery in the late preterm period. The consequences of inappropriate early or late...

Prognostic value of umbilical-middle cerebral artery pulsatility index ratio in fetuses with growth restriction

Objective: To study the utility of Doppler velocimetry and computerized cardiotocography in the management of intrauterine growth restriction and prediction of neonatal outcome. Patients and methods: Seventy-two pregnant women with fetuses showing growth restriction and delivered within 48 h of their last Doppler velocimetry evaluation. The last computerized cardiotocographic trace from these fetuses was used for statistical analysis, and the last trace from the healthy fetuses of 93 consecutive women undergoing cesarean section was used as control. Umbilical artery pulsatility index (UA PI), middle cerebral artery pulsatility index (MCA PI), UA PI / MCA PI ratio, and uterine artery resistance index (Ut RI) were assessed. Results: Among women with growth-restricted fetuses, all parameters were significantly higher in those who had hypertension; and in those who had diabetes, only the UA PI / MCA ratio was significantly higher. Umbilical artery PI values and the UA PI / MCA ratio were higher in those who had a nonreassuring result to computerized nonstress test immediately before delivery. A multiple logistic analysis showed that the UA PI / MCA ratio was the only Doppler velocimetry parameter predicting cardiotocographic nonreactivity; furthermore, the predictivity of extended newborn hospitalization (longer than 15 days) was verified, with a sensitivity of 56% and a specificity of 92% when the ratio was higher than 1.26. Conclusion: The MCA PI of fetuses with growth restriction should be assessed. The UA PI / MCA ratio is predictive of a nonreactive computerized cardiotocography trace and of prolonged neonatal hospitalization.

External cephalic version induced fetal cerebral and umbilical blood flow changes are related to the amount of pressure exerted.

To correlate the applied pressure during external cephalic version with the changes in fetal middle cerebral arterial and umbilical arterial flow before and after the procedure. A prospective observational study over a two-year period. External cephalic version was performed in a university hospital. Sixty-nine women with singleton breech-presenting pregnancy at or above 36 weeks of gestation undergoing external cephalic version. During external cephalic version, the operator wore a pair of pressure-sensing gloves which had thin piezo-resistive sensors positioned on the palmar surface. During each version procedure, real-time pressure readings were recorded from all sensors, and then analysed with a computer program. The amount of pressure applied over time was presented by pressure-time integral. The pulsatility indices of both fetal middle cerebral artery and umbilical artery before and after external cephalic version were measured. The changes of pulsatility indices of both middle cerebral artery and umbilical artery were presented as a ratio of the post-external cephalic version pulsatility indices to pre-external cephalic version pulsatility indices, denoted by middle cerebral artery pulsatility index ratio and umbilical artery pulsatility index ratio, respectively. The statistical correlation between pressure-time integral and middle cerebral artery pulsatility index ratio and umbilical artery pulsatility index ratio are analysed using Pearson's correlation test. Changes in pulsatility indices of fetal middle cerebral and umbilical arteries and fetal heart rate after external cephalic version. The overall success rate of external cephalic version was 77%. There was a significant negative correlation between pressure-time integral and both middle cerebral artery pulsatility index ratio (P= 0.001) and umbilical artery pulsatility index ratio (P= 0.012). When women were categorised according to placental site, pressure-time integral was negatively correlated with middle cerebral artery pulsatility index ratio only when the placenta was posteriorly located (P= 0.003), and with umbilical artery pulsatility index ratio only when the placenta was laterally located (P= 0.03). The greater the force applied during external cephalic version, the greater the reduction in pulsatility indices of middle cerebral artery and umbilical artery, indicating an increase in blood flow through these arteries. The increase in cerebral blood flow after external cephalic version is more prominent when the placenta is lying posteriorly, while the increase in umbilical flow is more prominent when the placenta is lying laterally. These findings suggest that the vascular changes probably represent a direct effect of force exerted on the fetal head and the placenta.

Circulating S100beta protein is increased in intrauterine growth-retarded fetuses.

To determine whether S100beta, an acidic calcium-binding protein previously demonstrated as a reliable indicator of a brain lesion, could be helpful in the detection of brain distress in intrauterine growth-retarded (IUGR) fetuses, we studied, by a case-control study, the correlation between S100B protein and the degree of fetoplacental blood flow impairment. Maternal and umbilical blood samples and placental tissue specimens were collected at delivery from IUGR pregnancies with normal (n = 10) or abnormal (n = 10) umbilical artery Doppler findings and from 40 uncomplicated pregnancies. S100beta protein levels were measured by means of a specific RIA, and flow velocimetry waveforms were recorded from uterine, umbilical, and fetal middle cerebral arteries. Overall mean S100beta proteins in umbilical plasma levels were higher (p < 0.05) in IUGR patients (121.8 +/- 70.4 fmol/mL) than in control patients (54.7 +/- 21.9 fmol/mL). IUGR fetuses with redistribution of blood flow showed the higher concentration of the protein (163.7 +/- 55.2 fmol/mL). Fetal S100beta concentrations correlated with middle cerebral artery pulsatility index (r = -0.536, p < 0.03) and with umbilical artery pulsatility index to middle cerebral artery pulsatility index ratio (r = 0.469, p < 0.03). No difference in the localization or intensity of S100beta staining in the placental tissues or cord between uncomplicated and IUGR pregnancies was found. This study provides evidence that circulating S100beta protein is increased in IUGR fetuses and correlates with cerebral hemodynamics, suggesting that it may represent an index of cerebral cell damage in the perinatal period.

Adrenomedullin is increased in the fetoplacental circulation in intrauterine growth restriction with abnormal umbilical artery waveforms

Objective:To examine whether adrenomedullin, a novel vasoactive peptide produced by the placenta, participates in the uteroplacental hemodynamic alterations in intrauterine growth restriction, we studied the correlation between adrenomedullin levels and fetoplacental blood flow. Study Design:Maternal and umbilical blood samples were collected in pregnancies complicated by intrauterine growth restriction with abnormal umbilical artery Doppler findings and in control pregnancies. Adrenomedullin levels were measured by means of a specific radioimmuncassay, and flow velocimetry wave-forms were recorded from uterine, umbilical, and fetal middle cerebral arteries. Results:Mean adrenomedullin values in umbilical plasma were higher (P < .05) in patients with intrauterine growth restriction (63.7 ± 34.2 pg/mL; n = 16) than in control subjects (38.1 ± 14.8 pg/mL; n = 16). A significant correlation was found between maternal adrenomedullin levels and umbilical artery pulsatility index. Moreover, fetal adrenomedullin concentrations correlated negatively with middle cerebral artery pulsatility index and positively with umbilical artery pulsatility index/middle cerebral artery pulsatility index ratio. Conclusions:This study provides evidence that adrenomedullin is increased in fetuses with intrauterine growth restriction in response to reduced uteroplacental blood flow and suggests that it may participate in the fetal hemodynamic modifications.

Amniotic fluid nitric oxide and uteroplacental blood flow in pregnancy complicated by intrauterine growth retardation.

To examine the correlation between placental nitric oxide production and uteroplacental blood flow. Thirty-one pregnant women with fetuses with intrauterine growth retardation and 27 normal pregnancies as controls. Correlation between amniotic fluid measurements of nitrite metabolite in the third trimester and flow velocimetry waveforms recorded from uterine, umbilical and fetal middle cerebral arteries. Intrauterine growth retarded pregnancies were compared with controls. Concentrations of nitric oxide metabolites (NO2- and NO3-) in amniotic fluid were correlated with flow velocimetry waveforms findings by the determination of correlation coefficient. Overall median nitrite values in amniotic fluid were higher (P < 0.01) in intrauterine growth retarded patients (median 8.6 micromol/mg creatinine) than in controls (5.6 micromol/mg creatinine). Pathologic uterine flow velocimetry waveforms in uterine artery (-2SD) were observed in 12 women of the intrauterine growth retarded group, and the concentration of amniotic fluid nitrite was significantly lower (P < 0.01) in these patients (median 4.45 micromol/mg creatinine) than in those with normal flow velocity waveforms (median 11.43 micromol/mg creatinine). A significant negative correlation was observed between nitrite concentrations and uterine artery resistance index, umbilical artery pulsatility index and umbilical artery pulsatility index:middle cerebral artery pulsatility index ratio. We conclude that placental nitric oxide is significantly associated with uteroplacental blood flow and may be important in maintaining adequate uteroplacental perfusion in intrauterine growth retarded pregnancies.

Assessment of fetal compromise by Doppler ultrasound investigation of the fetal circulation. Arterial, intracardiac, and venous blood flow velocity studies.

Doppler studies of the fetal circulation in intrauterine growth retardation and hypoxia have demonstrated a compensatory redistribution of arterial blood flow with increased flow to the cerebrum and myocardium and decreased flow to the periphery. The aim of this study was to evaluate the significance of changes in fetal venous blood flow waveforms in high-risk pregnancies and to investigate the time relation between alterations in venous and arterial Doppler waveform indices in compromised fetuses. The cross-sectional study consisted of 108 high-risk singleton pregnancies between 23 and 42 weeks' gestation without fetal chromosomal abnormalities or major malformations. Blood flow velocity waveforms were recorded from the umbilical arteries, descending thoracic aorta, middle cerebral artery, tricuspid and mitral ventricular inflow, ductus venosus, inferior vena cava, and the right hepatic vein. The mean velocity and pulsatility index were calculated for arterial vessels, the E/A ratio for atrioventricular blood flow, and peak forward velocities during ventricular systole and early diastole, the lowest forward velocity or peak reverse velocity during arterial contraction, and time-averaged maximum velocity for venous vessels. Two ratios for venous waveforms, one of which is the equivalent of the pulsatility index, were calculated. Fetal biophysical assessment was based on a computerized cardiotocogram and the biophysical profile score. The compromised group consisted of 37 fetuses delivered by cesarean section for an abnormal heart rate trace (n = 21) or severe preeclampsia (n = 9) or which died in utero (n = 7) within 10 days of their last Doppler investigation. This group showed significant alterations in arterial and venous flow velocity waveforms but not in atrioventricular inflow. Additionally, to find out whether venous Doppler investigation may help to detect a worsening of the situation in fetuses already showing arterial blood flow redistribution, we analyzed the data of these fetuses separately. The 41 fetuses that had an aorta/middle cerebral artery pulsatility index ratio > 95th percentile were divided into compromised and non-compromised groups according to their biophysical assessment and whether or not they developed fetal distress (cesarean section for abnormal heart rate trace or intrauterine death). The mean values for Doppler parameters of the compromised groups differed significantly from the noncompromised groups in all venous vessels, whereas differences on the arterial side were much less pronounced. Velocity ratios of venous waveforms were significantly higher, and absent or reverse flow in the ductus venosus with atrial contraction indicated a poor prognosis, with a perinatal mortality of 5 out of 8. Fetal compromise is associated with significant alterations in the fetal arterial and venous circulation. Significant changes in venous Doppler waveforms develop due to increased afterload and perhaps myocardial failure in late deterioration after fetal arterial redistribution is established and seem to be closely related to abnormal biophysical assessment findings. Therefore, Doppler investigation of the fetal venous circulation may play an important role in monitoring the redistributing growth retarded fetus and thereby may help to determine the optimal time for delivery.