Antenatal dexamethasone effect on Doppler blood flow velocity in women at risk for preterm birth: prospective case series

Background

Maternal administration of corticosteroids is essential to improve fetal lung surfactant production and hasten the fetal lung maturity in women at risk for preterm birth.

Objectives

The current study aims to evaluate the effects of dexamethasone on fetal and uteroplacental circulation in pregnancies at risk for preterm birth after 24 hours of its administration.

Methods

A prospective cross-sectional study was carried out in a tertiary University Hospital and included 52 pregnant women with singleton pregnancies. Doppler studies were performed on maternal uterine arteries, umbilical artery, fetal middle cerebral artery (MCA) and fetal descending aorta and just before dexamethasone administration and repeated 24 hours after completion of the course.

Results

There was a statistically significant difference between all Doppler indices in the umbilical artery (PI= 1.09±0.4 and 1.05±0.39, RI= 0.66±0.14 and 0.63±0.14; p=0.001), fetal MCA (RI= 0.86±0.12 and 0.83±0.13, PI= 2.19±0.72 and 2.15±0.72; p=0.001) and aorta (RI= 0.9±0.55 and 0.87±0.55; p=0.001, PI= 1.91±0.44 and 1.89±0.44; p=0.040) in comparison before and 24 hours after maternal dexamethasone administration respectively. Also uterine artery PI was significantly different (0.9±0.27 and 0.87±0.26; p=0.001).

Conclusion

Antenatal dexamethasone for women at risk of preterm birth improves the fetal and uteroplacental blood flow at 24 hours after its administration.

Fetal responses to epidural analgesia as evidenced by Doppler indices

BACKGROUND

This study was designed to evaluate the maternal effects ofepidural analgesia by different local anesthetics and their impact on placental and fetal blood flow.

METHODS

Depending on the type of local anesthetics used, sixty full-term parturients were randomly allocated into 3 equal groups in a randomized blind study; Group (1) received Bupivacaine (0.125%), Group (2) received Ropivacaine (0.2%) and, Group (3) received Levobupivacaine (0.125%). Epidural fentanyl (100 microg) was added to all groups. Safety was assessed by recording the mothers' characters and vital signs as well as the fetal Doppler indices while efficacy was assessed by measuring severity of pain, onset and duration of analgesia, and the motor blockade. Doppler velocimetry studies for fetus included monitoring of Umbilical Artery Pulsitility Indices (UAPI) and Middle Cerebral Artery Pulsitility Indices (MCAPI).

RESULTS

Parturient in all groups were comparable. Pulse rate and arterial blood pressure were significantly decreased in all groups after analgesia, but remained within normal ranges. The pain score, had significant reduction in all groups with best results observed in Group 3. The onset of analgesia was relatively rapid in Group 2 followed by Group 3 then Group 1. The duration of analgesia was prolonged in Group 1 followed by Group 3 and then Group 2. There was no incidence of motor block except in 5 parturient (20%) in Group 1. UAPI was significantly decreased in the three studied groups after epidural analgesia. But, during uterine contraction, there was slight elevation in the UAPI in all groups. The best improvement in placental perfusion was observed in Group 3, then Group 1, and the least was Group 2. On the other hand, MCAPI was significantly increased in al groups after epidural analgesia. But, during uterine contraction, there was slight decrease in the MCAPI in the three groups. The best improvement in MCAPI was observed in Group 3, then Group 1, and the least was Group 2.

CONCLUSION

All local anesthetics produced excellent analgesia during labor. The Doppler indices were improved in the three groups with the best results in levobupivacaine group.

Betamethasone associated changes in umbilical artery flow velocity waveforms in multiple pregnancies with umbilical artery absent end diastolic flow

OBJECTIVES

It has been previously shown that glucocorticoids alter umbilical artery flow velocity waveforms in singleton pregnancies complicated by umbilical artery absent end diastolic flow. Whether similar effects are evident in multiple pregnancies where one fetus has umbilical artery absent end diastolic flow is not known.

METHODS

Women with a twin or triplet pregnancy complicated by umbilical artery absent end diastolic flow in one fetus were admitted to hospital for intensive fetal surveillance including daily umbilical artery flow velocity waveform studies, as per hospital protocol. All women received prophylactic betamethasone (11.4 mg x 2, 24 h apart) in anticipation of preterm delivery.

RESULTS

Between October 1996 and February 2002, 24 women with a multiple pregnancy complicated by umbilical artery absent end diastolic flow were cared for. Of these, six had a pregnancy with feto-fetal transfusion and excluded from further analysis. Of the remaining 18 women, eight had monochorionic diamniotic twins, eight had dichorionic twins, and two had trichorionic, triamniotic triplets. The median (range) gestation at diagnosis of umbilical artery absent end diastolic flow was 210.5 days (173-241). In nine (50%) of the 18 pregnancies the administration of betamethasone was associated with return of umbilical artery end diastolic flow for a median of 5 days. There was no association between this effect and chorionicity. The median (range) interval from diagnosis of umbilical artery absent end diastolic flow to delivery was 11 days (1-46).

CONCLUSIONS

As previously reported in singleton pregnancies, the maternal administration of betamethasone in multiple pregnancies with umbilical artery absent end diastolic flow is associated with a transient return of end diastolic flow.

Effects of maternal dexamethasone administration on fetal Doppler flow velocity waveforms

OBJECTIVE

To investigate the effects of maternal dexamethasone administration on umbilical and fetal cerebral artery flow velocity waveforms.

DESIGN

Cross-sectional study.

SETTING

Department of Obstetrics and Gynaecology, Robert Ballanger Hospital, Aulnay-sous-Bois, France.

SAMPLE

Twenty-six pregnant women with singleton pregnancies considered at risk for preterm delivery. At baseline, all pregnancies had normal fetoplacental vascular resistance.

METHODS

These women were given weekly six intravenous doses of 4 mg of dexamethasone eight hours apart.

MAIN OUTCOME MEASURES

Doppler studies were performed from both umbilical artery (UA) and fetal middle cerebral artery (MCA) before (day 0), during (day 2), immediately after (day 4) and shortly after (day 7) every steroid course.

RESULTS

No significant variation was noted in both umbilical artery pulsatility index (PI) and fetal heart rate through dexamethasone therapy. Compared with mean initial values, we found on day 4 a significant decrease in MCA PI of 0.28 (F = 7.17, P < 0.001) and a significant increase in UA:MCA PI ratio of 0.08 (F = 3.85, P = 0.013); in contrast no significant change was documented on days 2 and 7 in both MCA pulsatility index and UA:MCA PI ratio. After multiple regression analysis, only the decrease in fetal middle cerebral artery pulsatility index on day 4 remained significant (F= 5.84, P= 0.001).

CONCLUSIONS

The current study finds in healthy fetuses a transient, significant and unexplained decrease in fetal middle cerebral artery impedance on the fourth day following maternal dexamethasone administration. Further basic research and clinical studies including larger sample sizes or pregnancies with fetoplacental dysfunction are needed.

[Utero- and fetoplacental hemodynamic measurements with low dose aspirin]

A prospective randomized double-blind study of low-dose aspirin treatment (100 mg/d) was conducted on a population of 43 pregnant women at risk of pregnancy-induced hypertension, preeclampsia, intrauterine growth retardation. Doppler ultrasound blood flow measurements of the uterine arteries and the umbilical cord, at the fetal and placental end, were obtained on a two-weekly interval in between 18 to 40 weeks of gestation. During the course of pregnancy Doppler indices of both vessels decreased, whereas the absolute velocity of the uterine arteries increased. Perfusion of both vessels did not show any relevant differences in between the aspirin- and placebo-group. Both groups showed a similar median duration of gestation at time of delivery (278 d aspirin vs. 270 d placebo). Comparison of median birthweight (3152.5 g aspirin vs. 2900 g placebo) did not show any significant difference. There were no haemodynamic effects of low-dose aspirin on the utero- and fetoplacental circulation to be demonstrated.

The effects of S-nitrosoglutathione on platelet activation, hypertension, and uterine and fetal Doppler in severe preeclampsia

OBJECTIVE

To determine the effects of the platelet-specific nitric oxide donor S-nitrosoglutathione on women with severe preeclampsia.

METHODS

Ten women with severe preeclampsia or preeclampsia with severe fetal compromise at 21-33 weeks' gestation each received a 60-90-minute intravenous infusion of 50-250 micrograms/minute of S-nitrosoglutathione. Each was hypertensive, despite conventional oral antihypertensive therapy in eight. Maternal blood pressure, heart rate, platelet activation, uterine artery, and fetal Doppler indices were measured during the infusion.

RESULTS

A dose-dependent reduction in mean arterial pressure from 125 mmHg (95% confidence interval [CI] 117-133) to 103.5 (95% CI 97-111) (P < .005) and an increase in pulse rate from 73.7 beats per minute (95% CI 64.3-84.5) to 89.1 (95% CI 81.2-97.8) (P < .02) was observed during the infusion. Mean uterine artery resistance index fell from 0.76 (95% CI 0.73-0.81) to 0.70 (95% CI 0.65-0.75) (P < .009). Platelet activation measured by P-selectin expression was reduced from 3.02% (95% CI 2.09-4.36) to 1.22% (95% CI 0.94-1.58) (P < .01). Fetal Doppler indices (umbilical artery, middle cerebral artery, and thoracic aorta) showed no significant changes during the infusion.

CONCLUSION

S-nitrosoglutathione infusion reduced material mean arterial pressure, platelet activation, and uterine artery resistance without further compromising fetal Doppler indices. This study suggests that platelet-specific nitric oxide donors may prove beneficial in the management of severe preeclampsia.