Cerebral hemodynamics during early neonatal period in preterm infants with periventricular leukomalacia

Early postnatal color Doppler changes in neonates receiving delivery room resuscitation with low 5 min Apgar score-a pilot study

AIMS AND OBJECTIVES

To evaluate the Doppler changes in the intracranial arteries of neonates exposed to perinatal hypoxic insult and compare it with normal neonates.

MATERIALS AND METHODS

Color Doppler of bilateral anterior and middle cerebral arteries was performed within 6 h of birth in 26 healthy neonates and 50 neonates who received delivery room resuscitation (DRR) for perinatal depression and had a 5 min Apgar score <7. Comparisons of resistive index (RI) and peak systolic velocity (PSV) were made between the (a) control group (b) patients with low 5 min Apgar score <7 who without clinical features of neonatal encephalopathy at 24 h (c) neonates with perinatal depression with a clinical evidence of disturbed neurological function at 24 h of birth and examination consistent with mild, moderate, or severe encephalopathy using modified Sarnat and Sarnat's classification.

RESULTS

Significantly higher RI was observed in the neonates with to perinatal depression compared to the normal neonates. Significantly higher RI was seen in the patients with clinical features of neonatal encephalopathy (Group C) compared to group B. RI <0.6 and >0.82 was associated with severe neonatal encephalopathy. Differences in PSV were not statistically significant in the various groups.

CONCLUSION

The study presents the changes in early cerebral Doppler parameters observed in neonates with low 5 min Apgar score following DRR compared to the normal neonates. We also present the relations of Doppler parameters with increasing severity of neonatal encephalopathy according to Sarnat classification.

Diagnostic and predictive value of Doppler ultrasound for evaluation of the brain circulation in preterm infants: a systematic review

INTRODUCTION

Very and extremely preterm infants frequently have brain injury-related long-term neurodevelopmental problems. Altered perfusion, for example, seen in the context of a hemodynamically significant patent ductus arteriosus (PDA), has been linked to injury of the immature brain. However, a direct relation with outcome has not been reviewed systematically.

METHODS

A systematic review was conducted to provide an overview of the value of different cerebral arterial blood flow parameters assessed by Doppler ultrasound, in relation to brain injury, to predict long-term neurodevelopmental outcome in preterm infants.

RESULTS

In total, 23 studies were included. Because of heterogeneity of studies, a meta-analysis of results was not possible. All included studies on resistance index (RI) showed significantly higher values in subjects with a hemodynamically significant PDA. However, absolute differences in RI values were small. Studies using Doppler parameters to predict brain injury and long-term neurodevelopmental outcome were inconsistent.

DISCUSSION

There is no clear evidence to support the routine determination of RI or other Doppler parameters in the cerebral arteries to predict brain injury and long-term neurodevelopmental outcome in the preterm infant. However, there is evidence that elevated RI can point to the presence of a hemodynamically significant PDA.

Relationship between PCO2 and unfavorable outcome in infants with moderate-to-severe hypoxic ischemic encephalopathy

BACKGROUND

Abnormal PCO2 is common in infants with hypoxic ischemic encephalopathy (HIE). The objective was to determine whether hypocapnia was independently associated with unfavorable outcome (death or severe neurodevelopmental disability at 18 mo) in infants with moderate-to-severe HIE.

METHODS

This was a post hoc analysis of the CoolCap Study in which infants were randomized to head cooling or standard care. Blood gases were measured at prespecified times after randomization. PCO2 and follow-up data were available for 196 of 234 infants. Analyses were performed to investigate the relationship between hypocapnia in the first 72 h after randomization and unfavorable outcome.

RESULTS

After adjusting for pH, amplitude-integrated electroencephalogram background and seizures, birth weight, Apgar score at 5 min, cooling status, and Sarnat stage, PCO2 was inversely associated with unfavorable outcome (P < 0.001). The probability of unfavorable outcome was 0.20 ± 0.1 (point estimate ± SE), 0.53 ± 0.23 and 0.89 ± 0.16 for a PCO2 of 40, 30, and 20 mm Hg respectively and was greater in infants with severe HIE than with moderate HIE.

CONCLUSIONS

Hypocapnia in infants with moderate-to-severe HIE was independently associated with unfavorable outcome. Future studies of controlled normocapnia will be important.

Fetal and Neonatal Effects of N-Acetylcysteine When Used for Neuroprotection in Maternal Chorioamnionitis

OBJECTIVE

To evaluate the clinical safety of antenatal and postnatal N-acetylcysteine (NAC) as a neuroprotective agent in maternal chorioamnionitis in a randomized, controlled, double-blinded trial.

STUDY DESIGN

Twenty-two mothers >24 weeks gestation presenting within 4 hours of diagnosis of clinical chorioamnionitis were randomized with their 24 infants to NAC or saline treatment. Antenatal NAC (100 mg/kg/dose) or saline was given intravenously every 6 hours until delivery. Postnatally, NAC (12.5-25 mg/kg/dose, n = 12) or saline (n = 12) was given every 12 hours for 5 doses. Doppler studies of fetal umbilical and fetal and infant cerebral blood flow, cranial ultrasounds, echocardiograms, cerebral oxygenation, electroencephalograms, and serum cytokines were evaluated before and after treatment, and 12, 24, and 48 hours after birth. Magnetic resonance spectroscopy and diffusion imaging were performed at term age equivalent. Development was followed for cerebral palsy or autism to 4 years of age.

RESULTS

Cardiovascular measures, cerebral blood flow velocity and vascular resistance, and cerebral oxygenation did not differ between treatment groups. Cerebrovascular coupling was disrupted in infants with chorioamnionitis treated with saline but preserved in infants treated with NAC, suggesting improved vascular regulation in the presence of neuroinflammation. Infants treated with NAC had higher serum anti-inflammatory interleukin-1 receptor antagonist and lower proinflammatory vascular endothelial growth factor over time vs controls. No adverse events related to NAC administration were noted.

CONCLUSIONS

In this cohort of newborns exposed to chorioamnionitis, antenatal and postnatal NAC was safe, preserved cerebrovascular regulation, and increased an anti-inflammatory neuroprotective protein.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00724594.

Can anomalies of fetal brain circulation be useful in the management of growth restricted fetuses?

Assessment of the fetal cerebral circulation provides important information on the hemodynamic changes associated with chronic hypoxia and intrauterine growth restriction. Despite the incorporation of new US parameters, the landmark for the fetal brain hemodynamic evaluation is still the middle cerebral artery. However, new vascular territories, such as the anterior and posterior cerebral arteries, might provide additional information on the onset of the brain sparing effect. The fractional moving blood volume estimation and three-dimensional power Doppler ultrasound indices are new techniques that seem to be promising in identifying cases at earlier stages of vascular deterioration; still, they are not available for clinical application and more information is needed on the reproducibility and advantages of three-dimensional power Doppler ultrasound blood flow indices. In the past, the brain sparing effect was considered as a protective mechanism; however, recent information challenges this concept. There is growing evidence of an association between brain sparing effect and increased risk of abnormal neurodevelopment after birth. Even in mild late-onset intrauterine growth restriction affected fetuses with normal umbilical artery blood flow, increased cerebral blood perfusion can be associated with a substantial risk of abnormal neuroadaptation and neurodevelopment during childhood.

Preterm twin gestation and cystic periventricular leucomalacia

OBJECTIVE

To identify risk factors for the development of cystic periventricular leucomalacia (PVL) in twin gestation.

DESIGN

Retrospective case-control study.

SETTING

Tertiary care university hospital, Department of Paediatrics, Division of Neonatology, Graz, Austria.

PATIENTS

Preterm twin gestations with one sibling having developed cystic PVL, diagnosed by ultrasound scans, compared with their co-twins without PVL, in hospital between 1988 and 2000.

MAIN OUTCOME MEASURES

Perinatal and postnatal risk factors for the development of PVL.

RESULTS

Eighteen preterm twin gestations were included. Monochorionicity was evident in 47% of the pregnancies, and twin to twin transfusion syndrome occurred in two cases (11%). Fetal distress correlated inversely with PVL (15% v 53%, p = 0.019, relative risk (RR) = 2.057, 95% confidence interval (CI) = 1.067 to 3.968). Hypocarbia with Pco(2) levels below 30 mm Hg (4 kPa) was diagnosed in 29% of the cases compared with 6% of the controls (p = 0.038, RR = 1.944, 95% CI = 1.113 to 3.396). There were no significant differences between groups with regard to premature rupture of the membranes, early onset infection, respiratory distress syndrome, mechanical ventilation, arterial hypotension, persistent ductus arteriosus, and hyperbilirubinaemia. Asphyxia was only evident in three controls. Three infants died and another three were lost to follow up. None of the cases compared with 62% of the controls were diagnosed as having developed normally (p < 0.001), and 14 cases (82%) compared with two controls (15%) developed cerebral palsy (p < 0.001).

CONCLUSION

Hypocarbia was the only risk factor strongly associated with cystic PVL. The general outcome of the infants was poor.

Polyuria and impaired renal blood flow after asphyxia in preterm fetal sheep

Renal impairment is common in preterm infants, often after exposure to hypoxia/asphyxia or other circulatory disturbances. We examined the hypothesis that this association is mediated by reduced renal blood flow (RBF), using a model of asphyxia induced by complete umbilical cord occlusion for 25 min (n = 13) or sham occlusion (n = 6) in chronically instrumented preterm fetal sheep (104 days, term is 147 days). During asphyxia there was a significant fall in RBF and urine output (UO). After asphyxia, RBF transiently recovered, followed within 30 min by a secondary period of hypoperfusion (P < 0.05). This was mediated by increased renal vascular resistance (RVR, P < 0.05); arterial blood pressure was mildly increased in the first 24 h (P < 0.05). RBF relatively normalized between 3 and 24 h, but hypoperfusion developed again from 24 to 60 h (P < 0.05, analysis of covariance). UO significantly increased to a peak of 249% of baseline between 3 and 12 h (P < 0.05), with increased fractional excretion of sodium, peak 10.5 +/- 1.4 vs. 2.6 +/- 0.6% (P < 0.001). Creatinine clearance returned to normal after 2 h; there was a transient reduction at 48 h to 0.32 +/- 0.02 ml.min(-1).g(-1) (vs. 0.45 +/- 0.04, P < 0.05) corresponding with the time of maximal depression of RBF. No renal injury was seen on histological examination at 72 h. In conclusion, severe asphyxia in the preterm fetus was associated with evolving renal tubular dysfunction, as shown by transient polyuria and natriuresis. Despite a prolonged increase in RVR, there was only a modest effect on glomerular function.

[Neonatal Doppler velocimetry in full term small-for-gestational age newborns]

This study aimed to evaluate the cerebral blood flow of full term small-for-gestational age newborns, using cranial ultrasound Doppler at birth. This study was performed at CAISM/UNICAMP (Tertiary Health Center for Women). Sixty term newborns were selected and divided in two groups: appropriate-for-gestational age (AGA) (36 neonates) and small-for-gestational age (SGA) (24 neonates). Cranial ultrasound Doppler evaluation was performed on both groups, between 24 and 48 hours after birth. Cerebral blood flow velocity (CBFV) was lower in the small-for-gestational age group, in the anterior cerebral artery (ACA). Doppler measurements were different statistically between the groups only for values related to peak systolic flow velocity (PSFV) and mean flow velocity (MFV) in the ACA. There was no significant difference for any evaluated parameters of flow velocity in the middle cerebral artery (MCA). It was concluded that SGA newborns showed PSFV and MFV significantly reduced only in the ACA. Weight/gestational age, neonatal polycythemia and mean arterial blood pressure values were statistically related to MFV in the ACA. In presence of fetal suffering, mean arterial blood pressure values and smoking in the pregnancy were statistically related to MFV in the MCA.