Comparison of cerebral blood flow velocity estimation with cranial ultrasound imaging for early prediction of outcome in preterm infants

Changes in cerebral blood flow parameters among preterm 30-34 week neonates who are initiated on kangaroo mother care - A prospective analytical observational study

BACKGROUND

Kangaroo mother care (KMC) is recommended standard of care for preterm neonates. They are vulnerable for cerebral blood flow (CBF) fluctuations linked to intraventricular hemorrhage and periventricular leukomalacia, which have implications on neurodevelopment. This study was designed to document any change in CBF in middle cerebral artery (MCA) of stabilized preterm 30-34 weeks neonates who are initiated on KMC.

METHODS

We designed a prospective analytical observational study in a tertiary care neonatal unit. We enrolled 30-34 weeks preterm neonates eligible for KMC after their stabilization (n = 40). CBF was measured in supine position via right MCA Doppler through the temporal window before any KMC, after 2 h of 1st KMC session and following 24 h of 1st session. CBF was quantified in terms of pulsatility index (PI), Resistive Index (RI), peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (MV) and values were compared against the existing normative values.

RESULTS

Mean gestation of study population was 31.91 weeks with a mean birth weight of 1432.75 g. Median day of initiation of KMC was 7 days with mean duration of KMC on day 1 was 4.56 h. We could find statistically significant decrease in the values of PI and RI from 90th centile towards 50th centile of normative values with a mean difference of 0.22 (99 % CI 0.02-0.43, p 0.005) for PI and 0.05 (99 % CI 0.02-0.07, p = 0.000) for RI post the first session of KMC. Following 24 h of 1st KMC session, we could find a significant increase in values of PSV, EDV and MV comparing values of pre-initiation with day 2 pre-KMC but values of PI and RI were not significantly different.

CONCLUSION

CBF among 30-34 week preterm neonates tend to optimize after initiation of KMC.

Cardiovascular and Cerebrovascular Implications of Growth Restriction: Mechanisms and Potential Treatments

Fetal growth restriction (FGR) is a common complication of pregnancy, resulting in a fetus that fails to reach its genetically determined growth potential. Whilst the fetal cardiovascular response to acute hypoxia is well established, the fetal defence to chronic hypoxia is not well understood due to experiment constraints. Growth restriction results primarily from reduced oxygen and nutrient supply to the developing fetus, resulting in chronic hypoxia. The fetus adapts to chronic hypoxia by redistributing cardiac output via brain sparing in an attempt to preserve function in the developing brain. This review highlights the impact of brain sparing on the developing fetal cardiovascular and cerebrovascular systems, as well as emerging long-term effects in offspring that were growth restricted at birth. Here, we explore the pathogenesis associated with brain sparing within the cerebrovascular system. An increased understanding of the mechanistic pathways will be critical to preventing neuropathological outcomes, including motor dysfunction such as cerebral palsy, or behaviour dysfunctions including autism and attention-deficit/hyperactivity disorder (ADHD).

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.

Using senses to encourage head and upper limb voluntary movement in young infants: Implications for early intervention

PRIMARY OBJECTIVE

It has long been suggested that a neonate's movement and responses to external stimuli are the product of reflexive reactions rather than purposeful movements. However, several studies have demonstrated that this is not the case. Rationale of literature included: This study seeks to review reports showing that sensory stimuli resulted in newborns recognising and responding to different stimuli with active head or upper limb movements. We also discuss this in the context of current literature about early training on the advancement of movement and brain development. Results and outcomes: Taken together, it is clear that early active experience shapes learning in newborns.

CONCLUSIONS

The impact of this research is most exciting for applications that would induce infants to make purposeful movements, especially as a means for early intervention and rehabilitation for the treatment of infants with or at high risk for developmental delay.

Enhanced Monitoring of the Preterm Infant during Stabilization in the Delivery Room

Monitoring of preterm infants in the delivery room (DR) remains limited. Current guidelines suggest that pulse oximetry should be available for all preterm infant deliveries, and that if intubated a colorimetric carbon dioxide detector should provide verification of correct endotracheal tube placement. These two methods of assessment represent the extent of objective monitoring of the newborn commonly performed in the DR. Monitoring non-invasive ventilation effectiveness (either by capnography or respiratory function monitoring) and cerebral oxygenation (near-infrared spectroscopy) is becoming more common within research settings. In this article, we will review the different modalities available for cardiorespiratory and neuromonitoring in the DR and assess the current evidence base on their feasibility, strengths, and limitations during preterm stabilization.

Cerebrovascular function and cognition in childhood: a systematic review of transcranial Doppler studies

Background

The contribution of cerebrovascular function to cognitive performance is gaining increased attention. Transcranial doppler (TCD) is portable, reliable, inexpensive and extremely well tolerated by young and clinical samples. It enables measurement of blood flow velocity in major cerebral arteries at rest and during cognitive tasks.

Methods

We systematically reviewed evidence for associations between cognitive performance and cerebrovascular function in children (0-18 years), as measured using TCD. A total of 2778 articles were retrieved from PsychInfo, Pubmed, and EMBASE searches and 25 relevant articles were identified.

Results

Most studies investigated clinical groups, where decreased blood flow velocities in infants were associated with poor neurological functioning, and increased blood flow velocities in children with Sickle cell disease were typically associated with cognitive impairment and lower intelligence. Studies were also identified assessing autistic behaviour, mental retardation and sleep disordered breathing. In healthy children, the majority of studies reported cognitive processing produced lateralised changes in blood flow velocities however these physiological responses did not appear to correlate with behavioural cognitive performance.

Conclusion

Poor cognitive performance appears to be associated with decreased blood flow velocities in premature infants, and increased velocities in Sickle cell disease children using TCD methods. However knowledge in healthy samples is relatively limited. The technique is well tolerated by children, is portable and inexpensive. It therefore stands to make a valuable contribution to knowledge regarding the underlying functional biology of cognitive performance in childhood.

Cerebral blood flow velocity asymmetry, neurobehavioral maturation, and the cognitive development of premature infants across the first two years

OBJECTIVE

Premature infants are at risk of adverse developmental outcomes even with no demonstrable neurological damage. Neonatal physiological measures that can serve as indicators of later development are therefore important for early evaluation and intervention.

METHODS

We followed the development of 51 low birth weight, premature infants across the first 2 years. Mean systolic cerebral blood flow velocity (CBFV) in the left and right middle cerebral arteries was measured at 37 weeks gestational age, neurobehavioral maturation was assessed with the Neonatal Behavior Assessment Scales (NBAS), and cognitive development was evaluated at 6, 12, and 24 months.

RESULTS

Different patterns emerged for CBFV in the right versus left middle cerebral artery. Greater absolute values of right systolic CBFV were related to poorer performance on the habituation and orientation scales of the NBAS, whereas greater left systolic CBFV absolute values were related to better Mental Development Index (MDI) scores at 24 months. Right systolic CBFV asymmetry was related to poor neonatal orientation and low MDI score at 24 months. On the other hand, infants with left systolic CBFV asymmetry showed a more rapid increase in cognitive skills from 12 to 24 months and better cognitive performance at 2 years.

CONCLUSION

Measurement of systolic CBFV in the neonatal period may assist in identifying infants at risk of poor developmental outcome.

Which to measure, systemic or organ blood flow? Middle cerebral artery and superior vena cava flow in very preterm infants

AIM

To describe, in very preterm babies, postnatal changes in measures of middle cerebral artery (MCA) Doppler variables. To relate these peripheral measures to echocardiographic measures of systemic blood flow and ductal shunting, and to study their relation to subsequent intraventricular haemorrhage (IVH).

METHODS

126 babies born before 30 weeks were studied with serial echocardiography and cerebral and Doppler ultrasound of the MCA at 5, 12, 24, and 48 hours of age. Echocardiographic measures included superior vena cava (SVC) flow and colour Doppler diameter of the ductal shunt. MCA Doppler measures included mean velocity, pulsatility index (PI), and estimated colour Doppler diameter.

RESULTS

MCA mean velocity increased whereas the PI decreased significantly over the first 48 hours. Babies with low SVC flow had significantly lower MCA mean velocity and estimated diameter than babies with normal SVC flow. There was no difference in PI. On multivariant analysis, the significant associations with MCA mean velocity were mean blood pressure (MBP), heart rate, SVC flow, and lower calculated vascular resistance. The significant associations with PI were larger ductal diameter and lower mean MBP. The significant associations with MCA diameter were higher SVC flow and lower calculated vascular resistance. After controlling for gestation, there was a highly significant association between lowest SVC flow and subsequent IVH but no association between IVH and lowest MCA mean velocity, estimated diameter, PI, or MBP.

CONCLUSIONS

These data are consistent with the speculation that SVC flow is a reflection of cerebral blood flow. Low SVC flow is more strongly associated with subsequent IVH than cerebral artery Doppler measures or MBP.

Postnatal adaptation of brain circulation in preterm infants

Global and regional postnatal cerebral circulatory changes in stable preterm infants were studied, and their relation to brain injury was assessed. Thirty-five preterm infants were studied on the first and second days of age. Cerebral blood flow (CBF) (mL/hg per min) and cerebral blood volume (CBV) (mL/hg) were measured using near-infrared spectroscopy. The cerebral blood flow velocity (cm/second) (peak systolic, diastolic flow, mean flow) and resistance index (RI) were determined in the internal carotid, anterior cerebral, and striate arteries by color Doppler flow imaging. Serial cerebral ultrasound studies were performed to detect changes in brain parenchymal echogenicity or intraventricular hemorrhage (IVH); the maximum severity of these findings was considered. CBF and cerebral blood flow velocity increased significantly with time, and such changes were independent of mean blood pressure, PO(2), PCO(2), hematocrit, or glycemia. In contrast, CBV and RI remained unchanged. According to the results of sonograms, no differences were found in postnatal CBF and cerebral blood flow velocity changes, regardless of whether patients had or did not have parenchymal lesions or IVH. However, higher CBV values were found on the second day in infants with IVH compared with infants without IVH. Early coupling of CBF and metabolic demands is independent of blood pressure. Improved venous return, instead of vasodilation, could be important in this adaptation.

Neonatal cerebral Doppler: arterial and venous flow velocity measurements using color and pulsed Doppler system

OBJECTIVE

To contribute to the establishment of reference values of blood flow velocity assessed by cerebral Doppler in healthy infants related to gestational age and birth weight during the first week of life.

METHODS

Five arteries and three veins were evaluated respectively in 120 (74 premature) newborns and in 100 (70 preterm) infants. In a quarter of the latter three recordings at 5-minute intervals were made to assess reproducibility. The relation between flow measurements and gestational age was assessed by linear regression, means by analysis of variance (or Kruskall-Wallis test) and paired samples by Student's t test.

RESULTS

There was a significant increase of arterial velocities with increasing gestational age and birth weight, but not for venous velocities. Significant higher values were found in the internal carotid artery followed by the medium cerebral artery. The venous velocities were highly reproducible and the main patterns observed were bandlike and sinusoid type.

CONCLUSION

The knowledge of normal cerebrovascular physiology is essential to understand the pathogenesis of neonatal brain damage and can help pediatricians in an accurate interpretation of the flow profile in neurological pathology.

Cerebral blood flow velocity and pulsation in neonatal respiratory distress syndrome and periventricular hemorrhage

The present study addressed the hypotheses that cerebral ischemia and/or excessive cerebral blood pulsation contribute to periventricular hemorrhage in preterm newborns with respiratory distress and that the pulse width is a valuable tool to estimate the contribution of cerebral blood pulsation. These hypotheses were tested by following preterm newborns at risk for respiratory distress and periventricular hemorrhage. We monitored for cerebral blood flow velocity (CBFV), cerebral pulse width, and cerebral pulsatility index; for patent ductus arteriosus, capillary Pco2, heart rate (HR) and behavior; and for the occurrence of respiratory distress and periventricular hemorrhage (PVH). The data obtained were analyzed with linear regression with the mode of respiration (spontaneous or supported) and postnatal age as additional covariates. We observed that (a) respiratory distress, either uncomplicated or complicated by PVH, correlates with a low CBFV and a high cerebral pulsatility index; (b) PVH also correlates with a high cerebral pulse width; (c) the increased pulse width precedes the onset of the hemorrhage; and (d) these CBF alterations can be partly attributed to ductal shunting and are ameliorated by mechanical ventilation.