Cerebral blood flow velocities and cerebrovascular resistance in normal-term neonates in the first 72 hours

Quantification of brain-wide vascular resistivity via ultrafast Doppler in human neonates helps early detection of white matter injury

Preterm birth is associated with cerebrovascular development disruption and can induce white matter injuries (WMI). Transfontanellar ultrasound Doppler is the most widely used clinical imaging technique to monitor neonatal cerebral vascularisation and haemodynamics based on vascular indexes such as the resistivity index (RI); however, it has poor predictive value for brain damage. Indeed, these RI measurements are currently limited to large vessels, leading to a very limited probing of the brain's vascularisation, which may hinder prognosis. Here we show that ultrafast Doppler imaging (UfD) enables simultaneous quantification, in the whole field of view, of the local RI and vessel diameter, even in small vessels. Combining both pieces of information, we defined two new comprehensive resistivity parameters of the vascular trees. First, we showed that our technique is more sensitive in the early characterisation of the RI modifications between term and preterm neonates and for the first time we could show that the RI depends both on the vessel diameter and vascular territory. We then showed that our parameters can be used for early prediction of WMI. Our results demonstrate the potential of UfD to provide new biomarkers and pave the way for continuous monitoring of neonatal brain resistivity.

Effect of delayed cord clamping on cerebral hemodynamics in preterm infants

Background

Unstable cerebral hemodynamics is an important cause of intracranial hemorrhage in premature infants. The increased blood flow of delayed cord clamping (DCC) compared to immediate cord clamping (ICC) is equivalent to 1/3-1/4 of newborn blood volume. Our objective was to assess whether the increased blood flow causes fluctuations in cerebral blood flow and how.

Methods

This experiment was a prospective, observational study. Neonatologists selected preterm infants eligible for inclusion and exclusion, and divided them into DCC group and ICC group according to the way of umbilical cord ligation performed by obstetrics department, and matched them 1:1 according to gestational age. The peak systolic velocity （PSV) ，end diastolic velocity (EDV)，and resistance index (RI) of middle cerebral artery was measured by Mindray M9 color ultrasonic diagnostic instrument within 1 h, 24±1 h, 48±1 h, 72±1 h, respectively.

Results

There was no significant difference in PSV, EDV and RI in middle cerebral artery between DCC group and ICC group (P > 0.05). There were no significant differences between groups and time (P > 0.05). The hemoglobin and hematocrit in DCC group were higher than those in ICC group within 2 h after birth (P < 0.05). (P > 0.05).

Conclusion

DCC can increase hemoglobin and hematocrit in preterm infants, but does not cause cerebral blood flow fluctuation within a certain range. DCC is a safe method of placental transfusion.

Cerebral Blood Flow of the Neonatal Brain after Hypoxic-Ischemic Injury

OBJECTIVE

Hypoxic-ischemic encephalopathy (HIE) in infants can have long-term adverse neurodevelopmental effects and markedly reduce quality of life. Both the initial hypoperfusion and the subsequent rapid reperfusion can cause deleterious effects in brain tissue. Cerebral blood flow (CBF) assessment in newborns with HIE can help detect abnormalities in brain perfusion to guide therapy and prognosticate patient outcomes.

STUDY DESIGN

The review will provide an overview of the pathophysiological implications of CBF derangements in neonatal HIE, current and emerging techniques for CBF quantification, and the potential to utilize CBF as a physiologic target in managing neonates with acute HIE.

CONCLUSION

The alterations of CBF in infants during hypoxia-ischemia have been studied by using different neuroimaging techniques, including nitrous oxide and xenon clearance, transcranial Doppler ultrasonography, contrast-enhanced ultrasound, arterial spin labeling MRI, 18F-FDG positron emission tomography, near-infrared spectroscopy (NIRS), functional NIRS, and diffuse correlation spectroscopy. Consensus is lacking regarding the clinical significance of CBF estimations detected by these different modalities. Heterogeneity in the imaging modality used, regional versus global estimations of CBF, time for the scan, and variables impacting brain perfusion and cohort clinical characteristics should be considered when translating the findings described in the literature to routine practice and implementation of therapeutic interventions.

KEY POINTS

· Hypoxic-ischemic injury in infants can result in adverse long-term neurologic sequelae.. · Cerebral blood flow is a useful biomarker in neonatal hypoxic-ischemic injury.. · Imaging modality, variables affecting cerebral blood flow, and patient characteristics affect cerebral blood flow assessment..

A Scoping Review of Cerebral Doppler Arterial Waveforms in Infants

Cerebral Doppler ultrasound has been an important tool in pediatric diagnostics and prognostics for decades. Although the Doppler spectrum can provide detailed information on cerebral perfusion, the measured spectrum is often reduced to simple numerical parameters. To help pediatric clinicians recognize the visual characteristics of disease-associated Doppler spectra and identify possible areas for future research, a scoping review of primary studies on cerebral Doppler arterial waveforms in infants was performed. A systematic search in three online bibliographic databases yielded 4898 unique records. Among these, 179 studies included cerebral Doppler spectra for at least five infants below 1 y of age. The studies describe variations in the cerebral waveforms related to physiological changes (43%), pathology (62%) and medical interventions (40%). Characteristics were typically reported as resistance index (64%), peak systolic velocity (43%) or end-diastolic velocity (39%). Most studies focused on the anterior (59%) and middle (42%) cerebral arteries. Our review highlights the need for a more standardized terminology to describe cerebral velocity waveforms and for precise definitions of Doppler parameters. We provide a list of reporting variables that may facilitate unambiguous reports. Future studies may gain from combining multiple Doppler parameters to use more of the information encoded in the Doppler spectrum, investigating the full spectrum itself and using the possibilities for long-term monitoring with Doppler ultrasound.

Effect of Kangaroo Mother Care on Cerebral Hemodynamics in Preterm Neonates Assessed by Transcranial Doppler Sonography in Middle Cerebral Artery

OBJECTIVE

To study the effect of KMC in premature newborns on cerebral hemodynamics in the middle cerebral artery (MCA) using transcranial doppler sonography.

METHODS

In this descriptive study, 40 clinically stable preterm neonates admitted to the neonatal intensive care unit of our institute and undergoing Kangaroo mother care (KMC) were enrolled. Physiological and cerebral blood flow parameters of MCA were obtained by using transcranial doppler sonography at baseline, at 60 minutes of KMC, and after 60 minutes of stopping KMC.

RESULTS

Of the 40 enrolled neonates (24 males), the mean (SD) birth weight, gestation age, and postnatal age were 1698.25 (495.44) g, 33.00 (1.67) wk, and 6.80 (4.51) days, respectively. The mean (SD) cerebral blood flow velocities increased (peak systolic velocity (PSV), P=0.03; end diastolic velocity, P<0.001; mean velocity, P<0.001) and doppler indices decreased (resis-tive index, P=0.001; pulsatility index, P<0.001) significantly; whereas, heart rate (P<0.001) decreased but SpO2 (P=0.001) and mean blood pressure (P=0.003) increased significantly at 60 minutes of KMC as compared to baseline. Sixty minutes after stopping KMC, all parameters (except PSV) were higher than baseline, indicating post KMC effect.

CONCLUSION

KMC improves cerebral hemodynamics in clinically stable preterm neonates.

Effect of Kangaroo Mother Care on Cerebral Hemodynamics in Preterm Neonates Assessed by Transcranial Doppler Sonography in Middle Cerebral Artery

Objective

To study the effect of KMC in premature newborns on cerebral hemodynamics in the middle cerebral artery (MCA) using transcranial doppler sonography.

Methods

In this descriptive study, 40 clinically stable preterm neonates admitted to the neonatal intensive care unit of our institute and undergoing Kangaroo mother care (KMC) were enrolled. Physiological and cerebral blood flow parameters of MCA were obtained by using transcranial doppler sonography at baseline, at 60 minutes of KMC, and after 60 minutes of stopping KMC.

Results

Of the 40 enrolled neonates (24 males), the mean (SD) birth weight, gestation age, and postnatal age were 1698.25 (495.44) g, 33.00 (1.67) wk, and 6.80 (4.51) days, respectively. The mean (SD) cerebral blood flow velocities increased (peak systolic velocity (PSV), P=0.03; end diastolic velocity, P<0.001; mean velocity, P<0.001) and doppler indices decreased (resistive index, P=0.001; pulsatility index, P<0.001) significantly; whereas, heart rate (P<0.001) decreased but SpO2 (P=0.001) and mean blood pressure (P=0.003) increased significantly at 60 minutes of KMC as compared to baseline. Sixty minutes after stopping KMC, all parameters (except PSV) were higher than baseline, indicating post KMC effect.

Conclusion

KMC improves cerebral hemodynamics in clinically stable preterm neonates.

An exploratory study to identify neonatal arterial ischemic stroke: A single-center study

BACKGROUND

Neonatal arterial ischemic stroke (NAIS) presents as seizures, including convulsions, subtle seizures, and apnea, and most patients experience neurological sequelae. Diagnosis is often delayed owing to low test sensitivity. The present study aimed to identify the early clinical diagnostic factors for NAIS in neonates with seizures.

METHODS

The present study included 54 patients born at ≥36 weeks of gestation during the last 15 years who presented to the neonatal intensive care unit with neonatal seizures and underwent brain magnetic resonance imaging (MRI), 6 of whom were diagnosed with NAIS. Maternal background, clinical characteristics, and transcranial pulsed Doppler sonography results were retrospectively reviewed.

RESULTS

Of the 24 patients who presented with convulsions or subtle seizures, 3 (13%) were diagnosed with NAIS and 3 of 30 patients (10%) presented with apnea. Maternal premature ventricular contraction complications were higher in the NAIS group than in the non-NAIS group (p = 0.01). NAIS group showed lower mean middle cerebral artery (MCA) resistance index (RI) was lower the non-NAIS group (p = 0.009), while the left-right RI difference (p = 0.019), mean MCA blood velocity (MnV; p = 0.04), and left-right MnV difference (p < 0.001) in cerebral blood flow velocities (CBFVs) were higher in the NAIS group.

CONCLUSIONS

Our results revealed that maternal arrhythmia may be a diagnostic factor for NAIS in neonates with seizures. Early brain MRI is essential in neonates with seizures and findings of low MCA-RI, high MCA-MnV, or high left-right difference in CBFVs to distinguish between NAIS and non-NAIS.

Does abnormal Doppler on cranial ultrasound predict disability in infants with hypoxic-ischaemic encephalopathy? A systematic review

AIM

To evaluate whether abnormal resistive index or cerebral blood flow velocity (CBFV) on cranial ultrasound predicts disability (≥1 year) in infants with hypoxic-ischaemic encephalopathy (HIE).

METHOD

This was a systematic review and meta-analysis of studies comparing developmental outcomes of infants with HIE with normal versus abnormal resistive index or CBFV.

RESULTS

Twenty-six studies were included (pre-therapeutic hypothermia era, 20; therapeutic hypothermia era, six). Data from 15 studies (pre-therapeutic hypothermia, 10; therapeutic hypothermia, five) were available for meta-analysis. Pooled sensitivity and specificity, summary area under the receiver operating characteristic curve, and diagnostic odds ratio of resistive index or CBFV for predicting 'death or severe disability' were as follows. Pre-therapeutic hypothermia era: 0.83 (95% confidence interval [CI] 0.45-0.97) and 0.92 (95% CI 0.74-0.98), 0.94 (95% CI 0.92-0.96), 54 (95% CI 7-391). Therapeutic hypothermia era (measurements before therapeutic hypothermia): 0.62 (95% CI 0.41-0.80) and 0.96 (95% CI 0.88-0.99), 0.93 (95% CI 0.89-0.94), 23 (95% CI 6-91). Therapeutic hypothermia era (measurements during/after therapeutic hypothermia): 0.51 (95% CI 0.24-0.78) and 0.83 (95% CI 0.73-0.90), 0.81 (95% CI 0.78-0.85), 5 (95% CI 2-13). Overall Grading of Recommendations Assessment, Development and Evaluation (GRADE) rating of evidence was 'low' or 'very low'.

INTERPRETATION

Low-level evidence suggests that abnormal resistive index or CBFV can predict death or disability with high sensitivity and specificity in infants with HIE who are not cooled. The specificity of these tests was high when performed before starting cooling in infants who received therapeutic hypothermia.

WHAT THIS PAPER ADDS

Cerebral doppler ultrasound may be useful in predicting death or disability in infants with hypoxic-ischaemic encephalopathy who are not cooled. Cerebral doppler ultrasound may also be useful in infants who are cooled, if done before starting cooling. Cerebral doppler ultrasound may not be useful when performed during or after completing cooling.

Current understanding and future potential applications of cerebral microvascular imaging in infants

Microvascular imaging is an advanced Doppler ultrasound technique that detects slow flow in microvessels by suppressing clutter signal and motion-related artifacts. The technique has been applied in several conditions to assess organ perfusion and lesion characteristics. In this pictorial review, we aim to describe current knowledge of the technique, particularly its diagnostic utility in the infant brain, and expand on the unexplored but promising clinical applications of microvascular imaging in the brain with case illustrations.

Low frequency cerebral arterial and venous flow oscillations in healthy neonates measured by NeoDoppler

BACKGROUND

A cerebroprotective effect of low frequency oscillations (LFO) in cerebral blood flow (CBF) has been suggested in adults, but its significance in neonates is not known. This observational study evaluates normal arterial and venous cerebral blood flow in healthy neonates using NeoDoppler, a novel Doppler ultrasound system which can measure cerebral hemodynamics continuously.

METHOD

Ultrasound Doppler data was collected for 2 h on the first and second day of life in 36 healthy term born neonates. LFO (0.04-0.15 Hz) were extracted from the velocity curve by a bandpass filter. An angle independent LFO index was calculated as the coefficient of variation of the filtered curve. Separate analyses were done for arterial and venous signals, and results were related to postnatal age and behavioral state (asleep or awake).

RESULTS

The paper describes normal physiologic variations of arterial and venous cerebral hemodynamics. Mean (SD) arterial and venous LFO indices (%) were 6.52 (2.55) and 3.91 (2.54) on day one, and 5.60 (1.86) and 3.32 (2.03) on day two. After adjusting for possible confounding factors, the arterial LFO index was estimated to decrease by 0.92 percent points per postnatal day (p < 0.001). The venous LFO index did not change significantly with postnatal age (p = 0.539). Arterial and venous LFO were not notably influenced by behavioral state.

CONCLUSION

The results indicate that arterial LFO decrease during the first 2 days of life in healthy neonates. This decrease most likely represents normal physiological changes related to the transitional period. A similar decrease for venous LFO was not found.

Early Use of Transcranial Doppler Ultrasonography to Stratify Neonatal Encephalopathy

BACKGROUND

The dynamic nature of neonatal hypoxic-ischemic encephalopathy (HIE) after birth necessitates reliable biomarkers to identify infants with evolving brain injury. This prospective cohort aims to use serial Doppler ultrasonography (US) to measure cerebral blood flow velocity and resistance index (RI) to help detect the time and evolution of the clinical encephalopathy.

METHODS

A total of 60 neonates were enrolled all ≥36 weeks' gestation with perinatal acidemia, defined as a blood gas pH ≤ 7.0 or base deficit ≥16 mmol/L and encephalopathy including a matched control group without encephalopathy. Each neonate received one to three serial Doppler recordings starting at six to 24 hours of life. Mean RI ≤ 0.55 was considered abnormal.

RESULTS

Mean RIs obtained shortly after birth were significantly lower with increasing severity of encephalopathy. On the first Doppler recordings, abnormal mean RIs were seen in 11 of 18 (61%) neonates with mild, 13 of 17 (76%) with moderate, and two of two (100%) with severe HIE. Of the neonates with mild HIE and abnormal mean RIs, congruity abnormal amplitude electroencephalography (45%), brain magnetic resonance imaging (45%), and abnormal head ultrasound (44%) are here reported.

CONCLUSIONS

Doppler measurements can provide bedside adjunct biomarkers indicating the time and severity of neonatal HIE.

Effect of aortic arch surgery in newborns' cerebral and gastrointestinal hemodynamics: evaluation by Doppler ultrasonography

AIM

In this study, we investigated changes in newborns' cerebral and intestinal blood flow who had undergone aortic arch surgery.

METHOD

This study was carried out prospectively as a preliminary study in patients younger than 30 days at the time of aortic arch reconstruction between 1 August and 1 December, 2019. Cerebral and gastrointestinal hemodynamics were evaluated with Doppler USG before and 7 days after the operation. The middle cerebral artery (MCA) and celiac artery (CA) were used as measurement sites. Patients' peak systolic velocity (PSV), mean systolic velocity (MV), end diastolic velocity (EDV), resistive index (RI) and pulsatility index (PI) were evaluated.

RESULTS

A total of 16 patients enrolled in the study. The patients' median weight was 3.2 kg (2.7-4.5 kg), and age was 21 days (7-30 days). Six of them were female. Seven of the patients who underwent arcus reconstruction had an additional ventricular septal defect. The preoperative Doppler USG values of patients' were as follows: for MCA, the mean PSV was 37 ± 12 cm/s, EDV 12 ± 5 cm/s, MV 22 ± 19 cm/s, RI 0.70 ± 0.03, PI 1.24 ± 0.23, and for CA mean PSV was 67 ± 32 cm/s, EDV 29 ± 14 cm/s, MV 24 ± 9 cm/s, RI 0.79 ± 0.27, and PI 1.63 ± 0.89. Doppler USG values of patients' at the postoperative seventh day were as follows: for the MCA, mean PSV 41 ± 13 cm/s, EDV 13 ± 4 cm/s, MV 25 ± 10 cm/s, RI 0.64 ± 0.05, PI 1.23 ± 0.20, and for the CA mean PSV 70.5 ± 34 cm/s, EDV 32 ± 16 cm/s, MV 26 ± 8 cm/s, RI 0.75 ± 0.1, and PI 1.60 ± 0.38. There was a significant decrease in RI of both MCA and CA on the postoperative 7th day compared to the preoperative period (p < 0.05).

CONCLUSION

In newborns, there are significant changes in cerebral and intestinal blood flows after aortic arch surgery. RI decreased significantly, especially in the CA and MCA.

Feasibility of Doppler Ultrasound for Cortical Cerebral Blood Flow Velocity Monitoring During Major Non-cardiac Surgery of Newborns

Background and Aim: Newborns needing major surgical intervention are at risk of brain injury and impaired neurodevelopment later in life. Disturbance of cerebral perfusion might be an underlying factor. This study investigates the feasibility of serial transfontanellar ultrasound measurements of the pial arteries during neonatal surgery, and whether perioperative changes in cerebral perfusion can be observed and related to changes in the perioperative management. Methods: In this prospective, observational feasibility study, neonates with congenital diaphragmatic hernia and esophageal atresia scheduled for surgical treatment within the first 28 days of life were eligible for inclusion. We performed transfontanellar directional power Doppler and pulsed wave Doppler ultrasound during major high-risk non-cardiac neonatal surgery. Pial arteries were of interest for the measurements. Extracted Doppler ultrasound parameters were: peak systolic velocity, end diastolic velocity, the resistivity index and pulsatility index. Results: In 10 out of 14 patients it was possible to perform perioperative measurements; the others failed for logistic and technical reasons. In 6 out of 10 patients, it was feasible to perform serial intraoperative transfontanellar ultrasound measurements with directional power Doppler and pulsed wave Doppler of the same pial artery during neonatal surgery. Median peak systolic velocity was ranging between 5.7 and 7.0 cm s^-1 and end diastolic velocity between 1.9 and 3.2 cm s^-1. In patients with a vasoactive-inotropic score below 12 the trend of peak systolic velocity and end diastolic velocity corresponded with the mean arterial blood pressure trend. Conclusion: Perioperative transfontanellar ultrasound Doppler measurements of the pial arteries are feasible and provide new longitudinal data about perioperative cortical cerebral blood flow velocity. Trial Registration: https://www.trialregister.nl/trial/6972, identifier: NL6972.

Effects of tilt on cerebral hemodynamics measured by NeoDoppler in healthy neonates

BACKGROUND

Today, there are conflicting descriptions of how neonates respond to tilt. Examining physiologic responses of cerebral blood flow velocities (BFVs) in challenging situations like a tilt requires equipment that can cope with positional changes. We aimed to characterize how healthy term neonates respond to mild cerebral hemodynamic stress induced by a 90° tilt test using the recently developed NeoDoppler ultrasound system.

METHODS

A small ultrasound probe was fixated to the neonatal fontanel by a cap, and measured cerebral BFV in healthy neonates during and after a 90° head-up tilt test, five min in total, at their first and second day of life. Unsupervised k-means cluster analysis was used to characterize common responses.

RESULTS

Fifty-six ultrasound recordings from 36 healthy term neonates were analyzed. We identified five distinct, immediate responses that were related to specific outcomes in BFV, heart rate, and pulsatility index the next two min. Among 20 neonates with two recordings, 13 presented with different responses in the two tests.

CONCLUSIONS

Instant changes in cerebral BFV were detected during the head-up tilt tests, and the cluster analysis identified five different hemodynamic responses. Continuous recordings revealed that the differences between groups persisted two min after tilt.

IMPACT

NeoDoppler is a pulsed-wave Doppler ultrasound system with a probe fixated to the neonatal fontanel by a cap that can measure continuous cerebral blood flow velocity. Healthy neonates present with a range of normal immediate cerebral hemodynamic responses to a 90° head-up tilt, categorized in five groups by cluster analysis. This paper adds new knowledge about connection between immediate responses and prolonged responses to tilt. We demonstrate that the NeoDoppler ultrasound system can detect minute changes in cerebral blood flow velocity during a 90° head-up tilt.

Middle cerebral artery velocity is associated with the severity of MRI brain injury in neonates received therapeutic hypothermia

Background

No previous study has investigated the relationship between middle cerebral artery (MCA) flow velocity and the severity of hypoxic ischemic encephalopathy (HIE) evaluated by magnetic resonance imaging (MRI). The aim of this study was to assess the correlation between cerebral blood flow as assessed by transcranial Doppler sonography and the severity of MRI brain injury in asphyxiated neonates with clinical HIE who received therapeutic hypothermia.

Methods

This retrospective cohort study was conducted in the neonatal intensive care unit at Chang Gung Memorial Hospital between April 2011 and May 2014. All neonates with HIE who received therapeutic hypothermia, transcranial Doppler examinations, and brain MRI were eligible. Brain MRI was performed at 11 days of age (interquartile range: 8.5–15 days) and the severity of MRI brain injuries was evaluated using the MR scoring system proposed by Barkovich et al. Serial transcranial Doppler examinations were performed in pre-hypothermia, hypothermia, and post-hypothermia phases.

Results

Twenty-six neonates met the eligibility criteria for this study. Neonates with an abnormal MCA mean flow velocity (MFV) during the hypothermia phase had a higher risk of brain MRI abnormalities (77.8% vs. 22.2%, p = 0.017) and neonates with abnormal high MFV of MCA had higher MR scores of basal ganglia (p = 0.022). However, there were no statistical differences between abnormal MFV of MCA and brain MRI abnormalities during pre- and post-hypothermia phases.

Conclusions

During therapeutic hypothermia, mean cerebral blood flow velocity of the MCA was associated with the severity of MRI brain injury in the neonates with clinical HIE.

Postnatal middle cerebral artery Dopplers in growth-restricted neonates

This prospective observational study compared the middle cerebral artery (MCA) Doppler characteristics of FGR neonates (N = 20) with abnormal antenatal Dopplers, with those of appropriately grown (AGA) neonates (N = 20), in the immediate postnatal period. MCA peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and resistive index (RI) were measured on day 1 and day 3. MCA PSV and EDV values were not significantly different between FGR (mean (SD) gestation: 31.4 (3.1) weeks, weight 1205 (463) grams) and AGA (31.1 (3.0) weeks; 1668 (490) grams) groups, on day 1 and day 3. Both FGR (30.85 (10.02) vs. 42.12 (9.16) cm/s, p = 0.007) and AGA groups (31.77 (9.32) vs. 42.0 (8.98) cm/s, p = 0.001) showed a significant increase in MCA PSV, but only the FGR group showed significant increase in EDV values (7.01 (4.23) vs. 11.78 (4.98), p = 0.002) from day 1 to day 3. This was associated with significant differences in RI (0.72 (0.10) vs. 0.79 (0.07), p = 0.01) and PI (1.36 (0.47) vs. 1.73 (0.4), p = 0.01) values between FGR and AGA groups on day 3.Conclusion: Significant differences in MCA resistive and pulsatility indices were noted in the first few days of life of FGR neonates with abnormal antenatal Doppler as compared with AGA neonates. This may suggest a delayed transition or persistence of cerebral redistribution in FGR neonates.What is Known:• FGR infants have increased risk of neonatal morbidity and mortality, and long-term neuro-disabilities.• Antenatal Doppler Ultrasound is the most common modality used to assess fetal growth restriction.What is New:• Antenatally detected abnormal cerebral Dopplers may persist during the neonatal period in growth-restricted neonates.• Early cerebral Doppler values may be a useful marker to identify "at risk" growth-restricted neonates..

NeoDoppler: New ultrasound technology for continous cerebral circulation monitoring in neonates

BACKGROUND

There is a strong need for continuous cerebral circulation monitoring in neonatal care, since suboptimal cerebral blood flow may lead to brain injuries in preterm infants and other critically ill neonates. NeoDoppler is a novel ultrasound system, which can be gently fixed to the anterior fontanel and measure cerebral blood flow velocity continuously in different depths of the brain simultaneously. We aimed to study the feasibility, accuracy, and potential clinical applications of NeoDoppler in preterm infants and sick neonates.

METHOD

Twenty-five infants born at different gestational ages with a variety of diagnoses on admission were included. The probe was placed over the anterior fontanel, and blood flow velocity data were continuously recorded. To validate NeoDoppler, we compared the measurements with conventional ultrasound; agreement was assessed using Bland-Altman plots.

RESULTS

NeoDoppler can provide accurate and continuous data on cerebral blood flow velocity in several depths simultaneously. Limits of agreement between the measurements obtained with the two methods were acceptable.

CONCLUSION

By monitoring the cerebral circulation continuously, increased knowledge of cerebral hemodynamics in preterm infants and sick neonates may be acquired. Improved monitoring of these vulnerable brains during a very sensitive period of brain development may contribute toward preventing brain injuries.

Supine vs. Prone Position With Turn of the Head Does Not Affect Cerebral Perfusion and Oxygenation in Stable Preterm Infants ≤32 Weeks Gestational Age

Intraventricular hemorrhage (IVH) is a frequent major damage to the brain of premature babies ≤32 weeks gestational age, and its incidence (20–25%) has not significantly changed lately. Because of the intrinsic fragility of germinal matrix blood vessels, IVH occurs following disruption of subependymal mono-layer arteries and is generally attributed to ischemia-reperfusion alterations or venous congestion, which may be caused by turn of the head. Therefore, supine position with the head in a midline position is considered a standard position for preterm infants during their first days of life. We asked whether a change in body position (supine vs. prone) linked with a turn of the head by 90° in the prone position would change blood flow velocities and resistance indices in major cerebral arteries and veins of stable premature babies at two different time points (t0, day of life 2, vs. t1, day 9). Moreover, we assessed cerebral tissue oxygenation (cStO2) by near-infrared spectroscopy and determined correlations for changes in velocities and oxygenation. Twenty one premature infants [gestational age 30 (26–32) weeks] with sufficiently stable gas exchange and circulation were screened by ultrasonography and near-infrared spectroscopy. Peak systolic and end-diastolic blood flow velocities in the anterior cerebral arteries (29 ± 6 m/s vs. 28 ± 7 peak flow at t0, 36 ± 8 vs. 35 ± 7 at t1), the basilar artery, the right and the left internal carotid artery, and the great cerebral vein Galen (4.0 ± 0.8 m/s vs. 4.1 ± 1.0 maximum flow at t0, 4.4 ± 0.8 vs. 4.4 ± 1.0 at t1) did not show significant differences following change of body and head position. Also, there were no differences in cStO₂ (83 ± 7% vs. 84 ± 7 at t0, 76 ± 10 vs. 77 ± 11 at t1) and in vital signs such as heart rate and blood pressure. We conclude that change in body position with turn of the head in the prone position does not elicit significant alterations in cerebral blood flow velocities or in oxygenation of cerebral tissues. Maturational changes in arterial flow velocities and cStO₂ are not correlated. For this subgroup of premature infants at low risk of IVH our data do not support the concept of exclusive preterm infant care in supine position.