Neonatal color Doppler US study: normal values of cerebral blood flow velocities in preterm infants in the first month of life

Correlation of anterior cerebral artery resistive index with early comorbidities in preterm neonates

Introduction

This study was undertaken to find the clinical correlation of resistive index (RI) in the anterior cerebral artery (ACA) of preterm neonates admitted to the Neonatal Intensive care unit (NICU) with comorbidities such as perinatal asphyxia, neonatal sepsis, and necrotizing enterocolitis (NEC).

Methods

An observational analytical study was conducted, including preterm neonates (<35 weeks) admitted to the NICU. Ultrasound cranium scans were performed on days 1-3 and 7 of life as per the study protocol. Baseline and clinical data of asphyxia, sepsis, and NEC were obtained. Images were acquired using a 4-8-MHz probe on a Sonosite M-turbo machine (Bothell, WA, USA). All statistical calculations were done using SPSS version 21.0 (SPSS Inc., Chicago, IL, USA) with the application of the Kolmogorov-Smirnov test and the Mann-Whitney test.

Results

During the study period, a total of 739 neonates were admitted. Of these, 73 neonates constituted the study group. Among the 73 patients, 33 were preterm neonates without comorbidities and 40 neonates had comorbidities such as perinatal asphyxia, sepsis, and NEC stage 2 and 3 (necrotizing enterocolitis). In the present study, the mean RI on day 3 of life was 0.76 ± 0.04 in neonates without comorbidities and 0.77 ± 0.04 in neonates with comorbidities, with a p-value of 0.247. On the 7th day of life, the mean RI was 0.82 ± 0.03 in both groups, with a p-value of 0.42.

Conclusion

We could not find any significant clinical correlation of RI in the ACA of preterm neonates <35 weeks of gestation with comorbidities.

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.

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.

Cerebral monitoring of very preterm infants with anterior cerebral artery resistive index and early NIRS

BACKGROUND

The prediction of adverse conditions in the preterm neonatal brain might be improved by cerebral monitoring using combined measures of cerebral function, including oxygenation and blood flow parameters. To perform the consecutive measurements of the resistive index (RI) from the anterior cerebral artery (ACA) within the first week of life and to evaluate the association of these measurements with cerebral oxygen saturation (Csat) detected by near-infrared spectroscopy (NIRS).

METHODS

This prospective cohort study enrolled very preterm infants, <32 weeks of gestational age, admitted to a tertiary neonatal intensive care unit. Csat levels were continuously monitored using NIRS for 72 h after birth. ACA RI measurements were obtained on the first, third, and seventh days of life by using transcranial Doppler ultrasound. These measurements were also compared between infants with and without unfavorable outcomes, including severe intraventricular hemorrhage (IVH) and early mortality.

RESULTS

A total of 96 preterm infants with Csat and ACA RI measurements were analyzed. Age at birth was 28.3 ± 1.9 weeks and birth weight was 1090 ± 305 g. The mean Csat of the infants was 77.1% ± 8.2% during the first 72 h of life. Mean ACA RI values were 0.76 ± 0.10, 0.75 ± 0.08, and 0.77 ± 0.08 on the first, third, and seventh days of life, respectively. RI on the first day of life was significantly higher in infants delivered by cesarian section than in those delivered vaginally (0.77 vs. 0.69; p = 0.017). Infants who died earlier had significantly higher ACA RI values on the first day than infants who survived beyond the first 7 postnatal days (0.83 vs. 0.76; p < 0.001).

DISCUSSION

There was no association between ACA RI and Csat in the early period of life. ACA RI values on the first postnatal day might be significant for predicting early mortality in very preterm infants.

Neonatologist-Performed Cranial Ultrasonography in the Neonatal Intensive Care Unit

Cranial ultrasound (CUS) is an initial screening imaging tool used to evaluate the neonatal brain. It is an accessible, inexpensive, and harmless technique that can be used at bedside as frequently as required. Timely focused CUS in the neonatal care unit can play a major role in the diagnosis, follow-up, and management of brain damage. Despite the increasing use of point-of-care ultrasonography by intensive care physicians, neonatologist-performed CUS remains unusual. This review aims to provide an overview of neonatal CUS to neonatologists, focusing on the optimal settings, standard planes of the brain, and main pathologies in preterm infants. Adding Doppler studies allows evaluation of the patency of intracranial arteries and veins, flow velocities, and indices. This may provide an opportunity for earlier targeted circulatory support to prevent brain injury and improve long-term neurodevelopmental outcomes.

Critical Closing Pressure by Diffuse Correlation Spectroscopy in a Neonatal Piglet Model

The critical closing pressure (CrCP) of the cerebral vasculature is the arterial blood pressure (ABP) at which cerebral blood flow (CBF) ceases. Because the ABP of preterm infants is low and close to the CrCP, there is often no CBF during diastole. Thus, estimation of CrCP may become clinically relevant in preterm neonates. Transcranial Doppler (TCD) ultrasound has been used to estimate CrCP in preterm infants. Diffuse correlation spectroscopy (DCS) is a continuous, noninvasive optical technique that measures microvascular CBF. Our objective was to compare and validate CrCP measured by DCS versus TCD ultrasound. Hemorrhagic shock was induced in 13 neonatal piglets, and CBF was measured continuously by both modalities. CrCP was calculated using a model of cerebrovascular impedance, and CrCP determined by the two modalities showed good correlation by linear regression, median r ² = 0.8 (interquartile range (IQR) 0.71-0.87), and Bland-Altman analysis showed a median bias of -3.5 (IQR -4.6 to -0.28). This is the first comparison of CrCP determined by DCS versus TCD ultrasound in a neonatal piglet model of hemorrhagic shock. The difference in CrCP between the two modalities may be due to differences in vasomotor tone within the microvasculature of the cerebral arterioles versus the macrovasculature of a major cerebral artery.

Assessing key clinical parameters before and after intraventricular hemorrhage in very preterm infants

Intraventricular cerebral hemorrhage (IVH) is one of the most severe complications of premature birth, potentially leading to lifelong disability. The purpose of this paper is the assessment of the evolution of three of the most relevant parameters, before and after IVH: mean arterial pressure (MAP), arterial carbon dioxide pressure (pCO2), and cerebral blood flow (CBF). Clinical records of 254 preterm infants with a gestational age of 23-30 weeks, with and without a diagnosis of IVH, were reviewed for MAP and arterial pCO2 in the period up to 7 days before and 3 days after IVH or during the first 10 days of life in cases without IVH.Conclusion: A statistically significant increase in pCO2 and decrease in MAP in patients with IVH compared with those without were detected. Both the mean values and the mean absolute deviations of CBF were computed in this study, and the latter was significantly higher than in control group. High deviations of CBF, as well as hypercapnia and hypotension, are likely to contribute to the rupture of cerebral blood vessels in preterm infants, and consequently, to the development of IVH.What is Known:• The origin of IVH is multifactorial, but mean arterial pressure, carbon dioxide partial pressure, and cerebral blood flow are recognized as the most important parameters.• In premature infants, the autoregulation mechanisms are still underdeveloped and cannot compensate for cerebral blood flow fluctuations.What is New:• The numerical simulation of CBF is shown to be a promising approach that may be useful in the care of preterm infants.• The mean values of CBF before and after IVH in the affected group were similar to those in the control group, but the mean absolute deviations of CBF in the affected group before and after IVH were significantly higher than that in the control group.

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..

Early energy restriction in premature infants and bronchopulmonary dysplasia: a cohort study

Bronchopulmonary dysplasia (BPD) is a multifactor pathology. Animal studies and cohort studies suggest that poor nutrient intake after birth increases the risk of BPD. The objective of the present study was to determine the existence of association between BPD in very low birth weight (VLBW) and energy intake during the first week of life. We recorded in a retrospective cohort study the intake of enteral and parenteral macronutrients during this period by examining the nutritional and clinical history of 450 VLBW newborns admitted to the neonatal intensive care unit. After applying the relevant exclusion criteria, data for 389 VLBW infants were analysed, of whom 159 developed some degree of BPD. Among the newborns with BPD, energy and lipid intake was significantly lower and fluid intake was significantly higher. The energy intake for the 25th percentile in the group without BPD was 1778·2 kJ/kg during the first week of life. An energy intake <1778·2 kJ/kg in this period was associated with a 2-fold increase in the adjusted risk of BPD (OR 2·63, 95 % CI 1·30, 5·34). The early nutrition and the increase of energy intake in the first week of life are associated in our sample with a lower risk of BPD developing.

Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique

Objective:

To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns.

Methods:

This is an intervention study, which included 40 preterm infants (≤34 weeks) aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5min. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed.

Results:

Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50), the end diastolic flow velocity (p=0.17), the mean flow velocity (p=0.07), the resistance index (p=0.41) and the pulsatility index (p=0.67) over time.

Conclusions:

The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants.

[Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique]

OBJECTIVE

To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns.

METHODS

This is an intervention study, which included 40 preterm infants (≤34 weeks) aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5minutes. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed.

RESULTS

Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50), the end diastolic flow velocity (p=0.17), the mean flow velocity (p=0.07), the resistance index (p=0.41) and the pulsatility index (p=0.67) over time.

CONCLUSIONS

The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants.

Effects of preeclampsia on the amplitude integrated electroencephalography activity in preterm infants

OBJECTIVE

Preeclampsia leads to chronic intrauterine hypoxia by interfering with placental blood supply. The aim of this study was to investigate whether preeclampsia exposure has an influence on the central nervous system of infants, as monitored by amplitude integrated electroencephalography (aEEG).

METHODS

We recruited 52 infants with gestational age between 30 and 34 weeks. Twenty-seven infants were born to preeclamptic mothers, and 25 gestational age-matched infants whose mothers were healthy were enrolled as a control group. aEEG recordings were performed between 24 and 48 h of life using a cerebral function monitor (CFM) (Olympic Brainz monitor). Along with aEEG, middle cerebral artery (MCA) blood flow velocities (BFV) were measured using Doppler ultrasound.

RESULTS

The duration of quiet sleep was significantly shorter (P=0.001), and Burdjalov score was lower (P=0.04) in the preeclampsia group. However, there was no change in MCA BFV in this group.

CONCLUSIONS

Preeclampsia altered cerebral electrical activity of premature infants born to preeclamptic mothers.

Resistive indices of cerebral arteries in very preterm infants: values throughout stay in the neonatal intensive care unit and impact of patent ductus arteriosus

BACKGROUND

Little is known about cerebral artery resistive index values in infants born extremely preterm.

OBJECTIVE

To report resistive index values in various cerebral arteries in a prospective cohort of preterm infants born at <29 weeks' gestation, and to compare resistive index in these arteries and assess the relationship between resistive index and hemodynamically significant patent ductus arteriosus.

MATERIALS AND METHODS

Using Doppler imaging, we obtained resistive index values of internal carotid arteries, basilar artery, anterior cerebral artery, and pial and striatal arteries in the first 3 days of age and weekly thereafter until discharge or death. We analyzed paired observations using the Wilcoxon signed-rank test, between-group comparisons with the Mann-Whitney test.

RESULTS

We performed 771 examinations in 235 infants. Resistive indices differed among arteries: vessels with larger diameters showed significantly higher resistive indices. Resistive index in infants without patent ductus arteriosus was lower than that in infants with hemodynamically significant patent ductus arteriosus (median in anterior cerebral artery: 0.75 and 0.82, respectively; P<0.001), though this was not statistically significant in all arteries. There was no difference in pre- and post-ligation resistive indices in infants who underwent patent ductus arteriosus ligation.

CONCLUSION

For accurate follow-up and comparison of cerebral artery resistive index, the same artery should be examined on each occasion.

Randomized, Placebo-Controlled Trial of Dobutamine for Low Superior Vena Cava Flow in Infants

OBJECTIVE

To gather information for a future confirmatory trial of dobutamine (DB) for circulatory impairment (ie, low superior vena cava [SVC] flow).

STUDY DESIGN

A total of 127 infants born at < 31 weeks gestational age were serially scanned from birth to 96 hours after birth. The infants were randomly assigned to 2 groups and were treated with DB (stepwise dose increase, 5-10-15-20 μg/kg/min) or placebo if they had an SVC flow < 41 mL/kg/min within the first 24 hours after birth. The primary outcome measures were the achievement and maintenance of an SVC flow ≥ 41 mL/kg/min. Secondary outcome measures were the short-term evolution of clinical and biochemical variables, near-infrared spectroscopy, cranial Doppler ultrasound, and clinical outcomes.

RESULTS

SVC flow increased throughout the first 96 hours for the entire cohort. All of the randomized infants (n = 28) except 2 achieved and maintained an SVC flow ≥ 41 mL/kg/min after intervention; however, the infants treated with DB (n = 16) showed a higher heart rate and improved base excess compared with those treated with placebo (n = 12). Low SVC flow was associated with low gestational age (P = .02) and poor condition at birth (P = .02). Low SVC flow significantly increased the risk of severe ischemic events (OR, 13; 95% CI, 2.4-69.2; P < .01).

CONCLUSION

This exploratory trial demonstrates a tendency toward improved short-term clinical and biochemical perfusion variable outcomes in infants with low SVC flow treated with DB.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01605279) and the European Clinical Trials Database (EurodraCT 2009-010901-35).

Effects of antenatal magnesium sulfate treatment on cerebral blood flow velocities in preterm neonates

OBJECTIVE

The objective of this study is to investigate the effects of antenatal magnesium sulfate (MgSO4) on cerebral blood flow (CBF) velocities in preterm neonates.

STUDY DESIGN

In this prospective case-control study, we included 53 neonates born between 26 and 34 weeks of gestation. Twenty neonates were exposed to MgSO4 antenatally and 33 were not. Serial daily Doppler flow measurements of middle cerebral artery (MCA) were performed.

RESULT

Significantly increased MCA mean velocities were found in the MgSO4 group. A progressive increase in serial Doppler measurements of MCA mean velocity from day 1 to day 5 of life was detected in both groups.

CONCLUSION

There is significant increase in MCA mean velocities in preterm neonates receiving antenatal MgSO4. This increment in CBF velocities might explain the protective role of MgSO4 in ischemic events and hypoxic brain damage.

Cerebral oxygen metabolism in neonates with congenital heart disease quantified by MRI and optics

Neonatal congenital heart disease (CHD) is associated with altered cerebral hemodynamics and increased risk of brain injury. Two novel noninvasive techniques, magnetic resonance imaging (MRI) and diffuse optical and correlation spectroscopies (diffuse optical spectroscopy (DOS), diffuse correlation spectroscopy (DCS)), were employed to quantify cerebral blood flow (CBF) and oxygen metabolism (CMRO(2)) of 32 anesthetized CHD neonates at rest and during hypercapnia. Cerebral venous oxygen saturation (S(v)O(2)) and CBF were measured simultaneously with MRI in the superior sagittal sinus, yielding global oxygen extraction fraction (OEF) and global CMRO(2) in physiologic units. In addition, microvascular tissue oxygenation (StO(2)) and indices of microvascular CBF (BFI) and CMRO(2) (CMRO(2)(i)) in the frontal cortex were determined by DOS/DCS. Median resting-state MRI-measured OEF, CBF, and CMRO(2) were 0.38, 9.7 mL/minute per 100 g and 0.52 mL O(2)/minute per 100 g, respectively. These CBF and CMRO(2) values are lower than literature reports for healthy term neonates (which are sparse and quantified using different methods) and resemble values reported for premature infants. Comparison of MRI measurements of global S(v)O(2), CBF, and CMRO(2) with corresponding local DOS/DCS measurements demonstrated strong linear correlations (R(2)=0.69, 0.67, 0.67; P<0.001), permitting calibration of DOS/DCS indices. The results suggest that MRI and optics offer new tools to evaluate cerebral hemodynamics and metabolism in CHD neonates.

Observational study of cerebral hemodynamics during dopamine treatment in hypotensive ELBW infants on the first day of life

OBJECTIVE

To evaluate cerebral hemodynamics during dopamine treatment in hypotensive (mean arterial blood pressure (MABP)<gestational age) extremely low birth weight (ELBW) infants.

STUDY DESIGN

Continuous monitoring of cerebral blood flow velocity (CBFv), MABP and PCO2 was performed in hypotensive ELBW infants on the first day of life, beginning with an ∼15-min baseline reading and continued during advancing dopamine infusion until MABP was optimized. Physiological variables and CBFv reactivity were compared before and after MABP was optimized.

RESULT

Fifteen hypotensive ELBW infants (625±174 g; 24 (23 to 24.8) weeks) were studied. Mean CBFv increased from 10.9±3.7 to 15.7±5.7 cm s(-1) (P=0.001) simultaneously as MABP increased from 22.3±2.8 to 35.2±9.7 mm Hg (P<0.001). Mean CBFv reactivity (95% confidence interval (CI)) was 3.9 (1.6 to 6.2) %mm Hg(-1). Nine infants died and/or developed severe intraventricular hemorrhage (IVH).

CONCLUSION

Mean CBFv increased pressure-passively as MABP was optimized by dopamine treatment in very sick hypotensive ELBW infants on the first day of life.

Relationship of neonatal cerebral blood flow velocity asymmetry with early motor, cognitive and language development in term infants

The objective of this study was to examine the relationships of Doppler cerebral blood flow velocity (CBFV) asymmetry measures with developmental outcomes in term infants. Doppler CBFV parameters (peak systolic velocity [PSV] and mean velocity [MV]) of the bilateral middle cerebral arteries of 52 healthy term infants were prospectively examined on postnatal days 1-5, and then their motor, cognitive and language development was evaluated with the Bayley Scales of Infant and Toddler Development, Third Edition, at 6, 12, 18 and 24 months of age. The left CBFV asymmetry measure (PSV or MV) was calculated by subtracting the right-side value from the left-side value. Left CBFV asymmetry measures were significantly positively related to motor scores at 6 (r = 0.3-0.32, p < 0.05) and 12 (r = 0.35, p < 0.05) months of age, but were not related to cognitive or language outcome. Thus, the leftward hemodynamic status of the middle cerebral arteries, as measured by cranial Doppler ultrasound in the neonatal period, predicts early motor outcome in term infants.

Doppler middle cerebral artery peak systolic velocity for diagnosis of neonatal anemia

OBJECTIVES

The peak systolic velocity (PSV) of the middle cerebral artery was found to be predictive of fetal anemia and is routinely applied in the treatment of such fetuses. Our objective was to determine whether a correlation exists between the PSV in the neonatal middle cerebral artery and hemoglobin levels for possible future implementation in clinical practice.

METHODS

A prospective study on 151 neonates was conducted, examining their middle cerebral artery PSV concomitantly with their hemoglobin level during the first 36 hours after delivery. The study population included 122 normocythemic, 24 anemic, and 5 polycythemic neonates. An analysis of variance between normocythemic, anemic, and polycythemic neonates was performed, and a regression analysis of the PSV versus hemoglobin levels was conducted.

RESULTS

The normocythemic neonates had a mean middle cerebral artery PSV ± SD of 41.3 ± 11.4 cm/s, whereas the anemic neonates had a significantly higher PSV (63.8 ± 28.5 cm/s), and the polycythemic neonates had a significantly lower PSV (26.8 ± 7.4 cm/s; P < .001). A statistically significant correlation was found between hemoglobin levels and the middle cerebral artery PSV (P < .01).

CONCLUSIONS

Neonatal anemia and polycythemia can be rapidly diagnosed at the bedside by examining the middle cerebral artery PSV. This technique can be used as an ancillary measure to promptly diagnose acute neonatal blood volume changes for an immediate intervention.

Normal cerebral, renal and abdominal regional oxygen saturations using near-infrared spectroscopy in preterm infants

OBJECTIVE

The aim of this study is to characterize baseline regional oxygen saturations (rSO(2)) in stable preterm infants during the first weeks of life.

STUDY DESIGN

Cerebral, renal and abdominal rSO(2) were continuously monitored from the time of birth to 21 days in twelve preterm infants of 29-34 weeks gestation. Regional saturations were evaluated for trends over time, variability and differences between gestational ages (GAs) and reported pediatric values.

RESULT

Both cerebral (66-83%) and renal (64-87%) rSO(2) baselines were within the range of reported neonatal values but consistently decreased over the first weeks of life (P<0.01). The baseline abdominal rSO(2) was 32-66% and increased with GA (P=0.05). The rSO(2) variability was lowest for cerebral measurements and highest at the abdomen. Abdominal rSO(2) variability decreased over time (P≤0.05).

CONCLUSION

Daily baseline rSO(2) in preterm infants changes over the first weeks of life, especially at the abdomen. Evolution in baseline rSO2 over time may indicate regional developmental maturation of physiological oxygen balance.

External hydrocephalus in discordant birth weight twins: a case report

The term "external hydrocephalus (EH)" is used to describe excessively rapid head growth in infants who are found to have enlarged subarachnoid spaces and little or no ventricular enlargement. EH has not yet been described in discordant birth weight twins. We report the cases of two sets of discordant twins with normal neonatal course and normal neonatal brain ultrasound scans who developed an EH in the first months after birth and had a mild neurodevelopmental delay. Our findings suggest that EH may be part of neurologic morbidity in discordant birth weight twins and represents one of the potential complications to look for in the follow-up of these infants.

Cerebral hemodynamics in preterm infants during positional intervention measured with diffuse correlation spectroscopy and transcranial Doppler ultrasound

Four very low birth weight, very premature infants were monitored during a 12 degrees postural elevation using diffuse correlation spectroscopy (DCS) to measure microvascular cerebral blood flow (CBF) and transcranial Doppler ultrasound (TCD) to measure macrovascular blood flow velocity in the middle cerebral artery. DCS data correlated significantly with peak systolic, end diastolic, and mean velocities measured by TCD (p(A) =0.036, 0.036, 0.047). Moreover, population averaged TCD and DCS data yielded no significant hemodynamic response to this postural change (p>0.05). We thus demonstrate feasibility of DCS in this population, we show correlation between absolute measures of blood flow from DCS and blood flow velocity from TCD, and we do not detect significant changes in CBF associated with a small postural change (12 degrees ) in these patients.

Tracheal suctioning is associated with prolonged disturbances of cerebral hemodynamics in very low birth weight infants

OBJECTIVES

Examining the effects of tracheal suctioning on cerebral hemodynamics of normotensive ventilated very low birth weight (VLBW) infants with normal cranial ultrasounds; determining the factor(s) influencing changes in mean cerebral blood flow velocity (CBFv) after suctioning.

METHODS

Seventy-three VLBW infants had continuous monitoring of mean arterial blood pressure (MABP), PaCO(2), PaO(2) and mean CBFv before, during, and after 202 suctioning sessions during the first week of life. Peak (or nadir) and relative changes of the four variables for 45 min after suctioning were calculated. Multiple linear regression was used to determine the factor(s) influencing changes in mean CBFv after suctioning.

RESULT

Birth weight was 928+/-244 g; gestational age was 27.0+/-2.0 weeks. Mean CBFv increased to 31.0+/-26.4% after suctioning and remained elevated for 25 min. PaCO(2) was highly associated with mean CBFv (P<0.001), whereas MABP and PaO(2) were not.

CONCLUSION

We observed prolonged increases of mean CBFv following suctioning in ventilated VLBW infants that were previously unrecognized. This is concerning since disturbances of CBF may be associated with subsequent brain injury.