Early postnatal doppler assessment of cerebral blood flow velocity in healthy preterm and term infants

Assessment of systemic circulation using ultrasound Doppler in late onset neonatal sepsis and its clinical correlation: an observational study

OBJECTIVES

To measure the Doppler velocimetry parameters in the anterior cerebral artery (ACA), superior mesenteric artery (SMA), and main renal artery (RA) in neonates with late-onset sepsis and correlate it with associated clinical morbidities.

METHODOLOGY

Prospective observational study carried out at a tertiary-level neonatal intensive care unit in India in 2022, enrolling 20 neonates with late-onset neonatal sepsis (LONS). Baseline characteristics and sepsis parameters obtained. Serial ultrasound performed on days 1, 3, and 7 from the day of clinical sepsis in the ACA, SMA, and RA and velocimetry measurements obtained. The findings were compared with 20 gestational age (GA) matched neonates in the control arm.

RESULTS

The mean GA of neonates with LONS was 31.03 ± 2.79 weeks and their mean birthweight was 1474 ± 509.99 g. The peak systolic velocity, resistive and pulsatility indices were significantly higher in ACA, SMA, and RA and the end-diastolic velocity was significantly lower in ACA and RA (P < 0.05) in LONS. The incidences of intraventricular hemorrhage (IVH), necrotising enterocolitis (NEC), and acute kidney injury (AKI) in neonates with LONS were 45%, 50%, and 10% respectively. A subgroup analysis of the Doppler velocimetry parameters in the neonates with LONS and for neonates with and without clinical outcomes did not suggest a significant difference.

CONCLUSION

LONS is associated with alterations in cerebral, splanchnic, and renal perfusion seen as abnormal blood flow velocimetry and vascular resistance which may predispose to IVH, NEC, and AKI.

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.

Utility of Doppler ultrasound in early-onset neonatal sepsis

Background:

Neonatal sepsis is an important cause of morbidity and mortality among newborns. As there is paucity of literature regarding early alteration of the cerebral blood flow (CBF) in neonatal sepsis our study aims to evaluate the changes in the CBF velocities and Doppler indices in neonates with early-onset neonatal sepsis (EONS) and to evaluate the predictive accuracy of cerebral blood flow velocities (CBFV) by using ultrasound Doppler as a diagnostic marker of EONS.

Methods:

This cross-sectional analytical study was conducted over a period of 2 years with 123 neonates enrolled in the study. The neonates were divided into two groups: Group I (with 54 neonates) - neonates with EONS and group II (with 69 neonates) - age-matched neonates without any signs of sepsis. Ultrasound Doppler examination was performed and the cerebral hemodynamics assessed in neonates during the first seventy two hours of life. Doppler indices and CBFV were measured in the internal carotid artery (ICA), middle cerebral artery (MCA), and vertebral artery (VA) of either side. Data were analyzed using the statistical program SPSS version 23.0 (SPSS Inc., Chicago, IL, USA). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated at different selected cutoff values for CBFV parameters.

Results:

Lower resistance and higher peak systolic velocity and end diastolic velocity have been documented in neonates with EONS.

Conclusion:

Our study shows that the cerebral hemodynamics in neonates with EONS is altered which can be assessed bedside by noninvasive ultrasound Doppler examination.

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..

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.

Effects of Nasal Continuous Positive Airway Pressure on Cerebral Hemodynamics in Preterm Infants

Background: To evaluate the effects of pressure levels on cerebral hemodynamics in premature infants receiving nasal continuous positive airway pressure (nCPAP) during the first 3 days of life. Methods: Forty-four preterm infants treated with nCPAP were divided into two groups: very preterm infants [gestational age 1 (GA1), GA < 32 weeks, n = 24] and moderate/late preterm infants (GA2 group, GA 32-37 weeks, n = 20). During monitoring, pressure levels were set at 4 → 6 → 8 → 4 cmH₂O, and cerebral hemodynamics was assessed by near-infrared spectroscopy (NIRS). Vital signs, peripheral oxygen saturation (SpO₂) and transcutaneous carbon dioxide pressure (TcPCO₂) were simultaneously recorded. Results: Pressures of 4-8 cmH₂O had no significant influence on cerebral hemodynamics, TcPCO₂, SpO₂ or other vital signs. The tissue oxygenation index (TOI), the difference between oxygenated hemoglobin (ΔHbO₂) and deoxygenated hemoglobin (ΔHHb) (ΔHbD), and cerebral blood volume (ΔCBV) were all significantly positively correlated with gestational and post-natal age, with fluctuations being greater in the GA1 group. ΔHbD and ΔCBV were also significantly positively correlated with TcPCO₂. Conclusions: No significant differences were observed in cerebral hemodynamics when the nCPAP pressure was set to 4-8 cmH₂O.

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.

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.

Calibrating Doppler imaging of preterm intracerebral circulation using a microvessel flow phantom

Introduction: Preterm infants are born during critical stages of brain development, in which the adaptive capacity of the fetus to extra-uterine environment is limited. Inadequate brain perfusion has been directly linked to preterm brain damage. Advanced high-frequency ultrasound probes and processing algorithms allow visualization of microvessels and depiction of regional variation. To assess whether visualization and flow velocity estimates of preterm cerebral perfusion using Doppler techniques are accurate, we conducted an in vitro experiment using a microvessel flow phantom.

Materials and Methods: An in-house developed flow phantom containing two microvessels (inner diameter 200 and 700 μm) with attached syringe pumps, filled with blood-mimicking fluid, was used to generate non-pulsatile perfusion of variable flow. Measurements were performed using an Esaote MyLab70 scanner.

Results: Microvessel mimicking catheters with velocities as low as 1 cm/s were adequately visualized with a linear ultrasound probe. With a convex probe, velocities <2 cm/s could not be depicted. Within settings, velocity and diameter measurements were highly reproducible [intra-class correlation 0.997 (95% CI 0.996–0.998) and 0.914 (0.864–0.946)]. Overall, mean velocity was overestimated up to threefold, especially in high velocity ranges. Significant differences were seen in velocity measurements when using steer angle correction and in vessel diameter estimation (p < 0.05).

Conclusion: Visualization of microvessel-size catheters mimicking small brain vessels is feasible. Reproducible velocity and diameter results can be obtained, although important overestimation of the values is observed. Before velocity estimates of microcirculation can find its use in clinical practice, calibration of the ultrasound machine for any specific Doppler purpose is essential. The ultimate goal is to develop a sonographic tool that can be used for objective study of regional perfusion in routine practice.