Exploratory Assessment of the Relationship Between Hemoglobin Volume Phase Index, Magnetic Resonance Imaging, and Functional Outcome in Neonates with Hypoxic–Ischemic Encephalopathy

Massaro, An N.; Lee, Jennifer K.; Vézina, Gilbert; Glass, Penny; O'Kane, A; Li, Ruoying; Chang, Taeun; Brady, Kenneth Martin; Govindan, Rathinaswamy B.

doi:10.1007/s12028-020-01150-8

Cited by 7 publications

(10 citation statements)

References 56 publications

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“…Hemoglobin volume phase index, which relies on an estimated relative total hemoglobin from NIRS along with continuous MAP to assess CA, was recently used in a cohort of neonates with HIE. Those with higher hemoglobin volume phase values at 24 h of life (indicating impaired CA) had a higher rate of death or severe brain injury by MRI ( 166 ). The author's proposed cutoff of hemoglobin volume phase index had a sensitivity of 86% and specificity of 74% for death or severe brain injury by MRI.…”

Section: Cerebral Blood Flow In Vulnerable Fetal and Neonatal Populationsmentioning

confidence: 99%

Cerebral Blood Flow Monitoring in High-Risk Fetal and Neonatal Populations

et al. 2022

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Cerebrovascular pressure autoregulation promotes stable cerebral blood flow (CBF) across a range of arterial blood pressures. Cerebral autoregulation (CA) is a developmental process that reaches maturity around term gestation and can be monitored prenatally with both Doppler ultrasound and magnetic resonance imaging (MRI) techniques. Postnatally, there are key advantages and limitations to assessing CA with Doppler ultrasound, MRI, and near-infrared spectroscopy. Here we review these CBF monitoring techniques as well as their application to both fetal and neonatal populations at risk of perturbations in CBF. Specifically, we discuss CBF monitoring in fetuses with intrauterine growth restriction, anemia, congenital heart disease, neonates born preterm and those with hypoxic-ischemic encephalopathy. We conclude the review with insights into the future directions in this field with an emphasis on collaborative science and precision medicine approaches.

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Section: Cerebral Blood Flow In Vulnerable Fetal and Neonatal Populationsmentioning

confidence: 99%

Cerebral Blood Flow Monitoring in High-Risk Fetal and Neonatal Populations

et al. 2022

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“…Dysfunctional autoregulation is known to be associated with brain injury in newborns with HIE ( 35 , 41 , 42 ). We previously showed that having blood pressure below MAPopt is associated with greater brain injury on early MRI and poorer 2-year neurodevelopmental outcomes ( 4 – 6 , 16 ).…”

Section: Discussionmentioning

confidence: 99%

“…The hemoglobin volume phase index (HVP) is one example of wavelet autoregulation monitoring that uses only frequency decomposition and a specific spectral coherence identified by multivariate autoregressive models. The HVP identified an association between dysfunctional autoregulation and brain injury on MRI, developmental delay, or death ( 35 ). Additional research is needed to identify potential prognostic differences between these related but different wavelet methods.…”

Section: Discussionmentioning

confidence: 99%

“…No other studies have calculated MAPopt using wavelet or multi-window autoregulation monitoring in HIE to our knowledge. Nonetheless, a separate study of HIE using a different wavelet autoregulation index showed that an approximate mean index difference of ≥0.25 identified neonates who died or suffered brain injury ( 35 ). Using these estimates, a sample of 17 newborns with brain injury and 17 without injury would have power >0.80 at the alpha 0.05 level (PS Power and Sample Size Calculations, v. 3.0) ( 36 , 37 ).…”

Section: Methodsmentioning

confidence: 99%

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Wavelet Autoregulation Monitoring Identifies Blood Pressures Associated With Brain Injury in Neonatal Hypoxic-Ischemic Encephalopathy

et al. 2021

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Dysfunctional cerebrovascular autoregulation may contribute to neurologic injury in neonatal hypoxic-ischemic encephalopathy (HIE). Identifying the optimal mean arterial blood pressure (MAPopt) that best supports autoregulation could help identify hemodynamic goals that support neurologic recovery. In neonates who received therapeutic hypothermia for HIE, we hypothesized that the wavelet hemoglobin volume index (wHVx) would identify MAPopt and that blood pressures closer to MAPopt would be associated with less brain injury on MRI. We also tested a correlation-derived hemoglobin volume index (HVx) and single- and multi-window data processing methodology. Autoregulation was monitored in consecutive 3-h periods using near infrared spectroscopy in an observational study. The neonates had a mean MAP of 54 mmHg (standard deviation: 9) during hypothermia. Greater blood pressure above the MAPopt from single-window wHVx was associated with less injury in the paracentral gyri (p = 0.044; n = 63), basal ganglia (p = 0.015), thalamus (p = 0.013), and brainstem (p = 0.041) after adjustments for sex, vasopressor use, seizures, arterial carbon dioxide level, and a perinatal insult score. Blood pressure exceeding MAPopt from the multi-window, correlation HVx was associated with less injury in the brainstem (p = 0.021) but not in other brain regions. We conclude that applying wavelet methodology to short autoregulation monitoring periods may improve the identification of MAPopt values that are associated with brain injury. Having blood pressure above MAPopt with an upper MAP of ~50–60 mmHg may reduce the risk of brain injury during therapeutic hypothermia. Though a cause-and-effect relationship cannot be inferred, the data support the need for randomized studies of autoregulation and brain injury in neonates with HIE.

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“…Cerebral autoregulation holds CBF relatively steady across changes in mean arterial blood pressure (MAP) through vasoreactivity. Autoregulatory function during therapeutic hypothermia has been shown to be associated with neurologic outcomes in multiple studies of HIE [6][7][8][9][10][11][12][13][14]. Despite evidence that autoregulation monitoring could help clarify hemodynamic goals that optimize cerebral vasoreactivity, no autoregulation metric has been proposed in neonatal clinical care medicine.…”

Section: Introductionmentioning

confidence: 99%

The Utility of Cerebral Autoregulation Indices in Detecting Severe Brain Injury Varies by Cooling Treatment Phase in Neonates with Hypoxic-Ischemic Encephalopathy

et al. 2022

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Identifying the hemodynamic range that best supports cerebral perfusion using near infrared spectroscopy (NIRS) autoregulation monitoring is a potential physiological marker for neonatal hypoxic-ischemic encephalopathy (HIE) during therapeutic hypothermia. However, an optimal autoregulation monitoring algorithm has not been identified for neonatal clinical medicine. We tested whether the hemoglobin volume phase (HVP), hemoglobin volume (HVx), and pressure passivity index (PPI) identify changes in autoregulation that are associated with brain injury on MRI or death. The HVP measures the phase difference between a NIRS metric of cerebral blood volume, the total hemoglobin (THb), and mean arterial blood pressure (MAP) at the frequency of maximum coherence. The HVx is the correlation coefficient between MAP and THb. The PPI is the percentage of coherent MAP-DHb (difference between oxygenated and deoxygenated hemoglobin, a marker of cerebral blood flow) epochs in a chosen time period. Neonates cooled for HIE were prospectively enrolled in an observational study in two neonatal intensive care units. In analyses adjusted for study site and encephalopathy level, all indices detected relationships between poor autoregulation in the first 6 h after rewarming with a higher injury score on MRI. Only HVx and PPI during hypothermia and the PPI during rewarming identified autoregulatory dysfunction associated with a poor outcome independent of study site and encephalopathy level. Our findings suggest that the accuracy of mathematical autoregulation algorithms in detecting the risk of brain injury or death may depend on temperature and postnatal age. Extending autoregulation monitoring beyond the standard 72 hours of therapeutic hypothermia may serve as a method to provide personalized care by assessing the need for and efficacy of future therapies extending past the hypothermia treatment phase.

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Exploratory Assessment of the Relationship Between Hemoglobin Volume Phase Index, Magnetic Resonance Imaging, and Functional Outcome in Neonates with Hypoxic–Ischemic Encephalopathy

Cited by 7 publications

References 56 publications

Cerebral Blood Flow Monitoring in High-Risk Fetal and Neonatal Populations

Cerebral Blood Flow Monitoring in High-Risk Fetal and Neonatal Populations

Wavelet Autoregulation Monitoring Identifies Blood Pressures Associated With Brain Injury in Neonatal Hypoxic-Ischemic Encephalopathy

The Utility of Cerebral Autoregulation Indices in Detecting Severe Brain Injury Varies by Cooling Treatment Phase in Neonates with Hypoxic-Ischemic Encephalopathy

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