Fast Doppler as a novel bedside measure of cerebral perfusion in preterm infants

Abstract

Background: Altered cerebral perfusion from impaired autoregulation may contribute to the morbidity and mortality associated with premature birth. We hypothesized that fast Doppler imaging could provide a reproducible bedside estimation of cerebral perfusion and autoregulation in preterm infants. Methods: This is a prospective pilot study using fast Doppler ultrasound to assess blood flow velocity in the basal ganglia of 19 subjects born at 26-32 wk gestation. Intraclass correlation provided a measure of test-retest reliability, and linear regression of cerebral blood flow velocity and heart rate or blood pressure allowed for estimations of autoregulatory ability. results: The intraclass correlation when imaging in the first 48 h of life was 0.634. We found significant and independent correlations between the systolic blood flow velocity and both systolic blood pressure and heart rate (P = 0.015 and 0.012 respectively) only in the 26-28 wk gestational age infants in the first 48 h of life. conclusion: Our results suggest that fast Doppler provides reliable bedside measurements of cerebral blood flow velocity at the tissue level in premature infants, acting as a proxy for cerebral tissue perfusion. Additionally, autoregulation appears to be impaired in the extremely preterm infants, even within a normal range of blood pressures.

Evaluating a Targeted Bedside Measure of Cerebral Perfusion in a Nonhuman Primate Model of Neonatal Hypoxic‐Ischemic Encephalopathy

“…We found good intraobserver repeatability with US imaging of the thalamus in this primate model of HIE, which was consistent with our previous report on imaging the human basal ganglia 12 as well as reports on other cerebral hemodynamic measures, such as superior vena cava flow. 19 The thalamus RI measures did not show an improved ability to predict outcomes over anterior cerebral artery measures, but they had a consistently stronger association with clinical measures of disease severity, such as serum and MRS lactate, outside the first 24 hours of life.…”

“…This speed allows for high sensitivity, especially in deeper tissues, and the ability to quantify flow information over entire regions of interest. Our group previously demonstrated that fast Doppler US could effectively measure blood flow velocities in the deep gray matter of human neonates . We hypothesized that measuring the RI at the level of the thalamus using fast Doppler US in a nonhuman primate model of HIE would show a stronger association with adverse neurologic outcomes, clinical illness severity, and death than measuring the RI in the anterior cerebral artery.…”

Cerebral Perfusion Is Perturbed by Preterm Birth and Brain Injury

“…Several prior studies have assessed cerebral brain perfusion in the neonate using various techniques such as cerebral artery Doppler, near-infrared spectroscopy, PET, and xenon-enhanced CT. [8][9][10][11] These techniques lack anatomic detail, use indirect cerebral perfusion measurements, and/or have a risk of radiation or the need for intravenous contrast. [12][13][14] Conversely, in the present study, we used the arterial spin-labeling (ASL) MR imaging technique, which has recently emerged as a promising noninvasive method for direct quantitative assessment of cerebral perfusion in high-risk neonates, including neonates with perinatal stroke 15 or hypoxic-ischemic encephalopathy, 16 without radiation risk or the need for intravenous contrast.…”

Inotropes do not increase cardiac output or cerebral blood flow in preterm piglets

“…There is also evidence of a significant cerebral hypoxic burden in many preterm infants over the first days after birth (22). In addition, cerebral autoregulation is inconsistent in very preterm infants (20,23). Together, these factors suggest that low cerebral blood flow could contribute to the high disability rate experienced by preterm newborns (2).…”