New developments in cerebral blood flow autoregulation analysis in preterm infants: a mechanistic approach

Abstract

Background: Impaired autoregulation capacity implies that changes in cerebral perfusion follow changes in blood pressure; however, no analytical method has explored such a signal causality relationship in infants. We sought to develop a method to assess cerebral autoregulation from a mechanistic point of view and explored the predictive capacity of the method to classify infants at risk for adverse outcomes. Methods: The partial directed coherence (PDC) method, which considers synchronicity and directionality of signal dependence across frequencies, was used to analyze the relationship between spontaneous changes in mean arterial pressure (MAP) and the cerebral tissue oxygenation index (TOI). PDC MAP>>TOI indicated that changes in TOI were induced by MAP changes, and PDC TOI>>MAP indicated the opposite. results: The PDC MAP>>TOI and PDC TOI>>MAP values differed. PDC MAP>>TOI adjusted by gestational age predicted low superior vena cava flow (≤41 ml/kg per min), with an area under the receiver operating characteristic curve of 0.72 (95% CI: 0.63-0.81; P < 0.001), whereas PDC TOI>>MAP did not. The adjusted pPDC MAP>>TOI (the average value per patient) predicted severe intracranial hemorrhage and mortality. conclusion: PDC MAP>>TOI allows for a noninvasive physiological interpretation of the pressure autoregulation process in neonates. PDC MAP>>TOI is a good classifier for infants at risk of brain hypoperfusion and adverse outcomes.

No neurodevelopmental benefit of cerebral oximetry in the first randomised trial (SafeBoosC II) in preterm infants during the first days of life

“…Being born extremely preterm carries a 20% risk of death, and 25% of survivors have moderate‐to‐severe neurodevelopmental impairment, namely cerebral palsy (CP) or cognitive impairment . The respiratory and circulatory systems of extremely preterm infants are immature, and cerebral autoregulation is impaired, especially during the transition from intrauterine to extrauterine life . In addition, oxygen transport may be impaired by low haemoglobin levels and this makes the developing premature brain susceptible to fluctuations in cerebral blood flow .…”

Diagnostic and predictive value of Doppler ultrasound for evaluation of the brain circulation in preterm infants: a systematic review

“…13 In addition, impaired autoregulation is correlated with adverse outcome in infants. 14,15 In 1979, Bada et al first reported that cerebral Doppler studies played a role in the diagnosis of neonatal intracranial injury. 16,17 Doppler provides a valuable tool to follow changes in flow velocities, to assess changes in cerebrovascular resistance and to determine the lower limits of cerebral blood flow autoregulation.…”

Cerebral Hemodynamics in Premature Infants

“…The upper and lower limit of autoregulation are depicted, above and below which the brain is more susceptible to injury. The critical closing pressure (CrCP) is the arterial blood pressure at which the cerebral blood flow is zero.gula tion was associated with increased mortality in this atrisk population28,29)…”