Measuring Near-Infrared Spectroscopy Derived Cerebral Autoregulation in Neonates: From Research Tool Toward Bedside Multimodal Monitoring

Abstract

Introduction: Cerebral autoregulation (CAR), the ability of the human body to maintain cerebral blood flow (CBF) in a wide range of perfusion pressures, can be calculated by describing the relation between arterial blood pressure (ABP) and cerebral oxygen saturation measured by near-infrared spectroscopy (NIRS). In literature, disturbed CAR is described in different patient groups, using multiple measurement techniques and mathematical models. Furthermore, it is unclear to what extent cerebral pathology and outcome can be explained by impaired CAR.Aim and methods: In order to summarize CAR studies using NIRS in neonates, a systematic review was performed in the PUBMED and EMBASE database. To provide a general overview of the clinical framework used to study CAR, the different preprocessing methods and mathematical models are described and explained. Furthermore, patient characteristics, definition of impaired CAR and the outcome according to this definition is described organized for the different patient groups.Results: Forty-six articles were included in this review. Four patient groups were established: preterm infants during the transitional period, neonates receiving specific medication/treatment, neonates with congenital heart disease and neonates with hypoxic-ischemic encephalopathy (HIE) treated with therapeutic hypothermia. Correlation, coherence and transfer function (TF) gain are the mathematical models most frequently used to describe CAR. The definition of impaired CAR is depending on the mathematical model used. The incidence of intraventricular hemorrhage in preterm infants is the outcome variable most frequently correlated with impaired CAR. Hypotension, disease severity, dopamine treatment, injury on magnetic resonance imaging (MRI) and long term outcome are associated with impaired CAR. Prospective interventional studies are lacking in all research areas.Discussion and conclusion: NIRS derived CAR measurement is an important research tool to improve knowledge about central hemodynamic fluctuations during the transitional period, cerebral pharmacodynamics of frequently used medication (sedatives-inotropes) and cerebral effects of specific therapies in neonatology. Uniformity regarding measurement techniques and mathematical models is needed. Multimodal monitoring databases of neonatal intensive care patients of multiple centers, together with identical outcome parameters are needed to compare different techniques and make progress in this field. Real-time bedside monitoring of CAR, together with conventional monitoring, seems a promising technique to improve individual patient care.

Assessing low-frequency oscillations in cerebrovascular diseases and related conditions with near-infrared spectroscopy: a plausible method for evaluating cerebral autoregulation?

“…93 To our knowledge, the only studies using the two methods on the same group of patients are conducted by Tachtsidis et al 24 and Rowley et al 55 showing similar trends in PSD, while it is difficult to assess it quantitatively from the publicized results. Other methods are described thoroughly and compared in an excellent review by Thewissen et al 94 regarding NIRS investigations of CA in neonates.…”

Cerebral Oxygenation During Neonatal Intubation–Ancillary Study of the Prettineo–Study

“…However, systemic hypotension, defined as a mean arterial blood pressure (MABP) (in mmHg) lower than gestational age (in weeks) (14), is poorly associated with low systemic blood flow (15). A multimodal evaluation has been proposed to assess cerebral hemodynamics and oxygenation beyond blood pressure monitoring (16), using Near Infra Red Spectroscopy (NIRS) (17). This technology offers a non-invasive monitoring of peripheral microcirculation, reflecting the adequacy between oxygen delivery and consumption in situ (18).…”

Cerebral autoregulation and activity after propofol for endotracheal intubation in preterm neonates

“…CAR can be calculated using different mathematical models to describe the similarities between the dynamically changing rScO 2 and MABP signals. 13 This is especially of interest during fluctuations in MABP (i.e., drug-related hypotension). 14 Multi-modal monitoring of physiological measurements with amplitude-integrated electroencephalography (aEEG) and cerebral fractional tissue oxygen extraction (cFTOE) can elucidate the effect of sedative drugs on cerebral activity and cerebral metabolism.…”