ABSTRACT:The coupling of cerebral intravascular oxygenation (dHbD) with mean arterial blood pressure (MABP) was taken as a reflection of autoregulation assuming constant arterial oxygen content. However, this method is sensitive to movement artifacts. We examined whether the cerebral tissue oxygenation index (cTOI) and regional oxygen saturation (rScO 2 ) may replace dHbD and changes in total Hb (dHbT), respectively. Correlation (COR) and coherence (COH) were used to measure the agreement of MABP with rScO 2 /dHbT and cTOI/dHbD. dHbD/cTOI and dHbT/rScO 2 recordings of, respectively, 34 and 20 preterm infants in need for intensive care were studied during the first days of life. dHbD and cTOI were obtained with the NIRO300 and rScO 2 and dHbT with the INVOS4100. Invasive MABP was measured continuously. COR and COH scores of MABP versus dHbD/ dHbT were compared with the corresponding ones by replacing dHbD/ dHbT by cTOI/rScO 2 , respectively. Generally, no significant score differences were found for dHbD/cTOI. Differences for dHbT/rScO 2 were slightly larger but still within the normal variation of the parameters. Differences become insignificant when restricting calculations to epochs of larger variation in MABP (Ͼ10 mm Hg). Hence, we suggest that cTOI and rScO 2 can be used to study cerebral autoregulation in newborns. (Pediatr Res 69: 548-553, 2011) L assen (1) was the first to describe cerebral autoregulation in man. Cerebral autoregulation is a property of arteries in the brain to constrict in response to an increase in transmural blood pressure and to dilate in response to a decrease in blood pressure, with the effect of keeping blood flow more or less constant within a range of arterial blood pressures. This response has a limited capacity and as a result blood flow will decrease or increase when blood pressure decreases below a lower threshold or increases above an upper threshold, respectively (2). Pryds et al. (3) described a loss of autoregulation in very sick preterm infants, which resulted in the hypothesis that there was a loss of autoregulation in preterm infants and that controlling blood pressure would prevent cerebral damage. However, there is no good evidence that a correlation (COR) between blood pressure and cerebral damage exists, indicating that autoregulation is more complex in premature infants than originally thought (4). Even with very low blood pressures, normal cerebral blood flow (CBF) was described in very LBW infants (5). Both dynamic and static autoregulation are described. Dynamic autoregulation describes the response of autoregulation within 5 to 10 s after a change in blood pressure and can be assessed noninvasively with Doppler ultrasound (6 -8) and near-infrared spectroscopy (NIRS) (9). Tsuji et al. (10) were the first to report on the use of NIRS to assess autoregulation. In a previous study (11), the authors validated changes in the cerebral intravascular oxygenation (dHbD) as a measure of CBF in an experimental model. dHbD, representing the difference between changes in o...

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The ductal clipping in se has no negative effect on the cerebral oxygenation.

The concordance between the change in the Mean Arterial Blood Pressure (MABP) and the Cerebral Blood Flow (CBF) is studied using the Correlation, Coherence and Partial Coherence methods in order to detect Impaired Cerebral Autoregulation in Neonates. The presence of impaired autoregulation is assessed by the use of the Critical Percentage of Recording Time (CPRT). The changes in CBF are reflected by the measurement of changes in cerebral intravascular oxygenation (HbD), regional cerebral oxygen saturation (rSO(2)), and cerebral tissue oxygenation (TOI), as measured by Near-Infrared Spectroscopy (NIRS) (INVOS4100 and NIRO300). The relation between impaired autoregulation and long term clinical outcomes in premature infants is studied.

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