Carbon Dioxide-Related Changes in Cerebral Blood Volume and Cerebral Blood Flow in Mechanically Ventilated Preterm Neonates: Comparison of Near Infrared Spectrophotometry and 133Xenon Clearance

Pryds, Ole; Greisen, Gorm; Skov, Liselotte; Friis-Hansen, B

doi:10.1203/00006450-199005000-00006

Cited by 165 publications

(98 citation statements)

References 9 publications

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“…Hypercarbia also causes cerebral vasodilatation (37) resulting in increased cerebral blood flow and oxygen delivery (38,39). CFOE is therefore expected to fall with increasing PaCO 2 -an association observed in both the present study and a previous study on newborn lambs (40).…”

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confidence: 70%

Effect of carbon dioxide on background cerebral electrical activity and fractional oxygen extraction in very low birth weight infants just after birth

et al. 2005

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Decreased arterial carbon dioxide tension (PaCO 2 ) results in decreased cerebral blood flow, which is associated with diminished cerebral electrical activity. In such a situation, cerebral fractional oxygen extraction (CFOE) would be expected to increase to preserve cerebral oxygen delivery. This study aimed to determine whether changes in blood gases in infants less than 30 wk' gestation were associated with changes in background electroencephalograms (EEG) and CFOE. Thirty-two very low birth weight infants were studied daily for the first three days after birth. Digital EEG recordings were performed for 75 min each day. CFOE, mean blood pressure and arterial blood gases were measured midway through each recording. EEG was analysed by (a) spectral analysis and (b) manual calculation of interburst interval. Blood pressure, pH and PaCO 2 did not have any effect on the EEG. On day one, only PaCO 2 showed a relationship with the relative power of the delta frequency band (0.5-3.5 Hz) and the interburst interval. The relative power of the delta band remained within normal limits when PaCO 2 was between 24 and 55 mm Hg on day one. There was a negative association between PaCO 2 and CFOE. The associations between PaCO 2 and EEG measurements were strongest on day one, weaker on day two, and absent on day three. The slowing of EEG and increased CFOE at lower levels of PaCO 2 are likely to be due to decreased cerebral oxygen delivery induced by hypocarbia. When PaCO 2 was higher, there was suppression of the EEG. Periventricular leukomalacia is an important cause of neurologic morbidity in very low birth weight infants (1) and has been associated with severe hypocarbia during the first 24 h after birth. This effect of arterial carbon dioxide tension (PaCO 2 ) on the brain is likely to be mediated through its effect on cerebral blood flow, which is decreased by hypocarbia. In such a situation, cerebral fractional oxygen extraction (CFOE) would be expected to increase, as cerebral oxygen delivery is reduced (8). Decreased cerebral oxygen delivery would also be expected to be associated with reduced cerebral electrical activity. A positive relationship between cerebral blood flow and integrated amplitude of the EEG has been demonstrated on a group of infants between 27 and 33 wk' gestation (9). However, no studies have described the relationship between background cerebral electrical activity and PaCO 2 in very low birth weight infants.Electroencephalography provides a noninvasive technique for monitoring cerebral electrical activity. The normal EEG pattern of infants less than 30 wk' gestation is markedly discontinuous and consists of long isoelectric periods called interburst intervals, interspersed with bursts of high voltage and mixed frequency activity (10). Two separate studies have linked adverse neurologic outcome of such infants with an abnormal background EEG activity characterised by prolonged Received February 18, 2004; accepted November 16, 2004

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confidence: 70%

Effect of carbon dioxide on background cerebral electrical activity and fractional oxygen extraction in very low birth weight infants just after birth

et al. 2005

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“…This method has been used to measure the response of the cerebral circulation to changes in arterial carbon dioxide tension (Pryds et al 1990 ;Wyatt et al 1991). Discrepancies have been observed between the change in CBV calculated by this method and CBV derived by the indicator dilution technique (Brun et al 1994).…”

Section: Nirs Studies In Newborn Infantsmentioning

confidence: 99%

Cerebral oxygenation and haemodynamics in the foetus and newborn infant

Wyatt

1997

Phil. Trans. R. Soc. Lond. B

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SUMMARYuantitative techniques have been derived for the measurement of global cerebral blood flow, cerebral blood volume, its response to changing arterial carbon dioxide tension and mixed cerebral venous saturation in the human newborn undergoing intensive care. Normal ranges have been established and significant disturbances of cerebral oxygenation and perfusion have been demonstrated in a variety of pathological conditions. Recently, absolute cerebral deoxyhaemoglobin concentration has been obtained in the newborn using second differential spectroscopy. When combined with the measurement of total cerebral haemoglobin concentration, the mean saturation of cerebral blood (SmcO # ) may be obtained, allowing global cerebral oxygenation to be determined continuously in the intensive care unit.Marked changes in the concentrations of cerebral oxy-and deoxyhaemoglobin have been observed in foetuses undergoing labour. Measurements of SmcO # from the foetal brain prior to delivery have shown the expected close correlation with acid-base status at birth. Although movement artefact remains a theoretical risk during uterine contractions, preliminary measurements of optical path length by intensitymodulated spectroscopy have demonstrated only small fluctuations. In future the clinical application of time, phase and spatially resolved spectroscopy is likely to improve both the quantitative accuracy and the regional specificity of physiological measurements in the foetal and neonatal brain.

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“…Clinical factors related to impaired cerebrovascular autoregulation are lower gestational age (GA) [29,34,35], lower birth weight (BW), lower glucose levels [29,34,36], higher clinical risk index for babies (CRIB) score [34], increased infant mortality [34,37], and higher PaCO 2 levels [15,38,39]. Perinatal risk factors such as pregnancy induced hypertension; antepartum hemorrhage and placental infarction are also associated with impaired cerebrovascular autoregulation [29].…”

Section: Clinical Factorsmentioning

confidence: 99%

“…Experience was initially gained by data from animal models like preterm lambs [11,12]. Early techniques that were used to study static autoregulation in preterm infants are the xenon clearance ( 133 Xe) technique or the oxyhemoglobin (HbO 2 ) method by NIRS [13][14][15].…”

Section: Concepts Of Static and Dynamic Autoregulationmentioning

confidence: 99%

“…Many physiological and biochemical mechanisms may interact and affect this complex mechanism. Accordingly, autoregulation results should be reviewed with changes in pH, PaCO 2 , PaO 2 , metabolism, blood glucose, sympathetic activation, and effects of neurovascular coupling [4,15,19,20] taken into account. We refer to other reviews for more in-depth information on these important confounders affecting cerebral vasoreactivity [4,7,[21][22][23].…”

Section: Concepts Of Static and Dynamic Autoregulationmentioning

confidence: 99%

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Measuring cerebrovascular autoregulation in preterm infants using near-infrared spectroscopy: an overview of the literature

Kooi¹,

Verhagen

Elting

et al. 2017

Expert Review of Neurotherapeutics

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(2017) Measuring cerebrovascular autoregulation in preterm infants using near-infrared spectroscopy: an overview of the literature, Expert Review of Neurotherapeutics, 17:8, 801-818, DOI: 10.1080/14737175.2017 Introduction:The preterm born infant's ability to regulate its cerebral blood flow (CBF) is crucial in preventing secondary ischemic and hemorrhagic damage in the developing brain. The relationship between arterial blood pressure (ABP) and CBF estimates, such as regional cerebral oxygenation as measured by near-infrared spectroscopy (NIRS), is an attractive option for continuous non-invasive assessment of cerebrovascular autoregulation. Areas covered: The authors performed a literature search to provide an overview of the current literature on various current clinical practices and methods to measure cerebrovascular autoregulation in the preterm infant by NIRS. The authors focused on various aspects: Characteristics of patient cohorts, surrogate measures for cerebral perfusion pressure, NIRS devices and their accompanying parameters, definitions for impaired cerebrovascular autoregulation, methods of measurements and clinical implications. Expert commentary: Autoregulation research in preterm infants has reported many methods for measuring autoregulation using different mathematical models, signal processing and data requirements. At present, it remains unclear which NIRS signals and algorithms should be used that result in the most accurate and clinically relevant assessment of cerebrovascular autoregulation. Future studies should focus on optimizing strategies for cerebrovascular autoregulation assessment in preterm infants in order to develop autoregulation-based cerebral perfusion treatment strategies. ARTICLE HISTORY

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Carbon Dioxide-Related Changes in Cerebral Blood Volume and Cerebral Blood Flow in Mechanically Ventilated Preterm Neonates: Comparison of Near Infrared Spectrophotometry and 133Xenon Clearance

Cited by 165 publications

References 9 publications

Effect of carbon dioxide on background cerebral electrical activity and fractional oxygen extraction in very low birth weight infants just after birth

Effect of carbon dioxide on background cerebral electrical activity and fractional oxygen extraction in very low birth weight infants just after birth

Cerebral oxygenation and haemodynamics in the foetus and newborn infant

Measuring cerebrovascular autoregulation in preterm infants using near-infrared spectroscopy: an overview of the literature

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