Tomoko Nishida

Developmental changes of optical properties in neonates determined by near-infrared time-resolved spectroscopy.

Near-infrared spectroscopy has been used for measurement of changes in cerebral Hb concentrations in infants to study cerebral oxygenation and hemodynamics. In this study, measurements by time-resolved spectroscopy (TRS) were performed in 22 neonates to estimate the values of light absorption coefficient and reduced scattering coefficient (μs), cerebral Hb oxygen saturation (Sco2), cerebral blood volume (CBV), and differential pathlength factor (DPF), and the relationships between postconceptional age and μs, Sco2, CBV, and DPF were investigated. A portable three-wavelength TRS system with a probe attached to the head of the neonate was used. The mean μs values at 761, 795, and 835 nm in neonates were estimated to be (mean ± SD) 6.46 ± 1.21, 5.90 ± 1.15 and 6.40 ± 1.16/cm, respectively. There was a significant positive relationship between postconceptional age and μs at those three wavelengths. The mean Sco2 value was calculated to be 70.0 ± 4.6%, and postconceptional age and Sco2 showed a negative linear relationship. The mean value of CBV was 2.31 ± 0.56 mL/100 g. There was a significant positive relationship between postconceptional age and CBV. The mean DPF values at 761, 795, and 835 nm were estimated to be 4.58 ± 0.41, 4.64 ± 0.46, and 4.31 ± 0.42, respectively. There was no relationship between postconceptional age and DPF at those three wavelengths. The results demonstrated that our near-infrared TRS method can be used to monitor μs, Sco2, CBV, and DPF in the neonatal brain at the bedside in an intensive care unit.

Functional lateralization of sensorimotor cortex in infants measured using multichannel near-infrared spectroscopy.

Multichannel near-infrared spectroscopy (MNIRS) was used for the functional imaging of the sensorimotor cortex of newborn infants during passive knee and elbow movement under sedated sleep. Contralateral knee and elbow movement caused a marked increase in the concentration of oxyhemoglobin ([oxyHb]) from the baseline values at site within the sensorimotor area in all infants. During ipsilateral knee and elbow movement, [oxyHb] showed smaller changes, equivalent to 64 ± 23 and 66 ± 28% of the changes that occurred with contralateral stimulation, respectively. The mean times corresponding to maximal changes in [oxyHb] were 16.1 ± 3.3 s for contralateral knee movement and 17.9 ± 5.7 s for contralateral elbow movement. No significant difference was noted between the mean latencies showing the maximal changes in [oxyHb] between contralateral and ipsilateral movement. There was a significant difference in the area and degree of response between the contralateral and ipsilateral movement. MNIRS could be a useful tool to understand the pathophysiology of the developing brain and monitor cortical responses in various clinical situations.

Extrauterine environment affects the cortical responses to verbal stimulation in preterm infants.

Using optical topography, changes in the cerebral oxygenation were compared in the parieto-temporal lobe of preterm and term infants of equal postconceptional age in response to verbal stimulation. Eight preterm infants of gestational age 23-34 weeks were studied at postconceptional term age (38-46 weeks). Ten term infants were studied at 2-11 days after birth. Twenty-four-channel near-infrared optical topography (NIOT) was used to measure changes in concentration of oxyhemoglobin ([oxyHb]), deoxyhemoglobin ([deoxyHb]) and total hemoglobin ([totalHb]) in the bilateral temporal cortices. Verbal stimulation was provided by a recording of a Japanese fairy tale. The latency in response to verbal stimulation was significantly shorter in the preterm infants than in the term infants. This time is thought to reflect brain development, particularly the development of the neuro-vascular coupling mechanisms in the cerebral cortex. The present results indicate that the number of days after birth is more closely related to development of auditory system and neuro-vascular coupling than is postconceptional age. Thus, this suggests that early extrauterine environment affects the cortical responses to verbal stimulation in preterm infants.

Relationship between cerebral oxygenation and phosphorylation potential during secondary energy failure in hypoxic-ischemic newborn piglets.

The aim of this study was to evaluate the hypothesis that cerebral hemoglobin (Hb) oxygenation is related to phosphorylation potential during primary and secondary cerebral energy failure in newborn infants who have experienced birth asphyxia. We subjected newborn piglets to severe transient cerebral hypoxic-ischemia followed by resuscitation and examined cerebral energy metabolism by 31P-magnetic resonance spectroscopy and evaluated changes in cerebral Hb oxygen saturation (ScO2) using full-spectrum near-infrared spectroscopy before, during, and up to 54 h after the hypoxic-ischemic insult. ScO2 was significantly decreased during the hypoxic-ischemic insult compared with baseline values. During secondary energy failure, piglets were separated based on the relationship between the ratio of phosphocreatine to inorganic phosphate and ScO2; those with a negative correlation were less injured than those with a positive correlation. These results indicate that changes in ScO2 as measured by near-infrared spectroscopy are related to phosphorylation potential during secondary energy failure in asphyxiated infants.

In vitro production of bilirubin photoisomers by light irradiation using neoBLUE

Background: The light‐emitting diode is used as one of the new light sources for phototherapy. NeoBLUE (Atom Medical, Tokyo, Japan) incorporates blue light‐emitting diodes for the treatment of neonatal hyperbilirubinemia. The authors compared the in vitro efficacy of neoBLUE with conventional phototherapy devices.

The effect of blood transfusion on cerebral hemodynamics in preterm infants

Anemia of prematurity commonly occurs in infants with very low birth weight; blood transfusion is an important treatment. However, there is no clear evidence to support the criteria currently widely used, based on blood hemoglobin (bHb) and hematocrit indices. Previous studies showed that overtransfusion or a low threshold for transfusion could induce complications or neurologic sequelae, respectively. We hypothesized that a cerebral hemodynamic index may provide an appropriate criterion for determining the need for transfusion in anemic preterm infants.

Simultaneous measurement of cerebral hemoglobin oxygen saturation and blood volume in asphyxiated neonates by near-infrared time-resolved spectroscopy.

BACKGROUND Hypoxic-ischemic encephalopathy (HIE) usually results in a poor clinical outcome even when treated with hypothermic therapy (HT). Early postnatal changes in cerebral blood oxygenation and hemodynamics may be critical determinants of brain injury and the efficacy of HT. OBJECTIVES We measured cerebral hemoglobin oxygen saturation (ScO2) and cerebral blood volume (CBV) by near-infrared time-resolved spectroscopy (TRS) in HT-treated and non-HT-treated neonatal HIE patients to assess the influence of these parameters on clinical outcome. METHODS We retrospectively compared ScO2, CBV, and clinical outcomes of 11 neonates with HIE: 5 were treated by HT (HT-treated; 33.5°C±0.5°C for 72h starting approximately 6h after delivery) and 6 were not (non-HT-treated). Both CBV and ScO2 were measured by TRS at 6, 24, 48, and 72h after birth. Magnetic resonance imaging (MRI) was performed 1-2weeks after birth to assess brain injury. RESULTS Five neonates had adverse outcomes (3 HT-treated, 2 non-HT-treated). Of these, 1 died within 3days of birth and 4 had abnormal MRI findings, including basal ganglia, white matter, and/or thalamic lesions. The other 6 neonates had normal MRI findings (favorable outcome). At 6h after birth, CBV was significantly higher in neonates with adverse outcomes compared with those with a favorable outcome. At 24h after birth, ScO2 was significantly higher in neonates with adverse outcomes. Furthermore, we found that combined CBV at 24h after birth plus ScO2 had the best predictive ability for neurological outcome: sensitivity, specificity, positive predictive value, and negative predictive value were all 100%. CONCLUSION Early postnatal CBV and ScO2 elevations were predictive of a poor outcome in HIE. Therefore, measuring combined CBV plus ScO2 at 24h after birth can allow more precise prediction of neurological outcome. Control of postnatal CBV and ScO2 is critical for effective HIE treatment.

Cortisol levels in umbilical vein and umbilical artery with or without antenatal corticosteroids.

Abstract  Background : The developmental changes of the umbilical cortisol levels in neonates at gestational age of 23–41 weeks were studied and the effect of antenatal steroid administration on the umbilical cortisol levels were examined.

Extrauterine environment influences spontaneous low-frequency oscillations in the preterm brain

Low-frequency oscillations in cerebral blood flow that are suggestive of resting-state brain activity have recently been reported, but no study on the development of resting-state brain activity in preterm infants has been performed. The objective of this study was to measure the cerebral blood flow oscillations, which are assumed to represent brain function in the resting state, in preterm and term infants of the same postconceptional age. The subjects were 9 preterm infants who had reached full term (gestational age (GA): 23-34 weeks, postconceptional age: 37-46 weeks) and 10 term infants (GA: 37-40 weeks, postconceptional age: 37-41 weeks). Their changes in concentration of oxyhemoglobin ([oxyHb]) and deoxyhemoglobin ([deoxyHb]) were measured in the parieto-temporal region during quiet sleep using multi-channel near-infrared spectroscopy, and the power spectral densities (PSD) of the oscillations in the concentrations of these molecules were analyzed and compared. The preterm infants displayed a higher proportion of 0.06-0.10 Hz low frequency oscillations of [oxyHb] and [deoxyHb] than the term infants, and the gestational age and the proportion of low frequency oscillations were inversely correlated. These findings suggest that resting-state cerebral blood flow oscillations differ between preterm and term infants, and that the development of circulatory regulation and nerve activity in preterm infants are influenced by the extrauterine environment.

Changes in Breast Hemodynamics in Breastfeeding Mothers

The purpose of the present study was to measure changes in blood volume and the oxygenation state of breast tissue during breastfeeding with the use of near-infrared time-resolved spectroscopy (TRS) as a noninvasive method. Forty breastfeeding mothers were divided into 2 groups in which measurements were made in the contralateral breast (group A) and in the ipsilateral breast (group B). The tissue concentrations of oxyhemoglobin, deoxyhemoglobin, and total hemoglobin and the hemoglobin oxygen saturation were measured in the breast by using TRS during a breastfeed. In both groups A and B, the values of all parameters decreased significantly after the start of breastfeeding compared with the pre-breastfeeding values. The values of all parameters fluctuated cyclically after the beginning of the breastfeed. Time-resolved spectroscopy is an effective noninvasive method for investigating the hemodynamics of the breast during breastfeeding. J Hum Lact. 24(4):415-421. El propósito de este estudio fue la medición de los cambios en el volumen sanguíneo y laoxigenación del tejido mamario durante la lactancia con el uso de espectroscopia de resolución de tiempo (TRS) como método no invasivo. Cuarenta madres lactantes se dividieron en dos grupos donde se hicieron mediciones en el seno contralateral (grupo A) y en el mismo seno (grup B). Se midieron en el tejido concentraciones de oxihemoglobina, deoxihemoglobina y hemoglobina total y saturación de oxígeno en hemoglobina a través del uso de TRS durante la lactancia. En ambos grupos A y B, los valores de todos los parámetros disminuyeron significativamente después del comienzo de la lactancia comparado con los valores antes de la lactancia. Los valores de todos los parámetros fluctuaron cíclicamente después del principio de la lactancia. El TRS en un método no invasivo efectivo para investigar la hemodinámica del seno durante la lactancia.