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 (' s ), cerebral Hb oxygen saturation (ScO 2 ), cerebral blood volume (CBV), and differential pathlength factor (DPF), and the relationships between postconceptional age and ' s , ScO 2 , 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 ' s values at 761, 795, and 835 nm in neonates were estimated to be (mean Ϯ SD) 6.46 Ϯ 1.21, 5.90 Ϯ 1.15 and 6.40 Ϯ 1.16/cm, respectively. There was a significant positive relationship between postconceptional age and ' s at those three wavelengths. The mean ScO 2 value was calculated to be 70.0 Ϯ 4.6%, and postconceptional age and ScO 2 showed a negative linear relationship. The mean value of CBV was 2.31 Ϯ 0.56 mL/100 g. There was a significant positive relationship between postconceptional age and CBV. During the perinatal period, the brain undergoes anatomic, functional, and metabolic changes. The anatomic changes include neuronal proliferation, migration, organization, and myelination, and the metabolic changes match the process of initial overproduction and subsequent elimination of excessive neurons, synapses, and dendritic spines known to occur in the developing brain. Noninvasive assessment of cerebral anatomic changes and of oxygen delivery and utilization is useful for evaluating the effectiveness of therapy and for preventing oxygen toxicity in seriously ill neonates.Near-infrared spectroscopy (NIRS) has been used in the clinical field with various measuring devices using several wavelengths. A method using continuous-wave NIRS has been developed and reported to be suitable for clinical use in infants (1-7). However, current commercially available NIRS systems can detect only changes in cerebral Hb. Because NIRS is based on the modified Beer-Lambert law, a change in hematocrit and blood volume as well as developmental and pathophysiologic changes in brain tissue affect the pathlength of near-infrared light. In a few recent studies, absolute values of cerebral Hb oxygen saturation (ScO 2 ) and cerebral blood volume (CBV) in infants were measured without inducing Hb concentration changes by using full-spectral near-infrared spectroscopy (8 -11) and spatially resolved spectroscopy (12). However, these

Near-infrared spectroscopy (NIRS) has been used for measurement of cerebral hemoglobin (Hb) concentrations in neonates to study cerebral oxygenation and hemodynamics. We perform measurements by portable three-wavelength NIR time-resolved spectroscopy (TRS) in a piglet hypoxia model with various degrees of oxygenation to estimate the absorption coefficient (mu(a)) and reduced scattering coefficient (mu(s)') of the head. Measurements of absolute values of mu(a) at three wavelengths enable estimation of Hb concentration and Hb oxygen saturation in the head (SO2). However, there is a problem concerning which background absorption should be used to estimate Hb concentration in the head derived from mu(a) at three wavelengths because it is different from a simple in vitro model. Therefore, we use two different background absorption values with the assumption that background absorption is due only to 85% (by volume) water or that background absorption is equal to absorption of the piglet head with blood exchange transfusion by fluorocarbon (FC), and we compared SO2 measured by TRS with arterial Hb oxygen saturation (SaO2) and sagittal sinus venous Hb oxygen saturation (SvO2) measured by a co-oximeter at several inspired fractional O2(FI(O2)) concentrations. We find that SO2 values using the absorption (abs) of the piglet head with blood exchange transfusion (BET) by FC are not significantly different from SO2 values using the water-only background at FI(O2) in the range of 15 to 100%, but that the values using abs of the head with BET by FC are lower than the values using the water-only background at FI(O2) in the range of 12 to 4%. The SO2 values calculated from the water-only background are higher than those of SaO2 at FI(O2) in the range of 10 to 4%. However, SO2 values using the abs of the head with BET by FC are between those of SaO2 and SvO2 over the whole range of FI(O2). Therefore, abs of the head with BET by FC is more useful for estimation of the absolute values of oxyHb and deoxyHb of the piglet head.

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The objective of this study was to confirm physiological reactions in the breast and brain in mothers during breastfeeding and collect basic objective data, aiming at effective support for breastfeeding. Ten healthy women who were exclusively breastfeeding their babies participated in this study. Changes in the concentration of oxygenated Hb (oxyHb) and deoxygenated Hb in the breasts and frontal cortex of these women during breastfeeding lactation were measured using double-channel near-infrared spectroscopy (NIRS). Changes were measured in three conditions: (1) in both breasts; (2) the ipsilateral breast and frontal cortex; and (3) the contralateral breast and frontal cortex. OxyHb and total Hb (totalHb) levels in the bilateral breasts decreased significantly after the onset of breastfeeding in comparison with prebreastfeeding levels. These two values repeatedly increased and decreased thereafter. In the frontal cortex, regardless of which breast was involved, oxyHb and totalHb levels increased significantly in comparison with prebreastfeeding levels. Similar hemodynamic changes occurred simultaneously in the bilateral breasts during breastfeeding regardless of the feeding or nonfeeding side. Hemodynamic changes were also noted in the frontal cortex, but the reactions in the breast and prefrontal cortex were different and not synchronous, confirming that the physiological circulatory dynamics during breastfeeding vary among organs.

ABSTRACT: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 31 P-magnetic resonance spectroscopy and evaluated changes in cerebral Hb oxygen saturation (ScO 2 ) using full-spectrum nearinfrared spectroscopy before, during, and up to 54 h after the hypoxic-ischemic insult. ScO 2 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 ScO 2 ; those with a negative correlation were less injured than those with a positive correlation. These results indicate that changes in ScO 2 as measured by near-infrared spectroscopy are related to phosphorylation potential during secondary energy failure in asphyxiated infants. (Pediatr Res 65: 317-322, 2009) H ypoxic-ischemic encephalopathy remains a major cause of permanent neurodevelopmental disability and infant mortality. Phosphorus nuclear magnetic resonance spectroscopy ( 31 P-MRS) has shown that on the first day of life there are no differences in the high-energy phosphate metabolites found in the brains of infants who have experienced birth asphyxia and normal infants (1,2). However, over the next several days, inverse changes in the concentrations of phosphocreatine (PCr) and inorganic phosphate (Pi) cause a significant reduction in the ͓PCr͔/͓Pi͔ ratio of asphyxiated infants, despite optimal medical management. Low values of ͓PCr͔/͓Pi͔ were found to be associated with very poor prognoses for survival and early neurodevelopmental outcome (1,2). The late metabolic deterioration that is characteristic of asphyxiated infants indicates the existence of metabolic stress and implies that there may be a therapeutic window during which appropriate therapy could improve outcomes.Near-infrared spectroscopy (NIRS), which uses light in the near-infrared range, can detect changes in the oxygenation state of hemoglobin (Hb) and water in biologic tissues. Several studies have shown the usefulness of NIRS as a noninvasive means of measuring hemodynamic changes in infants (3-10), particularly for quantifying cerebral blood volume (CBV) during small-induced changes in arterial oxygen saturation (4,7), for quantifying cerebral blood flow with rapid changes in oxyHb (or indocyanine green as an intravascular tracer) (5,8,9), and for quantifying cerebrovenous oxygen saturation during downward tilting of the head or jugular venous occlusion (10).Cerebral vascular Hb oxygen saturation (ScO 2 ) is another parameter that can be measured in absolute terms using NIRS without manipulating inspired oxygen concentration or impeding venous outflow. The output value is the weighted average ...