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To understand the value of measuring neonatal cerebral regional oxygen saturation (rSO2) using near infrared spectroscopy (NIRS) in assessing cerebral oxygenation, to establish the normal range of neonatal cerebral rSO2 and to collect data of the changes of cerebral rSO2 under certain disease status.Nine large hospitals participated in the multicenter randomized clinical trial from Jan 2007 to Apr 2008. Using the NIRS human tissue oximeter (TSAH-100) independently developed in China, the cerebral rSO2 of 223 normal full-term and 95 otherwise healthy preterm neonates without any special disease, was detected at 1, 2 and 3 days after birth, respectively. The cerebral rSO2 of 102 neonates with diseases which may affect the cerebral oxygenation, was also detected during the severe phases. The pulse oxygen saturation (SpO2) measured at the finger tip, and also the arterial oxygen saturation (SaO2) measured by blood gas analysis, which could indicate the oxygen supply of the whole body, were obtained simultaneously. The correlations among cerebral rSO2, pulse SpO2 and arterial SaO2 were analyzed.(1) The cerebral rSO2 of the normal full-term neonates was (62+/-2)%. Cerebral hypoxia was defined as rSO2 lower than 58%. The cerebral rSO2 of the normal full-terms was steady at 1, 2 and 3 days after birth respectively, without any significant differences among them (F=0.610, P0.05). The cerebral rSO2 of the neonates with diseases was (55+/-7)%, which was significantly lower than that of the normal full-term neonates (t=15.492, P0.05). (2) The cerebral rSO2 was positively correlated with the SpO2 (r=0.74, P0.01) and the SaO2 (r=0.71, P0.01). (3) Under some special diseases, the changes of cerebral rSO2 was asynchronous with those of the SpO2: (1) For 18 cases under severe cerebral damages or under relatively low hemoglobin concentration, the cerebral rSO2 was significantly low (50%-58%), but the SpO2 was still normal (above 90%). (2) During the recovery of some critically ill neonates, the increase of cerebral rSO2 was lagged as compared with that of pulse SpO2. Especially, during the severe phases of 6 cases with multi-organ failure, the SpO2 and the cerebral rSO2 were both significantly low (55%-80% for SpO2, and 44%-50% for cerebral rSO2); when the diseases were alleviated, although the SpO2 recovered to above 85%, the cerebral rSO2 was still significantly low (around 50%). (3) In 3 cases, during the severe phases of serious hypoxic-ischemic encephalopathy (HIE), the cerebral rSO2 significantly increased to 70%-72%, which was significantly higher than the normal value (62%).The range of cerebral rSO2 of the normal full-term neonates was (62+/-2)%. Cerebral oxygenation can be externally indicated by the rSO2 noninvasively and continuously measured by NIRS, which was positively correlated with traditional pulse SpO2 and arterial SaO2. In some special diseases, the rSO2 measured by NIRS can be helpful for clinical diagnoses and treatments.

As a non-invasive technique for measuring tissue oxygenation, near-infrared spectroscopy (NIRS) has increasing applications in detecting cerebral hypoxia-ischemia. The authors, introduced the basic principle of the NIRS oximeter developed independently by our group (TSAH-100). The authors achieved the optimal coupling between the probe and the detected cerebral tissue. The present study investigated different regional oxygen saturations of brain (rSO2) measured non-invasively by NIRS, arterial blood oxygen saturation (SaO2) measured invasively by blood gas analysis and physiological parameters in newborn pigs with different hypoxia, in order to prove if the non-invasively cerebral rSO2 can indicate cerebral oxygenation status in clinical practice. Using this oximeter, cerebral rSO2 of 28 newborn piglets under different oxygenation status was detected. After mechanical ventilation and inhalation of 8%-17% oxygen for 30 min in the newborn pigs, the pigs were grouped according to the inhalation of oxygen. With the inhalation of 13%-17% oxygen was mild hypoxia group, with 10%-13% was moderate hypoxia group, and with 8%-10% was severe hypoxia group. There were 4 animals in mild hypoxia group, 8 animals in moderate hypoxia group, 12 animals in severe hypoxia group and 4 animals were in the normal control group. The physiological parameters were monitored during the experiment. The SaO2 were invasively measured by blood gas analysis after the experiment. The results indicate that both rSO2 and SaO2 decreased after different degree of hypoxia and there was a good correlation between cerebral rSO2 non-invasively measured by NIRS and SaO2 invasively measured by blood gas analysis (p0.001). Cerebral rSO2 was also consistent with the degree of hypoxia and the changes in physiological parameters after hypoxia. The arterial pH and the mean arterial pressure (MAP) in the severe hypoxia group was lower than that in the control group (p0.05). The blood lactic acid in the severe hypoxia group was higher than that in the control group (p0.05). Thus, the rSO2 can accurately and directly indicate cerebral oxygenation status and can also replace the SaO2 invasively measured by blood gas analysis. Cerebral hypoxia-ischemia can be non-invasively and conveniently diagnosed using NIRS.

To study correlation of brain hypoxia of different degrees with brain function and damage.The brain regional oxygen saturation (rSO2) was determined by using a non-invasive near infrared spectroscopy (NIRS) technique in 15 piglets; the piglets were subjected to inhale 3% - 11% oxygen-nitrogen mixed gas through mechanical ventilation for 30 min. The piglets were divided into groups according to the level of brain rSO2 (i.e.30%, 30% - 35%, 35% - 40%, and 40% - 50%), and the data were compared with those of the control group (rSO260%). Changes of brain function were detected through amplitude and frequency of EEG waves and signal complexity. The piglets were sacrificed via decapitation 72 h after brain damage, and then histopathological and ultrastructural examinations were performed on cerebral cortex and hippocampal CA1 area.In the group with rSO240%, the mean arterial pressure (MAP) after hypoxia was (56 +/- 0.00) mm Hg (1 mm Hg = 0.133 kPa), the blood lactic acid (LA) was (2.3 +/- 1.2) mmol/L, the EEG findings were within normal range, and there was no change in brain tissue ultrastructure. In the group with brain rSO2 = 30% approximately 40%, the MAP was (73 +/- 8) mm Hg, the LA was (8.2 +/- 3.9) mmol/L, the EEG waves showed decreased amplitude, frequency and complexity, but restored to some extent after hypoxia. The brain tissue ultrastructure showed damages to the cerebral cortex and neuron mitochondria at hippocampal CA1 area. In the group with brain rSO230%, the MAP was (35 +/- 0) mm Hg, the LA was (12 +/- 2) mmol/L, the EEG showed decreased amplitude, frequency, and complexity of signals compared with those of the normal control group, and was difficult to restore after hypoxia in some of the piglets; the brain tissue ultrastructure appeared to be similar to the changes seen with high-degree swollen cerebral cortex and neuron mitochondria at hippocampal CA1 area.Different degrees of hypoxia had different influence on brain function and brain damage. The lower the brain rSO2, the more severe the damages to the brain and its function. The rSO2 of brain tissues detected with noninvasive NIRS can reflect brain injury and its severity during cerebral anoxia.

To compare the differences in cerebral oxygenation responses between the infants born preterm and full-term infants and to evaluate the early cognitive ability of infants born preterm.Cerebral oxygenation after light stimulation was detected by near infrared spectroscopy (NIRS) in preterm infants at 3 or 6 months corrected gestational age (GA). The results were compared with those of age-matched infants born at term.The start and peak response time of cerebral oxygenation occurring after light stimulation in preterm infants at 3 months corrected GA was 17.2 +/- 5.2 and 38.4 +/- 9.6 seconds respectively, which were significantly longer than in age-matched term infants (13.1 +/- 2.7 and 28.9 +/- 5.0 seconds respectively) (P0.05). The maximum response value of hemoglobin, oxyhemoglobin and regional oxygen saturation of the preterm infants at 3 months corrected GA was (1.2 +/- 0.5)%, (1.5 +/- 0.6)%, and (1.3 +/- 0.4)% respectively , which were significantly lower than that of the term infants [(2.3 +/- 0.3)%, (2.8 +/- 0.3)% and (2.4 +/- 0.5)% respectively] (P0.05). Cerebral oxygenation responses to light stimulation in preterm infants examined at 6 months corrected GA were not significantly different from age-matched term infants.Cerebral oxygenation responses to light stimulation in infants born preterm at 3 months corrected GA are not as good as age-matched term infants, but were close to the level of age-matched term infants at 6 months corrected GA. This suggests that the early cognitive ability of preterm infants before 3 months corrected GA might fall behind age-matched term infants.

To study the relationship between early brain response to extrinsic stimulation and neurodevelopment in preterm infants, assess the brain function of preterm infants in the early stage, and thereby to provide objective evidence for the degree of neurodevelopment in preterm infants and to evaluate prognosis.Using near infrared spectroscopy (NIRS), the brain response to sound stimulation of 90 preterm infants at different gestational age was observed and compared with the result obtained from 20 full term infants. The neonatal behavioral neurological assessment (NBNA) was performed at corrected age of 40 weeks, and the infants were followed up for 2 years. The effect of gestational age and brain damage on preterm infants, the relation between early brain response in preterm infants and their neurodevelopment was evaluated.All the preterm infants responded to different degrees to auditory stimulation after birth. The time to beginning to react and the time to appearance of the peak reaction were attained after auditory stimulation and the time to beginning to resume when the auditory stimulation was stopped was (278 +/- 94) s, (446 +/- 67) s and (199 +/- 52) s, respectively, which were significantly longer than those observed in the full term infants (107 +/- 30) s, (264 +/- 51) s and (131 +/- 46) s, respectively. The maximum reactions of hemoglobin, oxyhemoglobin and regional oxygen saturation in the infants after gestational age 32 weeks was (0.3 +/- 0.3)%, (0.7 +/- 0.5)% and (0.3 +/- 0.3)%, respectively, which were significantly lower than those in the full term infants (1.7 +/- 0.7)%, (1.7 +/- 0.8)% and (1.6 +/- 0.7)%, respectively. When the brain response of preterm infants was compared with that in infants without brain damage, the speed of the reaction was slow, the maximum reaction was low. The brain response in preterm infant was correlated with NBNA at corrected age of 40 weeks. It was found during the following-up that abnormal neurodevelopment was associated with poor brain reaction.NIRS can be used to evaluate brain response of infants. Preterm infants display brain response to auditory stimulation. Early brain response is correlated with neurodevelopment.

The absorption andreduced scattering parameters of tissue can provide information on a variety of physiologic processes. In the present paper, the local optical properties of 23 infant foreheads were measured with a two-wavelength (788 and 832 nm) portable frequency-domain NIR spectroscopic techinque, based on a standard reference phantom with known optical properties. The single source-detector separation is 40 mm. The cerebral blood volume and tissue oxygensaturation were also derived from themeasured absorption coefficients.