The application of extended modified Lambert Beer model for measurement of blood carboxyhemoglobin and oxyhemoglobin saturation

This work presents the use of extended Modified Lambert Beer(MLB)model for accurate andcontinuous monitoring of percent blood carboxyhemoglobin(COHb)(SCO)and oxyhemoglobin(OxyHb)saturation(SO,)via a fitting procedure.This quantification technique is based on theabsorption characteristics of hemoglobin derivatives in the wavelength range of 520-600 nm togive the best estimates of the required parameters.A comparison of the performance of the developed model and MILB law is made using attenuation data from Monte Carlo simulations for a two-layered skin model.The results revealed a lower mean absolute error of 0.4%in the valuesestimated by the developed model as compared to 10%that is given by the MILB law.This studyshowed that the discussed approach is able to provide consistent and accurate measurement ofblood SO,and SCO across diferent skin pigmen tations suggesting that it may potentially be usedas an alternative means for clinical diagnosis of carbon monoxide(CO)poisoning.

Nerve growth factor affects focal cerebral cortical neuronal Bcl-2 and Bax expression in a mouse model of oxyhemoglobin-induced subarachnoid hemorrhage

BACKGROUND： Studies have demonstrated that oxyhemoglobin （OxyHb） can induce brain cell apoptosis in vivo.OBJECTIVE： To observe the effects of exogenous nerve growth factor （NGF） on cerebral cortical neuronal Bcl-2 and Bax expression in mice with OxyHb-induced subarachnoid hemorrhage. DESIGN, TIME AND SETTING： A completely randomized grouping, controlled animal experiment was performed at the Experimental Center for Biomedicine, College of Medicine, Xi＇an Jiaotong University between February and April 2005. MATERIALS： Fifty-four healthy, male, adult, ICR mice were included in this study. Subarachnoid hemorrhage was induced by a subarachnoid injection of OxyHb in 48 mice. Mouse NGF was obtained from Xiamen Beidazhilu Bioengineering Co., Ltd., China.METHODS： All 54 mice were randomly divided into three groups： control （n = 6）, injury （n = 24）, and NGF （n = 24）. The NGF group received a subarachnoidal administration of OxyHb, immediately followed by a caudal vein injection of NGF （1 μg）. The injury group was injected with OxyHb, and subsequently with physiological saline. The control group only received intravenous physiological saline. MAIN OUTCOME MEASURES： At 1,6, 24, and 48 hours following subarachnoid hemorrhage induction, expression levels of Bcl-2 and Bax were detected by immunohistochemistry in the cerebral cortex 3 mm anterior and posterior to the injection site. RESULTS： At all time points following OxyHb injection, cerebral cortical Bax levels were significantly higher in the injured group than in the control and NGF groups （P 〈 0.01）. During the first 24 hours following OxyHb injection, cerebral cortical Bcl-2 levels were significantly lower in the injury group compared to the control group （P 〈 0.05 0.01）. Between 1 and 48 hours, Bcl-2 levels were significantly higher in the NGF group than in the injury group （P 〈 0.01 ）. CONCLUSION： Exogenous NGF can inhibit increased neuronal Bax expression and decreased Bcl-2 expression in the cerebral cortex of mice with OxyHb -induced subarachnoid hemorrhage.

CORRELATIONS BETWEEN OXY-HEMOGLOBIN AND RESPIRATORY EXCHANGE RATIO IN THE QUADRICEPS DURING THE EARLY PHASE OF EXERCISES

The early stage of exercises is crucial in sports training;however,its physiological mechanism is still unclear.The hemodynamic response was reported to be associated with respiratory exchange.Here,we aimed to explore the relationship between oxy-hemoglobin concentration change(HbO_(2))and respiratory exchange ratio(RER)during the early phase of exercises.Sixteen athletes of middle-distance race were selected from Wuhan Institute of Physical Education to conduct intermittent exercises on MERCURY4.0 at 80%VO_(2)peak intensity.Multiple physiological parameters were acquired by use of a near-infrared spectroscopy muscle oxygen monitor,a Cardiopulmonary Function MAX-II and a P-Lar,including HbO_(2),RER and others.A significant correlation was found between RER and HbO_(2)in quadriceps muscle in the thigh during the early phase of exercises.Thus,NIRS is capable of supervising sports training in terms of HbO_(2),which actually acted as an interpreter of RER change.

Oxygen affinity and 2,3-diphosphoglycerate level of erythrocytes in patients with cor pulmonale

Arterial blood gases,intraerythrocytic pH (pHi),2,3-diphosphoglycerate,standardP 50 (P 50std) and in vivo P 50 (P 50iv) were determined in 54 patients with cor pulmonale and23 normal subjects.It was found that no significant change of pHi was observed but the differ-ence of pHi and extraerythrocytic pH was decreased.P 50std was significantly decreased whileP 50iv remained essentially unchanged in those cases showing type I respiratory failure.Thesefindings suggest that P 50std cannot accurately reflect the changes of P 50iv in patients of corpulmonale;P 50iv in cases of cor pulmonale usually keeps relatively stable and coincides withthe ‘optimal P 50’,which indicates the adaptation of the organism to chronic hypoxia;and rel-ative intraerythrocytic alkalosis plays an important role in the relief of hypercapnia in cases ofcor pulmonale.

PHASE DIFFERENCE BETWEEN LOW-FREQUENCY OSCILLATIONS OF CEREBRAL DEOXY-AND OXY-HEMOGLOBIN CONCENTRATIONS DURING A MENTAL TASK

Hemodynamic low-frequency(~0.1 Hz)spontaneous oscillations as detected in the brain by nearinfrared spectroscopy have potential applications in the study of brain activation,cerebral autoregulation,and functional connectivity.In this work,we have investigated the phase lag between oscillations of cerebral deoxy-and oxy-hemoglobin concentrations in the frequency range 0.05-0.10 Hz in a human subject during a mental workload task.We have obtained a measure of such phase lag using two different methods:(1)phase synchronization analysis as used in the theory of chaotic oscillators and(2)a novel cross-correlation phasor approach.The two methods yielded comparable initial results of a larger phase lag between low-frequency oscillations of deoxy-and oxyhemoglobin concentrations during mental workload with respect to a control,rest condition.

USING FUNCTIONAL NEAR-INFRARED SPECTROSCOPY TO MEASURE COGNITIVE FUNCTION:WHEN WILL IT BECOME AN ACCEPTED CLINICAL TOOL FOR COGNITIVE AGING AND PRODROMAL DEMENTIA SCREENING?

This article presents a historical perspective of foundational studies utilizing near-infrared spectroscopy(NIRS)to measure the hemodynamics,oxygenation,and activation of the human brain cortex during cognitive tasks,called functional NIRS(fNIRS).It discusses studies representative of the diagnostic power and potential that fNIRS has shown for providing increased understanding of cognitive changes with aging and dementia.It concludes by discussing challenges that continue to confront the implementation of NIRS and fNIRS in clinical and translational research,in particular,the challenges to measure cognitive function and impairment in aged,chronically ill,and fragile subjects with or without dementia.It is written specifically in memoriam,honoring Britton Chance,therefore papers authored by him and his collaborative research family are weighted to illustrate the significant foundation and legacy he has left to this world.

Odorant discrimination using functional near-infrared spectroscopy of the main olfactory bulb in rats

We characterize the hemodynamic response changes near-infrared spectroscopy （NIRS） during the presentation of in the main olfactory bulb （MOB） of anesthetized rats with three different odorants： （i） plain air as a reference （Blank）, （ii） 2-heptanone （HEP）, and （iii） isopropylbenzene （Ib）. Odorants generate different changes in the concentrations of oxy- hemoglobin. Our results suggest that NIRS technology might be useful in discriminating various odorants in a non-invasive manner using animals with a superb olfactory system.