Skin blood flow differentially affects near-infrared spectroscopy-derived measures of muscle oxygen saturation and blood volume at rest and during dynamic leg exercise

The impact of skin blood flow changes on near-infrared spectroscopy (NIRS)-derived measures of muscle oxygen saturation (SmO₂) and blood volume has not been fully established. We measured SmO₂ and total hemoglobin concentration ([tHb]) responses of the right vastus lateralis during rest and dynamic knee extension exercise in ten young, healthy males. The protocol was repeated four times: twice without thigh heating for reliability, and twice with different grades of thigh heating for assessing the impact of cutaneous vasodilation on SmO₂ and Δ[tHb]. The reliability of our SmO₂ and [tHb] measurements was good. Thigh heating at 37 and 42°C caused marked increases in cutaneous vascular conductance (CVC) during rest and exercise (P < 0.001 between each condition), and small increases in SmO₂ during rest (from 69 ± 8% to 71 ± 7% and 73 ± 6%, respectively; P < 0.05 between each condition), but not during exercise (e.g. 1 min exercise: 51 ± 11% vs. 51 ± 11% and 52 ± 11%, respectively; P > 0.05 at all time points). In contrast, heating-induced increases in %CVC_peak were accompanied by increases in [tHb] at rest and during exercise and a decrease in Δ[tHb] during exercise (all P < 0.05). Our findings suggest that NIRS-derived measures of SmO₂ and blood volume are differentially affected by skin blood flow at rest and during exercise. The findings from this study should be considered in NIRS experiments where skin blood flow can change markedly (e.g. high-intensity and/or prolonged exercise).     

Changes in interstitial noradrenaline, trapezius muscle activity and oxygen saturation during low-load work and recovery

Both physical as well as mental demands result in an increased activity in the sympathetic nervous system (SNS) with changes in blood-pressure and heart-rate. Through local release of catecholamines, e.g. noradrenaline (NAd) SNS exerts various actions at the muscle level. The aims of this study were to investigate the effects of low-load repetitive work alone and in combination with mental demands on local muscle interstitial noradrenaline concentration [NAd]_i, muscle activity and oxygenation, assessed with microdialysis_, surface electromyography, and near-infrared spectroscopy, respectively. Healthy females (n = 15) were exposed to (1) 30 min repetitive work (RW) and (2) 30 min repetitive work with superimposed mental load (RWML) on two different occasions. Muscle [NAd]_i and muscle activity increased significantly in response to RW, but did not increase further during RWML. For RW, [NAd]_i was found to be inversely correlated to muscle activity. Oxygenation decreased significantly during work, independently of occasion. Our findings indicate that low-load work causes significantly increased trapezius muscle [NAd]_i in healthy females, and short periods of superimposed mental load do not add to this increase and further, that both muscle activity and oxygenation were unaffected by the superimposed mental load.     

Brain tissue oxygen concentration measurements

Brain function depends exquisitely on oxygen for energy metabolism. Measurements of brain tissue oxygen tension, by a variety of quantitative and qualitative techniques, going back for >50 years, have led to a number of significant conclusions. These conclusions have important consequences for understanding brain physiology as it is now being explored by techniques such as blood-oxygen-level-dependent functional magnetic resonance imaging (BOLD fMRI) and near-infrared spectroscopy (NIRS). It has been known for some time that most of the measured oxygen tensions are less than venous pO2 and are distributed in a spatially and temporally heterogeneous manner on a microregional scale. Although certain large-scale methods can provide reproducible average brain pO2 measurements, no useful concept of a characteristic oxygen tension or meaningful average value for brain tissue oxygen can be known on a microregional level. Only an oxygen field exists with large local gradients due to local tissue respiration, and the most useful way to express this is with a pO2 distribution curve or histogram. The neurons of the brain cortex normally exist in a low-oxygen environment and on activation are oxygenated by increases in local capillary blood flow that lead to increases in hemoglobin saturation and tissue oxygen.     

Myoglobin concentration and partial oxygen pressure in muscle tissue during allergic reactions

The effect of sensitization to horse serum, brucellas, and BCG, and also the effect of allergic reactions induced by these antigens on the partial pressure of oxygen and myoglobin concentration in muscle tissue were studied. The myoglobin concentration was found to be reduced during the formation of increased sensitivity but only in the case of sensitization by living microbial strains. Allergic reactions of immediate and delayed types caused a decrease in the myoglobin concentration both in the myocardium and skeletal muscles. The partial pressure of oxygen in the skeletal muscles was lowered.Central Research Laboratory, Alma-Ata Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR N. D. Beklemishev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 5, pp. 452–454, May, 1979.     

Changes in cerebral hemoglobin concentration and oxygen saturation immediately after birth in the human neonate using full-spectrum near infrared spectroscopy

Using full-spectrum near infrared spectroscopy (fsNIRS), we measured changes in oxy- and deoxyhemoglobin (HbO2 and Hb), total hemoglobin (T-Hb) concentration, and hemoglobin oxygen saturation (SbO2) in the brain tissue of seven neonates immediately following birth. It was found that HbO2 rose rapidly within 2-3 min after birth. During the same time, there was a transient increase in T-Hb concentration, after which it decreased together with Hb. SbO2 increased rapidly after birth, from 18% at 1.5 min to about 55% at 5-6 min, followed by a gradual increase of about 10%. Oxygenation in the brain occurred much sooner in three subjects given oxygen for a short time immediately after birth than in those who did not receive oxygen. This preliminary study indicated that dynamic changes occur in cerebral circulation and oxygenation as part of the physiological changes taking place soon after birth.     

Regional difference of muscle oxygen saturation and blood volume during exercise determined by near infrared imaging device.

Using a near infrared (NIR) imaging device, we tested the hypothesis that regional differences in oxygen status could be detected in the gastrocnemius muscle during exercise and recovery. Six healthy subjects performed the standing plantar flexion exercises for 2 min; the frequency was one contraction per second. The NIR imaging device was placed over the medial head of the right gastrocnemius muscle and the signals from two optical sensors situated on the middle proximal and middle distal portions were used. The NIR-O(2) saturation (difference between deoxygenated and oxygenated Hb signals) and NIR-blood volume (sum of the oxygenated and deoxygenated Hb signals) were calculated in optical density units. Plantar flexion resulted in more deoxygenation during exercise and more reoxygenation during recovery in the distal portion compared with the proximal portion. The changes in NIR-O(2) between rest and a 2 min exercise, and between a 2 min exercise and a 3 min recovery were 0.11 and -0.23, respectively, in the distal portion, which were significantly larger than proximal values (0.05 and -0.10, p < 0.05). Plantar flexion resulted in lower NIR-blood volumes during exercise and greater recovery of blood after exercise in the distal portion compared with the proximal portion. The changes in NIR blood volume between rest and a 2 min exercise and between a 2 min exercise and a 3 min recovery were -0.19 and 0.31, respectively, in the distal portion, significantly larger than proximal values (-0.07 and 0.12, p < 0.05 for all comparisons). These findings indicate that the distal portion of the medial gastrocnemius had larger changes in NIR-O(2) saturation and NIR-blood volume than the proximal portion had. This is consistent with the distal portion having a greater impairment of blood flow possibly because of the higher intramuscular pressure during exercise. In conclusion: (1) regional differences in oxygen status in the gastrocnemius muscle were detected with exercise, with the distal portion having greater NIR-O(2) saturation and NIR-blood volume changes, and (2) the NIR imaging device might be a useful method to detect the regional differences of oxygen status in the muscle.     

Regional tissue oxygen saturation: comparability and reproducibility of different devices

Comparability and reproducibility of different near-infrared spectroscopy devices measuring regional tissue oxygen saturation remain poor. Aim of the present study was to compare values and reproducibility of cerebral∕peripheral "tissue-oxygenation-index" (TOI; NIRO 300, Hamamatsu(?), Japan) with cerebral∕peripheral "regional-oxygen-saturation" (rSO; INVOS5100, Somanetics(?), USA), and to analyze the influence of quality criteria. Methods: cTOI and crSO2 were measured on the left forehead, pTOI and prSO2 were measured on the left calf. To analyse reproducibility, optodes were reapplied five times. A quality criterion was introduced for cTOI, crSO2 and prSO2. For pTOI quality criteria were introduced in combination with a venous occlusion technique. Results: Cerebral measurements were performed in 37 neonates. cTOI (72.7+∕-6.2%) was lower than crSO2 (83.3+∕-5.8%) (p < 0.001). The mean difference between cTOI and crSO2 was 10%. Mean standard deviations of cTOI and crSO2 were similar (cTOI: 4.9+∕-3.6; crSO2: 4.5+∕-2.6). Peripheral measurements were performed in 39 neonates. pTOI (66.0+∕-7.9%) was lower than prSO2 (82.0+∕-7.0%)(p < 0.001). The mean difference between pTOI and prSO2 was 15%. Mean standard deviations of pTOI (3.7+∕-2.6%) were lower than of prSO2 (5.0+∕-3.0%) (p = 0.047). Conclusion: TOI values were significantly lower than rSO2 values, in cerebral and peripheral measurements. Reproducibility was higher for pTOI than for prSO2.     

Measurement of oxygen saturation in venous blood by dynamic near infrared spectroscopy

A method for the measurement of oxygen saturation in the venous blood, SvO2, based on optical measurements of light absorption in the infrared region is presented. The method consists of applying relatively low external pressure of 25 mm Hg on the forearm, thereby increasing the venous blood volume in the tissue, and comparing the light absorption before and after the external pressure application. SvO2 has been determined from light absorption measurements in two wavelengths, before and after the pressure application, using a formula derived for two adjacent wavelengths. The method has been applied to the hands and fingers of 17 healthy male subjects, using wavelengths of 767 and 811 nm. SaO2, the oxygen saturation for arterial blood, was also obtained from photoplethysmographic measurements in these two wavelengths (pulse oximetry) using the same formula. The mean (+/- SD) value of SaO2 was 94.5% (+/- 3.0). The mean value of SvO2 was 86.2% (+/- 4.1) for the finger and 80.0% (+/- 8.2) for the hand. These SvO2 values are reasonable for the finger and the hand where arterio-venous anastomoses exist. The method enables the measurement of SvO2 in the limbs, a parameter which is related to tissue blood flow and oxygen consumption.     

Noninvasive measurement of cerebral hemoglobin oxygen saturation using two near infrared spectroscopy approaches

Spatially resolved spectroscopy (SRS) is a new near infrared spectroscopy (NIRS) method that, using the multi-distance approach, measures local cerebral cortex hemoglobin oxygen saturation [J. Matcher, P. Kirkpatrick, K. Nahid, M. Cope, and D. T. Delpy, Proc. SPIE 2389, 486-495 (1995)]. Using a conventional continuous wave NIRS photometer, cerebral venous oxygen saturation (SvO2) can be calculated from oxyhemoglobin and total hemoglobin rise induced by partial occlusion of jugular vein [C. E. Elwell, S. J. Matcher, L. Tyszczuk, J. H. Meek, and D. T. Delpy, Adv. Exp. Med. Biol. 411, 453-460 (1997)]. The aim of this study was to compare direct measurements of forehead tissue oxygenation index (TOI) with the calculated SvO2 during venous occlusion in 16 adult volunteers using a clinical two-channel SRS oximeter (NIRO-300). Measured TOI and calculated SvO2 values of either right or left forehead did not significantly differ. A good agreement between the two NIRS methods was also demonstrated. On 16 other subjects, no significant differences were found between the right and left forehead TOI values measured simultaneously, and between the TOI values measured by channel 1 or 2 on the same side. The results confirm that cerebral cortex hemoglobin oxygen saturation, measured directly by the SRS method, reflects predominantly the saturation of the intracranial venous compartment of circulation.     

母乳喂养对比配方奶喂养对足月新生儿组织血氧饱和度、血红蛋白浓度指数及肠道菌群的影响

目的:对比母乳喂养与配方奶喂养对足月新生儿组织血氧饱和度、血红蛋白浓度指数及肠道菌群的影响.方法:选取2020年6月至2020年12月500例于上海市第一妇婴保健院出生的足月新生儿为研究对象,按喂养方式的不同分为母乳喂养组(n=238)与配方奶喂养组(n=262).比较两组新生儿生长发育指标(体重、身长、头围)、组织血...     

Effect of norepinephrine on myocardial intracellular hydrogen ion concentration.

The effect of norepinephrine (NE) on the intracellular hydrogen ion concentration [H+]i of isolated rat hearts perfused with a modified Krebs-Henseleit solution (SHS) was determined. The [H+]i was calculated with the [14C]-dimethyloxazolidinedione method. Respiratory or metabolic acidosis was produced by equilibrating the KHS with 20% C02 or decreasing the [HC03-] of the KHS, respectively. Three types of experiments were carried out: 1) beta blockade--MJ 1999 (Sotalol) was added to the KHS; 2) control--no pharmacological treatment; and 3) NE-norepinephrine was added to the KHS. The effective CO2 buffer values (delta[HC03-]i/deltapHi) during respiratory acidosis were: beta blockade, 11; control, 35; and NE, 84. The production of metabolic acidosis resulted in the following [H+]i changes: beta blockade, 52 mM; control, 60 nM; and NE 7 nM. These results suggest that NE markedly attenuates the changes in [H+]i accompanying respiratory and metabolic acidosis and may account in part for previous observations that the effective C02 buffer value of cardiac muscle in vivo is greater than that in vitro.     

Protein concentration in interstitial and lymphatic fluids from the subcutaneous tissue.

The protein content of interstitial fluid and lymph from the same tissue was determined fluid samples of nanolitre volumes being taken from the subcutaneous tissue of rabbits by micropuncture. In the same area lymph was collected from lymphatic vessels of 30-100 mum. An electrophoretic technique in polyacrylamide gels in glass capillaries was used for the analysis of proteins. The gels were stained and then scanned on a microscope equipped with a moving table and photomultiplier. The area under each protein band was calculated from the recorded densitograms. The method required only a few nanolitres of fluid for analysis. Using solutions of known protein concentrations the relationship between the amount of protein and the area under the densitogram band was investigated. This relationship was found to be linear, making it possible to quantify the protein content of both interstitial fluid and lymph samples. The interstitial fluid/plasma concentration ratios for albumin, transferrin, globulins and total proteins were 0.42, 0.42, 0.32 and 0.37. The albumin/globulin ratio in interstitial fluid was found to be 1.60 of the plasma value although the values obtained for lymph were similar to those found for interstitial fluid. The similarity between the protein concentration of interstitial fluid and lymph indicated that the endothelial lining of the terminal lymphatics did not restrict the passage of macromolecules into the lymphatics.     

Absolute quantification of deoxyhaemoglobin concentration in tissue near infrared spectroscopy

We describe a simple technique for non-invasively determining the absolute concentration of deoxyhaemoglobin (Hb) in living tissue using near infrared spectroscopy (NIRS). The technique uses second-differential spectroscopy to determine the relative concentration of Hb to tissue water by fitting of the spectral features of these two chromophores in the 710 nm to 840 nm region of the near infrared (NIR) spectrum. Since the concentration of tissue water is generally known with accuracies of a few per cent, one can then obtain the absolute concentration of Hb ([Hb]). The validity and likely accuracy of the technique is assessed by applying it to artificially generated NIRS data. Some clinical validation is presented by comparing, during an in vivo study, changes in [Hb] obtained by this method and those calculated using more conventional techniques of relative quantification. Finally, we discuss the likely clinical significance of the measurement of absolute Hb concentration.     

Redistribution of hydrogen ion and chloride,and water shift across the red cell membrane of human and ruminant blood with changes in oxygen saturation

On oxygenation of blood the distribution ratios of H⁺ and Cl^– across red cell membrane are decreased and shift of water out of the red cell is produced. The magnitudes of these changes with 100% increase in oxygen saturation of blood were investigated for human and ruminant blood. A distribution ratio of H⁺, H _plasma ⁺ /H⁺(DMO)_cell=R_H(DMO), was determined, in which H _plasma ⁺ was measured by a pH electrode method and H⁺(DMO)_cell, by the¹⁴C-DMO method. R_H(DMO) was compared with the values of R_Cl and R_aH obtained previously (Takano et al., 1976). R_Cl represented a distribution ratio of Cl^– and R_aH, a distribution ratio of H⁺ in which H _plasma ⁺ and H _cell ⁺ have been measured by a pH electrode method. Water shift was computed from a change in mean corpuscular hemoglobin concentration. On oxygenation R_H(DMO), R_Cl and R_aH were decreased in the magnitudes of 0.04–0.09 in human blood at plasma pH 7.40 and at 37° C. In ruminant blood the decreases in R_H(DMO) and R_Cl were similar to those in human blood while that in R_aH was not significant. On oxygenation the water shift produced was at a rate of 1.1–1.5% in human blood whilst in ruminant blood there was no significant shift. The results for water shift underlined the relevance of the results for R_aH but not for R_H(DMO) nor R_Cl in ruminant blood. The results for R_aH and water shift suggest that the redistribution of H⁺, Cl^– and water with oxygenation of blood is smaller in ruminant blood than in human blood.