Near-infrared Spectroscopy Measurements Research Articles

Neural correlates of response to joint attention in 2-to-5-year-olds in relation to ASD and social-communicative abilities: An fNIRS and behavioral study.

Autism spectrum disorder (ASD) is associated with life-long challenges with social cognition, and one of its earliest and most common manifestations is atypical joint attention, which is a pivotal skill in social-cognitive and linguistic development. Early interventions for ASD children often focus on training initiation of joint attention (IJA) and response to joint attention bids (RJA), which are important for social communication and cognition. Here, we used functional near-infrared spectroscopy and behavioral measures to test typically developing (TD, n = 17) and ASD children (n = 18), to address the relationship between the neural correlates of RJA and social-communicative behavior. Group-level differences were present for RJA-specific activation over right temporal sites, where TD children showed higher levels of activation during RJA than ASD children, whereas the two groups did not differ in the control condition. Correlations between neural activation and behavioral traits suggest that, in ASD children, neural activation during RJA is related to the frequency of RJA behavior when the former is measured over left temporal sites, and to social affect symptoms when considered for right temporal sites. Possible implications of the evidenced correlations are discussed.

The efficacy and safety of MARS-PD: Meridian activation remedy system for Parkinson's disease-A single-center, assessor and statistician-blinded, parallel-group randomized, controlled trial protocol.

Parkinson's disease (PD) patients face a substantial unmet need for disease-modifying interventions. Potential approaches such as exercise and acupuncture have been investigated to slow PD progression. To address this unmet need, we developed a novel therapeutic approach that integrates acupuncture and exercise: the Meridian Activation Remedy System for PD patients (MARS-PD). Building upon promising outcomes observed in our preliminary pilot study, where MARS-PD exhibited a large clinically important difference on the Movement Disorder Society Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS Part III), we embark on a randomized controlled trial with the primary objective of examining the efficacy, safety, and economic impact of MARS-PD. In this single-center, assessor and statistician-blinded, parallel-group randomized controlled trial, we aim to investigate the clinical efficacy of MARS-PD through 16 interventions administered over 8 weeks in 88 PD patients. Participants will be randomly assigned to the experimental (n = 44) or control (n = 44) groups. The experimental group will receive MARS-PD intervention alongside standard care, while the control group will solely receive standard care. The intervention period spans 8 weeks, followed by a 12-week post-intervention follow-up. The primary endpoint is the change in MDS-UPDRS Part III score from baseline to the conclusion of the 8-week intervention. Secondary outcomes encompass various assessments, including MDS-UPDRS, International Physical Activity Questionnaire Short Form, Parkinson Self Questionnaire, Parkinson's Disease Sleep Scale, Timed Up and Go test, GAITRite metrics, Functional Near-Infrared Spectroscopy measurements, smart band outcomes, gut microbiome analysis results, and iris connective tissue texture. Previous studies by the authors have indicated MARS-PD's safety and benefits for PD patients. Building upon this foundation, our current study aims to provide a more comprehensive and detailed confirmation of the efficacy of MARS-PD. cris.nih.go.kr KCT0006646 -First posted on 7 October 2021; ClinicalTrials.gov NCT05621772 -First posted on 11 November 2022.

Directed physiological networks in the human prefrontal cortex at rest and post transcranial photobiomodulation

Cerebral infra-slow oscillation (ISO) is a source of vasomotion in endogenic (E; 0.005–0.02 Hz), neurogenic (N; 0.02–0.04 Hz), and myogenic (M; 0.04–0.2 Hz) frequency bands. In this study, we quantified changes in prefrontal concentrations of oxygenated hemoglobin (Δ[HbO]) and redox-state cytochrome c oxidase (Δ[CCO]) as hemodynamic and metabolic activity metrics, and electroencephalogram (EEG) powers as electrophysiological activity, using concurrent measurements of 2-channel broadband near-infrared spectroscopy and EEG on the forehead of 22 healthy participants at rest. After preprocessing, the multi-modality signals were analyzed using generalized partial directed coherence to construct unilateral neurophysiological networks among the three neurophysiological metrics (with simplified symbols of HbO, CCO, and EEG) in each E/N/M frequency band. The links in these networks represent neurovascular, neurometabolic, and metabolicvascular coupling (NVC, NMC, and MVC). The results illustrate that the demand for oxygen by neuronal activity and metabolism (EEG and CCO) drives the hemodynamic supply (HbO) in all E/N/M bands in the resting prefrontal cortex. Furthermore, to investigate the effect of transcranial photobiomodulation (tPBM), we performed a sham-controlled study by delivering an 800-nm laser beam to the left and right prefrontal cortex of the same participants. After performing the same data processing and statistical analysis, we obtained novel and important findings: tPBM delivered on either side of the prefrontal cortex triggered the alteration or reversal of directed network couplings among the three neurophysiological entities (i.e., HbO, CCO, and EEG frequency-specific powers) in the physiological network in the E and N bands, demonstrating that during the post-tPBM period, both metabolism and hemodynamic supply drive electrophysiological activity in directed network coupling of the prefrontal cortex (PFC). Overall, this study revealed that tPBM facilitates significant modulation of the directionality of neurophysiological networks in electrophysiological, metabolic, and hemodynamic activities.

Estimation of differential pathlength factor from NIRS measurement in skeletal muscle

The utilization of continuous wave (CW) near-infrared spectroscopy (NIRS) device to measure non-invasively muscle oxygenation in healthy and disease states is limited by the uncertainties related to the differential path length factor (DPF). DPF value is required to quantify oxygenated and deoxygenated heme groups’ concentration changes from measurement of optical densities by NIRS. An integrated approach that combines animal and computational models of oxygen transport and utilization was used to estimate the DPF value in situ. The canine model of muscle oxidative metabolism allowed measurement of both venous oxygen content and tissue oxygenation by CW NIRS under different oxygen delivery conditions. The experimental data obtained from the animal model were integrated in a computational model of O2 transport and utilization and combined with Beer-Lambert law to estimate DPF value in contracting skeletal muscle. A 2.1 value was found for DPF by fitting the mathematical model to the experimental data obtained in contracting muscle (T3) (Med.Sci.Sports.Exerc.48(10):2013-2020,2016). With the estimated value of DPF, model simulations well predicted the optical density measured by NIRS on the same animal model but with different blood flow, arterial oxygen contents and contraction rate (J.Appl.Physiol.108:1169–1176, 2010 and 112:9–19,2013) and demonstrated the robustness of the approach proposed in estimating DPF value. The approach used can overcome the semi-quantitative nature of the NIRS and estimate non-invasively DPF to obtain an accurate concentration change of oxygenated and deoxygenated hemo groups by CW NIRS measurements in contracting skeletal muscle under different oxygen delivery and contraction rate.

Transmission of slow waves in Masimo O3 near infrared spectroscopy measures

IntroductionCerebral autoregulation (CA) dysfunction is a key complication following brain injury. CA assessment using near-infrared spectroscopy (NIRS) offers a promising alternative to the current non-invasive standard, cerebral blood flow velocity (CBFV) measured with transcranial Doppler. Research questionCan autoregulatory slow waves (frequency range 0.005–0.05 Hz) associated with spontaneous and induced changes in ABP in healthy volunteers be detected by parameters measured with the Masimo O3 NIRS device? MethodsABP, CBFV and Masimo O3 parameters were measured in 10 healthy volunteers at baseline and during ABP oscillations induced by squat/stand manoeuvres. Transmission of slow waves was assessed with power spectral density and coherence analysis in NIRS signals and compared to that of CBFV. ResultsAt baseline, slow waves were detected with sufficient power that substantially exceeded the signals’ measurement resolution in all parameters except cerebral oxygen saturation. During ABP oscillations in the 0.033 Hz range (induced by squat/stand), the power of slow waves increased in all parameters in a similar pattern, with total (cHb) and oxygenated (O2Hb) haemoglobin concentrations most closely mirroring CBFV (median standardised power [first-third quartile], baseline vs squat/stand: CBFV 0.35 [0.28–0.42] vs 0.50 [0.45–0.62], O2Hb 0.47 [0.33–0.68] vs 0.61 [0.59–0.69]). Coherence with ABP increased for both CBFV and NIRS measures from low at baseline (<0.4) to high during induced changes (>0.8). ConclusionSpontaneous fluctuations in ABP can be observed in analysed Masimo O3 metrics to a varying degree. The clinical utility of Masimo O3 signals in CA assessment requires further investigation in brain injury patients.

Acute and chronic hyperglycemia blunts microvascular reactivity in postmenopausal women with type 2 diabetes

Type 2 diabetes (T2D) is strongly associated with increased risk of cardiovascular diseases via endothelial dysfunction. Hyperglycemia causes microvascular endothelial dysfunction and reduces muscle perfusion. Near-infrared spectroscopy (NIRS) measures microvascular reactivity in skeletal muscle during vascular occlusion/reperfusion. However, the impact of acute and chronic hyperglycemia on macrovascular endothelial function (brachial flow-mediated dilation, FMD) and microvascular reactivity (NIRS-derived tissue oxygen saturation index, TOI) has not been examined in postmenopausal women with and without T2D. We hypothesized that T2D women would have decreased FMD and TOI responsiveness in the fasted condition and greater vascular impairments during acute hyperglycemia compared to controls.Ten T2D (61 ± 5 years) and 10 normoglycemic postmenopausal women (CON, 62 ± 7 years) participated in the study. Hemoglobin A1C (HbA1C) and blood glucose were measured by finger prick at baseline (fasted condition). Brachial artery FMD was evaluated using ultrasound. Forearm muscle TOI magnitude and slope during arterial occlusion and reperfusion periods were measured using NIRS. An oral glucose tolerance test (OGTT) was performed to induce acute hyperglycemia. Blood glucose, FMD, and TOI were measure at baseline and 1 hour (1-h) after OGTT. Abdominal fat was assessed by waist circumference and visceral adipose tissue (VAT) obtained by a whole-body dual-energy X-ray absorptiometry scan.Fasting HbA1C and glucose, waist circumference, and VAT were higher in T2D compared to CON (all p &lt; 0.05). The increase in blood glucose at 1-h was higher in T2D (Δ143 ± 15 mg/dl) compared to CON (Δ49 ± 5 mg/dl) (p &lt; 0.01). FMD at baseline and the decreases in FMD at 1-h were similar in T2D (Δ-2.2 ± 0.2%) and CON groups (Δ-1.9 ± 0.4%) (all p &lt; 0.01). At baseline, T2D showed blunted TOI occlusion magnitude (T2D: -16 ± 1 vs. CON: -21 ± 2%), TOI occlusion slope (T2D: -0.05 ± 0.01 vs. CON: -0.07 ± 0.01), TOI reperfusion magnitude (T2D: 21 ± 2 vs. CON: 32 ± 3%), and TOI reperfusion slope (T2D: 0.79 ± 0.10 vs. CON: 1.19 ± 0.14) compared to CON (all p &lt; 0.05). At 1-h, T2D exhibited lower TOI occlusion magnitude (T2D: -17 ± 2 vs. CON: -24 ± 3%), TOI occlusion slope (T2D: -0.06 ± 0.01 vs. CON: -0.08 ± 0.01), TOI reperfusion magnitude (T2D: 23 ± 2 vs. CON: 33 ± 4%), and TOI reperfusion slope (T2D: 0.90 ± 0.19 vs. CON: 1.14 ± 0.15) compared to CON (all p &lt; 0.05). HbA1C, a measure of chronic hyperglycemia, was positively correlated with VAT (r = 0.514, p = 0.02) and TOI occlusion slope (r = 0.460, p = 0.04) and negatively correlated with TOI reperfusion magnitude (r = -0.506, p = 0.02) and slope at baseline (r = -0.493, p = 0.03). In conclusion, women with T2D exhibited blunted microvascular reactivity despite similar FMD compared with normoglycemic women in the fasted condition. Acute hyperglycemia further blunted microvascular function, but not macrovascular endothelial function, in women with T2D. Blunted microvascular reactivity was associated with chronic hyperglycemia and elevated VAT in postmenopausal women. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

On-farm NIR sensor for milk analysis: Exploitation of bias monitoring and bias correction

Long-term studies have shown a bias drift over time in the prediction performance of near-infrared spectroscopy measurement systems. This bias drift generally requires extra laboratory reference measurements to detect and correct for this bias. Since these reference measurements are expensive and time consuming, there is a need for advanced methodologies for bias drift monitoring and correction without the need for taking extra samples. In this study, we propose and validate a method to monitor the bias drift and two methods to tackle it. The first method requires no extra measurements and uses a modified version of Partial Least Squares Regression to estimate and correct the bias. This method is based on the assumption that the mean concentration of the predicted component remains constant over time. The second method uses regular bulk milk measurements as a reference for bias correction. This method compares the measured concentrations of the bulk milk to the volume-weighted average concentrations of individual milk samples predicted by the sensor. Any difference between the actual and calculated bulk milk composition is then used to perform a bias correction on the predictions by the sensor system. The effectiveness of these methods to improve the component prediction was evaluated on data originating from a custom-built sensor that automatically measures the NIR reflectance and transmittance spectra of raw milk on the farm. We evaluate the practical use case where models for predicting the milk composition are trained upon installation of the sensor at the farm, and later used to predict the composition of subsequent samples over a period of more than 6 months. The effectiveness of the fully unsupervised method was confirmed when the mean concentration of the milk samples remained constant, while the effectiveness reduced when this was not the case. The bulk milk correction method was effective when all relevant samples for the component were measured by the sensor and included in the analyzed bulk milk, but is less effective when samples included in the bulk which are not measured by the sensor system. When the necessary conditions are met, these methods can be used to extend the lifetime of deployed prediction models by significantly reducing the bias on the predicted values.

Reproducibility and sex differences in muscle oxygenation during brachial artery occlusion in healthy participants.

Near-infrared spectroscopy (NIRS) measurement is a widely used technique to measure muscle oxygenation. A knowledge of the reproducibility of NIRS measurements is essential for the correct interpretation of data. Our aim was to test the reproducibility and sex differences of NIRS measurements during brachial artery occlusion in healthy participants. An NIRS device was used to measure muscle oxygenation and microvascular function during a 5 min brachial occlusion. Muscle oxygen consumption (mVO2) and tissue saturation index (TSI%) were used. The occlusion test was performed three times on separate days for males (n = 13, 28 ± 8 years) and females (n = 13, 29 ± 7 years). During the occlusion phase, the reproducibility of mVO2 was excellent (intraclass correlation; ICC = 0.90). During the reperfusion phase, the maximal change in TSI% revealed the best reproducibility (ICC = 0.77). There were no sex differences in reproducibility. Male participants had higher muscle oxygenation during occlusion (mVO2, 0.054 ± 0.010 vs. 0.038 ± 0.012 mLO2/min/100 g, p = 0.001, male and female, respectively). There were no sex differences during the reperfusion phase. The reproducibility of NIRS to measure muscle oxygenation and microvascular function during circulation occlusion and reperfusion is good to excellent. Muscle oxygen capacity measured during occlusion is higher in males compared to females, and there are no sex differences in microvascular function during the reperfusion phase.

Intraparenchymal near-infrared spectroscopy for detection of delayed cerebral ischemia in poor-grade aneurysmal subarachnoid hemorrhage

ObjectiveDetection of delayed cerebral ischemia (DCI) is challenging in comatose patients with poor-grade aneurysmal subarachnoid hemorrhage (aSAH). Brain tissue oxygen pressure (PbtO2) monitoring may allow early detection of its occurrence. Recently, a probe for combined measurement of intracranial pressure (ICP) and intraparenchymal near-infrared spectroscopy (NIRS) has become available. In this pilot study, the parameters PbtO2, Hboxy, Hbdeoxy, Hbtotal and rSO2 were measured in parallel and evaluated for their potential to detect perfusion deficits or cerebral infarction. MethodsIn patients undergoing multimodal neuromonitoring due to poor neurological condition after aSAH, Clark oxygen probes, microdialysis and NIRS-ICP probes were applied. DCI was suspected when the measured parameters in neuromonitoring deteriorated. Thus, perfusion CT scan was performed as follow up, and DCI was confirmed as perfusion deficit. Median values for PbtO2, Hboxy, Hbdeoxy, Hbtotal and rSO2 in patients with perfusion deficit (Tmax > 6 s in at least 1 vascular territory) and/or already demarked infarcts were compared in 24- and 48-hour time frames before imaging. ResultsData from 19 patients (14 University Hospital Zurich, 5 Charité Universitätsmedizin Berlin) were prospectively collected and analyzed. In patients with perfusion deficits, the median values for Hbtotal and Hboxy in both time frames were significantly lower. With perfusion deficits, the median values for Hboxy and Hbtotal in the 24 h time frame were 46,3 [39.6, 51.8] µmol/l (no perfusion deficits 53 [45.9, 55.4] µmol/l, p = 0.019) and 69,3 [61.9, 73.6] µmol/l (no perfusion deficits 74,6 [70.1, 79.6] µmol/l, p = 0.010), in the 48 h time frame 45,9 [39.4, 51.5] µmol/l (no perfusion deficits 52,9 [48.1, 55.1] µmol/l, p = 0.011) and 69,5 [62.4, 74.3] µmol/l (no perfusion deficits 75 [70,80] µmol/l, p = 0.008), respectively. In patients with perfusion deficits, PbtO2 showed no differences in both time frames. PbtO2 was significantly lower in patients with infarctions in both time frames. The median PbtO2 was 17,3 [8,25] mmHg (with no infarctions 29 [22.5, 36] mmHg, p = 0.006) in the 24 h time frame and 21,6 [11.1, 26.4] mmHg (with no infarctions 31 [22,35] mmHg, p = 0.042) in the 48 h time frame. In patients with infarctions, the median values of parameters measured by NIRS showed no significant differences. ConclusionsThe combined NIRS-ICP probe may be useful for early detection of cerebral perfusion deficits and impending DCI. Validation in larger patient collectives is needed.

Near-infrared spectroscopy data for foot skin oxygen saturation in healthy subjects.

Our objective was to evaluate normative data for near-infrared spectroscopy (NIRS) in 110 healthy volunteers by Fitzpatrick skin type (FST) and region of the foot. We obtained measurements of the dorsum and plantar foot using a commercially available device (SnapshotNIR, Kent Imaging, Calgary Canada). On the dorsum of the foot, people with FST6 had significantly lower oxygen saturation compared to FST1-5 (p < 0.001), lower oxyhaemoglobin compared to FST2-5 (p = 0.001), but there was no difference in deoxyhaemoglobin. No differences were found on the plantar foot. When comparing dorsal and plantar foot, there was higher oxyhaemoglobin (0.40 ± 0.09 vs. 0.51 ± 0.12, p < 0.001) and deoxyhaemoglobin (0.16 ± 0.05 vs. 0.21 ± 0.05, p < 0.001) on the plantar foot, but no differences in oxygen saturation (dorsal 70.7 ± 10.8, plantar 70.0 ± 9.5, p = 0.414). In 6.4% of feet, there were black areas, for which no NIRS measurements could be generated. All areas with no data were on the dorsal foot and only found in FST 5-6. People with FST6 had significantly larger areas with no data compared to FST 5 (22.2 cm2 ± 20.4 vs. 1.9 cm2 ± 0.90, p = 0.007). These findings should be considered when using NIRS technology. Skin pigmentation should be evaluated in future NIRS studies.

Robust, high-density lesion mapping in the left atrium with near-infrared spectroscopy.

Radiofrequency ablation (RFA) procedures for atrial fibrillation frequently fail to prevent recurrence, partially due to limitations in assessing extent of ablation. Optical spectroscopy shows promise in assessing RFA lesion formation but has not been validated in conditions resembling those in vivo. Catheter-based near-infrared spectroscopy (NIRS) was applied to porcine hearts to demonstrate that spectrally derived optical indices remain accurate in blood and at oblique incidence angles. Porcine left atria were ablated and mapped using a custom-fabricated NIRS catheter. Each atrium was mapped first in phosphate-buffered saline (PBS) then in porcine blood. NIRS measurements showed little angle dependence up to 60deg. A trained random forest model predicted lesions with a sensitivity of 81.7%, a specificity of 86.1%, and a receiver operating characteristic curve area of 0.921. Predicted lesion maps achieved a mean structural similarity index of 0.749 and a mean normalized inner product of 0.867 when comparing maps obtained in PBS and blood. Catheter-based NIRS can precisely detect RFA lesions on left atria submerged in blood. Optical parameters are reliable in blood and without perpendicular contact, confirming their ability to provide useful feedback during in vivo RFA procedures.

Application of near-infrared spectroscopy for predicting the wood density of teakwood stands by increment cores and thin wood surface sampling

Density, as the most critical information for wood materials could be predicted by near-infrared (NIR) spectroscopy. Increment cores and thin wood samples of teakwood ( Tectona grandis) served as research materials for this new approach to sampling for NIR spectroscopy, explained in detail. Density data were combined with their NIR spectra data for analysis using cross-validation partial least squares regression as chemometrics to produce a density prediction model. A new approach of increment cores from teakwood stands for NIR spectroscopy measurements for density predictions resulting in a 0.34 coefficient of determination for cross-validation (R2CV) and 0.40 of R2CV for thin wood samples as the best result from the first derivative with 25 smoothing points of NIR spectra. The improvement from the previous research for density prediction accuracy resulted in an R2CV value of 0.55. The smaller diameter of the increment core sample than the NIR light beam's diameter and illuminated mixed surface (transversal and radial) are supposed to give weaker prediction accuracy by this new approach.

Development of a Simultaneous Quantification Method for Multiple Modes of Nitrogen in Leaf Models Using Near-Infrared Spectroscopic Measurement.

By focusing our attention on nitrogen components in plants, which are important for cultivation management in data-driven agriculture, we developed a simple, rapid, non-chemical and simultaneous quantification method for proteinic and nitrate nitrogen in a leaf model based on near-infrared (NIR) spectroscopic information obtained using a compact Fourier Transform NIR (FT-NIR) spectrometer. The NIR spectra of wet leaf models impregnated with a protein-nitric acid mixed solution and a dry leaf model obtained by drying filter paper were acquired. For spectral acquisition, a compact MEMS (Micro Electro Mechanical Systems) FT-NIR spectrometer equipped with a diffuse reflectance probe accessory was used. Partial least square regression analysis was performed using the spectral information of the extracted absorption bands based on the determination coefficients between the spectral absorption intensities and the contents of the two-dimensional spectral analysis between NIR and mid-infrared spectral information. Proteinic nitrogen content in the dry leaf model was well predicted using the MEMS FT-NIR spectroscopic method. Additionally, nitrate nitrogen in the dry leaf model was also determined by the provided method, but the necessity of adding the data for a wider range of nitric acid concentrations was experimentally indicated for the prediction of nitrate nitrogen content in the wet leaf model. Consequently, these results experimentally suggest the possibility of the application of the compact MEMS FT-NIR for obtaining the bioinformation of crops at agricultural on-sites.

3T 31P/1H calf muscle coil for 1H and 31P MRI/MRS integrated with NIRS data acquisition.

Our aim was to design and build a 3T 31P/1H calf coil that is capable of providing both good 31P and 1H transmit and receive performance, as well as being capable of accommodating a near-infrared spectroscopy (NIRS) device for simultaneous NIRS data and MRI/MRS acquisition. In this work, we propose a new 3T 31P/1H birdcage combination design consisting of two co-centrically positioned birdcages on the same surface to maximize transmit efficiency and sensitivity for both nuclei. The 31P birdcage is a high-pass birdcage, whereas the 1H birdcage is a low-pass one to minimize coupling. The diameter of the 31P/1H birdcage combination was designed to be large enough to accommodate a NIRS device for simultaneous NIRS data and MRI/MRS acquisition. The one-layer coil structure of the birdcage combination significantly streamlines the mechanical design and coil assembly process. Full-wave simulation results show that the 31P and 1H are very well decoupled with each other, and the 1H and 31P SNR surpasses that of their standalone counterparts in the central area. Experiment results show that the inclusion of a NIRS device does not significantly affect the performance of the coil, thus enabling simultaneous NIRS and MRI readouts during exercise. Our findings demonstrate the feasibility and effectiveness of this dual-tuned coil design for combined NIRS and MRS measurements, offering potential benefits for studying metabolic and functional changes in the skeletal muscle in vivo.

Multimodal assessment of tinnitus using functional near-infrared spectroscopy and psychophysiological measures

Objective To use a multimodal approach to classify individuals with tinnitus from controls, and individuals with mild versus severe tinnitus. Design We have previously shown feasibility of a non-invasive imaging technique called functional near-infrared spectroscopy (fNIRS) to detect tinnitus-related changes in cortical activity and classify individuals with tinnitus from controls, as well as individuals with mild versus severe tinnitus. In this study we have used a multimodal approach by recording heart rate, heart rate variability and skin conductance, in addition to fNIRS signals, from individuals with tinnitus and controls. Study Sample Twenty-seven participants with tinnitus and 21 controls were recruited. Results Our findings show, addition of heart rate measures can improve accuracy of classifying tinnitus severity, in particular loudness as rated subjectively. The f1-score, a measure of classification accuracy, increased from 0.73 to 0.86 when using a support vector machine classifier for differentiating low versus high tinnitus loudness. Conclusions Subjective tinnitus is a condition that can only be described by the individual experiencing it, as there are currently no objective measures to determine tinnitus presence and severity, or assess the effectiveness of treatments. Objective measurement of tinnitus is a critical step in developing reliable treatments for this debilitating condition.

Bilateral Prefrontal Cortex Blood Flow Dynamics during Silent and Oral Reading Using Near-Infrared Spectroscopy.

This study aimed to investigate blood flow dynamics in the bilateral prefrontal cortex during silent and oral reading using near-infrared spectroscopy (NIRS). The subjects were 40 right-handed university students (20.5±1.8 years old, 20 men and 20 women). After completing the NIRS measurements, the subjects were asked to rate their level of proficiency in silent and oral reading, using a 5-point Likert scale. During oral reading, the left lateral prefrontal cortex (Broca's area) was significantly more active than the right side. During silent reading, prefrontal cortex activity was lower than that during oral reading, and there was no significant difference between both sides of the brain. A significant negative correlation was found between the change in oxy-hemoglobin (oxy-Hb) concentration in the left and right lateral prefrontal cortex during silent reading and silent reading speed. In addition, students with lower self-reported reading proficiency had significantly greater changes in oxy-Hb concentrations in the left and right lateral prefrontal cortex during silent/oral reading than did students with higher self-reported reading proficiency. Reading task assessment using NIRS may be useful for identifying language lateralization and Broca's area. The results demonstrate that NIRS is useful for assessing effortful reading and may be used to diagnose developmental dyslexia in children. J. Med. Invest. 71 : 92-101, February, 2024.

The utility of NIRS in follow-up of patients with acute ischaemic stroke treated with IV thrombolysis and mechanical thrombectomy in the emergency department.

Revascularization treatments (IV thrombolysis, mechanical thrombectomy) related to ischemic stroke have developed in recent years. With devices such as NIRS, non-invasive monitoring of treatment efficacy is provided. In this study, we aimed to use near-infrared spectroscopy (NIRS) as an objective monitoring method to see the effect of intravenous (IV) thrombolysis or mechanical thrombectomy treatments applied for cerebral oxygenation in patients with acute ischemic stroke.This study was carried out as a prospective study involving patients admitted to the emergency department in the years 2021-2022. NIRS measured regional oxygen saturation (rSO2) of both hemispheres of the brain before IV thrombolysis treatment, during the treatment at 0. min, 15. min, 30. min, 45. min, 60. min, after the treatment, and before and after the mechanical thrombectomy procedure. The significance level of the change in rSO2 values measured by NIRS was examined.80 patients were included in the study. IV thrombolysis was applied to 58 patients, mechanical thrombectomy was applied to 5 of them, and both treatments were applied to 17 of them. In patients receiving IV thrombolysis, a significant difference was found in the affected hemisphere between the NIRS values measured at 0.min-15.min, 0.min-30.min, 0.min-45.min, 0.min-60.min, 0.min-post-treatment, 15.min-60.min (p < 0.001). In the patients included in the study, there was a strong and significant negative correlation between the deltaNIHSS value and the deltaNIRS values in the affected hemisphere (r=- 0.307, p = 0.013). There was a significant increase in the NIRS measurement values during and after the IV thrombolysis treatment in the affected hemisphere in the group with clinical improvement (p < 0.001).It is thought that IV thrombolysis or mechanical thrombectomy treatment applied to patients admitted to the emergency department with acute ischemic stroke can be followed objectively by NIRS.

How NIRS can predict the outcome of patient in low systemic pressure: a case series

Mitral valve replacement (MVR) is a surgical procedure to treat mitral regurgitation (MR). As there is an increase in the afterload in the postoperative period, patients tend to have low cardiac output syndrome. This condition may limit oxygen delivery to body tissues. Improved venous saturation has been linked to positive neurological outcomes. Near-infrared spectroscopy (NIRS) is the new technique to monitor regional oxygenation in real time. This study reports on four patients who underwent MVR due to a combination of severe mitral stenosis (MS) and mild MR. All patients had complaints of dyspnea on exertion to unbearable chest pain. Physical and work-up examination led to a diagnosis of decompensated heart failure, concomitant valve disorder, fluid overload, and cardiomegaly. Preoperative catheterization to stratify the risks of the procedure was done on all four patients. The surgery planned was cardiopulmonary bypass (CPB) with standard monitoring and additional NIRS measurement. The measurement of mean arterial pressure (MAP) and NIRS were tightly monitored and maintained in each patient, with the use of vasoactive agents. All four patients suffered unstable hemodynamics and were admitted to intensive care unit with the support of mechanical ventilation and other supportive therapies. Cerebral perfusion can reach the baseline normal value even though in low cardiac output syndrome, and NIRS can predict the outcome of the patients better than the conservative monitoring.&#x0D; Key words: CPB; Low Systemic Pressure; Cerebral perfusion; Mitral Valve Replacement; NIRS.&#x0D; Citation: Purwoko, Permana SA, Dewi FH, Prihandana PA. How NIRS can predict the outcome of patient in low systemic pressure: a case series. Anaesth. pain intensive care 2023;27(6):757−762; DOI: 10.35975/apic.v27i6.2350&#x0D; Received: May 29, 2023; Reviewed: September 20, 2023; Accepted: October 30, 2023

Muscle ultrasound shear wave elastography for detection of early onset lower limb ischemia in patients with veno-arterial extracorporeal membrane oxygenation

Background and objectivesLimb ischemia or compartment syndrome, requiring surgery, are some of the frequent cannula-related complications in patients supported with veno-arterial extracorporeal membrane oxygenation (VA-ECMO). The purpose of this exploratory study is to depict and evaluate the dynamic changes in the lower limb muscles with ultrasound shear wave elastography as marker for early lower limb ischemia.MethodsEleven patients with VA-ECMO after cardiac arrest were included in this study. Seven patients received distal perfusion cannula (DPC) after implantation of the VA-ECMO, whereas 4 had no DPC after VA-ECMO. Compartment syndrome was clinically excluded in all patients. Both lower limbs, e.g., with and without arterial cannula, were monitored with near-infrared spectroscopy (NIRS) for the oxygen saturation of the local tissue. We performed ultrasound shear wave elastrography (SWE) to assess dynamic changes of the medial gastrocnemius muscle at maximum passive muscle stretch (exercise) of both legs. Color-coded duplexsonography was conducted to examine the blood flow velocity of the popliteal artery of the lower limb.ResultsWe found no difference between DPC and no DPC (p = 0.115) during use of VA-ECMO. However, we detected marked lower limb muscle perfusion deficits of cannulated (58.9 ± 13.5 kPa) vs. cannula-free limb (95.7 ± 27.9 kPa: p < 0.001), applying SWE. No relationship was detected between NIRS measurements and SWE values (kPa) of both lower limbs. The mean peak systolic velocity of the popliteal artery at the cannulated side (30.0 ± 11.7 cm/s) was reduced compared to the non-cannulated side (39.3 ± 18.6 cm/s; p = 0.054).ConclusionsRegardless of DPC after implantation of VA-ECMO, the gastrocnemius muscles seem to lose function due to cannula-related microcirculatory deficits. Muscle function analysis via SWE combined with NIRS might offer a sensitive indicator for early onset leg ischemia during VA-ECMO-related arterial cannulation.

Precision and normal values of cerebral blood volume in preterm neonates using time-resolved near-infrared spectroscopy.

To investigate cerebral blood volume (CBV) in preterm neonates using time-resolved near-infrared spectroscopy. In this prospective observational study, time-resolved near-infrared spectroscopy measurements of CBV using tNIRS-1 were performed in 70 preterm neonates. For measurements, a sensor was placed for a duration of 1 min, followed by four further reapplications of the sensor, overall five measurements. In this study, 70 preterm neonates with a mean ± SD gestational age of 33.4 ± 1.7 weeks and a birthweight of 1931 ± 398 g were included with a postnatal age of 4.7 ± 2.0 days. Altogether, 2383 CBV values were obtained with an overall mean of 1.85 ± 0.30 mL/100 g brain. A total of 95% of the measured CBV values varied in a range from -0.31 to 0.33 from the overall individual mean. Taking the deviation of the mean of each single application for each patient, this range reduced from -0.07 to 0.07. The precision of the measurement defined as within-variation in CBV was 0.24 mL/100 g brain. The overall mean CBV in stable preterm neonates was 1.85 ± 0.30 mL/100 g brain. The within-variation in CBV was 0.24 mL/100 g brain. Based on the precision obtained by our data, CBV of 1.85 ± 0.30 mL/100 g brain may be assumed as normal value for this cohort.