Blood Flow Index Research Articles

Non-invasive optical and laboratory hematologic biomarkers correlate in patients with sickle cell disease.

The goal of this study is to identify non-invasive optical hemodynamic biomarkers that can index laboratory hematology measurements in sickle cell disease (SCD). We acquired frequency-domain NIRS (FD-NIRS) and diffuse correlation spectroscopy (DCS) data from the forearms and foreheads of 17 participants in a randomized, double-blind, placebo-controlled trial evaluating effects of isoquercetin (IQ) on thromboinflammation in SCD. We observed multiple, significant correlations between optical and hematology biomarkers including cerebral tissue oxygen saturation (StO2) and hematocrit (HCT); oxyhemoglobin ([O2Hb]) recovery rate and intercellular adhesion molecule 1 (ICAM-1); and blood flow index (BFI) reperfusion rate and coagulation index (CI). The potential of these non-invasive optical biomarkers for assessing vascular pathophysiology for the management of SCD warrants further exploration.

Assessment of endometrial and subendometrial three-dimensional power Doppler angiography evaluated by the VOCAL method in frozen-thawed embryo transfer cycles on hormone replacement therapy

BACKGROUND: The effectiveness of in vitro fertilization cycles / frozen-thawed embryo transfer cycles depends on a number of factors, the endometrial one being of great importance. Adequate endometrial and subendometrial blood supply is considered necessary for successful implantation. Currently, the possibilities of non-invasive assessment of the implantation properties of the endometrium are limited to the use of ultrasound. AIM: The aim of this study was to assess the performance of endometrial and subendometrial three-dimensional power Doppler angiography combined with the Virtual Organ Computer-aided Analysis (VOCAL) method in frozen-thawed embryo transfer cycles on hormone replacement therapy and compare the obtained data among the women examined. MATERIALS AND METHODS: This prospective study included 20 women. Doppler measurements were carried out three times — on the day of progesterone initiation, the day before embryo transfer and on the day of embryo transfer. The VOCAL software assessed the endometrial and subendometrial volume and blood flow indices such as vascularization index, flow index, and vascularization flow index. Patients were divided into two study groups depending on the onset of clinical pregnancy. RESULTS: On the day of progesterone initiation among patients who got pregnant, we observed higher vascularization (3.52 ± 1.99 vs. 1.05 ± 1.36; p = 0.03) and vascularization flow (1.54 ± 0.98 vs. 0.63 ± 0.55; p = 0.03) indices compared to women with a negative result. Moreover, endometrial vascularization index on the day of progesterone initiation was positively correlated with the estrogen dose among both pregnant (r = 0.61; p = 0.04) and non-pregnant (r = 0.9; p = 0.0008) women. No differences in subendometrial blood flow indices depending on the onset of pregnancy were obtained, just as endometrial blood flow indices the day before embryo transfer and on the day of embryo transfer were comparable between women in the both study groups. CONCLUSIONS: Three-dimensional power Doppler angiography evaluated by the Virtual Organ Computer-aided Analysis (VOCAL) method is a promising tool for non-invasive assessment of endometrial receptivity in frozen-thawed embryo transfer programs. However, further studies are required on a larger patient sample to form conclusions that are more accurate.

Study of Time-Resolved Dynamics in Turbid Medium Using a Single-Cavity Dual-Comb Laser.

In measuring cerebral blood flow (CBF) noninvasively using optical techniques, diffusing-wave spectroscopy is often combined with near-infrared spectroscopy to obtain a reliable blood flow index. Measuring the blood flow index at a determined depth remains the ultimate goal. In this study, we present a simple approach using dual-comb lasers where we simultaneously measure the absorption coefficient (μa), the reduced scattering coefficient (μs '), and dynamic properties. This system can also effectively differentiate dynamics from various depths, which is crucial for analyzing multilayer dynamics. For CBF measurements, this capability is particularly valuable as it helps mitigate the influence of the scalp and skull, thereby enhancing the specificity of deep tissue.

Characteristics of the reproductive potential of women with ovarian endometrioma

Endometriosis is one of the most studied hormone-dependent pathological conditions in modern gynecological practice, which is diagnosed in 300 million women of reproductive age worldwide. The frequency of endometriosis in the general population of women is 10–15%, its rate is 46% among the patients with infertility and 80% – among the patients with pelvic pain syndrome. Ovarian endometriomas in the structure of external genital endometriosis account for 64%.The objective: to determine the state of the ovarian reserve in women of reproductive age with ovarian endometriomas depending on the surgical treatment method.Materials and methods. The study involved 120 women of reproductive age with ovarian endometriomas, who were surgically treated by laparoscopic access, and 30 women of the control group, who were included in the examination for the purpose of evaluating the physiological parameters of the ovarian reserve, who applied for the solution of contraception issues.Group I included 60 women who underwent intraoperative bipolar coagulation (BC) of the ovarian medulla for the purpose of hemostasis, 30 persons of them underwent inversion cystectomy (Subgroup IA) and 30 patients underwent traditional cystectomy (Subgroup IB).Group II included 60 patients who underwent intraoperative BC of the medullary and cortical layers, of which 30 underwent inversion cystectomy (Subgroup IIA) and 30 underwent traditional cystectomy (Subgroup IIB).For the assessment the functional state of the ovaries echographic examination, Doppler study and hormonal examination were carried out (determination of the concentration of anti-Mullerian hormone (AMH), basal level of follicle-stimulating hormone (FSH), inhibin B in blood plasma) before and 3 months after surgical treatment.Results. The indicators of the ovarian reserve of the patients of the studied groups before the surgical treatment were significantly different from the indicators of the women of the control group, which was manifested by a decreased number of antral follicles (AF) by 1.6 times, a decreased volume of ovarian tissue by 1.5 times, a decreased vascularization index (IV) by 2.4 times and the blood flow index (IC) by 1.2 times, an increase in the FSH index by 1.3 times, a decreased AMH level by 1.3 times and a decreased inhibin B concentration by 2.3 times (p<0, 05).After the surgical intervention, even more pronounced pathological changes in the reproductive potential were found, which were associated with deep neurovascular disorders in the ovaries and the death of part of the generative cells as a result of the cystectomy and hemostasis with the use of high-frequency energy.Conclusions. When using BC of the medullary and cortical layers of the ovaries a decreased number of AF by 48.8% and the decreased volume of the tissue of the operated ovary by 41.3% were found compared to the preoperative period, which is 4.1 and 3.1 times more than with BC of the medullary layer (p<0.05). Hormonal homeostasis disorders were manifested by a compensatory increased level of FSH by 46.8% and a decreased AMH concentration by 23.5% (p<0.05).In the case of the use of BC of the medulla of the ovary with inversion cystectomy, the decrease in the ovarian reserve is expressed at least. The use of BC of the medullary and cortical layers of the ovary with inversion cystectomy leads to a decreased ovarian reserve to a low level 2.2 times less often than when using a classic cystectomy (p<0.05).

Correlation of diabetic renal hypoperfusion with microvascular responses of the skeletal muscle: a rat model study using diffuse correlation spectroscopy.

Using diffuse correlation spectroscopy, we assessed the renal blood flow and thigh muscle microvascular responses in a rat model of type 2 diabetes. The blood flow index at the renal surface decreased significantly with arterial clamping, cardiac extirpation, and the progression of diabetic endothelial dysfunction. Renal blood flow measured in diabetic and nondiabetic rats also showed a significant correlation with the reactive hyperemic response of the thigh muscle. These results suggest shared microcirculatory dysfunction in the kidney and skeletal muscle and support endothelial responses in the skeletal muscle as a potential noninvasive biomarker of renal hypoperfusion.

Non-Invasive Monitoring of Microvascular Oxygenation and Reactive Hyperemia using Hybrid, Near-Infrared Diffuse Optical Spectroscopy for Critical Care.

The detection of levels of impairment in microvascular oxygen consumption and reactive hyperemia is vital in critical care. However, there are no practical means for a robust and quantitative evaluation. This paper describes a protocol to evaluate these impairments using a hybrid near-infrared diffuse optical device. The device contains modules for near-infrared time-resolved and diffuse correlation spectroscopies and pulse-oximetry. These modules allow the non-invasive, continuous, and real-time measurement of the absolute, microvascular blood/tissue oxygen saturation (StO2) and the blood flow index (BFI) along with the peripheral arterial oxygen saturation (SpO2). This device uses an integrated, computer-controlled tourniquet system to execute a standardized protocol with optical data acquisition from the brachioradialis muscle. The standardized vascular occlusion test (VOT) takes care of the variations in the occlusion duration and pressure reported in the literature, while the automation minimizes inter-operator differences. The protocol we describe focuses on a 3-min occlusion period but the details described in this paper can readily be adapted to other durations and cuff pressures, as well as other muscles. The inclusion of an extended baseline and post-occlusion recovery period measurement allows the quantification of the baseline values for all the parameters and the blood/tissue deoxygenation rate that corresponds to the metabolic rate of oxygen consumption. Once the cuff is released, we characterize the tissue reoxygenation rate, magnitude, and duration of the hyperemic response in BFI and StO2. These latter parameters correspond to the quantification of the reactive hyperemia, which provides information about the endothelial function. Furthermore, the above-mentioned measurements of the absolute concentration of oxygenated and deoxygenated hemoglobin, BFI, the derived metabolic rate of oxygen consumption, StO2, and SpO2 provide a yet-to-be-explored rich data set that can exhibit disease severity, personalized therapeutics, and management interventions.

How to harvest the left internal mammary artery-a randomized controlled trial.

It is uncertain whether Thunderbeat has a place in harvesting the left internal mammary artery (LIMA) and whether skeletonization is superior to pedicle-harvested LIMA. Some investigations have shown improved flowrates in the skeletonized graft. The aim of this study was to compare 3 groups of harvesting techniques: Pedicled, surgical skeletonized and skeletonized with Thunderbeat in terms of flow rates in the LIMA and postoperative in-hospital outcomes. Patients undergoing coronary artery bypass grafting with the LIMA to the anterior descending artery were randomized to pedicled (n = 56), surgical skeletonized (n = 55) and skeletonized with Thunderbeat (n = 54). Main outcomes were blood flow and pulsatility index in the graft. No statistical difference between groups regarding flow in LIMA or pulsatility index. Similarly, no difference in postoperative bleeding or days of hospitalization. The duration of harvesting was faster for the pedicled technique compared with surgical skeletonized and skeletonized with Thunderbeat [mean total min: pedicled 20.2 min standard deviation (SD) ± 5.4; surgical skeletonized 28.6 min SD ± 8.7; skeletonized with Thunderbeat 28.3 min SD ± 9.11, P < 0.001]. No grafts discarded due to faulty harvesting and there was no graft failure within hospital stay. We found no difference between the harvesting methods except for a significantly faster harvesting time with the pedicled technique. However, non-touch skeletonized LIMA harvesting with Thunderbeat seems to be an effective alternative to traditional surgical skeletonized LIMA. The future will reveal whether patency is harvesting dependent. ClinicalTrials.gov Identifier: NCT05562908.

Impact of Peripheral Versus Central Insulin on Cerebrovascular Compliance in Healthy Young Adults

Objective: Vascular compliance is an essential component of cerebral blood flow regulation. Prior work has shown cerebral vasodilation (elicited by hypercapnia) reduces cerebrovascular compliance (Ci); however, this work has yet to be translated to other vasoactive compounds. Insulin has important vasodilatory effects in the peripheral circulation, but less is known about the role of insulin in cerebrovascular control. Herein, we hypothesized both peripheral (intravenous) and central (intranasal) insulin administration would increase indices of cerebral blood flow and reduce Ci in healthy young adults. Methods: Twenty-five healthy young adults (8 female; 26±7 yrs, 25±3 kg/m2) were assigned to two separate protocols (NCT05244694, NCT05153395). Middle cerebral artery blood velocity (MCAv, transcranial Doppler ultrasound) was measured at baseline and under two study conditions: 1) at the end of a 60 min hyperinsulinemic euglycemic infusion, and 2) 60 min following 160 IU of intranasal insulin. Indices of Ci were calculated using a modified Windkessel model applied to blood pressure (finger photoplethysmography) and corresponding MCAv waveforms collected over a 5-min period (10 waveforms) at baseline and during the aforementioned insulin conditions. Results: Blood glucose remained unchanged throughout both protocols (both p&gt;0.05). MCAv was maintained over time under both insulin conditions (protocol 1: 60±13 to 62±17 cm/s, p=0.635; protocol 2: 58±9 to 53±14 cm/s, p=0.146). In contrast, Ci decreased (0.00028±0.00010 to 0.00021±0.00007 cm/s/mmHg, p=0.010) from baseline during peripheral (intravenous) insulin administration. No change in Ci (0.00049±0.00025 to 0.00040±0.00018 cm/s/mmHg, p=0.189) were observed following intranasal insulin administration. Conclusions: Contrary to our hypothesis, there was no effect of peripheral or central insulin administration on resting MCAv in healthy young adults. However, intravenous (but not intranasal) insulin reduced Ci by approximately 25% from baseline values. These findings advance our understanding of cerebrovascular control mechanisms during insulin exposure and provide the opportunity to extend this work to diseased states characterized by insulin resistance, including diabetes. CAFNR Joy of Discovery (JKL, JP). 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.

Assessment of Microvascular Hemodynamic Adaptations in Finger Flexors of Climbers.

Climbing performance is greatly dependent on the endurance of the finger flexors which, in turn, depends on the ability to deliver and use oxygen within the muscle. Near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) have provided new possibilities to explore these phenomena in the microvascular environment. The aim of the present study was to explore climbing-related microvascular adaptations through the comparison of the oxygen concentration and hemodynamics of the forearm between climbers and non-climber active individuals during a vascular occlusion test (VOT). Seventeen climbers and fifteen non-climbers joined the study. Through NIRS and DCS, the oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) concentrations, tissue saturation index (TSI), and blood flow index (BFI) were obtained from the flexor digitorum profundus during the VOT. During the reactive hyperemia, climbers presented greater blood flow slopes (p = 0.043, d = 0.573), as well as greater O2Hb maximum values (p = 0.001, d = 1.263) and HHb minimum values (p = 0.009, d = 0.998), than non-climbers. The superior hemodynamics presented by climbers could indicate potential training-induced structural and functional adaptations that could enhance oxygen transportation to the muscle, and thus enhance muscle endurance and climbing performance.

Evaluating the accuracy of cerebrovascular computational fluid dynamics modeling through time-resolved experimental validation

Accurate modeling of cerebral hemodynamics is crucial for better understanding the hemodynamics of stroke, for which computational fluid dynamics (CFD) modeling is a viable tool to obtain information. However, a comprehensive study on the accuracy of cerebrovascular CFD models including both transient arterial pressures and flows does not exist. This study systematically assessed the accuracy of different outlet boundary conditions (BCs) comparing CFD modeling and an in-vitro experiment. The experimental setup consisted of an anatomical cerebrovascular phantom and high-resolution flow and pressure data acquisition. The CFD model of the same cerebrovascular geometry comprised five sets of stationary and transient BCs including established techniques and a novel BC, the phase modulation approach. The experiment produced physiological hemodynamics consistent with reported clinical results for total cerebral blood flow, inlet pressure, flow distribution, and flow pulsatility indices (PI). The in-silico model instead yielded time-dependent deviations between 19–66% for flows and 6–26% for pressures. For cerebrovascular CFD modeling, it is recommended to avoid stationary outlet pressure BCs, which caused the highest deviations. The Windkessel and the phase modulation BCs provided realistic flow PI values and cerebrovascular pressures, respectively. However, this study shows that the accuracy of current cerebrovascular CFD models is limited.

An extensive upgrading of contact diffuse CorrelationTomography system

AbstractDiffuse correlation tomography (DCT) is an emerging tissue blood flow index (BFI) imaging technique that typically requires a large number of source‐detector pairs, resulting in high instrumentation costs. We developed a low‐cost paradigm for upgrading the DCT system with time‐sharing hardware sensors via optical switches, wherein the S‐D configuration was spatially optimized and combined with a novelty Nth‐order linear algorithm for image reconstruction. We verified this system through the phantom experiment and the lower limb skeletal muscle cuff occlusion test. The reconstructed BFI images exhibit the excellent performance of the upgraded DCT system in retrieval of the target location, outline, and anomaly contrast. For the deepest quasi‐solid anomaly, location accuracy was 90% with the αDB‐contrast of 0.75. While, for the deepest liquid tube anomaly, a good linear relationship was achieved between contrast and pump speed, with the αDB‐contrast of 3.29 at 600 mL/h. For human experiments, it was found that the BFI in the relaxed state was ten times higher than in the cuff occlusion state. This study demonstrates the feasibility of the proposed upgraded low‐cost DCT system for diagnosing various diseases associated with local perfusion abnormalities.

A prospective study on the colour doppler indices of follicular and endometrial blood flow as a predictor of pregnancy in intrauterine insemination (IUI) cycles

A prospective study on the colour doppler indices of follicular and endometrial blood flow as a predictor of pregnancy in intrauterine insemination (IUI) cycles

Combined frequency domain near-infrared spectroscopy and diffuse correlation spectroscopy system for comprehensive metabolic monitoring of inspiratory muscles during loading.

Mechanical ventilation (MV) is a cornerstone technology in the intensive care unit as it assists with the delivery of oxygen in critically ill patients. The process of weaning patients from MV can be long and arduous and can lead to serious complications for many patients. Despite the known importance of inspiratory muscle function in the success of weaning, current clinical standards do not include direct monitoring of these muscles. The goal of this project was to develop and validate a combined frequency domain near-infrared spectroscopy (FD-NIRS) and diffuse correlation spectroscopy (DCS) system for the noninvasive characterization of inspiratory muscle response to a load. The system was fabricated by combining a custom digital FD-NIRS and DCS system. It was validated via liquid phantom titrations and a healthy volunteer study. The sternocleidomastoid (SCM), an accessory muscle of inspiration, was monitored during a short loading period in fourteen young, healthy volunteers. Volunteers performed two different respiratory exercises, a moderate load and a high load, which consisted of a one-minute baseline, a one-minute load, and a six-minute recovery period. The system has low crosstalk between absorption, reduced scattering, and flow when tested in a set of liquid titrations. Faster dynamics were observed for changes in blood flow index (), and metabolic rate of oxygen () compared with hemoglobin + myoglobin (Hb+Mb) based parameters after the onset of loads in males. Additionally, larger percent changes in , and were observed compared with Hb+Mb parameters in both males and females. There were also sex differences in baseline values of oxygenated Hb+Mb, total Hb+Mb, and tissue saturation. The dynamic characteristics of Hb+Mb concentration and blood flow were distinct during loading of the SCM, suggesting that the combination of FD-NIRS and DCS may provide a more complete picture of inspiratory muscle dynamics.

Retraction.

Retraction: El Behery, M. M., Diab, A. E., Mowafy, H., Ebrahiem, M. A., Shehata, A. E. (2010) Effect of laparoscopic ovarian drilling on vascular endothelial growth factor and ovarian stromal blood flow using 3-dimensional power Doppler. International Journal of Gynecology & Obstetrics, 112: 119-121. https://doi.org/10.1016/j.ijgo.2010.08.018. The above article, published online on 08 December 2010 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor-in-Chief, Professor Michael Geary, the International Federation of Gynecology and Obstetrics, and John Wiley and Sons Ltd. The retraction has been agreed due to major overlap between this article and the following article: Amin, A.F., Abd El Aal, D.E.M., Darwish, A.M, Meki, A.-R.M.A. (2003). Evaluation of the impact of laparoscopic ovarian drilling on Doppler indices of ovarian stromal blood flow, serum vascular endothelial growth factor, and insulin-like growth factor-1 in women with polycystic ovary syndrome. Fertility and Sterility, 79: 938-941. https://doi.org/10.1016/S0015-0282(02)04849-5. Following a complaint from a third party, an investigation by the editorial office and Wiley concluded that there are extensive duplications in the study design, sample sizes, tables, and results between the two articles. The authors did not respond to a request for an explanation and original data by the publisher. Representatives at Zagazig University did not respond to requests to begin an investigation.

Fetal anemia causes placental and maternal cellular damage: a lesson from fetal hemoglobin Bart's disease

IntroductionThe studies about effect of fetal anemia on placental and maternal molecular changes have rarely been published. This study aimed to compare oxidative stress levels and mitochondrial function in the placenta and maternal peripheral blood mononuclear cell (PMBCs) between anemic fetuses (using fetal Hb Bart's disease as a study model) and non-anemic fetuses. MethodsA cross-sectional study was conducted on pregnancies affected by Hb Bart's disease and non-anemic fetuses between 16 and 22 weeks of gestation. Placental tissue and maternal blood for PBMCs were collected after pregnancy termination for determination of oxidative stress and mitochondrial function. ResultsA total of 18 pregnancies affected by Hb Bart's disease and 12 non-anemic fetuses were enrolled. Placental thickness was significantly greater (p-value <0.001) in the affected pregnancies, whereas all Doppler indices of uteroplacental blood flow were comparable. Mitochondrial dysfunction was significantly increased (p-value <0.001) in the placenta of the affected fetuses. In the mothers of affected fetuses, there was an increase in mitochondrial oxidative stress levels with a significant increase in mitochondrial dysfunction in isolated PBMCs (p-value <0.001). DiscussionIn the presence of normal uteroplacental Doppler studies, fetal anemia can induce a significant increase in oxidative stress and mitochondrial dysfunction in the placentas and mothers. The findings support that the placenta can be a source of oxidative stress agents which are released into systemic circulation prior to development of maternal adverse outcomes, and may explain pathophysiology of subsequent preeclampsia in late gestation, as commonly seen in pregnancies affected by fetal Hb Bart's disease, if pregnancy is not terminated.

An endometrial receptivity scoring system evaluated by ultrasonography in patients undergoing frozen-thawed embryo transfer: a prospective cohort study.

Ultrasound has become a routine method for endometrial receptivity (ER) evaluation. However, there is controversy over the independent evaluation values of various ultrasound indicators. Some researchers have designed multi-indicator prediction systems, but their prediction values are uneven. To further our understanding of ER, we conducted this prospective cohort study to estimate ER noninvasively and effectively. Women who underwent the first frozen-thawed embryo transfer (FET) cycle from April 2019 to July 2021 were included in the study. On the day of transfer, transvaginal three-dimensional ultrasound examination was performed to evaluate ER, including endometrial thickness, morphology, volume, movement, blood flow and flow index. The clinical pregnancy rate was the primary outcome. Based on whether clinical pregnancy was achieved, enrolled patients were divided into pregnant and nonpregnant groups. This study analyzed 197 FET patients (139 pregnancies in total, 70.5%). The protective factors for clinical pregnancy included primary infertility [adjusted odds ratio (aOR), 1.98; 95% confidence interval (CI), 1.01-3.882; p = 0.047] and more frequent endometrial peristalsis (aOR, 1.33; 95% CI, 1.028-1.722; p = 0.03). Scores of 1-2 were assigned according to the relationship between different ultrasound indicators and the clinical pregnancy rate (CPR). The ER score of the patient was the sum of the scores of the 6 items. The ER score of the pregnant group was significantly higher than that of the nonpregnant group (7.40 ± 1.73 vs. 6.33 ± 1.99, p = 0.001). The CPR increased with an increasing ER score. The CPR in the ER < 6 group was significantly lower than that in the ER >6 group (45.5% vs. 75.6%, p = 0.001). A noninvasive ultrasound scoring system for ER was proposed. This system may provide a non-invasive guidance perspective, in conjunction with invasive assessments currently used in clinical practice, to achieve more effective embryo transfer.

Impact of Insulin-Induced Relative Hypoglycemia on Vascular Insulin Sensitivity and Central Hemodynamics in Prediabetes.

Relative hypoglycemia (RH) is linked to sympathetic responses that can alter vascular function in individuals with type 2 diabetes. However, less is known about the role of RH on hemodynamics or metabolic insulin sensitivity in prediabetes. Determine if RH alters peripheral endothelial function or central hemodynamics to a greater extent in those with prediabetes (PD) versus normoglycemia (NG). Seventy adults with obesity were classified using ADA criteria as PD (n=34 (28F); HbA1c=6.02±0.1%) or NG (n=36 (30F); HbA1c=5.4±0.0%). Brachial artery endothelial function, skeletal muscle capillary perfusion, and aortic waveforms were assessed at 0 and 120min of a euglycemic clamp (40 mU/m2/min, 90 mg/dl). Plasma nitrate/nitrite and endothelin-1 (ET-1) were measured as surrogates of nitric oxide-mediated vasodilation and vasoconstriction, respectively. RH was defined as the drop in glucose (%) from fasting to clamp steady state. There were no differences in age, weight, or VO2max between groups. PD had higher HbA1c (P<0.01) and a greater drop in glucose in response to insulin (14 vs. 8%; P=0.03). Further, heart rate (HR) increased in NG compared to PD (P<0.01), while forward wave (Pf) decreased in PD (P=0.04). Insulin also tended to reduce arterial stiffness (cfPWV) in NG versus PD (P=0.07), despite similar increases in pre-occlusion diameter (P=0.02), blood flow (P=0.02), and lower augmentation index (AIx75) (P≤0.05). Compared with NG, insulin-induced RH corresponded with a blunted rise in HR and drop in Pf during insulin infusion in adults with PD, independent of changes in peripheral endothelial function.

Differential changes in blood flow and oxygen utilization in active muscles between voluntary exercise and electrical muscle stimulation in young adults.

The physiological effects on blood flow and oxygen utilization in active muscles during and after involuntary contraction triggered by electrical muscle stimulation (EMS) remain unclear, particularly compared with those elicited by voluntary (VOL) contractions. Therefore, we used diffuse correlation and near-infrared spectroscopy (DCS-NIRS) to compare changes in local muscle blood flow and oxygen consumption during and after these two types of muscle contractions in humans. Overall, 24 healthy young adults participated in the study, and data were successfully obtained from 17 of them. Intermittent (2-s contraction, 2-s relaxation) isometric ankle dorsiflexion with a target tension of 20% of maximal VOL contraction was performed by EMS or VOL for 2 min, followed by a 6-min recovery period. DCS-NIRS probes were placed on the tibialis anterior muscle, and relative changes in local tissue blood flow index (rBFI), oxygen extraction fraction (rOEF), and metabolic rate of oxygen (rMRO2) were continuously derived. EMS induced more significant increases in rOEF and rMRO2 than VOL exercise but a comparable increase in rBFI. After EMS, rBFI and rMRO2 decreased more slowly than after VOL and remained significantly higher until the end of the recovery period. We concluded that EMS augments oxygen consumption in contracting muscles by enhancing oxygen extraction while increasing oxygen delivery at a rate similar to the VOL exercise. Under the conditions examined in this study, EMS demonstrated a more pronounced and/or prolonged enhancement in local muscle perfusion and aerobic metabolism compared with VOL exercise in healthy participants.NEW & NOTEWORTHY This is the first study to visualize continuous changes in blood flow and oxygen utilization within contracted muscles during and after electrical muscle stimulation (EMS) using combined diffuse correlation and near-infrared spectroscopy. We found that initiating EMS increases blood flow at a rate comparable to that during voluntary (VOL) exercise but enhances oxygen extraction, resulting in higher oxygen consumption. Furthermore, EMS increased postexercise muscle perfusion and oxygen consumption compared with that after VOL exercise.

Interferometric near-infrared spectroscopy (iNIRS) reveals that blood flow index depends on wavelength.

Blood flow index (BFI) is an optically accessible parameter, with unit distance-squared-over-time, that is widely used as a proxy for tissue perfusion. BFI is defined as the dynamic scattering probability (i.e. the ratio of dynamic to overall reduced scattering coefficients) times an effective Brownian diffusion coefficient that describes red blood cell (RBC) motion. Here, using a wavelength division multiplexed, time-of-flight- (TOF) - resolved iNIRS system, we obtain TOF-resolved field autocorrelations at 773 nm and 855 nm via the same source and collector. We measure the human forearm, comprising biological tissues with mixed static and dynamic scattering, as well as a purely dynamic scattering phantom. Our primary finding is that forearm BFI increases from 773 nm to 855 nm, though the magnitude of this increase varies across subjects (23% ± 19% for N = 3). However, BFI is wavelength-independent in the purely dynamic scattering phantom. From these data, we infer that the wavelength-dependence of BFI arises from the wavelength-dependence of the dynamic scattering probability. This inference is further supported by RBC scattering literature. Our secondary finding is that the higher-order cumulant terms of the mean squared displacement (MSD) of RBCs are significant, but decrease with wavelength. Thus, laser speckle and related modalities should exercise caution when interpreting field autocorrelations.

Immediate Effect of Electro-acupuncture on Endometrial Blood Flow in Patients with Recurrent Implantation Failure: A Randomized Controlled Trial.

To investigate the immediate effects of electro-acupuncture (EA) on endometrial blood flow among recurrent implantation failure (RIF) patients. Eighty RIF patients, enrolled from March 2022 to December 2022, were randomly allocated into either the EA group (40 cases) or the waiting-list (WL) group (40 cases) by using a random number table. The EA group underwent acupuncture at points of Shenting (GV 24), Baihui (GV 4), Benshen (GB 13), bilateral Zigong (EX-CA 1), Huangshu (KI 16), Sanyinjiao (SP 6) and Xuehai (SP10), and electric acupuncture apparatus was connected to EX-CA 1, KI 16, SP 6, and SP 10 with disperse-dense waves at 4/20 Hz frequencies for 30 min after transvaginal ultrasound, while the WL group received no intervention. The primary outcome measured was the endometrial volume blood flow. The secondary outcomes included the bilateral uterine artery index, endometrial volume, endometrial blood flow type, vascular distribution index (VIMV) for endometrial and ovary, clinical pregnancy rate, and embryo implantation rate. In the EA group, there was a notable decrease in the bilateral pulsatility index and a significant improvement in the endometrial blood flow type post-EA (P<0.05). Both the endometrial blood flow type and VIMV for the endometrium and right ovary were markedly higher in the EA group compared to the WL group post-treatment (P<0.05). Conversely, no significant disparities were observed in vascular index, flow index, vascular blood flow index, uterine arterial blood flow indices, endometrial volume, clinical pregnancy rate and embryo implantation rate between the two groups after treatment (P>0.05). Besides, no adverse events related to EA were observed. EA can promptly ameliorate VIMV for the endometrial and right ovary, and endometrial blood flow type. Future randomized controlled trials are warranted to investigate the long-term effects of EA on blood flow of RIF patients and its implications for pregnancy outcomes. (Trial registration No. ChiCTR2200057377).