The Impact of Cuff Width on Perceptual Responses During and Following Blood Flow Restricted Walking Exercise

Narrow cuffs cause less discomfort than wide cuffs immediately following elbow flexion exercise in combination with blood flow restriction, possibly due to a balling up effect of the bicep underneath the cuff. In this study, we sought to examine the impact of cuff width, sex, and pressure on perceived discomfort in the quadriceps, following knee extensions. One hundred participants completed three separate experiments. In Experiment 1, we compared participants’ discomfort at rest after using a 5 and a 12 cm cuff. In Experiment 2, we compared the discomfort from these two cuffs after four sets of exercise. In Experiment 3, we used the same exercise protocol as in Experiment 2, but we compared the discomfort between a 12 cm cuff inflated to an inappropriate pressure and a 12 cm cuff inflated to the recommended pressure. We found no sex differences in Experiments 1 and 3. In Experiment 1, the narrow cuff had higher discomfort (16 vs 12 AU). In Experiment 2, men reported higher discomfort than women, with no discomfort differences related to cuff width, though narrow cuffs were most preferred. In Experiment 3, cuffs inflated to a pressure intended for narrow cuffs were associated with higher discomfort, and participants preferred to use it less. In summary, we found no strong evidence for discomfort differences due to cuff width. There was some indication that participants preferred narrow cuffs with pressures inflated to the recommended relative pressure. Muscle shape may influence how cuff width affects discomfort.

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Effekt of blood flow shutdown on the vein damage when exposed to HIFU

ZHurnal «Patologicheskaia fiziologiia i eksperimental`naia terapiia» ◽

10.25557/0031-2991.2017.02.46-50 ◽

2017 ◽

pp. 46-50

Author(s):

Н.Н. Петрищев ◽

Д.Ю. Семенов ◽

А.Ю. Цибин ◽

Г.Ю. Юкина ◽

А.Е. Беркович ◽

...

Keyword(s):

Blood Flow ◽

Structural Changes ◽

Focused Ultrasound ◽

Vena Cava ◽

Posterior Wall ◽

High Intensity Focused Ultrasound ◽

Vein Wall ◽

Ultrasound Exposure ◽

Isolated Segment ◽

The Impact

The purpose. In the study we investigated the impact of the partial blood flow shutdown on structural changes in the rabbit vena cava posterior wall after exposure to high-intensity focused ultrasound (HIFU). Methods. Ultrasound Exposure: frequency of 1.65 MHz, the ultrasound intensity in the focus of 13.6 kW/cm, the area of the focal spot 1 mm, continuous ultrasound, exposure for 3 seconds. Results. Immediately after HIFU exposure all layers of the vein wall showed characteristic signs of thermal damage. A week after exposure structural changes in the intima, media and adventitia was minimal in the part of vessel with preserved blood flow, and after 4 weeks the changes were not revealed. A week after HIFU exposure partial endothelium destruction, destruction of myocytes, disorganization and consolidation of collagen fibers of the adventitia were observed in an isolated segment of the vessel, and in 4 weeks endothelium restored and signs of damage in media and adventitia persisted, but were less obvious than in a week after exposure. Conclusion. The shutdown of blood flow after exposure to HIFU promotes persistent changes in the vein wall. Vein compression appears to be necessary for the obliteration of the vessel, when using HIFU-technology.

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Advanced Constitutive Modeling of the Thixotropic Elasto-Visco-Plastic Behavior of Blood: Steady-State Blood Flow in Microtubes

Materials ◽

10.3390/ma14020367 ◽

2021 ◽

Vol 14 (2) ◽

pp. 367

Author(s):

Konstantinos Giannokostas ◽

Yannis Dimakopoulos ◽

Andreas Anayiotos ◽

John Tsamopoulos

Keyword(s):

Blood Flow ◽

Steady State ◽

Constitutive Model ◽

Blood Plasma ◽

Constitutive Modeling ◽

Flow Direction ◽

Momentum Balance ◽

Plastic Behavior ◽

Flow Investigation ◽

The Impact

The present work focuses on the in-silico investigation of the steady-state blood flow in straight microtubes, incorporating advanced constitutive modeling for human blood and blood plasma. The blood constitutive model accounts for the interplay between thixotropy and elasto-visco-plasticity via a scalar variable that describes the level of the local blood structure at any instance. The constitutive model is enhanced by the non-Newtonian modeling of the plasma phase, which features bulk viscoelasticity. Incorporating microcirculation phenomena such as the cell-free layer (CFL) formation or the Fåhraeus and the Fåhraeus-Lindqvist effects is an indispensable part of the blood flow investigation. The coupling between them and the momentum balance is achieved through correlations based on experimental observations. Notably, we propose a new simplified form for the dependence of the apparent viscosity on the hematocrit that predicts the CFL thickness correctly. Our investigation focuses on the impact of the microtube diameter and the pressure-gradient on velocity profiles, normal and shear viscoelastic stresses, and thixotropic properties. We demonstrate the microstructural configuration of blood in steady-state conditions, revealing that blood is highly aggregated in narrow tubes, promoting a flat velocity profile. Additionally, the proper accounting of the CFL thickness shows that for narrow microtubes, the reduction of discharged hematocrit is significant, which in some cases is up to 70%. At high pressure-gradients, the plasmatic proteins in both regions are extended in the flow direction, developing large axial normal stresses, which are more significant in the core region. We also provide normal stress predictions at both the blood/plasma interface (INS) and the tube wall (WNS), which are difficult to measure experimentally. Both decrease with the tube radius; however, they exhibit significant differences in magnitude and type of variation. INS varies linearly from 4.5 to 2 Pa, while WNS exhibits an exponential decrease taking values from 50 mPa to zero.

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Independent and combined impact of hypoxia and acute inorganic nitrate ingestion on thermoregulatory responses to the cold

European Journal of Applied Physiology ◽

10.1007/s00421-021-04602-x ◽

2021 ◽

Vol 121 (4) ◽

pp. 1207-1218

Author(s):

Josh T. Arnold ◽

Stephen J. Bailey ◽

Simon G. Hodder ◽

Naoto Fujii ◽

Alex B. Lloyd

Keyword(s):

Blood Flow ◽

Cooling Rate ◽

Skin Blood Flow ◽

Rectal Temperature ◽

Onset Time ◽

Rate Of Change ◽

Vascular Control ◽

Delta Change ◽

Core Cooling ◽

The Impact

Abstract Purpose This study assessed the impact of normobaric hypoxia and acute nitrate ingestion on shivering thermogenesis, cutaneous vascular control, and thermometrics in response to cold stress. Method Eleven male volunteers underwent passive cooling at 10 °C air temperature across four conditions: (1) normoxia with placebo ingestion, (2) hypoxia (0.130 FiO2) with placebo ingestion, (3) normoxia with 13 mmol nitrate ingestion, and (4) hypoxia with nitrate ingestion. Physiological metrics were assessed as a rate of change over 45 min to determine heat loss, and at the point of shivering onset to determine the thermogenic thermoeffector threshold. Result Independently, hypoxia expedited shivering onset time (p = 0.05) due to a faster cooling rate as opposed to a change in central thermoeffector thresholds. Specifically, compared to normoxia, hypoxia increased skin blood flow (p = 0.02), leading to an increased core-cooling rate (p = 0.04) and delta change in rectal temperature (p = 0.03) over 45 min, yet the same rectal temperature at shivering onset (p = 0.9). Independently, nitrate ingestion delayed shivering onset time (p = 0.01), mediated by a change in central thermoeffector thresholds, independent of changes in peripheral heat exchange. Specifically, compared to placebo ingestion, no difference was observed in skin blood flow (p = 0.5), core-cooling rate (p = 0.5), or delta change in rectal temperature (p = 0.7) over 45 min, while nitrate reduced rectal temperature at shivering onset (p = 0.04). No interaction was observed between hypoxia and nitrate ingestion. Conclusion These data improve our understanding of how hypoxia and nitric oxide modulate cold thermoregulation.

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The Impact of Intraocular Pressure Elevation on Optic Nerve Head and Choroidal Blood Flow

Investigative Opthalmology & Visual Science ◽

10.1167/iovs.18-23872 ◽

2018 ◽

Vol 59 (8) ◽

pp. 3488 ◽

Cited By ~ 8

Author(s):

Naoki Kiyota ◽

Yukihiro Shiga ◽

Kohei Ichinohasama ◽

Masayuki Yasuda ◽

Naoko Aizawa ◽

...

Keyword(s):

Blood Flow ◽

Intraocular Pressure ◽

Optic Nerve ◽

Optic Nerve Head ◽

Choroidal Blood Flow ◽

Pressure Elevation ◽

Intraocular Pressure Elevation ◽

The Impact

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Mathematical Modeling on Blood flow through a stenosed artery with Heat Transfer under the Impact of Slip condition

Journal of Physics Conference Series ◽

10.1088/1742-6596/1850/1/012127 ◽

2021 ◽

Vol 1850 (1) ◽

pp. 012127

Author(s):

D. Karthikeyan ◽

V. Kavitha ◽

R. Sathishkumar

Keyword(s):

Mathematical Modeling ◽

Heat Transfer ◽

Blood Flow ◽

Slip Condition ◽

Stenosed Artery ◽

Flow Through ◽

The Impact

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The Impact of several Antihypertensive drugs and Medicinal herbs on Induced hypertension in rabbits

Research Journal of Pharmacy and Technology ◽

10.52711/0974-360x.2021.00839 ◽

2021 ◽

pp. 4832-4836

Author(s):

Hayder Sabah Hasan ◽

Imad Hashim ◽

Zaid Al-Attar

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Medicinal Plants ◽

Urine Output ◽

Effective Drug ◽

Aqueous Extracts ◽

Plantago Major ◽

Induced Hypertension ◽

Teucrium Polium ◽

The Impact

Objective: To assess the antihypertensive efficacy of the medicinal plants used Hibiscus subdariffa, Plantago major, Teucrium polium. Moreover, we aim to Investigate the mechanisms of actions of tested agents. Design: Induced hypertension in experimental animals is tested against several drugs and medicinal plants extracts. Animals and materials: Hypertension was induced in experimental rabbits with phenylephrine 0.2mg/kg i.v. with increasing the dose (until Blood pressure>130/90mmHg). Rabbits were divided to 7 groups: Control, atenolol, furosemide, candesartan, Hibiscus subdariffa, Plantago major, Teucrium polium. ANOVA with Dunnett's test was implemented for statistical calculations with p<0.05 as significance level. Results: Candesartan was the most effective in lowering both systolic and diastolic blood pressure. Concerning the blood flow, candesartan was found to be the most significantly effective drug in increasing blood flow followed by furosemide and Hibiscus subdariffa respectively. Concerning the urine output furosemide was found to be the most significantly effective drug in increasing urine output followed by Hibiscus subdariffa. The aqueous extracts of Plantago major and Teucrium polium showed no significant effect. Conclusions: Hibiscus subdariffa is effective as diuretic agent at the concentration mentioned. Its action involves diuretic and vasodilator effect. While aqueous extracts of Plantago major and Teucrium polium are not effective.

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