Heterogeneity of blood flow: impact of age on muscle specific tissue perfusion during exercise

Blood flow and high-energy phosphate (HEP) content were determined simultaneously in multiple microregions of left ventricular subendocardium in 29 normal anesthetized open-chest rabbits by use of a new micromethod to determine whether a direct linear relationship existed between these parameters. Tissue samples weighed 1-2 mg. ATP and creatine phosphate (CP) content were quantitated in quick-frozen hearts by fluorometry at sites where tissue perfusion was measured by H2 clearance by use of bare-tipped platinum electrodes. A series of validation studies were conducted to ensure that 1) no significant damage to the tissue surrounding the electrode occurred during the period of experimentation and 2) no significant loss of biochemical constituents had occurred due to labile processes during freezing or storage of the tissue. Blood flow, ATP, and CP values averaged 79.1 +/- 24.1 (SD) ml.min-1.100 g-1, 4.9 +/- 1.3 mumol/g tissue, and 8.0 +/- 3.0 mumol/g tissue, respectively, and are similar to those reported in studies using larger tissue samples. Correlation between the heterogeneous distribution of tissue perfusion and HEP revealed no direct linear relationship between these parameters in the normal unstressed rabbit subendocardium.

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WALANT–Epinephrine injection may lead to short term, reversible episodes of critical oxygen saturation in the fingertips

Archives of Orthopaedic and Trauma Surgery ◽

10.1007/s00402-020-03744-5 ◽

2021 ◽

Vol 141 (3) ◽

pp. 527-533

Author(s):

P. Moog ◽

M. Dozan ◽

J. Betzl ◽

I. Sukhova ◽

H. Kükrek ◽

...

Keyword(s):

Blood Flow ◽

Oxygen Saturation ◽

Substantial Reduction ◽

Tissue Perfusion ◽

Critical Levels ◽

Short Term ◽

Doppler Flowmetry ◽

Epinephrine Injection ◽

Venous Oxygen Saturation

Abstract Introduction Although the WALANT technique’s long-term safeness has been demonstrated in many studies, there are only few data investigating its short-term effects on tissue perfusion and oxygen levels. It was hypothesized that, temporarily, critical levels of tissue perfusion may occur. Methods Seventeen patients, who were scheduled for different procedures in WALANT technique, were injected with 5–7 ml of 1% Articain containing 1:200,000 epinephrine at the finger base. Capillary-venous oxygen saturation, hemoglobin volume in the capillaries, and relative blood flow in the fingertips were recorded once per second by white light spectrometry and laser Doppler flowmetry before, during and after injection for an average of 32 min. Results Clinically, no persistent tissue malperfusion was observed, and there were no postoperative complications. Capillary-venous oxygen saturation was reduced by ≥ 30% in seven patients. Critical levels of oxygen saturation were detected in four patients during 13 intervals, each lasting for 132.5 s on average. Oxygen saturation returned to noncritical values in all patients by the end of the observation period. Blood flow in the fingertips was reduced by more than 30% in nine patients, but no critical levels were observed, as with the hemoglobin. Three patients demonstrated a reactive increase in blood flow of more than 30% after injection. Conclusions Injection of tumescent local anesthesia containing epinephrine into finger base may temporarily cause a substantial reduction in blood flow and lead to critical levels of oxygen saturation in the fingertips. However, this was fully reversible within minutes and does not cause long-term complications.

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Monitoring skin blood flow to rapidly identify alterations in tissue perfusion during fluid removal using continuous veno-venous hemofiltration in patients with circulatory shock

Annals of Intensive Care ◽

10.1186/s13613-021-00847-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Wasineenart Mongkolpun ◽

Péter Bakos ◽

Jean-Louis Vincent ◽

Jacques Creteur

Keyword(s):

Blood Flow ◽

Blood Lactate ◽

Skin Blood Flow ◽

Removal Rate ◽

Lactate Concentration ◽

Tissue Perfusion ◽

Fluid Removal ◽

Hemodynamic Variables ◽

Group A ◽

Group B

Abstract Background Continuous veno-venous hemofiltration (CVVH) can be used to reduce fluid overload and tissue edema, but excessive fluid removal may impair tissue perfusion. Skin blood flow (SBF) alters rapidly in shock, so its measurement may be useful to help monitor tissue perfusion. Methods In a prospective, observational study in a 35-bed department of intensive care, all patients with shock who required fluid removal with CVVH were considered for inclusion. SBF was measured on the index finger using skin laser Doppler (Periflux 5000, Perimed, Järfälla, Sweden) for 3 min at baseline (before starting fluid removal, T0), and 1, 3 and 6 h after starting fluid removal. The same fluid removal rate was maintained throughout the study period. Patients were grouped according to absence (Group A) or presence (Group B) of altered tissue perfusion, defined as a 10% increase in blood lactate from T0 to T6 with the T6 lactate ≥ 1.5 mmol/l. Receiver operating characteristic curves were constructed and areas under the curve (AUROC) calculated to identify variables predictive of altered tissue perfusion. Data are reported as medians [25th–75th percentiles]. Results We studied 42 patients (31 septic shock, 11 cardiogenic shock); median SOFA score at inclusion was 9 [8–12]. At T0, there were no significant differences in hemodynamic variables, norepinephrine dose, lactate concentration, ScvO2 or ultrafiltration rate between groups A and B. Cardiac index and MAP did not change over time, but SBF decreased in both groups (p < 0.05) throughout the study period. The baseline SBF was lower (58[35–118] vs 119[57–178] perfusion units [PU], p = 0.03) and the decrease in SBF from T0 to T1 (ΔSBF%) higher (53[39–63] vs 21[12–24]%, p = 0.01) in group B than in group A. Baseline SBF and ΔSBF% predicted altered tissue perfusion with AUROCs of 0.83 and 0.96, respectively, with cut-offs for SBF of ≤ 57 PU (sensitivity 78%, specificity 87%) and ∆SBF% of ≥ 45% (sensitivity 92%, specificity 99%). Conclusion Baseline SBF and its early reduction after initiation of fluid removal using CVVH can predict worsened tissue perfusion, reflected by an increase in blood lactate levels.

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Preliminary Evaluation of a Cycling Cleat Designed for Diabetic Foot Ulcers

Journal of the American Podiatric Medical Association ◽

10.7547/15-198 ◽

2017 ◽

Vol 107 (6) ◽

pp. 475-482 ◽

Cited By ~ 2

Author(s):

Ryan T. Crews ◽

Steven R. Smith ◽

Ramin Ghazizadeh ◽

Sai V. Yalla ◽

Stephanie C. Wu

Keyword(s):

Blood Flow ◽

Diabetic Foot ◽

Plantar Pressure ◽

Tissue Perfusion ◽

Foot Ulcers ◽

Preliminary Evaluation ◽

Diabetic Foot Ulcers ◽

Time Integral ◽

Traditional Health ◽

Before And After

Background: Offloading devices for diabetic foot ulcers (DFU) generally restrict exercise. In addition to traditional health benefits, exercise could benefit DFU by increasing blood flow and acting as thermotherapy. This study functionally evaluated a cycling cleat designed for forefoot DFU. Methods: Fifteen individuals at risk of developing a DFU used a recumbent stationary bicycle to complete one 5-minute cycling bout with the DFU cleat on their study foot and one 5-minute bout without it. Foot stress was evaluated by plantar pressure insoles during cycling. Laser Doppler perfusion monitored blood flow to the hallux. Infrared photographs measured foot temperature before and after each cycling bout. Results: The specialized cleat significantly reduced forefoot plantar pressure (9.9 kPa versus 62.6 kPa, P < .05) and pressure time integral (15.4 versus 76.4 kPa*sec, P < .05). Irrespective of footwear condition, perfusion to the hallux increased (3.97 ± 1.2 versus 6.9 ± 1.4 tissue perfusion units, P < .05) after exercise. Infrared images revealed no changes in foot temperature. Conclusions: The specialized cleat allowed participants to exercise with minimal forefoot stress. The observed increase in perfusion suggests that healing might improve if patients with active DFU were to use the cleat. Potential thermotherapy for DFU was not supported by this study. Evaluation of the device among individuals with active DFU is now warranted.

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Cardiac Output Changes in Newborns With Hyperbilirubinemia Treated With Phototherapy

PEDIATRICS ◽

10.1542/peds.76.6.918 ◽

1985 ◽

Vol 76 (6) ◽

pp. 918-921

Author(s):

Frans J. Walther ◽

Paul Y. K. Wu ◽

Bijan Siassi

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Stroke Volume ◽

Skin Blood Flow ◽

Peripheral Blood ◽

Cardiovascular Effects ◽

Tissue Perfusion ◽

Peripheral Blood Flow ◽

Limb Blood Flow ◽

Term Infants

Phototherapy is known to increase peripheral blood flow in neonates, but information on the associated cardiovascular effects is not available. Using pulsed Doppler echocardiography we evaluated cardiac output and stroke volume in 12 preterm and 13 term neonates during and after phototherapy. We concomitantly measured arterial limb blood flow by strain gauge plethysmography and skin blood flow by photoplethysmography. Cardiac output decreased by 6% due to reduced stroke volume during phototherapy, whereas total limb blood flow and skin blood flow increased by 38% and 41%, respectively. Peripheral blood flow increments tended to be higher in the preterm than in the term infants. The reduced stroke volume during phototherapy may be an expression of reduced activity of the newborn during phototherapy. For healthy neonates the reduction in cardiac output is minimal, but for sick infants with reduced cardiac output, this reduction may further aggravate the decrease in tissue perfusion.

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Limb blood flow and tissue perfusion during exercise with blood flow restriction

European Journal of Applied Physiology ◽

10.1007/s00421-018-4029-2 ◽

2018 ◽

Vol 119 (2) ◽

pp. 377-387 ◽

Cited By ~ 5

Author(s):

Matthew A. Kilgas ◽

John McDaniel ◽

Jon Stavres ◽

Brandon S. Pollock ◽

Tyler J. Singer ◽

...

Keyword(s):

Blood Flow ◽

Tissue Perfusion ◽

Blood Flow Restriction ◽

Limb Blood Flow ◽

Flow Restriction

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Abstract 372: The Endothelial Glycocalyx Promotes Homogenous Blood Flow Distribution within the Microvasculature

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.36.suppl_1.372 ◽

2016 ◽

Vol 36 (suppl_1) ◽

Author(s):

P Mason McClatchey

Keyword(s):

Fluid Dynamics ◽

Blood Flow ◽

Blood Viscosity ◽

Tissue Perfusion ◽

Microvascular Perfusion ◽

Endothelial Glycocalyx ◽

Heterogeneous Distribution ◽

Disease States

Introduction: Impaired tissue oxygenation is observed in many disease states including congestive heart failure, diabetes, cancer and aging. Decreased tissue perfusion and heterogeneous distribution of blood flow in the microvasculature contributes to this pathology. The physiological mechanisms regulating homogeneity/heterogeneity of microvascular perfusion are presently unknown. We hypothesized that microfluidic properties of the glycocalyx would promote perfusion homogeneity. Methods: To test our hypothesis, we used established empirical formulations for modelling blood viscosity in vivo (blood vessels) and in vitro (glass tubes). We first assess distribution of blood flow in idealized arteriolar networks. We next simulated distribution of blood flow at an idealized capillary bifurcation. Finally, we simulated velocity profiles and pressure gradients within the vessel lumen with varying glycocalyx properties using a computational fluid dynamics approach. Results: We found that transit time heterogeneity (as assessed by STD to mean ratio) was increased approximately 9x (6.9x-10.6x) using in vitro formulations of blood viscosity relative to in vivo formulations. This effect was mathematically accounted for by increased effective blood viscosity in smaller arterioles. We also found that distribution of blood flow at an idealized microvascular bifurcation was more symmetric using the in vivo formulation than the in vitro formulation (approximately 2x greater disparity between flow in downstream vessels). This effect was mathematically accounted for by an increased hematocrit dependence of blood viscosity. Both the diameter- and hematocrit-based changes in blood viscosity were entirely predictable from fluid dynamics simulations incorporating a space-filling, semi-permeable glycocalyx layer. Summary: Our simulations indicate that the mechanical properties of the endothelial glycocalyx promote homogeneous microvascular perfusion. Conclusions: The literature provides evidence of both glycocalyx degradation and impaired tissue perfusion in the same disease states. Preservation or restoration of normal glycocalyx properties may be a viable strategy for improving tissue perfusion in a wide variety of diseases.

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Abstract 257: Unselective Pulmonary Vasodilation is an Important Factor in Sodium Nitroprusside Enhanced Cardiopulmonary Resuscitation Improved Blood Flow

Circulation ◽

10.1161/circ.138.suppl_2.257 ◽

2018 ◽

Vol 138 (Suppl_2) ◽

Author(s):

Adrian Ripeckyj ◽

Kadambari Chandra Shekar ◽

Sebastian Voicu ◽

Jennifer Rees ◽

Timothy Matsuura ◽

...

Keyword(s):

Blood Flow ◽

Lactic Acid ◽

Sodium Nitroprusside ◽

Standard Technique ◽

Tissue Perfusion ◽

Right Atrial ◽

Carotid Blood Flow ◽

Oxygen Gradient ◽

Pulmonary Vasodilation ◽

Potent Vasodilator

Introduction: Sodium nitroprusside enhanced CPR (SNPeCPR) is a novel CPR method that includes a potent vasodilator, active compression-decompression CPR, an inspiratory impedance threshold device and abdominal binding. SNPeCPR has been shown to improve vital organ flow and functional survival outcomes compared to standard CPR methods in animals. We hypothesize that one of the main effects of SNPeCPR mediated increase in cardiac output during prolonged resuscitation is profound pulmonary artery vasodilation. Methods: After electrically induced VF was left untreated for 3 min, 20 (44-48Kg) pigs were randomized to receive SNPeCPR (10) or standard CPR (10) for a total of 30 min; the first 10 minutes were BLS CPR followed by twenty minutes of ACLS. During ACLS, animals were given IV SNP (1mg bolus) or standard epinephrine (0.5mg) q5 min until ROSC or 45 min total CPR. Shocks were delivered after 30 minutes of CPR at 300J. If ROSC was achieved, animal was monitored until 4-hour endpoint. Ventilations were provided with 10ml/kg at 10/min with a mechanical ventilator. Initially during CPR, room air was used and FiO2 was adjusted q5 minutes to maintain O 2 %saturation &gt 92% based on ABG. Lactic acid was also measured. Aortic, right atrial, and coronary artery pressures and carotid blood flow were recorded continuously. A-a oxygen gradient was measured with standard technique. Results: SNPeCPR animals documented a significantly higher mean CPP, lower lactic acid and 3x higher carotid blood flow over 30 minutes compared to standard CPR as previously documented. A-a oxygen gradient was dramatically increased in the SNPeCPR and coincided with a decreased lactate level (see Figure 1). Discussion: SNPeCPR causes profound pulmonary vasodilation and increases flow through non-ventilated lung areas. Despite that, the overall increase in forward flow leads to higher minute O 2 delivery and improved tissue perfusion. SNPeCPR should be used with 100% oxygen in the first human clinical trial.

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Abstract 2831: Endomyocardial-to-Epimyocardial Blood Flow Ratio Distinguishes Severity of Coronary Artery Disease: A Perfusion CMR Study

Circulation ◽

10.1161/circ.118.suppl_18.s_783-a ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Amit R Patel ◽

Patrick F Antkowiak ◽

Kiran R Nandalur ◽

Vishal Arora ◽

Christopher M Kramer ◽

...

Keyword(s):

Blood Flow ◽

Arterial Input Function ◽

Tissue Perfusion ◽

Input Function ◽

Rate Pressure Product ◽

Planar Imaging ◽

Clinical Patient ◽

Blood Flow Ratio ◽

Artery Disease ◽

Perfusion Cmr

Background: Ischemia propagates as a wave front from the endocardial (ENDO) to the epicardial (EPI) surface. Normally, myocardial blood flow (MBF) is higher in the ENDO than EPI. We hypothesized that the ENDO/EPI ratio could differentiate the severity of coronary stenoses in a clinical patient population. Methods: Perfusion CMR was performed in 29 patients within 30 days of x-ray angiography and quantitative coronary analysis. During adenosine infusion and at rest, dual boluses of Gd-DTPA were infused (4ml/s) to quantify arterial input function (0.0075mM/kg) and tissue perfusion (0.075mM/kg) in 3 short axis slices using hybrid gradient echo/echo planar imaging. ENDO and EPI MBF for rest and stress were estimated by determining the peak amplitude of the impulse response derived from Fermi function deconvolution. Stress and rest ENDO/EPI ratios were calculated and then corrected (corr) for rate-pressure product (RPP) using the formula ENDO/EPI * (SBP*HR*10 −4 ). Results: Coronary stenosis (CS) >50% was present in 23 of 29 patients. Hypertension, diabetes, and dyslipidemia were present in 23, 9, and 26 patients, respectively. Stress corrENDO/EPI (mean±SE) was inversely related to CS (CS<50% = 1.356 ± 0.030, CS 50–70% = 1.266 ± 0.029, and CS>70% = 1.149 ± 0.039; p<0.05) (Figure ). The relationship persisted after exclusion of the 56 segments with a myocardial scar (p<0.05). No relationship existed between CS and rest ENDO/EPI, rest corrENDO/EPI, or uncorrected stress ENDO/EPI. Conclusions: Stress corrENDO/EPI is inversely related to the severity of CS. Quantitative stress endo/epi ratios can distinguish intermediate from severe stenoses in patients with known or suspected CS.

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Experimentally induced variations in canine gastric blood flow and its distribution

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1965.208.2.353 ◽

1965 ◽

Vol 208 (2) ◽

pp. 353-358 ◽

Cited By ~ 51

Author(s):

John P. Delaney ◽

Eugene Grim

Keyword(s):

Blood Flow ◽

Cardiac Output ◽

Gastric Secretion ◽

Vascular Resistance ◽

Tissue Perfusion ◽

Gastric Blood Flow ◽

Gastric Tissue ◽

Distribution Of Flow ◽

Experimentally Induced

Total gastric blood flow and its distribution between antrum and corpus, and to the mucosa, submucosa, and muscularis of the corpus were measured in dogs under the influence of several agents known to affect gastric secretion. Histamine, infused intravenously or administered chronically in beeswax intramuscularly, produced increases in cardiac output, the fraction of the output going to the stomach and, hence, gastric tissue perfusion Epinephrine infusions also caused significant increases in cardiac output and gastric perfusion. Norepinephrine was the only agent that raised gastric vascular resistance; despite an increase in cardiac output, blood flow to the stomach fell. Neither intravenous secretin nor inspired 10% CO2 affected gastric perfusion. All agents except histamine increased the antrum/corpus perfusion ratio. Only norepinephrine altered the distribution of flow to the several tissues of the corpus; it caused a shift of flow from mucosa to muscle. The results provide no support for the frequently stated conclusion that gastric blood flow and secretion are closely related.

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