Evaluation and validation of microsphere technique for determination of pancreatic blood flow

The purpose of this study was to evaluate the radiolabeled microsphere technique for pancreatic blood flow measurements. Using a canine model with an isolated pancreatic circulation, we assessed the shunting of 11- and 15-microns-diam microspheres in the pancreas, correlated pancreatic blood flow measurements obtained with the microsphere technique with those made with an ultrasonic flow probe, and determined the effects of high doses of microspheres on pancreatic blood flow and its measurement. Microspheres of 11 microns demonstrate significant shunting through the pancreatic microcirculation with underestimation of pancreatic blood flow of approximately 10% compared with results obtained with 15-microns microspheres. There is a close linear relationship between flow results obtained with 15-microns microspheres and with an ultrasonic flow probe for both the resting (r = 0.85) and the secretin-stimulated pancreas (r = 0.97). Left atrial injections of very large doses of 15-microns microspheres (50 x 10(6)) caused an acute transient reduction of pancreatic blood flow (to 39% of baseline flow) with a return to baseline values within 2 min. The accuracy of flow results and absence of physiological changes after repeated injections support the use of 15-microns microspheres for pancreatic blood flow measurements.

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Hybrid blood flow probe for simultaneous H2 clearance and laser-Doppler velocimetry

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1987.253.4.g573 ◽

1987 ◽

Vol 253 (4) ◽

pp. G573-G581 ◽

Cited By ~ 2

Author(s):

G. R. DiResta ◽

J. W. Kiel ◽

G. L. Riedel ◽

P. Kaplan ◽

A. P. Shepherd

Keyword(s):

Blood Flow ◽

Laser Doppler Velocimetry ◽

Regional Blood Flow ◽

Laser Doppler ◽

Doppler Velocimetry ◽

Flow Probe ◽

Flow Measurements ◽

Blood Flow Measurements ◽

Light Guides ◽

The Relationship

To perform two independent regional blood flow measurements in tissue volumes of similar dimensions, we designed a hybrid blood flow probe capable of measuring regional perfusion by both laser-Doppler velocimetry (LDV) and H2 clearance. The probe consisted of two fiber-optic light guides to conduct light between the surface of tissue of interest and a laser-Doppler blood flowmeter. Also contained within the probe were a platinum 25-microns H2-sensing electrode and a 125-microns H2-generating electrode. The probe can thus be used to measure local perfusion with H2 clearance. The H2 can either be inhaled or can be generated electrochemically at the locus of interest. Evaluation of the probe in the canine gastric mucosa indicated 1) that the relationship between mucosal flow measurements made simultaneously with H2 clearance and LDV was highly significant and linear and 2) that H2 clearance could potentially be used to calibrate the laser-Doppler blood flowmeter in absolute units. The methods of constructing the flow probes are discussed in detail.

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Determination of Diffusion Shunt in Brain and Its Influence on Blood Flow Measurements. A Diffusion Shunt Model

Cerebral Circulation and Metabolism ◽

10.1007/978-3-642-65814-3_37 ◽

1975 ◽

pp. 138-140

Author(s):

R. Wodick ◽

D. W. Lübbers

Keyword(s):

Blood Flow ◽

Flow Measurements ◽

Blood Flow Measurements

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The utility of intraoperative blood flow measurements in aneurysm surgery using an ultrasonic flow probe

Neurochirurgie ◽

10.1016/s0028-3770(05)83593-3 ◽

2005 ◽

Vol 51 (5) ◽

pp. 545

Author(s):

S. Amin-Hanjani ◽

G. Meglio ◽

R. Gatto ◽

F.T. Charbel

Keyword(s):

Blood Flow ◽

Aneurysm Surgery ◽

Flow Probe ◽

Flow Measurements ◽

Blood Flow Measurements

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Limitations to vasodilatory capacity and V̇o2 max in trained human skeletal muscle

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01396.2006 ◽

2007 ◽

Vol 292 (5) ◽

pp. H2491-H2497 ◽

Cited By ~ 19

Author(s):

Jeremy Barden ◽

Lesley Lawrenson ◽

Jennifer G. Poole ◽

Jeannie Kim ◽

D. Walter Wray ◽

...

Keyword(s):

Skeletal Muscle ◽

Blood Flow ◽

Venous Blood ◽

Knee Extensor ◽

Quadriceps Muscle ◽

Flow Measurements ◽

Blood Flow Measurements ◽

Increased Blood Flow ◽

Venous Blood Sampling

To further explore the limitations to maximal O2 consumption (V̇o2 max) in exercise-trained skeletal muscle, six cyclists performed graded knee-extensor exercise to maximum work rate (WRmax) in hypoxia (12% O2), hyperoxia (100% O2), and hyperoxia + femoral arterial infusion of adenosine (ADO) at 80% WRmax. Arterial and venous blood sampling and thermodilution blood flow measurements allowed the determination of muscle O2 delivery and O2 consumption. At WRmax, O2 delivery rose progressively from hypoxia (1.0 ± 0.04 l/min) to hyperoxia (1.20 ± 0.09 l/min) and hyperoxia + ADO (1.33 ± 0.05 l/min). Leg V̇o2 max varied with O2 availability (0.81 ± 0.05 and 0.97 ± 0.07 l/min in hypoxia and hyperoxia, respectively) but did not improve with ADO-mediated vasodilation (0.80 ± 0.09 l/min in hyperoxia + ADO). Although a vasodilatory reserve in the maximally working quadriceps muscle group may have been evidenced by increased leg vascular conductance after ADO infusion beyond that observed in hyperoxia (increased blood flow but no change in blood pressure), we recognize the possibility that the ADO infusion may have provoked vasodilation in nonexercising tissue of this limb. Together, these findings imply that maximally exercising skeletal muscle may maintain some vasodilatory capacity, but the lack of improvement in leg V̇o2 max with significantly increased O2 delivery (hyperoxia + ADO), with a degree of uncertainty as to the site of this dilation, suggests an ADO-induced mismatch between O2 consumption and blood flow in the exercising limb.

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Pancreatic islet blood flow in normal and obese-hyperglycemic (ob/ob) mice

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1996.271.6.e990 ◽

1996 ◽

Vol 271 (6) ◽

pp. E990-E995 ◽

Cited By ~ 17

Author(s):

P. O. Carlsson ◽

A. Andersson ◽

L. Jansson

Keyword(s):

Blood Flow ◽

Blood Perfusion ◽

Pancreatic Tissue ◽

Pancreatic Blood Flow ◽

Flow Measurements ◽

Islet Mass ◽

Arterial Blood ◽

Islet Blood Flow ◽

Different Strains ◽

Blood Flow Measurements

The present study evaluated whether a microsphere technique could be used for islet blood flow measurements in anesthetized mice. When this was confirmed, we applied the technique in different strains of mice. Approximately 9 x 10(4) microspheres could be given without interfering with mean arterial blood pressure. Mixing of the microspheres with arterial blood was adequate, and the extraction of microspheres in capillary beds was nearly 100%. In NMRI mice whole pancreatic blood flow was estimated to be 0.54 +/- 0.11 ml.min-1.g pancreatic tissue-1 and islet blood flow to be 18 +/- 4 microliters.min-1.g pancreas-1 (n = 12 animals per experiment), whereas corresponding values in lean C57Bl/6 mice were twice as high. In C57Bl/6 mice glucose (3 g/kg iv) doubled islet blood flow without affecting whole pancreatic blood flow, whereas no effect was seen after an equimolar dose of 3-O-methylglucose. In obese-hyperglycemic C57Bl/6 mice, islet blood flow was more than five times higher than in the lean C57Bl/6 mice when expressed as blood flow per gram pancreas. However, when islet blood perfusion was corrected for islet weight, it was lower in the obese than in the lean mice, suggesting an impaired ability in obese mice to increase blood flow in concert with the increased islet mass. This may contribute to the insufficient insulin secretion and resulting hyperglycemia seen in these animals.

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Determination of the patency of vascular prostheses implanted in the rat aorta by means of ultrasonic blood-flow measurements

Microsurgery ◽

10.1002/micr.1920080104 ◽

1987 ◽

Vol 8 (1) ◽

pp. 5-10 ◽

Cited By ~ 3

Author(s):

F. Hess ◽

S. Steeghs ◽

C. Jerusalem ◽

P. Wijn ◽

S. Skotnicki

Keyword(s):

Blood Flow ◽

Rat Aorta ◽

Flow Measurements ◽

Vascular Prostheses ◽

Blood Flow Measurements

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Pancreatic Blood Flow Measurements in the Pig Pancreatitis Model Using Perfusion CT with Deconvolution Method

Lecture Notes in Computer Science - Abdominal Imaging. Computational and Clinical Applications ◽

10.1007/978-3-319-13692-9_9 ◽

2014 ◽

pp. 94-102

Author(s):

Yoshihisa Tsuji ◽

Kazutaka Yamada ◽

Miori Kisimoto ◽

Shujiro Yazumi ◽

Hiroyoshi Isoda ◽

...

Keyword(s):

Blood Flow ◽

Perfusion Ct ◽

Pancreatic Blood Flow ◽

Deconvolution Method ◽

Flow Measurements ◽

Blood Flow Measurements

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Local cerebral PO2, PCO2, and blood flow measurements by mass spectrometry

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1983.245.3.h513 ◽

1983 ◽

Vol 245 (3) ◽

pp. H513-H518

Author(s):

J. Seylaz ◽

E. Pinard ◽

P. Meric ◽

J. L. Correze

Keyword(s):

Mass Spectrometry ◽

Blood Flow ◽

Cerebral Blood Flow ◽

Tracer Gas ◽

Local Cerebral Blood Flow ◽

Flow Measurements ◽

Partial Pressures ◽

Short Period ◽

Blood Flow Measurements

Partial pressures of intracerebral tissue gases (PO2, PCO2) and local cerebral blood flow (local CBF) were determined simultaneously by means of a single cannula implanted stereotaxically in a given structure. Minute quantities of the gases (O2, CO2, and tracer gas) were withdrawn continuously. After a short period of tracer (He) inhalation, CBF was measured by determination of the clearance rate (T1/2). The measurements of PO2 and PCO2 were continuous and quantitative, whereas the measurements of local CBF were sequential and quantitative. The results obtained for local CBF were compared with those found with two other methods (H2 clearance by polarography, thermoclearance) in the same structure of the same animal.

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