Determinations of blood flow and shunting of 9- and 15-micrometer spheres in regional beds

1979 ◽  
Vol 237 (1) ◽  
pp. H25-H33 ◽  
Author(s):  
F. C. Fan ◽  
G. B. Schuessler ◽  
R. Y. Chen ◽  
S. Chien
Keyword(s):  
Blood Flow ◽  
Portal Vein ◽  
Venous Blood ◽  
Sampling Technique ◽  
Organ Blood Flow ◽  
Venous Sampling ◽  
Flow Measurements ◽  
Arterial Blood ◽  
Blood Flow Measurements ◽  
The Brain

In 17 pentobarbitalized dogs, the shunting of 15-micrometer and 9-micrometer microspheres was studied in the brain, myocardium, kidney, intestine, and lung. The veins of these organs were catheterized for constant blood withdrawal for 2 min by direct venipuncture. The ratio of microsphere radioactivity in the venous blood to that in the arterial blood gave the shunting of microspheres by the venous sampling technique. The 15-micrometer microspheres showed 2% or less shunting for all organs studied, whereas the 9-micrometer microspheres had shunting ranging from 3% in the coronary sinus to 24% in the portal vein. The shunting of 9-micrometer microspheres was also calculated from direct tissue counting, where the 15-micrometer spheres were considered to be completely entrapped. The results of direct tissue counting indicate that the 2-min venous sampling underestimates microsphere shunting. CO2 administration increased significantly the shunting of 9-micrometer spheres, whereas the shunting of 15-micrometer spheres determined by venous sampling remained less than 2%. Consideration of shunting indicates that the 15-micrometer microspheres might be more appropriate for regional organ blood flow measurements, including the myocardium.

Thigh oxygen uptake at the onset of intense exercise is not affected by a reduction in oxygen delivery caused by hypoxia

2012 ◽  
Vol 303 (8) ◽  
pp. R843-R849 ◽  
Author(s):  
Peter M. Christensen ◽  
Nikolai Baastrup Nordsborg ◽  
Lars Nybo ◽  
Stefan P. Mortensen ◽  
Mikael Sander ◽  
...  
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Oxygen Delivery ◽  
Venous Blood ◽  
Knee Extensor ◽  
Intense Exercise ◽  
Muscle Lactate ◽  
Flow Measurements ◽  
Arterial Blood ◽  
Blood Flow Measurements

In response to hypoxic breathing most studies report slower pulmonary oxygen uptake (V̇o2) kinetics at the onset of exercise, but it is not known if this relates to an actual slowing of the V̇o2 in the active muscles. The aim of the present study was to evaluate whether thigh V̇o2 is slowed at the onset of intense exercise during acute exposure to hypoxia. Six healthy male subjects (25.8 ± 1.4 yr, 79.8 ± 4.0 kg, means ± SE) performed intense (100 ± 6 watts) two-legged knee-extensor exercise for 2 min in normoxia (NOR) and hypoxia [fractional inspired oxygen concentration (FiO2) = 0.13; HYP]. Thigh V̇o2 was measured by frequent arterial and venous blood sampling and blood flow measurements. In arterial blood, oxygen content was reduced ( P < 0.05) from 191 ± 5 ml O2/l in NOR to 180 ± 5 ml O2/l in HYP, and oxygen pressure was reduced ( P < 0.001) from 111 ± 4 mmHg in NOR to 63 ± 4 mmHg in HYP. Thigh blood flow was the same in NOR and HYP, and thigh oxygen delivery was consequently reduced ( P < 0.05) in HYP, but femoral arterial-venous oxygen difference and thigh V̇o2 were similar in NOR and HYP. In addition, muscle lactate release was the same in NOR and HYP, and muscle lactate accumulation during the first 25 s of exercise determined from muscle biopsy sampling was also similar (0.35 ± 0.07 and 0.36 ± 0.07 mmol·kg dry wt−1·s−1 in NOR and HYP). Thus the increase in thigh V̇o2 was not attenuated at the onset of intense knee-extensor exercise despite a reduction in oxygen delivery and pressure.

scholarly journals Optimally Repeatable Kinetic Model Variant for Myocardial Blood Flow Measurements with 82Rb PET

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Adrian F. Ocneanu ◽  
Robert A. deKemp ◽  
Jennifer M. Renaud ◽  
Andy Adler ◽  
Rob S. B. Beanlands ◽  
...  
Keyword(s):  
Blood Flow ◽  
Kinetic Model ◽  
Myocardial Blood Flow ◽  
Input Function ◽  
Blood Pool ◽  
Flow Measurements ◽  
Flow Reserve ◽  
Arterial Blood ◽  
Spillover Correction ◽  
Blood Flow Measurements

Purpose. Myocardial blood flow (MBF) quantification with Rb82 positron emission tomography (PET) is gaining clinical adoption, but improvements in precision are desired. This study aims to identify analysis variants producing the most repeatable MBF measures. Methods. 12 volunteers underwent same-day test-retest rest and dipyridamole stress imaging with dynamic Rb82 PET, from which MBF was quantified using 1-tissue-compartment kinetic model variants: (1) blood-pool versus uptake region sampled input function (Blood/Uptake-ROI), (2) dual spillover correction (SOC-On/Off), (3) right blood correction (RBC-On/Off), (4) arterial blood transit delay (Delay-On/Off), and (5) distribution volume (DV) constraint (Global/Regional-DV). Repeatability of MBF, stress/rest myocardial flow reserve (MFR), and stress/rest MBF difference (ΔMBF) was assessed using nonparametric reproducibility coefficients (RPCnp = 1.45 × interquartile range). Results. MBF using SOC-On, RVBC-Off, Blood-ROI, Global-DV, and Delay-Off was most repeatable for combined rest and stress: RPCnp = 0.21 mL/min/g (15.8%). Corresponding MFR and ΔMBF RPCnp were 0.42 (20.2%) and 0.24 mL/min/g (23.5%). MBF repeatability improved with SOC-On at stress (p<0.001) and tended to improve with RBC-Off at both rest and stress (p<0.08). DV and ROI did not significantly influence repeatability. The Delay-On model was overdetermined and did not reliably converge. Conclusion. MBF and MFR test-retest repeatability were the best with dual spillover correction, left atrium blood input function, and global DV.

Abstract 67: Vasopressin impairs Brain, Heart and Kidney Perfusion in Acute Heart Failure

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Stig Müller ◽  
Ole-Jakob How ◽  
Stig E Hermansen ◽  
Truls Myrmel
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Heart Function ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Arterial Blood Flow ◽  
Organ Blood Flow ◽  
Arterial Blood ◽  
Time Flow ◽  
The Brain

Arginin Vasopressin (AVP) is increasingly used to restore mean arterial pressure (MAP) in various circulatory shock states including cardiogenic shock. This is potentially deleterious since AVP is also known to reduce cardiac output by increasing vascular resistance. Aim: We hypothesized that restoring MAP by AVP improves vital organ blood flow in experimental acute cardiac failure. Methods: Cardiac output (CO) and arterial blood flow to the brain, heart, kidney and liver were measured in nine pigs by transit-time flow probes. Heart function and contractility were measured using left ventricular Pressure-Volume catheters. Catheters in central arteries and veins were used for pressure recordings and blood sampling. Left ventricular dysfunction was induced by intermittent coronary occlusions, inducing an 18 % reduction in cardiac output and a drop in MAP from 87 ± 3 to 67 ± 4 mmHg. Results: A low-dose therapeutic infusion of AVP (0.005 u/kg/min) restored MAP but further impaired systemic perfusion (CO and blood flow to the brain, heart and kidney reduced by 29, 18, 23 and 34 %, respectively). The reduced blood flow was due to a 2.0, 2.2, 1.9 and 2.1 fold increase in systemic, brain, heart and kidney specific vascular resistances, respectively. Contractility remained unaffected by AVP. The hypoperfusion induced by AVP was most likely responsible for observed elevated plasma lactate levels and an increased systemic oxygen extraction. Oxygen saturation in blood drawn from the great cardiac vein fell from 31 ± 1 to 22 ± 3 % dropping as low as 10 % in one pig. Finally, these effects were reversed forty minutes after weaning the pigs form the drug. Conclusion: The pronounced reduction in coronary blood flow point to a potentially deleterious effect in postoperative cardiac surgical patients and in patients with coronary heart disease. Also, this is the first study to report a reduced cerebral perfusion by AVP.

Methodological error and spatial variability of organ blood flow measurements using radiolabeled microspheres

1991 ◽  
Vol 191 (1) ◽  
pp. 47-63 ◽  
Author(s):  
B. Zwissler ◽  
R. Schosser ◽  
C. Weiss ◽  
V. Iber ◽  
M. Weiss ◽  
...  
Keyword(s):  
Blood Flow ◽  
Spatial Variability ◽  
Methodological Error ◽  
Organ Blood Flow ◽  
Flow Measurements ◽  
Blood Flow Measurements

Assessment of arterial blood flow measurements by digital angiography.

Radiology ◽  
1981 ◽  
Vol 141 (1) ◽  
pp. 39-47 ◽  
Author(s):  
J H Bürsch ◽  
H J Hahne ◽  
R Brennecke ◽  
D Grönemeier ◽  
P H Heintzen
Keyword(s):  
Blood Flow ◽  
Arterial Blood Flow ◽  
Digital Angiography ◽  
Flow Measurements ◽  
Arterial Blood ◽  
Blood Flow Measurements

Neuromuscular electrical stimulation for thromboprophylaxis: A systematic review

2015 ◽  
Vol 30 (9) ◽  
pp. 589-602 ◽  
Author(s):  
S Hajibandeh ◽  
S Hajibandeh ◽  
GA Antoniou ◽  
JRH Scurr ◽  
F Torella
Keyword(s):  
Systematic Review ◽  
Blood Flow ◽  
Electrical Stimulation ◽  
Venous Thromboembolism ◽  
Venous Blood ◽  
Neuromuscular Electrical Stimulation ◽  
Current Evidence ◽  
Venous Blood Flow ◽  
Flow Measurements ◽  
Blood Flow Measurements

Objective To evaluate the effect of neuromuscular electrical stimulation on lower limb venous blood flow and its role in thromboprophylaxis. Method Systematic review of randomised and non-randomised studies evaluating neuromuscular electrical stimulation, and reporting one or more of the following outcomes: incidence of venous thromboembolism, venous blood flow and discomfort profile. Results Twenty-one articles were identified. Review of these articles showed that neuromuscular electrical stimulation increases venous blood flow and is generally associated with an acceptable tolerability, potentially leading to good patient compliance. Ten comparative studies reported DVT incidence, ranging from 2% to 50% with neuromuscular electrical stimulation and 6% to 47.1% in controls. There were significant differences, among included studies, in terms of patient population, neuromuscular electrical stimulation delivery, diagnosis of venous thromboembolism and blood flow measurements. Conclusion Neuromuscular electrical stimulation increases venous blood flow and is well tolerated, but current evidence does not support a role for neuromuscular electrical stimulation in thromboprophylaxis. Randomised controlled trials are required to investigate the clinical utility of neuromuscular electrical stimulation in this setting.

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