Peak calf blood flow estimates are higher with Dohn than with Whitney plethysmograph

1996 ◽  
Vol 81 (3) ◽  
pp. 1418-1422 ◽  
Author(s):  
D. N. Proctor ◽  
J. R. Halliwill ◽  
P. H. Shen ◽  
N. E. Vlahakis ◽  
M. J. Joyner
Keyword(s):  
Blood Flow ◽  
Reactive Hyperemia ◽  
Arterial Occlusion ◽  
Venous Occlusion ◽  
Calf Blood Flow ◽  
Absolute Flow ◽  
Wide Range ◽  
Before And After ◽  
The Mean ◽  
Highly Correlated

Estimates of calf blood flow with venous occlusion plethysmography vary widely between studies, perhaps due to the use of different plethysmographs. Consequently, we compared calf blood flow estimates at rest and during reactive hyperemia in eight healthy subjects (four men and four women) with two commonly used plethysmographs: the mercury-in-silastic (Whitney) strain gauge and Dohn air-filled cuff. To minimize technical variability, flow estimates were compared with a Whitney gauge and a Dohn cuff on opposite calves before and after 10 min of bilateral femoral arterial occlusion. To account for any differences between limbs, a second trial was conducted in which the plethysmographs were switched. Resting flows did not differ between the plethysmographs (P = 0.096), but a trend toward lower values with the Whitney was apparent. Peak flows averaged 37% lower with the Whitney (27.8 +/- 2.8 ml.dl-1.min-1) than with the Dohn plethysmograph (44.4 +/- 2.8 ml.dl-1.min-1; P < 0.05). Peak flow expressed as a multiple above baseline was also lower with the Whitney (10-fold) than with the Dohn plethysmograph (14.5-fold; P = 0.02). Across all flows at rest and during reactive hyperemia, estimates were highly correlated between the plethysmographs in all subjects (r2 = 0.96-0.99). However, the mean slope for the Whitney-Dohn relationship was only 60 +/- 2%, indicating that over a wide range of flows the Whitney gauge estimate was 40% lower than that for the Dohn cuff. These results demonstrate that the same qualitative results can be obtained with either plethysmograph but that absolute flow values will generally be lower with Whitney gauges.

Intrinsic control of colonic blood flow and oxygenation

1980 ◽  
Vol 238 (6) ◽  
pp. G478-G484
Author(s):  
P. R. Kvietys ◽  
T. Miller ◽  
D. N. Granger
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Perfusion Pressure ◽  
Reactive Hyperemia ◽  
Venous Pressure ◽  
Arterial Occlusion ◽  
Venous Occlusion ◽  
Colonic Blood Flow ◽  
O2 Extraction ◽  
O2 Delivery

In a denervated autoperfused dog colon preparation, arterial perfusion pressure, venous outflow pressure, blood flow, and arteriovenous O2 difference were measured during graded arterial pressure alterations, arterial occlusion, venous pressure elevation, venous occlusion, and local intra-arterial infusion of adenosine. As perfusion pressure was reduced from 100 to 30 mmHg, colonic blood flow decreased and arteriovenous O2 difference increased. Although blood flow was not autoregulated O2 delivery was maintained within 10% of control between 70 to 100 mmHg and then decreased with further reduction in perfusion pressure. Arterial occlusion (15, 30, and 60 s) resulted in a postocclusion reactive hyperemia; the magnitude of the hyperemia was directly related to the duration of occlusion. Venous occlusion resulted in a postocclusion reactive hypoemia. Elevation of venous pressure from 0 to 20 mmHg increased vascular resistance, O2 extraction, and the capillary filtration coefficient, but decreased O2 delivery. Infusion of adenosine decreased vascular resistance and O2 extraction, but increased O2 delivery. These data suggest that both metabolic and myogenic mechanisms are involved in the control of colonic blood flow and oxygenation.

scholarly journals Hyperglycemia Increases Muscle Blood Flow and Alters Endothelial Function in Adolescents with Type 1 Diabetes

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Amanda S. Dye ◽  
Hong Huang ◽  
John A. Bauer ◽  
Robert P. Hoffman
Keyword(s):  
Blood Flow ◽  
Type 1 Diabetes ◽  
Endothelial Function ◽  
Vascular Function ◽  
Microvascular Complications ◽  
Muscle Blood Flow ◽  
Arterial Occlusion ◽  
Venous Occlusion ◽  
Before And After

Alterations of blood flow and endothelial function precede development of complications in type 1 diabetes. The effects of hyperglycemia on vascular function in early type 1 diabetes are poorly understood. To investigate the effect of hyperglycemia on forearm vascular resistance (FVR) and endothelial function in adolescents with type 1 diabetes, FVR was measured before and after 5 minutes of upper arm arterial occlusion using venous occlusion plethysmography in (1) fasted state, (2) euglycemic state (~90 mg/dL; using 40 mU/m2/min insulin infusion), and (3) hyperglycemic state (~200 mg/dL) in 11 adolescents with type 1 diabetes. Endothelial function was assessed by the change in FVR following occlusion. Seven subjects returned for a repeat study with hyperglycemia replaced by euglycemia. Preocclusion FVR decreased from euglycemia to hyperglycemia (P=0.003). Postocclusion fall in FVR during hyperglycemia was less than during euglycemia (P=0.002). These findings were not reproduced when hyperglycemia was replaced with a second euglycemia. These results demonstrate that acute hyperglycemia causes vasodilation and alters endothelial function in adolescents with type 1 diabetes. In addition they have implications for future studies of endothelial function in type 1 diabetes and provide insight into the etiology of macrovascular and microvascular complications of type 1 diabetes.

The reproducibility of limb blood flow measurements in human volunteers at rest and after exercise by using mercury-in-Silastic strain gauge plethysmography under standardized conditions

1986 ◽  
Vol 70 (6) ◽  
pp. 635-638 ◽  
Author(s):  
D. H. Roberts ◽  
Y. Tsao ◽  
A. M. Breckenridge
Keyword(s):  
Blood Flow ◽  
Coefficient Of Variation ◽  
Venous Occlusion ◽  
Limb Blood Flow ◽  
Flow Measurements ◽  
Post Exercise ◽  
Calf Blood Flow ◽  
Human Volunteers ◽  
The Mean ◽  
Blood Flow Measurements

1. A study to assess the reproducibility of limb blood flow measurements by venous occlusion plethysmography using mercury-in-Silastic strain gauges was performed in six normal volunteers under standardized conditions. 2. Using this technique forearm and calf blood flow were measured at rest and between 2 and 3 min after submaximal exercise on six separate occasions over a 1 month period. 3. The mean coefficient of variation for resting forearm blood flow was 10.5% (range 7.8-15.6%). 4. The mean coefficient of variation for resting calf blood flow was 11.5% (range 7.4-14.2%). 5. The mean coefficient of variation for post-exercise calf blood flow was 13% (range 11.5-16.4%). 6. The results suggest that limb blood flow measurement by this technique may be useful in studies where serial measurements are required.

Effect of short periods of arterial occlusion on blood flow and oxygen uptake

1961 ◽  
Vol 16 (5) ◽  
pp. 851-857 ◽  
Author(s):  
David I. Abramson ◽  
Samuel Tuck ◽  
Yvonne Bell ◽  
Roscoe E. Mitchell ◽  
Agenor M. Zayas
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Reactive Hyperemia ◽  
Arterial Occlusion ◽  
Normal Subjects ◽  
Venous Occlusion ◽  
Oxygen Debt ◽  
Base Line ◽  
Vascular Change ◽  
Fick Principle

In 17 experiments, performed on the forearm of normal subjects, the effect of 2½, 5, and 10 min of arterial occlusion was studied. Blood flow was obtained with the venous occlusion plethysmograph, and oxygen uptake was calculated using the Fick principle. Arterial occlusion resulted in the production of an oxygen debt which was subsequently repaid. With progressively longer periods of anoxia there was a proportionate increase in the magnitude of the debt. Similar conclusions could not be drawn from blood flow studies alone, since the vascular change represented only one means of repayment of the oxygen debt during reactive hyperemia, the other being a greater extraction of oxygen from each unit of blood early in the postocclusion period. The constant overswing on either side of the control base line, observed in the records of oxygen uptake, suggested the absence of delicately balanced and efficient checks on the mechanisms responsible for repayment of the oxygen debt incurred in the period of tissue anoxia. Submitted on March 27, 1961

Relation of blood-free to blood-inclusive postmortem lung water measurements in sheep

1985 ◽  
Vol 59 (2) ◽  
pp. 592-596 ◽  
Author(s):  
J. C. Collins ◽  
J. H. Newman ◽  
N. E. Wickersham ◽  
W. K. Vaughn ◽  
J. R. Snapper ◽  
...  
Keyword(s):  
Extravascular Lung Water ◽  
Weight Ratio ◽  
Lung Homogenate ◽  
Lung Water ◽  
Before And After ◽  
The Mean ◽  
Space Expansion ◽  
Highly Correlated ◽  
Linear Regressions ◽  
Better Than

Our purpose was to see if the postmortem weight ratio of extravascular lung water to blood-free dry lung (blood-free ratio) was related to similar ratios in blood-inclusive lung and in blood. We developed linear regressions of blood-free ratio on ratios for blood-inclusive lung and blood together and for blood-inclusive lung alone for 73 sheep studied under 11 different protocols and for two subgroups of sheep, one with plasma space expansion and the other without expansion. The relation of ratios of blood-free to blood-inclusive lungs was different between the two subgroups. Although all regressions were highly correlated, the fits of the blood-free ratio on ratios for blood-inclusive lung and blood together were better than for blood-inclusive lung alone. The mean error of prediction of extravascular lung water for all sheep was significantly less for the regression of blood-free ratio on ratios for blood and blood-inclusive lung together (11 g) than for blood-inclusive lung alone (18 g). This study shows that weights of lung homogenate and blood samples before and after simple oven drying can be used to provide accurate inexpensive estimates of postmortem extravascular lung water.

Maximal vascular leg conductance in trained and untrained men

1987 ◽  
Vol 62 (2) ◽  
pp. 606-610 ◽  
Author(s):  
P. G. Snell ◽  
W. H. Martin ◽  
J. C. Buckey ◽  
C. G. Blomqvist
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Reactive Hyperemia ◽  
Venous Occlusion ◽  
Vascular Conductance ◽  
Blood Flows ◽  
Arterial Blood ◽  
Sedentary Subjects

Lower leg blood flow and vascular conductance were studied and related to maximal oxygen uptake in 15 sedentary men (28.5 +/- 1.2 yr, mean +/- SE) and 11 endurance-trained men (30.5 +/- 2.0 yr). Blood flows were obtained at rest and during reactive hyperemia produced by ischemic exercise to fatigue. Vascular conductance was computed from blood flow measured by venous occlusion plethysmography, and mean arterial blood pressure was determined by auscultation of the brachial artery. Resting blood flow and mean arterial pressure were similar in both groups (combined mean, 3.0 ml X min-1 X 100 ml-1 and 88.2 mmHg). After ischemic exercise, blood flows were 29- and 19-fold higher (P less than 0.001) than rest in trained (83.3 +/- 3.8 ml X min-1 X 100 ml-1) and sedentary subjects (61.5 +/- 2.3 ml X min-1 X 100 ml-1), respectively. Blood pressure and heart rate were only slightly elevated in both groups. Maximal vascular conductance was significantly higher (P less than 0.001) in the trained compared with the sedentary subjects. The correlation coefficients for maximal oxygen uptake vs. vascular conductance were 0.81 (trained) and 0.45 (sedentary). These data suggest that physical training increases the capacity for vasodilation in active limbs and also enables the trained individual to utilize a larger fraction of maximal vascular conductance than the sedentary subject.

Lumped Parameter Thermal Model for the Study of Vascular Reactivity in the Fingertip

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
O. Ley ◽  
C. Deshpande ◽  
B. Prapamcham ◽  
M. Naghavi
Keyword(s):  
Heat Flux ◽  
Blood Flow ◽  
Thermal Model ◽  
Vascular Reactivity ◽  
Arterial Occlusion ◽  
Blood Perfusion ◽  
Cost Effective ◽  
Venous Occlusion ◽  
Cardiovascular Complications ◽  
Tissue Temperature

Vascular reactivity (VR) denotes changes in volumetric blood flow in response to arterial occlusion. Current techniques to study VR rely on monitoring blood flow parameters and serve to predict the risk of future cardiovascular complications. Because tissue temperature is directly impacted by blood flow, a simplified thermal model was developed to study the alterations in fingertip temperature during arterial occlusion and subsequent reperfusion (hyperemia). This work shows that fingertip temperature variation during VR test can be used as a cost-effective alternative to blood perfusion monitoring. The model developed introduces a function to approximate the temporal alterations in blood volume during VR tests. Parametric studies are performed to analyze the effects of blood perfusion alterations, as well as any environmental contribution to fingertip temperature. Experiments were performed on eight healthy volunteers to study the thermal effect of 3min of arterial occlusion and subsequent reperfusion (hyperemia). Fingertip temperature and heat flux were measured at the occluded and control fingers, and the finger blood perfusion was determined using venous occlusion plethysmography (VOP). The model was able to phenomenologically reproduce the experimental measurements. Significant variability was observed in the starting fingertip temperature and heat flux measurements among subjects. Difficulty in achieving thermal equilibration was observed, which indicates the important effect of initial temperature and thermal trend (i.e., vasoconstriction, vasodilatation, and oscillations).

Differences in reactive hyperemia between the intestinal mucosa and muscularis

1984 ◽  
Vol 247 (6) ◽  
pp. G617-G622
Author(s):  
A. P. Shepherd ◽  
G. L. Riedel
Keyword(s):  
Blood Flow ◽  
Metabolic Rate ◽  
Laser Doppler Velocimetry ◽  
Reactive Hyperemia ◽  
Arterial Occlusion ◽  
Oxygen Demand ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Total Blood ◽  
Total Blood Flow

In a previous study of regional intestinal blood flow by laser-Doppler velocimetry, we noted that the mucosa displayed reactive hyperemia following arterial occlusion but that the muscularis did not. Therefore, to determine whether this observation is generally valid, we compared responses of the mucosa and muscularis externa to arterial occlusion. We measured total blood flow to isolated loops of canine small bowel with an electromagnetic flow probe on the supply artery; blood flow either in the mucosa or in the muscularis was measured by laser-Doppler velocimetry. Mucosal and total blood flow consistently showed reactive hyperemia in response to a 60-s occlusion, but the muscularis did not. To determine whether metabolic rate influenced reactive hyperemia, we increased enteric oxygen uptake by placing 5% bile and transportable solutes in the lumen; these agents increased oxygen consumption by 36%. After a 60-s occlusion, the durations of both total and mucosal reactive hyperemia were significantly prolonged by increased metabolic rate. Similarly, the payback-to-debt ratios in both total and mucosal blood flows were significantly increased at elevated metabolic rate. These data support the conclusions that reactive hyperemia occurs more frequently and has a greater magnitude in the mucosa compared with the muscularis and both total and mucosal reactive hyperemia are strongly influenced by the preocclusive oxygen demand. These findings therefore constitute further evidence that metabolic factors contribute to reactive hyperemia in the intestinal circulation.

scholarly journals Have Standard Formulas Correcting Correlations for Range Restriction Been Adequately Tested?: Minor Sampling Distribution Quirks Distort Them

2017 ◽  
Vol 78 (6) ◽  
pp. 1021-1055 ◽  
Author(s):  
Wendy Johnson ◽  
Ian J. Deary ◽  
Thomas J. Bouchard
Keyword(s):  
Cognitive Ability ◽  
Sample Selection ◽  
Population Level ◽  
Maximum Likelihood Estimates ◽  
Range Restriction ◽  
Data Set ◽  
Wide Range ◽  
Before And After ◽  
Ability Tests ◽  
Highly Correlated

Most study samples show less variability in key variables than do their source populations due most often to indirect selection into study participation associated with a wide range of personal and circumstantial characteristics. Formulas exist to correct the distortions of population-level correlations created. Formula accuracy has been tested using simulated normally distributed data, but empirical data are rarely available for testing. We did so in a rare data set in which it was possible: the 6-Day Sample, a representative subsample of 1,208 from the Scottish Mental Survey 1947 of cognitive ability in 1936-born Scottish schoolchildren (70,805). 6-Day Sample participants completed a follow-up assessment in childhood and were re-recruited for study at age 77 years. We compared full 6-Day Sample correlations of early-life variables with those of the range-restricted correlations in the later-participating subsample, before and after adjustment for direct and indirect range restriction. Results differed, especially for two highly correlated cognitive tests; neither reproduced full-sample correlations well due to small deviations from normal distribution in skew and kurtosis. Maximum likelihood estimates did little better. To assess these results’ typicality, we simulated sample selection and made similar comparisons using the 42 cognitive ability tests administered to the Minnesota Study of Twins Reared Apart, with very similar results. We discuss problems in developing further adjustments to offset range-restriction distortions and possible approaches to solutions.

Effect of active muscle mass during ischemic exercise on peak lower leg vascular conductance

2005 ◽  
Vol 98 (3) ◽  
pp. 765-771 ◽  
Author(s):  
Aaron J. Polichnowski ◽  
Ellen K. Heyer ◽  
Alexander V. Ng
Keyword(s):  
Blood Flow ◽  
Muscle Mass ◽  
Plantar Flexion ◽  
Arterial Occlusion ◽  
Venous Occlusion ◽  
Lower Leg ◽  
Isokinetic Dynamometer ◽  
Active Muscle ◽  
Vascular Conductance ◽  
The Right

Uncertainty exists as to whether a period of passive arterial occlusion (PAO) or ischemic exercise (IE) results in peak lower leg vascular conductance (LVC). This uncertainty is due to the different body positions, active muscle mass, and occlusion times used for PAO or IE. The purpose of this study was to examine whether 10 min of PAO elicits a similar LVC compared with ischemic dorsiflexion (IDF), ischemic plantar flexion (IPF), and ischemic plantar-dorsiflexion (IPDF). Ten subjects (5 women, 27 ± 9 yr, 68 ± 3 kg) were studied on 3 days over 1 wk in a semireclined position with the right foot attached to an isokinetic dynamometer. Mean arterial pressure (Finapres) and lower leg blood flow (LBF, venous occlusion plethysmography) were measured at rest and after PAO and IE. PAO was administered randomly on 1 of the 3 days and before IE. IE protocols consisted of maximal isokinetic dorsiflexion and/or plantar flexion at 120 and 60°/s, respectively. In a second experiment, an additional eight subjects (4 women, 29 ± 12 yr, 77 ± 12 kg) were studied to examine the effect of isokinetic speed during IDF on peak LBF and LVC. Peak LVC (ml·min−1·100 ml−1·mmHg−1) was similar among IPF (0.590 ± 0.16), IPDF (0.532 ± 0.17), and PAO (0.511 ± 0.18), and significantly lower after IDF (0.334 ± 0.15). No differences in peak LBF and LVC were observed after IDF using different isokinetic speeds. We conclude that 10 min of PAO, IPF, and IPDF performed in a similar posture are adequate stimuli to elicit peak LVC.

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