Venous pressure-volume relation and calf blood flow determined by changes in posture

1976 ◽  
Vol 10 (2) ◽  
pp. 206-213 ◽  
Author(s):  
G. J. BARENDSEN ◽  
J. V. D. BERG
Keyword(s):  
Blood Flow ◽  
Venous Pressure ◽  
Calf Blood Flow ◽  
Volume Relation

Vascular perturbations in the chronic orthostatic intolerance of the postural orthostatic tachycardia syndrome

2000 ◽  
Vol 89 (4) ◽  
pp. 1505-1512 ◽  
Author(s):  
Julian M. Stewart ◽  
Amy Weldon
Keyword(s):  
Blood Flow ◽  
Orthostatic Intolerance ◽  
Venous Pressure ◽  
Fluid Collection ◽  
Lower Extremities ◽  
Postural Orthostatic Tachycardia Syndrome ◽  
Size Change ◽  
Venous Compliance ◽  
Edema Formation ◽  
Calf Blood Flow

Chronic orthostatic intolerance is often related to the postural orthostatic tachycardia syndrome (POTS). POTS is characterized by upright tachycardia. Understanding of its pathophysiology remains incomplete, but edema and acrocyanosis of the lower extremities occur frequently. To determine how arterial and venous vascular properties account for these findings, we compared 13 patients aged 13–18 yr with 10 normal controls. Heart rate and blood pressure were continuously recorded, and strain-gauge plethysmography was used to measure forearm and calf blood flow, venous compliance, and microvascular filtration while the subject was supine and to measure calf blood flow and calf size change during head-up tilt. Resting venous pressure was higher in POTS compared with control (16 vs. 10 mmHg), which gave the appearance of decreased compliance in these patients. The threshold for edema formation decreased in POTS patients compared with controls (8.3 vs. 16.3 mmHg). With tilt, early calf blood flow increased in POTS patients (from 3.4 ± 0.9 to 12.6 ± 2.3 ml · 100 ml−1 · min−1) but did not increase in controls. Calf volume increased twice as much in POTS patients compared with controls over a shorter time of orthostasis. The data suggest that resting venous pressure is higher and the threshold for edema is lower in POTS patients compared with controls. Such findings make the POTS patients particularly vulnerable for edema fluid collection. This may signify a redistribution of blood to the lower extremities even while supine, accounting for tachycardia through vagal withdrawal.

Reflex vascular defects in the orthostatic tachycardia syndrome of adolescents

2001 ◽  
Vol 90 (6) ◽  
pp. 2025-2032 ◽  
Author(s):  
Julian M. Stewart ◽  
Amy Weldon
Keyword(s):  
Blood Flow ◽  
Flow Resistance ◽  
Venous Pressure ◽  
Low Flow ◽  
Postural Orthostatic Tachycardia Syndrome ◽  
Venous Compliance ◽  
Calf Blood Flow ◽  
Normal Resistance ◽  
Head Up Tilt ◽  
Normal Controls

Dependent pooling occurs in postural orthostatic tachycardia syndrome (POTS) related to defective vasoconstriction. Increased venous pressure (Pv) >20 mmHg occurs in some patients (high Pv) but not others (normal Pv). We compared 22 patients, aged 12–18 yr, with 13 normal controls. Continuous blood pressure and strain-gauge plethysmography were used to measure supine forearm and calf blood flow, resistance, venous compliance, and microvascular filtration, and blood flow and swelling during 70° head-up tilt. Supine, high Pv had normal resistance in arms (26 ± 2 mmHg · ml−1 · 100 ml · min) and legs (34 ± 3 mmHg · ml−1 · 100 ml · min) but low leg blood flow (1.5 ± 0.4 ml · 100 ml−1 · min−1). Supine leg Pv (30 ± 2 vs. 13 ± 1 mmHg in control) exceeded the threshold for edema (isovolumetric pressure = 19 ± 3 mmHg). Supine, normal Pv had high blood flow in arms (4.1 ± 0.2 vs. 3.5 ± 0.2 ml · 100 ml−1 · min−1 in control) and legs (3.8 ± 0.4 vs. 2.7 ± 0.3 ml · 100 ml−1 · min−1 in control) with low resistance. With tilt, calf blood flow increased steadily in POTS with high Pv and transiently increased in normal Pv. Calf volume increased in all POTS patients. Arm blood flow increased in normal Pv only with forearm maintained at heart level. These data suggest that there are (at least) two subgroups of POTS characterized by high Pv and low flow or normal Pv and high flow. These may correspond to abnormalities in local or baroreceptor-mediated vasoconstriction, respectively.

Vascular adaptation to 4 wk of deconditioning by unilateral lower limb suspension

2005 ◽  
Vol 288 (4) ◽  
pp. H1747-H1755 ◽  
Author(s):  
Michiel W. P. Bleeker ◽  
Patricia C. E. De Groot ◽  
Fleur Poelkens ◽  
Gerard A. Rongen ◽  
Paul Smits ◽  
...  
Keyword(s):  
Blood Flow ◽  
Femoral Artery ◽  
Superficial Femoral Artery ◽  
Lower Limb ◽  
Venous Pressure ◽  
Venous Occlusion ◽  
Calf Blood Flow ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Echo Doppler Ultrasound

Physical inactivity or deconditioning is an independent risk factor for atherosclerosis and cardiovascular disease. In contrast to exercise, the vascular changes that occur as a result of deconditioning have not been characterized. We used 4 wk of unilateral lower limb suspension (ULLS) to study arterial and venous adaptations to deconditioning. In contrast to previous studies, this model is not confounded by denervation or microgravity. Seven healthy subjects participated in the study. Arterial and venous characteristics of the legs were assessed by echo Doppler ultrasound and venous occlusion plethysmography. The diameter of the common and superficial femoral artery decreased by 12% after 4 wk of ULLS. Baseline calf blood flow, as measured by plethysmography, decreased from 2.1 ± 0.2 to 1.6 ± 0.2 ml·min−1·dl tissue−1. Both arterial diameter and calf blood flow returned to baseline values after 4 wk of recovery. There was no indication of a decrease in flow-mediated dilation of the superficial femoral artery after ULLS deconditioning. This means that functional adaptations to inactivity are not simply the inverse of adaptations to exercise. The venous pressure-volume curve is shifted downward after ULLS, without any effect on compliance. In conclusion, deconditioning by 4 wk of ULLS causes significant changes in both the arterial and the venous system.

Pulmonary fluid balance following pulmocutaneous baroreceptor denervation in the toad

1986 ◽  
Vol 61 (1) ◽  
pp. 331-337 ◽  
Author(s):  
A. W. Smits ◽  
N. H. West ◽  
W. W. Burggren
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Venous Pressure ◽  
Driving Pressure ◽  
Pulmonary Hemodynamics ◽  
Pulmonary Capillaries ◽  
Neural Input ◽  
Order Of Magnitude ◽  
Capillary Resistance ◽  
Recurrent Laryngeal Nerves

Pulmonary hemodynamics and net transcapillary fluid flux (NTFF) were measured in conscious toads before and following bilateral denervation of the recurrent laryngeal nerves (rLN), which contain afferents from baroreceptors located in the pulmocutaneous arteries. Denervation caused an acute doubling of the arterial-venous pressure gradient across the lung and a threefold increase in pulmonary blood flow. Calculated pulmonary vascular resistance fell and remained below control values through the period of experimentation. NTFF increased by an order of magnitude (0.74–7.77 ml X kg-1 X min-1), as filtration increased in response to the hemodynamic changes caused by rLN denervation. There was a better correlation between NTFF and pulmonary blood flow than between NTFF and pulmonary driving pressure. Our results support the view that tonic neural input from pulmocutaneous baroreceptors protects the anuran lung from edema by restraining pulmonary driving pressure and blood flow and perhaps by reflexly maintaining vascular tone in the extrinsic pulmonary artery, therefore tending to increase the pre-to-postpulmonary capillary resistance ratio and biasing the Starling relationship in the pulmonary capillaries against filtration.

Lower vascular tone and larger plasma volume in Parkinson's disease with orthostatic hypotension

2011 ◽  
Vol 111 (2) ◽  
pp. 443-448 ◽  
Author(s):  
J. T. Groothuis ◽  
R. A. J. Esselink ◽  
J. P. H. Seeger ◽  
M. J. H. van Aalst ◽  
M. T. E. Hopman ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Blood Flow ◽  
Orthostatic Hypotension ◽  
Vascular Resistance ◽  
Plasma Volume ◽  
Venous Pressure ◽  
Dilution Method ◽  
Significant Difference ◽  
Head Up Tilt

The pathophysiology of orthostatic hypotension in Parkinson's disease (PD) is incompletely understood. The primary focus has thus far been on failure of the baroreflex, a central mediated vasoconstrictor mechanism. Here, we test the role of two other possible factors: 1) a reduced peripheral vasoconstriction (which may contribute because PD includes a generalized sympathetic denervation); and 2) an inadequate plasma volume (which may explain why plasma volume expansion can manage orthostatic hypotension in PD). We included 11 PD patients with orthostatic hypotension (PD + OH), 14 PD patients without orthostatic hypotension (PD − OH), and 15 age-matched healthy controls. Leg blood flow was examined using duplex ultrasound during 60° head-up tilt. Leg vascular resistance was calculated as the arterial-venous pressure gradient divided by blood flow. In a subset of 9 PD + OH, 9 PD − OH, and 8 controls, plasma volume was determined by indicator dilution method with radiolabeled albumin (125I-HSA). The basal leg vascular resistance was significantly lower in PD + OH (0.7 ± 0.3 mmHg·ml−1·min) compared with PD − OH (1.3 ± 0.6 mmHg·ml−1·min, P < 0.01) and controls (1.3 ± 0.5 mmHg·ml−1·min, P < 0.01). Leg vascular resistance increased significantly during 60° head-up tilt with no significant difference between the groups. Plasma volume was significantly larger in PD + OH (3,869 ± 265 ml) compared with PD − OH (3,123 ± 377 ml, P < 0.01) and controls (3,204 ± 537 ml, P < 0.01). These results indicate that PD + OH have a lower basal leg vascular resistance in combination with a larger plasma volume compared with PD − OH and controls. Despite the increase in leg vascular resistance during 60° head-up tilt, PD + OH are unable to maintain their blood pressure.

scholarly journals Effect of venesection on calf blood flow in polycythaemia.

BMJ ◽  
1982 ◽  
Vol 284 (6316) ◽  
pp. 619-620 ◽  
Author(s):  
D W Milligan ◽  
J E Tooke ◽  
J A Davies
Keyword(s):  
Blood Flow ◽  
Calf Blood Flow

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.

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