Rapid plasma volume decline upon quiet standing reflects large filtration capacity in dependent limbs

Lundvall, J.; Bjerkhoel, P.; Quittenbaum, S.; Lindgren, Pär

doi:10.1046/j.1365-201x.1996.521294000.x

Cited by 29 publications

(28 citation statements)

References 16 publications

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“…Earlier studies estimated that plasma volume decreased about 10-15 % after 20-30 min in the upright position (Waterfield, 1931;Hagan et al 1978;Hinghofer-Szalkay & Moser, 1986). However, Lundvall et al (Lundvall & Bjerkhoel, 1994;Lundvall et al 1996) recently demonstrated that venous blood sampled from the standing subject underestimated the time course and magnitude of reduction in plasma volume. The underestimation was ascribed to incomplete mixing of venous blood from dependent and non-dependent regions.…”

Section: Regulation Of Blood Pressure and Venous Capacitance In Healtmentioning

confidence: 99%

Pathophysiological basis of orthostatic hypotension in autonomic failure

Smit

Halliwill²,

Low

et al. 1999

The Journal of Physiology

323

209

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Patients with autonomic failure may be seriously incapacitated in activities of daily living due to orthostatic hypotension. Their low blood pressure is ascribed to a defective increase in arterial resistance and an excessive venous pooling upon standing. Effective pharmacological treatment is now available, but may aggravate supine hypertension and have other undesirable effects. Additionally, pharmacological treatment is less successful for hypotension with physical exercise or in warm surroundings (Bannister & Mathias, 1992). Non-pharmacological measures are regarded as a cornerstone in the treatment of orthostatic hypotension. These measures consist of chronic expansion of the extracellular volume or reducing the vascular volume in which pooling occurs (Bannister & Mathias, 1992). The latter includes protective measures like physical countermanoeuvres which can be applied by those patients with no major additional neurological and musculo-skeletal disorders, and external support garments which can be recommended to all patients. We reasoned that selection and use of appropriate protective measures would be facilitated by understanding the fundamental physiological mechanisms that prevent excessive orthostatic pooling in healthy subjects, why these mechanisms fail in patients with autonomic failure, and how these protective measures work. Therefore we reviewed the literature and summarized the available data about the amount and location of venous pooling in patients with autonomic failure and the effectiveness of physical countermanoeuvres and external support garments.

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Section: Regulation Of Blood Pressure and Venous Capacitance In Healtmentioning

confidence: 99%

Pathophysiological basis of orthostatic hypotension in autonomic failure

Smit

Halliwill²,

Low

et al. 1999

The Journal of Physiology

323

209

View full text Add to dashboard Cite

show abstract

“…19 The filtration coefficient can be chronically altered through exercise or electrical stimulation as well as disease. 20 -22 Our previous work intimated at increased K f in patients with POTS 11,23,24 but stopped short of any definitive statement because of patient heterogeneity, [lack of] subject selection, and technical considerations.…”

Section: Microvascular Filtration Coefficient Is Increased In Potsmentioning

confidence: 99%

Microvascular Filtration Is Increased in Postural Tachycardia Syndrome

Stewart

2003

Circulation

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Background— Postural tachycardia syndrome (POTS) is related to defective peripheral vasoconstriction of dependent extremities with redistributive hypovolemia. Methods and Results— To test whether enhanced microvascular filtration produces leg enlargement, we studied 12 patients 13 to 19 years of age with POTS and defective leg vasoconstriction and 13 age-matched healthy control subjects, with strain-gauge plethysmography used to measure venous pressure (P v ), forearm and calf blood flow, vascular capacitance, and the microvascular filtration coefficient (K f ). Measurements were made while the patient was supine and at steady state during upright tilt to 35°. Supine P v was not different in POTS, but upright leg P v tended to be increased above control. Arm and leg peripheral arterial resistance was decreased in the supine and upright positions in patients with POTS compared with control subjects ( P =0.01, upright legs). Supine K f was not significantly increased in the forearm in patients with POTS but was increased in the calf (9.3±2.2 versus 5.7±2.4 [10 −3 ] mL/100 mL per minute per mm Hg, P =0.04), correlating with calf blood flow (r s =0.84, P =0.002). K f was invariant with orthostasis. The hydraulic contribution to upright filtered flow at 35° tilt, the product of K f and P v , was approximately twice that of control (0.41±0.09 versus 0.19±0.04 mL/100 mL per minute, P =0.04). Conclusions— Increased microvascular filtration accounts for enhanced leg swelling in patients with POTS with increased arterial blood flow.

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“…Independent from the capacitance response, transcapillary fluid filtration is a significant contributor to lower limb volume load and thus important in the orthostatic reaction (10). Accordingly, it has been speculated that an increased capillary filtration during upright posture could affect stroke volume and thus contribute to a progressive fall in cardiac output in orthostatic VVS (66).…”

Section: Effects Of Venous Capacitance and Fluid Filtration On Lbnp Tmentioning

confidence: 99%

“…Previous studies have shown that net fluid filtration into extravascular tissue increases the measured calf volume substantially during VOP, lower body negative pressure (LBNP) and quiet standing (10,30,91,96,110). The effect of net fluid filtration may be especially important to consider because there is compelling evidence that filtration and/or CFC differs among different population groups, e.g., increased net fluid filtration has been shown in patients with postural orthostatic tachycardia syndrome (74) as well as in young women compared to age-matched men (91), whereas reduced net fluid filtration has been seen in aging women (111) and patients with diabetes (76,112).…”

Section: Intravenous Pressure and Correction Of Net Fluid Filtrationmentioning

confidence: 99%

“…Moreover, the increase in transmural capillary pressure in the dependent circulation results in a prominent filtration of plasma fluid into the extravascular tissue. During 5 min of quiet standing the decrease in plasma volume can be as much as 450 ml (10). This redistribution of blood decreases venous return, cardiac output (CO) and blood pressure (BP) and continued maintenance of upright posture necessitates the interaction between several cardiovascular regulatory systems (11).…”

Section: Introductionmentioning

confidence: 99%

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