Impedance plethysmography: the origin of electrical impedance changes measured in the human calf

Fa, Anderson; Bc, Penney; Na, Patwardhan; Hb, Wheeler

doi:10.1007/bf02443300

Cited by 21 publications

(7 citation statements)

References 10 publications

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“…We obtained different measures of venous function using the impedance plethysmography technique. 13,14 Our data suggest that both venous compliance and venous capacity are strongly influenced by genetic factors.…”

Section: Discussionmentioning

confidence: 73%

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Heritability of Venous Function in Humans

Brinsuk

Tank

Luft

et al. 2004

ATVB

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Objectives-Venous function contributes to the pathogenesis of thrombophlebitis, venous thrombosis, and possibly to arterial hypertension. Venous disease is presumably heritable; however, the genetic variance of venous function is unknown. Methods and Results-We determined the heritability of venous function in 46 twin pairs (24 monozygotic, age 35Ϯ11 years, 14 men, 34 women; 22 dizygotic, age 30Ϯ8 years, 19 men, 25 women). After a resting phase in the supine position, we determined venous function in both legs by impedance plethysmography. Venous capacity was determined by a standardized protocol. In addition, we obtained venous pressure volume curves by slowly deflating a thigh cuff from 60 to 0 mm Hg. Venous compliance was determined as the steepest part of the venous pressure volume curve. Heritability was estimated using a path modeling approach. Unadjusted heritability was 0.6 (PϽ0.05) for venous capacity and 0.9 (PϽ0.05) for venous compliance. The heritability estimate for venous capacity decreased to 0.3 after adjustment for age, body mass index, and body fat. The heritability estimate for venous compliance remained essentially unchanged after adjustment for sex and age. Key Words: twin study Ⅲ genetics Ⅲ plethysmography Ⅲ venous compliance A pproximately 75% of the circulating blood volume is contained in veins. Therefore, relatively small changes in venous function may have a substantial effect on the cardiovascular system. For example, an increase in venous tone may cause a shift of blood volume from the periphery toward the heart and increase cardiac output. This mechanism may contribute to increased cardiac output in the earlier stages of essential hypertension. 1,2 Venous function becomes particularly important during assumption of upright posture as 500 to 1000 mL are pooled below the diaphragm. 3 Variability in the amount of blood that is pooled during standing influences the propensity to experience orthostatic symptoms. 4 Venous function may also contribute to the pathogenesis of varicose veins, thrombophlebitis, and venous thrombosis. Thus, genes that influence venous function might play an important role in a variety of common cardiovascular ailments. Indeed, Ϸ60% of the variation in the susceptibility to venous thrombosis is related to genetic factors. 5 A positive family history substantially increases the likelihood to suffer from varicose veins, 6 vasovagal syncope, 7 or essential hypertension. However, the research on the genetics of all these conditions has largely neglected the possibility that venous function may be an important intermediate phenotype. The responsiveness of veins to adrenergic stimulation is influenced by genetic factors. 8,9 Yet, the mechanical properties of veins, such as compliance and capacity, may be more relevant to physiological function. The magnitude of the genetic contribution to these measures is not known. We determined the heritability of venous function in a cohort of normal twins. Conclusions-We Methods SubjectsWe investigated the heritability of venous ...

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Section: Discussionmentioning

confidence: 73%

“…[13][14][15] Changes in limb volume were expressed as ml/100 mL tissue (%). These measurements tend to be independent of body size.…”

Section: Evaluation Of Venous Functionmentioning

confidence: 99%

Heritability of Venous Function in Humans

Brinsuk

Tank

Luft

et al. 2004

ATVB

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“…An equivalent circuit representation of a four-electrode impedance plethysmograph. This approximation is widely used either to measure blood volume or liquid volume during limb and total body impedance plethymography (1,17,28,32,36,39). Z e1 , Z e2 , Z e3 , Z e4 are electrode tissue contact impedances, Z t1 , Z t2 , are the tissue impedances between the current drive electrodes and the measurement electrodes, Z L is the impedance of the body segment between the measurement electrodes, Z out and Z in are the source impedance of the current generator and the input impedance of the differential amplifier respectively, Z i , Z dr1 and Z dr2 are the stray capacitances between the leads.…”

Section: Electrical Impedance Plethsymographymentioning

confidence: 99%

“…Current is injected through two outer electrodes and voltage developed between the two inner electrodes is measured. However, sensitivity to impedance variations in inner regions is still poorer (1,43,53). blood is higher than the average conductivity of many other tissues (Table 1).…”

Section: Electrical Impedance Plethsymographymentioning

confidence: 99%

Electrical Impedance Plethysmography

Eyüboğlu

2006

Wiley Encyclopedia of Biomedical Engineering

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Variations of electrical impedance of various parts of human body with physiological activity are well known. Fluctuations in the electrical impedance of human thorax are synchronous with both respiratory activity and also with the cardiac cycle. Electrical impedance plethysmography is used to estimate the volume changes in different parts of the body due to pulsation of blood. Impedance pneumography is used to monitor volume changes in the thorax with ventilation. Impedance cardiography (ICG), a simple and noninvasive method, is used to estimate cardiac output based on the variation of thoracic impedance during the cardiac cycle. Clearly, changes in global impedance of the thorax, with cardiac activity, are produced not only by one source. Ventricular volume changes, blood volume in the great blood vessels, variation of blood flow rate and pulmonary circulation, changes in the geometry of the thorax are all contributors to the global impedance signal. But their relative contributions to the global impedance variation are not fully understood and still subject to continuing research.

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“…Fixed frequency bioelectrical impedance plethysmographic (IPG) techniques are valuable noninvasive tools that provide information about overall segmental volumes, blood flows, and hemodynamic status with a high degree of temporal resolution [9][10][11][12]. The second type, electrical bioimpedance spectroscopy (BIS) [13,14] is a multifrequency technique that, when coupled with computeraided equivalent circuit analysis, may be used to provide information about relative redistributions of fluids between the intra-and extracellular compartments of the monitored segments.…”

Section: Introductionmentioning

confidence: 99%

A system to monitor segmental intracellular, interstitial, and intravascular volume and circulatory changes during acute hemodialysis

Montgomery¹,

Montgomery²,

Gerth³

et al. 2017

Journal of Electrical Bioimpedance

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This paper describes a new combined impedance plethysmographic (IPG) and electrical bioimpedance spectroscopic (BIS) instrument and software that allows noninvasive real-time measurement of segmental blood flow and changes in intracellular, interstitial, and intravascular volumes during various fluid management procedures. The impedance device can be operated either as a fixed frequency IPG for the quantification of segmental blood flow and hemodynamics or as a multi-frequency BIS for the recording of intracellular and extracellular resistances at 40 discrete input frequencies. The extracellular volume is then deconvoluted to obtain its intra-vascular and interstitial component volumes as functions of elapsed time. The purpose of this paper is to describe this instrumentation and to demonstrate the information that can be obtained by using it to monitor segmental compartment volumes and circulatory responses of end stage renal disease patients during acute hemodialysis. Such information may prove valuable in the diagnosis and management of rapid changes in the body fluid balance and various clinical treatments.

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Impedance plethysmography: the origin of electrical impedance changes measured in the human calf

Cited by 21 publications

References 10 publications

Heritability of Venous Function in Humans

Heritability of Venous Function in Humans

Electrical Impedance Plethysmography

A system to monitor segmental intracellular, interstitial, and intravascular volume and circulatory changes during acute hemodialysis

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