BioImpedance Analysis

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Authors - P

Paolisso, G.; Gambardella, A.; Balbi, V.; Ammendola, S.;
        Damore, A.; Varricchio, M.
Title   Body composition, body fat distribution, and resting
        metabolic rate in healthy centenarians
Journal American Journal of Clinical Nutrition
        62
        4
        OCT
Year    1995
Page    746-750
Address G Paolisso
        Univ Naples 2
        Dept Geriatr Med & Metab Dis
        Serv Astanteria Med
        Piazza Miraglia 2-1 Policlin
        Naples, Italy
Serial# 0002-9165
Keys    healthy centenarians; body composition; body fat distribution;
        resting metabolic rate
        ENERGY-EXPENDITURE; BIOELECTRICAL IMPEDANCE; BASAL METABOLISM;
        AGING HUMANS; MEN; AGE; MUSCLE; WOMEN; MASS; STRENGTH
Abs.    Our study investigated body composition and body fat
        distribution in healthy centenarians. Body composition,
        body fat distribution, and resting metabolic rate (RMR)
        were studied in 40 adult subjects aged < 50 y, 35 aged
        subjects > 75 y, and 15 healthy centenarians aged > 100 y.
        Body composition was determined by bioimpedance analysis,
        body fat distribution was calculated as waist-hip ratio
        (WHR), and RMR was calculated by using the Arciero-Poehlman
        formula. Healthy centenarians bad a cognitive impairment
        and degree of disability greater than aged subjects.
        Despite such differences, fat-free mass (FFM) and RMR were
        not different in centenarians compared with aged subjects
        but were lower than in adult subjects. In contrast, healthy
        centenarians had a WHR lower than that of aged subjects but
        not different from that of the adult subjects. After the
        level of physical activity and degree of disability were
        adjusted for, FFM (44 +/- 2.7 and 40 +/- 1.1 kg; P < 0.05)
        and RMR (6757 +/- 761 and 5891 +/- 723 kJ/24 h; P < 0.05)
        were significantly higher in healthy centenarians than in
        aged subjects, respectively. Independent of age, sex, body
        weight, degree of disability, level of physical activity,
        and fasting plasma triiodothyronine, there was a strong
        correlation between RMR and FFM (r = 0.50, P < 0.05) in
        health) centenarians. In conclusion, healthy centenarians
        had a lower FFM and higher body fat content than aged
        subjects. Level of physical activity and degree of
        disability seem to be the major determinants for explaining
        such differences.

Pearsall, D.J.; Reid, J.G.; Livingston, L.A.
Segmental inertial parameters of the human trunk as
determined from computed tomography
Annals of Biomedical Engineering
24
2
MAR-APR
1996
198-210
DJ Pearsall
Mcgill Univ
Dept Phys Educ
475 Pine Ave W
Montreal
Pq H2W 1S4, Canada
0090-6964
body composition; body segment parameters; spine; biomechanics
POSTURE; GRAVITY; DENSITY; TISSUES
This study used computed tomography (CT) imaging to
determine in vivo mass, center of mass (CM), and moments of
inertia (Icm) about the CM of discrete segments of the
human torso. Four subjects, two males and two females,
underwent serial transverse CT scans that were collected at
l-cm intervals for the full length of the trunk. The pixel
intensity values of transverse images were correlated to
tissue densities, thereby allowing trunk section mass
properties to be calculated. The percentage of body mass
observed by vertebral levels ranged from 1.1% at Tl to 2.6%
at L5. The masses of the upper, middle, and lower trunk
segments as percentages of body mass were estimated to be
18.5, 12.2, and 10.7%, respectively. The whole trunk mass
was estimated to comprise 41.6% of the total body mass.
Transverse vertebral CM values were found to lie anterior
to their respective vertebral centroids by up to 5.0 cm in
the lower thoracic region. For the upper, middle, and lower
trunk segments, the average CM positions were found to be
25.9, 62.5, and 86.9% of the distance from the superior to
inferior ends of the trunk. The upper and middle trunk CMs
corresponded to approximately 4.0 cm anterior to T7/T8
vertebral centroid levels and 1.0 cm anterior to L3/L4
vertebral centroid levels, respectively. For the whole
trunk, the CM was 52.7% of the distance from the xiphoid
process and approximately 2.0 cm anterior to L1/L2
vertebral centroid levels. Variations in CM and Icm values
were observed between subject, but these were within the
range of previous reports of body segment parameters.
Differences from previous studies were attributable to
variations in boundary definitions, measurement techniques,
population groups, and body states (live versus cadaver)
examined. The disparity between previous findings and the
findings of this study emphasizes the need to better define
the segmental properties of the trunk so that improved
biomechanical representation of the body can be achieved.

Perko, G.; Tilgreen, R.; Secher, N.H.
Title   The venous pump does not affect the indifference point for
        electrical impedance in humans
Journal European Journal of Applied Physiology and Occupational
        Physiology
        72
        1-2
        DEC
Year    1995
Page    179-182
Address G Perko
        Rigshosp
        Dept Anaesthesia 2034
        Copenhagen Muscle Res Ctr
        Blegdamsvej 9
        DK-2100 Copenhagen 0, Denmark
Serial# 0301-5548
Keys    heart rate; volume distribution
Abs.    We have used regional electrical impedance at 2.5 and 100
        kHz over nine body sections (two thoracic, one abdominal,
        two thigh, two around the knee, and two lower leg) in eight
        subjects to determine the volume indifference point defined
        as the level at which fluid volume remained constant
        independent of body position changes in space. Passive head-
        up tilt and tilt with activation of the venous muscle pump
        of the legs were performed in 10 degrees increments from 0
        to 60 degrees over 6 min. The impedance changes in relation
        to 0 degrees were similar for the two frequencies. Over the
        thorax it increased in proportion to the head-up tilt angle
        by a mean of 3.8 (range 1.9 to 9.3) Omega (100 kHz) at 60
        degrees (P < 0.05), while the abdominal impedance did not
        change significantly. Over the thigh it decreased with
        increasing head-up tilt angle by a mean maximum of - 2.3
        (range - 9.4 to - 0.4) Omega and over the lower leg by a
        mean of - 2.7 (range - 6.0 to - 0.8) Omega. There were only
        marginal changes around the knee, mean - 1.5 (range - 2.3
        to - 0.2) Omega (P < 0.05), and no change around the ankle
        indicating that little or no fluid was accumulated in these
        regions. Changes in impedance during passive and active
        head-up tilt did not differ significantly in any but one
        position: between the greater trochanter and the mid thigh,
        where during passive tilt it decreased by a mean of - 4.8
        (range - 9.4 to - 1.9) Omega, and with activation of the
        venous pump by a mean of only - 1.2 Oange - 1.9 to - 0.4)
        Omega (P < 0.05). These results indicated that the vascular
        volume indifference point was positioned between the navel
        and iliac crest both during the passive and active head-up
        tilts although during the passive tilt, apparently more
        fluid was accumulated in the vessels of the thigh.

Piccoli, A.; Rossi, B.; Pillon, L.; Bucciante, G.
Title   Body fluid overload and bioelectrical impedance analysis in
        renal patients
Journal Mineral and Electrolyte Metabolism
        22
        1-3
        JAN-JUN
Year    1996
Page    76-78
Address A Piccoli
        Univ Padua Policlin
        Cattedra Nefrol
        Ist Med Interna
        Div Nephrol
        Via Giustiniani 2
        I-35128 Padua, Italy
Serial# 0378-0392
Keys    bioimpedance analysis; body composition; chronic renal
        failure; edema; hydration; interstitial fluid; nephrotic
        syndrome; obesity; uremia
        WATER
Abs.    Using a new bivariate vectorial approach to the standard
        bioimpedance analysis (tetrapolar, 50-kHz frequency), we
        evaluated the performance of a graphical method for the
        identification of patients with fluid overload. Two hundred
        and seventeen adult Caucasian subjects were divided into
        four classification groups: 86 healthy control subjects, 55
        patients with mild-to-terminal chronic renal failure in
        conservative treatment (15% with apparent edema), 36
        patients with idiopathic nephrotic proteinuria (58% with
        apparent edema), and 40 obese subjects. We found a
        bioimpedance threshold for apparent edema on the lower pole
        of the sex-specific 75% tolerance ellipse (bivariate
        tolerance interval) of the healthy population. This
        innovative graphical method allows identification,
        monitoring and therapy planning of patients with fluid
        overload using direct bioimpedance measurements without any
        assumption on body composition.

Author Piccoli, A.; Piazza, P.; Noventa, D.; Pillon, L.; Zaccaria, M.
Title   A new method for monitoring hydration at high altitude by
        bioimpedance analysis
Journal Medicine and Science in Sports and Exercise
        28
        12
        DEC
Year    1996
Page    1517-1522
Address A Piccoli
        Univ Padua
        Ist Med Interna
        Cattedra Nefrol
        Policlin Padua
        Via Giustiniani 2
        I-35128 Padua, Italy
Serial# 0195-9131
Keys    bioelectrical impedance; body composition; fluid balance;
        acclimatization; acute mountain sickness; climbing
        TOTAL-BODY WATER; MOUNTAIN-SICKNESS
Abs.    Our study evaluated the performance of a graphical method
        for monitoring the fluid variation at high altitude in
        seven adult Caucasian male subjects (average age 25 yr,
        average height 177 cm). The graphical approach is called
        the Resistance-Reactance (RXc) graph method and is based on
        standard bioimpedance analysis (tetrapolar, 50 kHz
        frequency). Measurements were taken at sea level before the
        expedition, at 5050 m after 1 wk and 3 wk, and again at sea
        level after descent. Plasma and urine electrolytes,
        osmolalities, and the free-water clearance were determined
        by standard methods. All climbers had baseline impedance
        vectors within the reference 95% tolerance ellipse for the
        Italian male population. The high altitude dehydration
        caused a significant lengthening of vectors, which after
        descent underwent a significant shortening and returned
        close to the baseline values. Average urine volume
        increased by 1.4 l . d(-1) in the first week and average
        body weight decreased by 4.4 kg after 3 wk. The RXc graph
        method could be useful in the planning of the individual
        climber's appropriate dehydration and fluid intake at
        altitude since a feedback control of the hydration is
        allowed without any assumption of body composition.

Pidcock, M.; Ciulli, S.; Ispas, S.
Title   Singularities of mixed boundary value problems in electrical
        impedance tomography
Journal Physiological Measurement
        16
         Suppl. 3A
        AUG
Year    1995
Page    A213-A218
Address M Pidcock
        Oxford Brookes Univ
        Sch Comp & Math Sci
        Oxford, England
Serial# 0967-3334
Abs.    The importance of accurate mathematical modelling in the
        development of image reconstruction algorithms for
        electrical impedance tomography (Err) has been discussed in
        a number of recent papers. It is particularly important in
        iterative reconstruction schemes where the forward problem
        of calculating the electric potential from Neumann boundary
        data is solved many times. One area which needs to be
        considered is the mathematical modelling of the electrodes
        used in the technique. In this paper we discuss one of the
        more sophisticated models which has been proposed and
        present the results of a number of numerical and analytic
        calculations which we have made as a contribution to the
        understanding of this question.

Pidcock, M.; Ciulli, S.; Ispas, S.
Title   Some boundary problems in electrical impedance tomography
Journal Physiological Measurement
        17
         Suppl. 4A
        NOV
Year    1996
Page    A91-A96
Address M Pidcock
        Oxford Brookes Univ
        Sch Comp & Math Sci
        Oxford OX3 0BP, England
Serial# 0967-3334
Abs.    Accurate mathematical modelling is important in the
        development of iterative image reconstruction algorithms
        for electrical impedance tomography (EIT). In such schemes
        the forward problem of calculating the electric potential
        from Neumann boundary data is solved many times. One aspect
        of this problem which has received some attention is the
        mathematical modelling of the electrodes used in the
        technique. In this paper we describe an integral equation
        formulation of a boundary value problem associated with
        this issue and we indicate some of the ways in which this
        formulation can be used to obtain numerical and analytic
        results.

Pietraszek-J; Atkinson-S
Concentrations of estrone sulfate and progesterone in plasma and
saliva, vaginal cytology, and bioelectric impedance during the
estrous cycle of the Hawaiian monk seal (Monachus schauinslandi).
Marine Mammal Science 10(4): 430-441
1994
English
Blood and saliva samples, vaginal swabs, and bioelectric impedance
measurements were collected 1-3 times per week from a captive
adult female Hawaiian monk seal (Monachus schauinslandi) during
the spring and summer of 1991. During 1992 saliva only was
collected on average 4 times weekly. Concentrations of
progesterone and estrone sulfate, and the periodic appearance of
cornified epithelial cells from the vagina indicated consecutive
estrous cycles ranging 35 +- 3 days in duration. Progesterone
concentrations in plasma and saliva had a correlation of 0.868,
while estrone sulfate had a correlation of 0.982. Bioimpedance of
the whole seal body resulted in a pattern similar to the estrone
sulfate concentrations, but shifted forward by 2 d. Bioimpedance
of the upper vaginal tissues paralleled the estrone sulfate
pattern while the bioimpedance of the lower reproductive tract
fluctuated without a distinct pattern. The luteal phase ranged
17-20 d and the follicular phase was 15-18 d in length. These
results indicate that: (1) the Hawaiian monk seal, in captivity,
is a polyestrous seal, in contrast to other phocid seals that have
been studied; (2) salivary concentrations of estrogen and
progesterone may provide an accurate, less-invasive method of
monitoring reproductive hormones in captive Hawaiian monk seals;
and (3) vaginal cytology and bioelectric impedance reflect
physiological changes associated with the estrous cycle.

Pliquett, F.; Pliquett, U.
Title   Passive electrical properties of human stratum corneum in
        vitro depending on time after separation
Journal Biophysical Chemistry
        58
        1-2
        JAN 16
Year    1996
Page    205-210
Address F Pliquett
        Univ Leipzig
        Inst Biophys & Med Phys
        Leibigstr 27
        D-04105 Leipzig, Germany
Serial# 0301-4622
Keys    skin; passive electrical properties; electrical impedance;
        time dependence
Abs.    The passive electrical properties of human skin after
        separation from the body are predominated by the stratum
        corneum. Skin within a bath medium (150 mM phosphate
        buffered saline) at constant temperature (37 degrees C)
        exhibits a characteristic change of the passive electrical
        properties with time. Independent of the time the locus in
        the Z-plane is a depressed semicircular are. The angle
        between the lines from the center of the are to the points
        where the locus reaches the real axis remains unchanged.
        The difference between the high and low frequency
        resistivity (R(0) - R(x)) increases over 10 h, reaches a
        pladden, R.H.; Gilmour, A.
Title   Impedance as an alte
        constant of about 40 h. As model for the impedance we used
        a 5 element electrical circuit (R(0), R(1), R(2), C-1, C-2),
        describing 3 pathways, (0) the de path (appendages; R(0)),
        (1) tortuous pathways around the cell structures (R(1), C-
        1) and (2) direct pathways involving the corneocytes (R(2),
        C-2). There are characteristic changes with time in the
        elements of the equivalent circuit up to about 200 h after
        excision. Dramatic changes in C-1 and R(2) at about this
        time after separation strongly suggests destruction of the
        lipid structures. It will be suggested that the use of
        separated human stratum corneum as model for in vivo yields
        unreliable results after this time.

Povill, R.; Riu, P.
Title   Quantification in multifrequency tomography
Journal Physiological Measurement
        16
         Suppl. 3A
        AUG
Year    1995
Page    A69-A78
Address R Povill
        Univ Politecn Catalunya
        Dept Electr Engn
        Div Instrumentac & Bioengn
        POB 30002
        E-08080 Barcelona, Spain
Serial# 0967-3334
Abs.    The time domain change in human body impedance, in short
        intervals, usually falls into the approximation Delta Z <<
        Z(0) (Delta Z: impedance change, Z(0): base impedance).
        This makes it possible to obtain both an image and an
        estimate of the log-conductivity change for the considered
        section using backprojection algorithms. In multifrequency
        tomography, however, the impedance change can be very large,
        depending on the applied frequencies. In this situation it
        is possible to obtain images using the methods applied in
        dynamic impedance imaging, but the estimate of the
        impedance change becomes highly non-linear.
        We have developed an algorithm based on the analytical
        solution of the linearized Poisson equation in a
        curvilinear space formed by the current lines and the
        equipotential lines. In order to set the correct boundary
        conditions, the current profile under the electrodes has
        been numerically computed.
        The behaviour of the algorithm has been assessed using the
        voltages obtained by analytically solving the direct
        problem in a circular region with small circular centred
        and non-centred perturbations of different size. The
        results are compared with those obtained using a
        backprojection algorithm. Although the developed algorithm
        displays higher linearity than a backprojection algorithm,
        it still shows a dependence on the perturbation size and
        position.
        This algorithm has been applied to the reconstruction of a
        series of measurements from 8 kHz to 500 kHz made in a
        sample of porcine liver immersed in a saline tank. A Cole-
        Cole model is fitted to the data. The parameters of this
        model are compared with those calculated from a 4-wire
        measurements using a commercial impedance analyser.

Author Probst, M.; Goris, M.; Vandereycken, W.; Vancoppenolle, H.
Title   Body composition in female anorexia nervosa patients
Journal British Journal of Nutrition
        76
        5
        NOV
Year    1996
Page    639-647
Address M Probst
        Univ Ctr St Joseph
        B-3070 Kortenberg, Belgium
Serial# 0007-1145
Keys    anorexia nervosa; body composition; anthropometry;
        densitometry; underwater weighing
        BIOELECTRICAL IMPEDANCE ANALYSIS; X-RAY ABSORPTIOMETRY; FAT-
        FREE MASS; BALLET DANCERS; ELECTRICAL-CONDUCTIVITY; ENERGY-
        EXPENDITURE; DENSITY; WATER; WOMEN; POTASSIUM
Abs.    For the first time, body composition has been studied in a
        very large sample of female anorexia nervosa patients (n
        200) using two methods: anthropometry (skinfold thickness)
        and densitometry (underwater weighing), The concurrent
        validity of both methods appeared to be good (r 0.84),
        Although the mean percentage of body fat (13.5) in our
        sample corresponds with most of the previous reports, the
        range (4.3-24.8) is great, Our study shows that BMI is not
        a good measure of fatness, Age and duration of illness were
        not related to body fat, Percentage fat was found to be
        different (t 2.76, P < 0.01) according to the diagnostic
        subtype of anorexia nervosa: restricters (12.9) v. bingers
        and/or purgers (14.7).