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Schierbauer J, Günther S, Haupt S, Zimmer RT, Herz D, Voit T, Zimmermann P, Wachsmuth NB, Aberer F, Moser O. Acute Fluid Intake Impacts Assessment of Body Composition via Bioelectrical Impedance Analysis. A Randomized, Controlled Crossover Pilot Trial. Metabolites 2023; 13:metabo13040473. [PMID: 37110132 PMCID: PMC10143694 DOI: 10.3390/metabo13040473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 03/23/2023] [Accepted: 03/24/2023] [Indexed: 03/29/2023] Open
Abstract
Bioelectrical impedance analysis (BIA) has proven to be particularly useful due to its inexpensive and rapid assessment of total body water and body density. However, recent fluid intake may confound BIA results since equilibration of fluid between intra- and extracellular spaces may take several hours and furthermore, ingested fluids may not be fully absorbed. Therefore, we aimed to evaluate the impact of different fluid compositions on the BIA. A total of eighteen healthy individuals (10 females, mean ± SD age of 23.1 ± 1.8 years) performed a baseline measurement of body composition before they consumed isotonic 0.9% sodium-chloride (ISO), 5% glucose (GLU) or Ringer (RIN) solutions. During the visit of the control arm (CON), no fluid was consumed. Further impedance analyses were conducted every 10 min after the fluid consumption for 120 min. We found statistically significant interactions between the effects of solution ingestion and time for intra- (ICW, p < 0.01) and extracellular water (ECW, p < 0.0001), skeletal muscle mass (SMM, p < 0.001) and body fat mass (FM, p < 0.01), respectively. Simple main effects analysis showed that time had a statistically significant effect on changes in ICW (p < 0.01), ECW (p < 0.01), SMM (p < 0.01) and FM (p < 0.01), while fluid intake did not have a significant effect. Our results highlight the importance of a standardized pre-measurement nutrition, with particular attention to hydration status when using a BIA for the evaluation of body composition.
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Affiliation(s)
- Janis Schierbauer
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
- Correspondence: ; Tel.: +49-(0)-921-55-3467
| | - Svenja Günther
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
| | - Sandra Haupt
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
| | - Rebecca T. Zimmer
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
| | - Daniel Herz
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
| | - Thomas Voit
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
| | - Paul Zimmermann
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
| | - Nadine B. Wachsmuth
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
| | - Felix Aberer
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
- Interdisciplinary Metabolic Medicine Trials Unit, Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria
| | - Othmar Moser
- Division of Exercise Physiology and Metabolism, Department of Sport Science, University of Bayreuth, 95440 Bayreuth, Germany; (S.G.); (S.H.); (R.T.Z.); (D.H.); (T.V.); (P.Z.); (N.B.W.); (F.A.)
- Interdisciplinary Metabolic Medicine Trials Unit, Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria
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Correlations between Repeated Use of Dry Sauna for 4 x 10 Minutes, Physiological Parameters, Anthropometric Features, and Body Composition in Young Sedentary and Overweight Men: Health Implications. BIOMED RESEARCH INTERNATIONAL 2019; 2019:7535140. [PMID: 30800676 PMCID: PMC6360547 DOI: 10.1155/2019/7535140] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 12/25/2018] [Indexed: 02/03/2023]
Abstract
Background The effect of thermal stress on the physiological parameters of young overweight and sedentary men who sporadically use the sauna remains insufficiently investigated. Aim The aim of the study was to determine the effect of sauna bathing on the physiological parameters of young overweight, physically inactive men and to test the correlations between physiological parameters versus anthropometric features and body composition parameters. Materials and Methods Forty-five overweight and sedentary men aged 20.76±2.4 y were exposed to four sauna sessions of 10 minutes each (temperature: 90-91°C; relative humidity: 14-16 %) with four 5-minute cool-down breaks. Body composition was determined before sauna, and body mass and blood pressure were measured before and after sauna. Physiological parameters were monitored during four 10-minute sauna sessions. Results A significant (p<0.0001) increase in all analyzed physiological parameters was observed during four successive 10-minute sauna sessions. Heart rate, energy expenditure, blood pressure, and body mass loss were most strongly correlated with anthropometric parameters (body mass, body mass index, and body surface area) and body composition parameters (percent body fat, body fat mass, and visceral fat level). The 60-minute treatment resulted in a significant reduction in body mass (0.65 kg). Conclusions Repeated use of Finnish sauna induces significant changes in the physiological parameters of young sedentary overweight men, and these changes are intensified during successive treatments. Deleterious cardiovascular adaptations were most prevalent in men characterized by the highest degree of obesity and the largest body size.
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Suehiro K, Morikage N, Ueda K, Samura M, Takeuchi Y, Nagase T, Mizoguchi T, Nakamura K, Hamano K. Correlation Between Changes in Extremity Volume and Bioelectrical Impedance in Arm and Leg Lymphedema. Lymphat Res Biol 2018; 16:385-389. [DOI: 10.1089/lrb.2017.0063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Kotaro Suehiro
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Noriyasu Morikage
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Koshiro Ueda
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Makoto Samura
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Yuriko Takeuchi
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Takashi Nagase
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Takahiro Mizoguchi
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Kaori Nakamura
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
| | - Kimikazu Hamano
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine, Yamaguchi, Japan
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Antonelou M, El-Kateb S, Davies N, Davenport A. Changes in serum osmotic pressure following haemodialysis treatments lead to changes in bioimpedance spectroscopy estimates of lean and adipose tissue. Eur J Clin Nutr 2017; 71:564-565. [DOI: 10.1038/ejcn.2016.270] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/25/2016] [Accepted: 11/27/2016] [Indexed: 12/12/2022]
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Suehiro K, Morikage N, Yamashita O, Harada T, Ueda K, Samura M, Tanaka Y, Takeuchi Y, Nakamura K, Hamano K. Distribution of Extracellular Fluid in Legs with Venous Edema and Lymphedema. Lymphat Res Biol 2016; 14:156-61. [PMID: 27603006 DOI: 10.1089/lrb.2016.0004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND This study aimed to determine the specific fluid distribution pattern in legs with lymphedema (LE) in comparison to normal legs and legs with venous edema (VE) using bioelectrical impedance analysis (BIA). METHODS AND RESULTS BIA was performed in 47 patients with lymphedema (LE; 63 legs), 33 patients with venous edema (VE; 60 legs), and 33 normal subjects (N; 66 legs). The ratio of intracellular fluid (ICF) resistance (Ri) to extracellular fluid (ECF) resistance (Re) of a whole leg normalized to the right arm (Ri/Re leg), a surrogate parameter for ECF/ICF, and the Ri/Re of the thigh and calf without normalization (Ri/Re thigh, Ri/Re calf, respectively) were obtained. Increases in Ri/Re leg (N 2.5 ± 0.7, VE 3.9 ± 3.7, LE 3.7 ± 1.5), Ri/Re thigh (N 1.8 ± 0.5, VE 3.2 ± 3.8, LE 3.8 ± 1.9), and Ri/Re calf (N 2.6 ± 0.6, VE 4.6 ± 1.7, LE 4.4 ± 2.2) were confirmed in VE and LE compared to normal subjects. However, the ratios of Ri/Re calf to Ri/Re thigh in normal subjects and those with untreated VE/LE were all ∼1.5 (N 1.5 ± 0.3, VE 1.5 ± 0.7, LE 1.6 ± 0.7). CONCLUSIONS Fluid content was increased in legs with VE and LE compared to normal subjects, while the mode of gravitational fluid distribution was similar among all legs. Thus, no specific finding for LE was confirmed.
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Affiliation(s)
- Kotaro Suehiro
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
| | - Noriyasu Morikage
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
| | - Osamu Yamashita
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
| | - Takasuke Harada
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
| | - Koshiro Ueda
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
| | - Makoto Samura
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
| | - Yuya Tanaka
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
| | - Yuriko Takeuchi
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
| | - Kaori Nakamura
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
| | - Kimikazu Hamano
- Division of Vascular Surgery, Department of Surgery and Clinical Science, Yamaguchi University Graduate School of Medicine , Yamaguchi, Japan
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Sauna-induced body mass loss in young sedentary women and men. ScientificWorldJournal 2014; 2014:307421. [PMID: 25614882 PMCID: PMC4295591 DOI: 10.1155/2014/307421] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 10/29/2014] [Accepted: 12/17/2014] [Indexed: 12/16/2022] Open
Abstract
The aim of the study was to evaluate the relationship between body mass index (BMI) and body mass loss (BML) induced by thermal stress in a dry sauna. The study was conducted on a group of 674 sedentary students, 326 women and 348 men aged 19-20. The correlations between BMI scores and BML were determined. The subjects were placed in supine position in a dry sauna for two sessions of 10 minutes each with a 5-minute break. The influence of BMI on the amount of BML in the sauna was determined by nonlinear stepwise regression. The smallest BML was noted in underweight subjects; students with normal weight lost more weight, whereas the greatest BML was reported in overweight and obese subjects. Persons with a high BMI are at higher risk of dehydration, and they should pay particular attention to replenishing fluids during a visit to the sauna. The proposed equations for calculating BML based on a person's BMI can be useful in estimating the amount of fluids that should be replenished by both men and women during a visit to a dry sauna.
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Nescolarde L, Doñate T, Piccoli A, Rosell J. Comparison of segmental with whole-body impedance measurements in peritoneal dialysis patients. Med Eng Phys 2008; 30:817-24. [DOI: 10.1016/j.medengphy.2007.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 09/20/2007] [Accepted: 09/20/2007] [Indexed: 01/10/2023]
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Nescolarde L, García-González MA, Rosell-Ferrer J, Doñate T, Querfeld U. Thoracic versus whole body bioimpedance measurements: the relation to hydration status and hypertension in peritoneal dialysis patients. Physiol Meas 2006; 27:961-71. [PMID: 16951456 DOI: 10.1088/0967-3334/27/10/003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The whole body bioimpedance technique is a highly promising non-invasive, reproducible, fast and inexpensive bed-side method for monitoring hydration status. Using segmental bioimpedance measurements, it is possible to obtain information about the fluid change in each body segment (Song, Lee, Kim and Kim 1999 Perit. Dial. Int. 19 386-90). In this pilot study we have measured 25 male patients (30-65 yr, BMI 20-32 kg m(-2)) undergoing continuous ambulatory peritoneal dialysis (CAPD). Tetrapolar impedance measurements were obtained using the right-side technique (whole body), and a segmental impedance method focused in the thorax region. Blood pressure (BP) measurements were taken manually with a sphygmomanometer. Patients were classified as either stable (group 0) or unstable (group 1) using clinical parameters of overall cardiovascular risk. The Mahalanobis distance (dM2) was calculated for the mean blood pressure (BP(mean)), and the impedance parameter R normalized by body height H for the right-side (R(RS)/H) and the thorax segment (R(TH)/H). Differences between groups were significant (p < 0.0001) for R(TH)/H and for BP(mean), and less significant (p = 0.016) for R(RS)/H. Group 1 patients showed a small dM2 as compared with a reference patient (a critical patient with acute lung edema) with high BP(mean) and low values of R(TH)/H and R(RS)/H. Moreover, Group 0 patients showed a larger dM2 with respect to the reference patient, with lower BP(mean) and higher values of R(TH)/H and R(RS)/H. All patients classified as unstable by clinical assessment were correctly classified using R(TH)/H in conjunction with BP(mean) using dM2. Segmental-monofrequency non-invasive bioimpedance of the thoracic region could provide a simple, objective non-invasive method of support for facilitating the clinical assessment of CAPD patients.
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Affiliation(s)
- L Nescolarde
- Electronic Engineering Department, Technical University of Catalonia (UPC), Jordi Girona 1-3 Edifici C4, 08034 Barcelona, Spain.
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Schaefer M, Gross W, Preuss M, Ackemann J, Gebhard MM. Monitoring of water content and water distribution in ischemic hearts. Bioelectrochemistry 2003; 61:85-92. [PMID: 14642913 DOI: 10.1016/j.bioelechem.2003.08.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We determined water content and water distribution by fitting dielectric spectra of ischemic canine hearts between 5 MHz and 3 GHz with a newly developed model which describes heart cells and subcellular organelles as rotational ellipsoids filled with electrolyte enclosed by an isolating membrane. The fraction of dry material is modelled by spherical particles with a small dielectric permittivity. Free model parameters were water content, cell volume fraction, and the conductivity of the electrolytes. Resulting model parameters were compared to data from tissue desiccation and to conductivity changes produced by protons and lactate ions. We investigated hearts in two states: during ischemia after interruption of blood flow (pure ischemia, PI, n=5) and during ischemia after resuscitation with Tyrode's solution (IAR, n=14). The difference between water content determined by tissue desiccation and by dielectric spectroscopy was less than 0.5%. During 360 min of ischemia, water content in IAR decreased from 85+/-1.6% to 83+/-2.2% and in PI from 80+/-0.8% to 78+/-1.5%. Cellular volume fraction in IAR increased from 0.47+/-0.045 to 0.63+/-0.031 and in PI from 0.62+/-0.014 to 0.73+/-0.013, which is consistent with published morphometric data. After 180 min of ischemia, the increase of the cytosolic conductivity was 0.14+/-0.02 S/m as calculated from the dielectric spectrum and was similar to the conductivity increase which was roughly estimated on the basis of tissue lactate concentration. In conclusion, dielectric spectroscopy combined with our model analysis facilitates the monitoring of water content and distribution by means of nondestructive surface probes.
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Affiliation(s)
- M Schaefer
- Department of Experimental Surgery, University of Heidelberg, Im Neuenheimer Feld 365, D-69120 Heidelberg, Germany.
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Bordelon DJ, Wingfield WE. Monitoring acute fluid shifts with bioelectrical impedance analysis: a review. J Vet Emerg Crit Care (San Antonio) 2002. [DOI: 10.1046/j.1435-6935.2002.00023.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
The aim of this study was to investigate the influence of long-lasting, extensive rowing training on body fluids in 12 experienced rowers (23.3 +/- 6.3 years, 188.7 +/- 5.9 cm, 82.0 +/- 10.8 kg, body mass index [BMI] 23.7 +/- 2.1). All rowers had a light traditional breakfast about 3 h before the training. The subjects rowed 2 h 17 min and covered 22.6 +/- 2.5 km. Before and immediately after the training session and after 30, 60, and 120 min of recovery, body fluid balance was measured using a multiple-frequency impedance device (Multiscan 5000, Bodystat Ltd., UK). Body resistance was measured at the right side of the body. Extracellular (ECW), intracellular (ICW), and total (TBW) body water were measured at 5, 200, and 50 kHz, respectively. Blood hemoglobin (Hgb) and hemotocrit (Hct) were measured, and changes in blood volume (BV), plasma volume (PV), and cell volume (CV) were measured according to Dill and Costill (1974). The body weight of the rowers decreased significantly (p < 0.05) from 82.0 +/- 10.8 kg to 80.6 +/- 11.2 kg during the endurance training. There were no significant changes in TBW immediately after the training session. Significant changes in the content of TBW occurred during the first 30 min of recovery (48.7 +/- 4.4 to 47.9 +/- 4.1; p < 0.05). The amount of ECW also decreased significantly during the first 30 min of recovery (23.3 +/- 2.0 to 22.7 +/- 1.91; p < 0.05). There were no significant changes in the balance of ECW. BV decreased during the training session by 2.5 +/- 5.2% (p < 0.05). There were significant relationships (p < 0.05) between the covered distance and the following parameters after the training session: body weight (r = -0.75), TBW (r = -0.75), and ECW (r = -0.83). Changes in the blood parameters did not correlate significantly with changes in body fluids and training volume. It was concluded that extensive rowing training significantly changed the balance of body fluids in rowers.
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Affiliation(s)
- J Jürimäe
- Institute of Sport Pedagogy, University of Tartu, Estonia.
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Ward L, Cornish BH, Paton NI, Thomas BJ. Multiple frequency bioelectrical impedance analysis: a cross-validation study of the inductor circuit and Cole models. Physiol Meas 1999; 20:333-47. [PMID: 10593227 DOI: 10.1088/0967-3334/20/4/301] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
It has been proposed that multiple frequency bioelectrical impedance models of the human body should include an inductive property for the circulatory system, the inductor circuit model (ICM), and that such a model, when coupled with a new method of data analysis, can improve the predictive power of multiple frequency bioelectrical impedance analysis (MFBIA). This hypothesis was tested using MFBIA measurements and gold standard measures of total body and extracellular water volumes in a cross-validation study in two subject groups (viz. controls and HIV). The MFBIA measurements were analysed using the current, widely accepted Cole model and the alternative ICM model which includes an inductive component. Correlations in the range 0.75 to 0.92 (for TBW) and 0.46 to 0.79 (for ECW) for impedance quotients versus gold standard measures within the subject groups were observed. These decreased, to as low as r = 0.50 for TBW and r = 0.29 for ECW, when the derived algorithms were applied to the alternative subject group. These results suggest that lack of portability of MFBIA algorithms between subject groups is not due to an inadequacy of the analogue circuit model per se but is possibly due more to fundamental flaws in the principles associated with its application. These include assuming a constant proportionality of body segment geometries and tissue fluid resistivities. This study has also demonstrated that this inadequacy cannot be overcome by simply introducing an inductive component into the analogue electrical circuit.
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Affiliation(s)
- L Ward
- Department of Biochemistry, University of Queensland, Brisbane, Australia.
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Rees AE, Ward LC, Cornish BH, Thomas BJ. Sensitivity of multiple frequency bioelectrical impedance analysis to changes in ion status. Physiol Meas 1999; 20:349-62. [PMID: 10593228 DOI: 10.1088/0967-3334/20/4/302] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bioelectrical impedance analysis has found extensive application as a simple noninvasive method for the assessment of body fluid volumes. The measured impedance is, however, not only related to the volume of fluid but also to its inherent resistivity. The primary determinant of the resistivities of body fluids is the concentration of ions. The aim of this study was to investigate the sensitivity of bioelectrical impedance analysis to bodily ion status. Whole body impedance over a range of frequencies (4-1012 kHz) of rats was measured during infusion of various concentrations of saline into rats concomitant with measurement of total body and intracellular water by tracer dilution techniques. Extracellular resistance (R0), intracellular resistance (R(i)) and impedance at the characteristic frequency (Z(c)) were calculated. R0 and Z(c) were used to predict extracellular and total body water respectively using previously published formulae. The results showed that whilst R0 and Z(c) decreased proportionately to the amount of NaCl infused, R(i) increased only slightly. Impedances at the end of infusion predicted increases in TBW and ECW of approximately 4-6% despite a volume increase of less than 0.5% in TBW due to the volume of fluid infused. These data are discussed in relation to the assumption of constant resistivity in the prediction of fluid volumes from impedance data.
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Affiliation(s)
- A E Rees
- Department of Biochemistry, University of Queensland, Brisbane, Australia
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