© 2007 European Society of Cardiology
Use of bioimpedance analysis in patients with chronic heart failure?
Division of Applied Cachexia Research, Department of Cardiology, University Hospital Charite, Campus Virchow-Klinikum Augustenburger Platz 1, 13353 Berlin, Germany
* Corresponding author Tel.: +49 30 450 55 33 99; fax: +49 30 450 55 39 51. E-mail address: anja.sandek{at}charite.de (A. Sandek)
Key Words: Bioimpedance • Chronic heart failure
Received June 9, 2006; With great interest we read the article by Uszko-Lencer et al. [1] who report a strong relation between the methods of dual-energy X-ray absorptiometry and deuterium dilution for assessment of metabolically and functionally active fat-free mass (FFM) in patients with chronic heart failure (CHF). The authors furthermore suggest bioelectrical impedance analysis (BIA) to be a suitable tool for measurement of FFM. However, we believe several points deserve further consideration.
Although Uszko-Lencer et al. [1] report the analysis of extracellular water by bromide dilution in their study population for a total of 33 out of 46 individuals, the corresponding Fig. 2 only reflects values for 9 clinically stable CHF patients and 20 controls. The authors conclude from this selected small group of 9 patients, the ratio between intracellular and extracellular water to be generally normal in all patients with CHF. Therefore, they use a two compartment model of BIA for body composition in the patient group. However, this model is not applicable in congested CHF patients [2] since water retention selectively increases the extracellular water compartment so that a two compartment model overestimates FFM, as stated by the authors themselves [1].
This raises, in our opinion, the question of whether a random measurement of extracellular water in a small group of 9 patients is representative for extracellular fluid status overall in these patients. Extracellular volume alterations occur in CHF patients even in the absence of obvious leg oedema, elevated jugular venous pressure and positive hepato-jugular reflux. Particularly, ascites can frequently be found in CHF without clinical symptoms, thereby overestimating FFM. We believe that the prediction equation for estimation of FFM by BIA in CHF established by Uszko-Lencer and colleagues needs to be interpreted with caution and deserves further validation in larger populations. This methodological limitation holds true even if one considers total body impedance not to be equally distributed within the body taking into account that the trunk only contributes by a relatively small amount to whole body impedance [2].
Usefulness of BIA to evaluate lean body mass in CHF patients needs to be confirmed by larger studies. Further, gender specific distribution of FFM and specific differences in cachectic and non-cachectic CHF patients due to severe changes in body composition [3] may additionally influence the prediction equation forwarded by Uszko-Lencer and colleagues.
Finally, there seems to be a confusion in the legend to Fig. 3, presenting female controls vs. male patients?
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- Uszko-Lencer N.H., Bothmer F., van Pol P.E., Schols A.M. Measuring body composition in chronic heart failure: a comparison of methods. Eur J Heart Fail (2006) 8:208–214.
[Abstract/Free Full Text] - Kyle U.G., Bosaeus I., De Lorenzo A.D., et al. Composition of the ESPEN Working Group. Bioelectrical impedance analysis-part I: review of principles and methods. Clin Nutr (2004) 5:1226–1243.
- Anker S.D., Ponikowski P.P., Clark A.L., et al. Cytokines and neurohormones relating to body composition alterations in the wasting syndrome of chronic heart failure. Eur Heart J (1999) 20:683–693.
[Abstract/Free Full Text]
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