Body composition and energy expenditure of patients with chronic cardiac failure

Abstract

Patients with acute cardiac failure have excess body water, and it is commonly assumed that this is also so in patients with stable chronic cardiac failure (CCF). To investigate this, we measured total body water (TBW) using stable isotope dilution and single-frequency bioelectrical impedance (BIA), and also extracellular volume (ECV) using bromide dilution in 12 patients with CCF and eight matched control subjects. TBW (kg⁻¹ body weight) was similar in the two groups [median ¹⁸O dilution 53.2% (range 46.5–57.1%) in patients vs. 54.8% (47.9–62.7) in control subjects; BIA 56.6% (42.7–73.1) vs. 58.0% (52.0–68.6)]. ECV was also similar in the two groups [0.25 L kg⁻¹ (0.20–0.29) vs. 0.25 (0.19–0.35)]. There was a strong correlation between stable isotope and BIA measurements of TBW for all subjects (r = 0.76), but BIA overestimated TBW by a mean difference of 2.4 kg (limits of agreement of –4.1 kg to +8.9 kg). Body fat content was similar in the two groups, whether measured by skinfold anthropometry, whole-body densitometry or by ¹⁸O dilution. Resting energy expenditure (REE), calculated from indirect calorimetry, and total energy expenditure (TEE), calculated from the ratio of ²H to ¹⁸O elimination rate after drinking doubly labelled water, were also similar in the two groups. It is concluded that the patients with stable CCF in this study had normal ECV and TBW, and so excess body water did not account for their persistent symptoms.