Multi-frequency bioelectric impedance measurements for predicting body water compartments in patients with non-ascitic liver cirrhosis

Abstract

We assessed total body water (TBW) and extracellular water (ECW) in thirty-four non-ascitic cirrhotics and twenty healthy controls by *H,O and Br dilution. In the same subjects, bioelectric impedance (BI) was recorded at multiple frequencies. Body hydration was similar for controls (mean 55.6 (SD 67)), lesssevere cirrhotics (Child-Pugh classification A; CPA; n 21, mean 56.2 (SD 6.2)) and moderately-severe cirrhotics (Child-Pugh classification B; CPB; n 13, mean 57.2 (SD 5.4)). However, intracellular water standardized per litre TBW was significantly higher in CPB subjects (mean 27.0 (SD 7-5); P c 0.01) compared with CPA (mean 21.3 (SD 10.6)) and control subjects (mean 18.0 (SD 9%)). Published formulas for predicting TBW and ECW from BI at multiple frequencies were applied to the cirrhotics. These formulas gave accurate predictions of TBW and ECW, although standard errors of estimates were higher for CPB subjects (TBW < 2 5 and ECW < 2-1 1) than those for CPA (TBW < 2-0 and ECW < 1.8 I) and control (TBW 1.4 and ECW 0.9 1) subjects.Liver cirrhosis: Total body water: Extracellular water: Bioelectric impedance Assessment of body water compartments is of great clinical interest. Body hydration and extracellular water (ECW) : intracellular water (ICW) ratio are known to change with nutritional status and under a variety of disease conditions. Malnourished patients often exhibit an increase in ECW relative to total body water (TBW; Rose 1994b). Nonetheless, obese subjects often show an increase in ECW relative to TBW, the pathophysiological basis of which is currently under investigation (Waki et al. 1991 ;Battistini et al. 1995). In addition to under-and overweight states, it has been shown that an increase in ECW relative to TBW may occur also in highly-trained athletes (Battistini et al. 1994). Thus, body-water distribution appears to be significantly linked to nutritional status in both physiological and clinical conditions.Measurements of TBW and ECW involve the use of invasive and time-consuming tracerdilution techniques and, therefore, are not suitable for use in clinical practice. Multifrequency bioelectric impedance analysis (MFBIA) is a novel technique for the assessment of TBW and ECW (van Marken Lichtenbelt et al. 1994). MFBIA has many advantages over dilution methods in that it is safe, inexpensive, portable and requires minimal training of the operator. Thus, MFBIA has a great potential to be employed as a 'bedside' technique for assessing body water volumes in ill subjects.

The prediction of total body water and extracellular water from bioelectric impedance in obese children

“…Our obese children had a lower TBW% and an higher ECW% as compared to controls and ZI allowed a reasonably good prediction of TBW but not of ECW on the pooled sample. Our study con®rms therefore that BIA is sensitive to changes in body water distribution and that it offers a more accurate prediction of ECW in groups with the lower variability in ECW% (Borghi et al, 1996). It should nonetheless be noted that all of the given equations need to be validated on external samples of children before being employed in clinical practice.…”

Value of the extracellular water ratio for assessment of cirrhotic patients with and without ascites

“…Previous studies of animals and healthy humans indicated that measurements of body water using multiple‐frequency BIA are reliable 10 . However, reports of the use of multiple‐frequency BIA for the assessment of body water compartments in cirrhotic patients with ascites are limited 24 . Lehnert et al .…”

“…10 However, reports of the use of multiple-frequency BIA for the assessment of body water compartments in cirrhotic patients with ascites are limited. 24 Lehnert et al found that ECW and TBW (as determined by isotope methods) were predicted accurately by multiplefrequency BIA (r = 0.73 and 0.89, respectively). 13 However, they noted that the 95% confidence interval for the limits of agreement between the multiplefrequency BIA and isotope methods was acceptable for the control group (1 5%) but was slightly higher for the cirrhotic group (1 9%).…”

The Validity of Bioelectrical Impedance Models in Clinical Populations

“…Because there is potential for between-subject variation in these factors, this model does not accurately predict TBW in altered fluid balance. 9 Eleven validation studies using discrete multifrequency BIA to predict TBW or ECW have been published in various clinical populations including growth-hormone deficiency, 62 Duchenne muscular dystrophy, 63 spinal cord injury, 64 the elderly, 43,[65][66][67] healthy Ethiopians, 68 nonascitic cirrhotics, 69 healthy subjects given diuretics, 70 and children with juvenile rheumatoid arthritis. 71 The results are so variable that no conclusions can be made regarding the validity of one frequency over another in the prediction of body fluid compartments.…”