New method of predicting dry weight using bioelectrical impedance analysis in haemodialysis patients.
OBJECTIVE
There were significant differences in the slopes of the ultrafiltration (UF) amount removed during haemodialysis (HD) sessions versus the percentage change in the extracellular fluid/total body water ratio for the right lower extremity (ECF/TBW(right leg)) plot in normohydrated (NH) and overhydrated states. The purpose of this study was to develop and validate a method for predicting dry weight (DW) using these results.


METHODS
It was hypothesized that for patients to become NH, the slope of the UF amount versus the percentage changes in ECF/TBW(right leg) plot should be same as that of NH patients and a method for predicting DW was developed. To validate the accuracy of this method, the ECF/TBW(right leg) was measured by eight-point tactile-electrode bioelectrical impedance analysis before and after HD in 17 newly enrolled NH patients. Using the current DW (cDW) of subjects as a reference, we compared the accuracies of pDW1 (our devised method) and pDW2 (the normovolaemia/hypervolaemia slope method).


RESULTS
The mean cDW, pDW1 and pDW2 values were 56.8 +/- 7.9, 56.4 +/- 7.7 and 56.3 +/- 8.0 kg, respectively. No significant differences existed between cDW, pDW1 and pDW2. pDW1 had a lower root mean square error than pDW2 (1.12 vs 1.69). On the Bland-Altman plot, differences between pDW1 and cDW were closer to zero than between pDW2 and cDW.


CONCLUSIONS
A new method was developed of predicting the DW using the relationship between the UF amount and the percentage change in the ECF/TBW ratio of the lower extremities after HD. The devised method appears to be as accurate as the normovolaemia/hypervolaemia slope method.
Lee
Seoung Woo
SW
Division of Nephrology and Hypertension, Department of Internal Medicine, Kidney Disease Research Group, Inha University College of Medicine, Incheon, Korea.
Kim
Deok Young
DY
Lee
Seung Hee
SH
Cho
Hyung Chan
HC
Kwon
Su Hyun
SH
Song
Joon Ho
JH
Kim
Moon Jae
MJ
D000328:Adult; D000368:Aged; D001834:Body Water / Q000378:metabolism*; D001835:Body Weight; D017097:Electric Impedance; D045604:Extracellular Fluid / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D014462:Ultrafiltration