Usefulness of segmental bioimpedance ratio to determine dry body weight in new hemodialysis patients: a pilot study.

BACKGROUND

The ratio of bioimpedance in the right leg (rl-RBI) may be helpful in adjusting dry body weight (DBW) in new hemodialysis (HD) patients.

METHODS

rl-RBI was calculated as follows: rl-RBI = impedance at 50 kHz/impedance at 500 kHz, as measured by bioimpedance spectroscopy (BIS). Theoretically, rl-RBI is inversely related to extracellular water. A reference range of rl-RBI was obtained from 137 chronic but stable HD patients already achieving DBW. In 34 new HD patients (females:males = 16:18; age 49 +/- 12 years), DBW(s) were stepwise adjusted under the guidance of rl-RBI by modifying the amount of ultrafiltration.

RESULTS

The target range of rl-RBI was defined as 1.106-1.150. rl-RBI before the first HD was 1.115 +/- 0.027. At the study endpoint, when the target range of rl-RBI was achieved, pretibial pitting edema and pulmonary edema were resolved without any episode of muscle cramping or intradialytic hypotension. Along with an increase in rl-RBI, pre-HD blood pressure tended to decrease at systole (p = 0.072) and diastole (p = 0.005). The cardiothoracic ratio also decreased significantly (p = 0.004).

CONCLUSION

The measurement of rl-RBI by BIS is worthy of further evaluation as an objective and applicable index for determining DBW in new HD patients.