Abstract
♦ Objective
This study was carried out to evaluate a procedure for converting bioimpedance spectroscopy (BIS) data to a clinically useful measure of fluid status that is easily interpreted by nursing staff and patients.
♦ Design
The ratio of extracellular water (ECW) to total body water (TBW) in a cohort of peritoneal dialysis (PD) patients was compared with the distribution for normal control subjects. The result was expressed as the difference between the measured ECW/TBW ratio and the mean ratio for age- and sex-matched controls divided by the standard deviation for the controls (the “hydration score”). Where possible, interventions were made to reduce the target weight in patients with a hydration score greater than +2.0.
♦ Setting
This clinical study was carried out in the nurseled outpatient PD unit at St. James's University Hospital. BIS measurements were carried out during routine clinic visits. The data for the control subjects were obtained in a range of settings in the UK and the Czech Republic.
♦ Patients
31 PD patients (21 M, 10 F; aged 19 – 78 years) who came to the PD unit for routine procedures during the study participated.
♦ Results
The mean hydration score for PD patients was significantly higher than for the control subjects (+1.3 vs 0.0, p < 0.0001). 11 (35%) patients had a hydration score greater than +2.0, compared with only 2.5% of the controls; systolic blood pressure was greater than 130 mmHg in only two of these patients. After a 3-month follow-up, a weight reduction of 3.6 ± 2.3 kg had been achieved in 7 patients through modality change and implementation of prescription changes, with no adverse effects.
♦ Conclusions
Although this was a small study, all the data collected indicated that the hydration score provides a reliable indication of fluid status in PD patients. BIS measurements are now carried out at 6-month intervals and are used to monitor the effect of interventions.
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