Comparison of fluid status in patients treated by different modalities of peritoneal dialysis using multi-frequency bioimpedance.
OBJECTIVE
Patients treated by peritoneal dialysis, especially those using automatic cyclers, are frequently found to be hypervolemic. To determine whether there are significant differences between the currently available modalities of peritoneal dialysis, we analyzed whether differences in transporter status and treatment modality had a discernible effect on extracellular fluid volumes as measured by multi-frequency bioimpedance.


METHODS
Two hundred prevalent peritoneal dialysis patients, 48% male, mean age 54.9 yr (SD+/-15.6), were studied using multi-frequency bioimpedance following a standard peritoneal equilibration test; 63 patients were treated by CAPD, 29 by APD, 96 by CCPD and 12 by OCCPD.


RESULTS
There were no differences in extracellular volumes, or extracellular volume adjusted for height, or as a ratio to total body water between the groups. As expected, extracellular volume adjusted for height depended upon bodyweight (r=0.412, p<0.001), sex (r=0.457, p<0.001) and systolic blood pressure (r=0.162, p=0.023), and extracellular volume to total body water related to the reciprocal of total daily peritoneal ultrafiltration losses (r=-0.0254, p=0.003) and urine output (-0.254, p=0.003). More importantly, on logistical regression analysis the ratio of extracellular fluid to total body fluid increased with falling albumin, F=21.5 p<0.001, increasing age, F=18.5 p<0.001, urine output F=6.46, p=0.014, total daily ultrafiltration, F=3.52 and protein intake p=0.003. Extracellular fluid adjusted for total body fluid was associated with CRP (males F=6.03, p=0.03, females F=4.438, p=0.04).


CONCLUSIONS
Patients were more likely to have an expanded extracellular fluid volume if they had reduced daily fluid losses, but also with biomarkers typically associated with poor nutrition and inflammation.
Davenport
Andrew
A
University College London Center for Nephrology, University College Medical School, London - UK. Andrew.davenport@royalfree.nhs.uk
Willicombe
Michelle
M
D000328:Adult; D000367:Age Factors; D000368:Aged; D001794:Blood Pressure; D001823:Body Composition; D001827:Body Height; D001835:Body Weight; D017097:Electric Impedance; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D010530:Peritoneal Dialysis / Q000009:adverse effects / Q000379:methods*; D012307:Risk Factors; D012737:Sex Factors; D014554:Urination; D014882:Water-Electrolyte Balance; D014883:Water-Electrolyte Imbalance / Q000209:etiology* / Q000503:physiopathology
D018836:Inflammation Mediators