Impact of convective flow on phosphorus removal in maintenance hemodialysis patients.
OBJECTIVE
Hyperphosphatemia leads to increased risk of death in maintenance hemodialysis patients (MHD). This study investigated phosphorus (P) removal, P reduction rate (PRR), and P rebound, comparing on-line, high-volume hemodiafiltration in postdilution (HDF) and high-flux hemodialysis (HD) in a setting of an equal amount of produced dialysate solution in both modalities.


METHODS
A total of 22 MHD patients, treated with regular 3 x 4 hours HDF weekly, were randomly dialyzed with one 4-hour session of HDF and of HD. In both modalities, an equal amount of produced dialysate solution of 800 mL/minute was used. The only variable was the fact that in HDF, 100 mL/min of this produced dialysate solution was used as replacement fluid. The other parameters were kept identical: blood flow rate, 350 mL/min; high-flux polysulfone F80 dialyzer; and 4800 E monitor, (Fresenius, Bad Homburg, Germany). The P removal was measured in total spent dialysate and ultrafiltrate volumes. Statistical analyses were done with the paired t-test.


RESULTS
The mean total P removed with HDF was 1159 +/- 296 mg, and 972 +/- 312 mg with HD (P < .001), ie, 19% higher in HDF; PRR was significantly higher in HDF (63.3%) versus HD (58.6%) (P = .014). The mean serum P did not differ: 5.3 mg/dL in HDF and 5.2 mg/dL in HD. There was a linear correlation between serum P and P removal. With a serum P level up to 5 to 5.5 mg/dL, HDF achieved a higher P removal compared with HD. The difference gradually decreased as the serum P value increased. Above 7 mg/dL, no difference in total P removal was observed. There was a high but equal rebound percentage at 60 minutes in HDF (42%) and HD (39%) (P = .42). With HDF, no predialysis metabolic acidosis was noted.


CONCLUSIONS
Treatment with on-line HDF in postdilution resulted in a higher P removal and higher PRR compared with HD. The long-term implementation of this modality may result in a more optimal serum P control, without an increase in the number of or lengthening of the dialysis sessions.
Lornoy
Willy
W
Department of Nephrology, Dialysis and Hypertension, Onze Lieve Vrouwziekenhuis, Aalst, Belgium. willy.lornoy.med@pandora.be
De Meester
Johan
J
Becaus
Ignace
I
Billiouw
Jean-Marie
JM
Van Malderen
Paul A
PA
Van Pottelberge
Mia
M
D000536:Aluminum Hydroxide / Q000008:administration & dosage; D001639:Bicarbonates / Q000097:blood; D002118:Calcium / Q000097:blood; D002119:Calcium Carbonate / Q000008:administration & dosage; D015314:Dialysis Solutions / Q000032:analysis; D005260:Female; D006801:Humans; D007811:Lanthanum / Q000008:administration & dosage; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000009:adverse effects / Q000097:blood; D010758:Phosphorus / Q000009:adverse effects / Q000032:analysis* / Q000097:blood*; D016226:Phosphorus, Dietary / Q000008:administration & dosage; D011446:Prospective Studies; D006435:Renal Dialysis / Q000379:methods*; D012709:Serum Albumin / Q000032:analysis
D001639:Bicarbonates; D015314:Dialysis Solutions; D010710:Phosphates; D016226:Phosphorus, Dietary; D012709:Serum Albumin; D010758:Phosphorus; D000536:Aluminum Hydroxide; D007811:Lanthanum; D002119:Calcium Carbonate; D002118:Calcium