Acid-Base Balance Determination on Ultrafiltrate in Two-Chamber Technique Hemodiafiltration (PFD)

Abstract

Correction of the acid-base balance in uremic patients during hemodiafiltration (HFD) may be biased by an inadequate monitoring of phi and blood gases. HDF performed with the two-chamber technique (PFD) generates pure ultrafiltrate (uf) unmixed with dialysate. We carried out 84 determinations of HCO⁻₃ levels in 15 different PFD patients by measuring the pH and pCO₂ of the uf, then correlated the values with those simultaneously evaluated on arterial blood with standard methods. The mean HCO⁻₃ levels (mmol/L) were 23.21±2.49 in blood samples and 25.54±3.07 in uf, with a mean difference of -2.33±1.46. Statistical analysis gave: t=13.5 (p=O) (one-sample analysis), r=0.86 (p=0) (linear regression analysis) and a good agreement between the two clinical measurements (81 out of 84 data points fell within the 95% confidence interval) (Bland-Altman analysis). In conclusion, we suggest that during HDF performed with the two-chamber technique, the patient's HCO⁻₃ level can be monitored on the uf without blood sampling.

Keywords

Hemodialysis PFD (paired filtration dialysis)Acid-base balance Acid-base monitoring

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