Absolute blood volume variations and vascular refilling in hemodialysis patients

The imbalance between ultrafiltration volume (UF) and vascular refilling is considered a major cause for intradialytic hypotension. Recent studies report a noninvasive method to estimate vascular refilling (VREF) by determining absolute blood volume (ABV). It was the aim of the study to analyze variations in ABV in a group of hemodialysis (HD) patients and examine VREF. Thirty one stable chronic HD patients were studied, aged 71.07 ± 13.31 years. Dialysis duration and UF requirements were based on physician prescription. VREF was calculated as: VREF = VUF − ΔV where ΔV is ABV variation during dialysis treatment. ABV at the beginning of the dialysis was 6.00 ± 2.39 L (92.82 ± 33.17 ml/kg) and at the end 5.38 ± 2.32 L (82.07 ± 31.41 ml/kg). Prescribed UF was 2.64 ± 0.83 L. Mean VREF was 2.05 ± 0.80 L, with a refilling fraction of 75.75 ± 12.79%. VREF was strongly correlated with UF volume (r2 0.877), and with pre‐dialysis volume overload (r2 0.617). Patients under beta‐blocker treatment showed significantly lower FREF. ABV measurement is an easy and noninvasive method that allows us to study VREF during HD. We found a strong correlation between VREF and UF.