The impact of reducing dialysate flows during haemodiafiltration and haemodialysis sessions

Although haemodialysis (HD) is an established treatment for kidney failure patients, HD treatments generate greenhouse gases. Hospitals in the United Kingdom have been tasked with reducing the environmental impact of HD. We reviewed the effect of reducing dialysate water usage.

Dialysate flows were reduced from 500 mL/min to dialysate/blood flow ratios of 1.5:1 for HD and 1.2:1 for haemodiafiltration (HDF) treatments in a single dialysis centre and the effects evaluated over 3 months.

One hundred ninety kidney failure dialysis patients; 65.8% male, 47.4% diabetic, dialysis vintage 48 (19-108) months, were switched to lower dialysate flows. The mean blood flow was 301 ± 16.3 mL/min, so by switching dialysate flows, the volume of dialysate water was reduced from 131 ± 19.4 to 100.7 ± 19.5 L/session, approximately 15 554.3 L/week, with a projected annual saving of 808 821 L of ultrapure quality water, and 1617 642 L accounting for water lost in the production of dialysate. There was no difference in sessional KtVurea (pre 1.18 ± 0.3, 1 month 1.20 ± 0.37, 3 months 1.16 ± 0.25) or serum β2 microglobulin (27.9 ± 6.6, 1 month 28.3 ± 7.5 and 3 months 28.2 ± 6.2 mg/L). Equally there were no differences in pre dialysis serum potassium, bicarbonate, or phosphate.

Reducing dialysate flows resulted in a major reduction in ultra-pure dialysis water usage and greenhouse gas emissions, with additional reductions in dialysate acid concentrate usage, and electricity without any adverse impact on small or middle molecular weight solute clearances. Extrapolating to a 30-station dialysis unit this would result in an annual reduction of around 9500 kg carbon dioxide equivalent emissions (CO2e) greenhouse gas.