Changing the paradigm of bicarbonate (HCO3−) hemodialysis prescription in Portugal: a 24-month prospective study

Abstract

Background Metabolic acidosis is common in hemodialysis (HD) patients. The KDOQI guidelines therapeutic goal is pre-dialysis HCO3− ≥ 22 mmol/L. The aim of the study was to evaluate an individualized HCO3− hemodialysis prescription as a preventing factor of metabolic changes. Methods Twenty-four-month prospective study of patients on online high-flux hemodiafiltration. Every 3 months, HCO3− blood levels were analyzed and hemodialysis HCO3− was changed using the following rules: HCO3− > 30 mmol/L: reduce 4 mmol/L HCO3− HCO3− ≥ 25 mmol/L: reduce 2 mmol/L HCO3− 20 mmol/L < HCO3− < 25 mmol/L: no change HCO3− ≤ 20 mmol/L: increase 2 mmol/L HCO3− HCO3− < 18 mmol/L: increase 4 mmol/L HCO3− Data collected comprised demographic information, renal disease etiology, comorbidities, HD treatment information, and lab results. Statistical analysis was performed using SPSS. Results Thirty-one patients were enrolled and completed the follow-up period. At baseline, average serum pH was 7.38 ± 0.06, serum HCO3− 25.92 ± 1.82 mmol/L, and every patient had a 32 mmol/L dialytic HCO3− prescription. At time point 9, average serum HCO3− was 23.87 ± 1.93 mmol/L and 58% of the patients had a dialytic HCO3− prescription of 28 mmol/L. Serum HCO3− differed with statistical significance during time and approached the reference serum HCO3− (23 mmol/L) that we have defined as ideal. Through time, the HCO3− prescription deviated more from the 32 mmol/L initial prescription that was defined as standard. Conclusions Our findings suggest that the standard HCO3− prescription of 32 mmol/L should be rethought, as an individualized HCO3− prescription could be beneficial for the patient.

Tailoring the dialysate bicarbonate eliminates pre-dialysis acidosis and post-dialysis alkalosis

“…Observational evidence shows a U-shaped correlation between pre-dialysis plasma bicarbonate levels and adverse effects such as haemodynamic instability [ 9 ] and all-cause mortality with both metabolic acidosis and alkalosis [ 5 , 10 ]. Despite there not being high-quality evidence determining which are the optimal pre- and post-dialysis bicarbonate values that physicians should target in this population [ 11 ] and the lack of consensus on this subject across guidelines [ 2 ], the latest Kidney Disease: Improving Global Outcomes recommendation is to target a pre-dialysis plasma bicarbonate level ˃22 mEq/L [ 12–15 ]. This recommendation has led to bicarbonate overshooting, increasing the number of patients with metabolic alkalosis, which has been associated with increased mortality in cases with pre-dialysis bicarbonate levels ˃27 mEq/L [ 5 , 16–18 ].…”